Add VAVDA, the VAAPI Video Decode Accelerator for Intel CPUs.

content/common/gpu/media/vaapi_h264_decoder.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "vaapi_h264_decoder.h"
+
+#include <algorithm>
+#include <dlfcn.h>
+
+#include "base/bind.h"
+#include "base/stl_util.h"
+#include "third_party/libva/va/va.h"
+#include "third_party/libva/va/va_x11.h"
+#include "ui/gfx/gl/gl_bindings.h"
+
+#define VA_LOG_ON_ERROR(va_res, err_msg)                   \
+  do {                                                     \
+    if ((va_res) != VA_STATUS_SUCCESS) {                   \
+      DVLOG(1) << err_msg                                  \
+               << " VA error: " << VAAPI_ErrorStr(va_res); \
+    }                                                      \
+  } while(0)
+
+#define VA_SUCCESS_OR_RETURN(va_res, err_msg, ret)         \
+  do {                                                     \
+    if ((va_res) != VA_STATUS_SUCCESS) {                   \
+      DVLOG(1) << err_msg                                  \
+               << " VA error: " << VAAPI_ErrorStr(va_res); \
+      return (ret);                                        \
+    }                                                      \
+  } while (0)
+
+namespace content {
+
+void *vaapi_handle = dlopen("libva.so", RTLD_NOW);
+void *vaapi_x11_handle = dlopen("libva-x11.so", RTLD_NOW);
+void *vaapi_glx_handle = dlopen("libva-glx.so", RTLD_NOW);
+
+typedef VADisplay (*VaapiGetDisplayGLX)(Display *dpy);
+typedef int (*VaapiDisplayIsValid)(VADisplay dpy);
+typedef VAStatus (*VaapiInitialize)(VADisplay dpy,
+                                    int *major_version,
+                                    int *minor_version);
+typedef VAStatus (*VaapiTerminate)(VADisplay dpy);
+typedef VAStatus (*VaapiGetConfigAttributes)(VADisplay dpy,
+                                             VAProfile profile,
+                                             VAEntrypoint entrypoint,
+                                             VAConfigAttrib *attrib_list,
+                                             int num_attribs);
+typedef VAStatus (*VaapiCreateConfig)(VADisplay dpy,
+                                      VAProfile profile,
+                                      VAEntrypoint entrypoint,
+                                      VAConfigAttrib *attrib_list,
+                                      int num_attribs,
+                                      VAConfigID *config_id);
+typedef VAStatus (*VaapiDestroyConfig)(VADisplay dpy, VAConfigID config_id);
+typedef VAStatus (*VaapiCreateSurfaces)(VADisplay dpy,
+                                        int width,
+                                        int height,
+                                        int format,
+                                        int num_surfaces,
+                                        VASurfaceID *surfaces);
+typedef VAStatus (*VaapiDestroySurfaces)(VADisplay dpy,
+                                         VASurfaceID *surfaces,
+                                         int num_surfaces);
+typedef VAStatus (*VaapiCreateContext)(VADisplay dpy,
+                                       VAConfigID config_id,
+                                       int picture_width,
+                                       int picture_height,
+                                       int flag,
+                                       VASurfaceID *render_targets,
+                                       int num_render_targets,
+                                       VAContextID *context);
+typedef VAStatus (*VaapiDestroyContext)(VADisplay dpy, VAContextID context);
+typedef VAStatus (*VaapiPutSurface)(VADisplay dpy,
+                                    VASurfaceID surface,
+                                    Drawable draw,
+                                    short srcx,
+                                    short srcy,
+                                    unsigned short srcw,
+                                    unsigned short srch,
+                                    short destx,
+                                    short desty,
+                                    unsigned short destw,
+                                    unsigned short desth,
+                                    VARectangle *cliprects,
+                                    unsigned int number_cliprects,
+                                    unsigned int flags);
+typedef VAStatus (*VaapiSyncSurface)(VADisplay dpy, VASurfaceID render_target);
+typedef VAStatus (*VaapiBeginPicture)(VADisplay dpy,
+                                      VAContextID context,
+                                      VASurfaceID render_target);
+typedef VAStatus (*VaapiRenderPicture)(VADisplay dpy,
+                                       VAContextID context,
+                                       VABufferID *buffers,
+                                       int num_buffers);
+typedef VAStatus (*VaapiEndPicture)(VADisplay dpy, VAContextID context);
+typedef VAStatus (*VaapiCreateBuffer)(VADisplay dpy,
+                                      VAContextID context,
+                                      VABufferType type,
+                                      unsigned int size,
+                                      unsigned int num_elements,
+                                      void *data,
+                                      VABufferID *buf_id);
+typedef const char* (*VaapiErrorStr)(VAStatus error_status);
+
+#define VAAPI_DLSYM(name, handle)                                 \
+    Vaapi##name VAAPI_##name =                                    \
+        reinterpret_cast<Vaapi##name>(dlsym((handle), "va"#name))
+
+VAAPI_DLSYM(GetDisplayGLX, vaapi_glx_handle);
+VAAPI_DLSYM(DisplayIsValid, vaapi_handle);
+VAAPI_DLSYM(Initialize, vaapi_handle);
+VAAPI_DLSYM(Terminate, vaapi_handle);
+VAAPI_DLSYM(GetConfigAttributes, vaapi_handle);
+VAAPI_DLSYM(CreateConfig, vaapi_handle);
+VAAPI_DLSYM(DestroyConfig, vaapi_handle);
+VAAPI_DLSYM(CreateSurfaces, vaapi_handle);
+VAAPI_DLSYM(DestroySurfaces, vaapi_handle);
+VAAPI_DLSYM(CreateContext, vaapi_handle);
+VAAPI_DLSYM(DestroyContext, vaapi_handle);
+VAAPI_DLSYM(PutSurface, vaapi_x11_handle);
+VAAPI_DLSYM(SyncSurface, vaapi_x11_handle);
+VAAPI_DLSYM(BeginPicture, vaapi_handle);
+VAAPI_DLSYM(RenderPicture, vaapi_handle);
+VAAPI_DLSYM(EndPicture, vaapi_handle);
+VAAPI_DLSYM(CreateBuffer, vaapi_handle);
+VAAPI_DLSYM(ErrorStr, vaapi_handle);
+
+static bool AreVaapiFunctionPointersInitialized() {
+  return VAAPI_GetDisplayGLX &&
+      VAAPI_DisplayIsValid &&
+      VAAPI_Initialize &&
+      VAAPI_Terminate &&
+      VAAPI_GetConfigAttributes &&
+      VAAPI_CreateConfig &&
+      VAAPI_DestroyConfig &&
+      VAAPI_CreateSurfaces &&
+      VAAPI_DestroySurfaces &&
+      VAAPI_CreateContext &&
+      VAAPI_DestroyContext &&
+      VAAPI_PutSurface &&
+      VAAPI_SyncSurface &&
+      VAAPI_BeginPicture &&
+      VAAPI_RenderPicture &&
+      VAAPI_EndPicture &&
+      VAAPI_CreateBuffer &&
+      VAAPI_ErrorStr;
+}
+
+class VaapiH264Decoder::DecodeSurface {
+ public:
+  DecodeSurface(const GLXFBConfig& fb_config,
+                Display* x_display,
+                VADisplay va_display,
+                VASurfaceID va_surface_id,
+                int32 picture_buffer_id,
+                uint32 texture_id,
+                int width, int height);
+  ~DecodeSurface();
+
+  VASurfaceID va_surface_id() {
+    return va_surface_id_;
+  }
+
+  int32 picture_buffer_id() {
+    return picture_buffer_id_;
+  }
+
+  uint32 texture_id() {
+    return texture_id_;
+  }
+
+  bool available() {
+    return available_;
+  }
+
+  int32 input_id() {
+    return input_id_;
+  }
+
+  int poc() {
+    return poc_;
+  }
+
+  Pixmap x_pixmap() {
+    return x_pixmap_;
+  }
+
+  // Associate the surface with |input_id| and |poc|, and make it unavailable
+  // (in use).
+  void Acquire(int32 input_id, int poc);
+
+  // Make this surface available, ready to be reused.
+  void Release();
+
+  // Has to be called before output to sync texture contents.
+  // Returns true if successful.
+  bool Sync();
+
+ private:
+  Display* x_display_;
+  VADisplay va_display_;
+  VASurfaceID va_surface_id_;
+
+  // Client-provided ids.
+  int32 input_id_;
+  int32 picture_buffer_id_;
+  uint32 texture_id_;
+
+  int width_;
+  int height_;
+
+  // Available for decoding (data no longer used for reference or output).
+  bool available_;
+
+  // PicOrderCount
+  int poc_;
+
+  // Pixmaps bound to this texture.
+  Pixmap x_pixmap_;
+  GLXPixmap glx_pixmap_;
+
+  DISALLOW_COPY_AND_ASSIGN(DecodeSurface);
+};
+
+VaapiH264Decoder::DecodeSurface::DecodeSurface(const GLXFBConfig& fb_config,
+                                               Display* x_display,
+                                               VADisplay va_display,
+                                               VASurfaceID va_surface_id,
+                                               int32 picture_buffer_id,
+                                               uint32 texture_id,
+                                               int width, int height)
+    : x_display_(x_display),
+      va_display_(va_display),
+      va_surface_id_(va_surface_id),
+      picture_buffer_id_(picture_buffer_id),
+      texture_id_(texture_id),
+      width_(width),
+      height_(height),
+      available_(false) {
+  // Bind the surface to a texture of the given width and height,
+  // allocating pixmaps as needed.
+  glEnable(GL_TEXTURE_2D);
+  glBindTexture(GL_TEXTURE_2D, texture_id_);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  XWindowAttributes win_attr;
+  int screen = DefaultScreen(x_display_);
+  XGetWindowAttributes(x_display_, RootWindow(x_display_, screen), &win_attr);
+  x_pixmap_ = XCreatePixmap(x_display_, RootWindow(x_display_, screen),
+                            width_, height_, win_attr.depth);
+  if (!x_pixmap_) {
+    DVLOG(1) << "Failed creating an X Pixmap for TFP";
+    return;
+  }
+
+  static const int pixmap_attr[] = {
+    GLX_TEXTURE_TARGET_EXT, GLX_TEXTURE_2D_EXT,
+    GLX_TEXTURE_FORMAT_EXT, GLX_TEXTURE_FORMAT_RGB_EXT,
+    GL_NONE,
+  };
+
+  glx_pixmap_ = glXCreatePixmap(x_display_, fb_config, x_pixmap_,
+                                pixmap_attr);
+
+  glBindTexture(GL_TEXTURE_2D, texture_id_);
+  glXBindTexImageEXT(x_display_, glx_pixmap_, GLX_FRONT_LEFT_EXT, NULL);
+
+  available_ = true;
+}
+
+VaapiH264Decoder::DecodeSurface::~DecodeSurface() {
+  // Unbind surface from texture and deallocate resources.
+  glXReleaseTexImageEXT(x_display_, glx_pixmap_, GLX_FRONT_LEFT_EXT);
+  glXDestroyGLXPixmap(x_display_, glx_pixmap_);
+  XFreePixmap(x_display_, x_pixmap_);
+}
+
+void VaapiH264Decoder::DecodeSurface::Acquire(int32 input_id, int poc) {
+  DCHECK_EQ(available_, true);
+  available_ = false;
+  input_id_ = input_id;
+  poc_ = poc;
+}
+
+void VaapiH264Decoder::DecodeSurface::Release() {
+  available_ = true;
+}
+
+bool VaapiH264Decoder::DecodeSurface::Sync() {
+  // Put the decoded data into XPixmap bound to the texture.
+  VAStatus va_res = VAAPI_PutSurface(va_display_,
+                                     va_surface_id_, x_pixmap_,
+                                     0, 0, width_, height_,
+                                     0, 0, width_, height_,
+                                     NULL, 0, 0);
+  VA_SUCCESS_OR_RETURN(va_res, "Failed putting decoded picture to texture",
+                       false);
+
+  // Wait for the data to be put into the buffer so it'd ready for output.
+  va_res = VAAPI_SyncSurface(va_display_, va_surface_id_);
+  VA_SUCCESS_OR_RETURN(va_res, "Failed syncing decoded picture", false);
+
+  return true;
+}
+
+VaapiH264Decoder::VaapiH264Decoder() {
+  Reset();
+  curr_sps_id_ = -1;
+  curr_pps_id_ = -1;
+  pic_width_ = -1;
+  pic_height_ = -1;
+  max_frame_num_ = 0;
+  max_pic_num_ = 0;
+  max_long_term_frame_idx_ = 0;
+  max_pic_order_cnt_lsb_ = 0;
+  state_ = kUninitialized;
+  num_available_decode_surfaces_ = 0;
+}
+
+VaapiH264Decoder::~VaapiH264Decoder() {
+  Destroy();
+}
+
+// This puts the decoder in state where it keeps stream data and is ready
+// to resume playback from a random location in the stream, but drops all
+// inputs and outputs and makes all surfaces available for use.
+void VaapiH264Decoder::Reset() {
+  frame_ready_at_hw_ = false;
+
+  curr_pic_.reset();
+
+  frame_num_ = 0;
+  prev_frame_num_ = -1;
+  prev_frame_num_offset_ = -1;
+
+  prev_ref_has_memmgmnt5_ = false;
+  prev_ref_top_field_order_cnt_ = -1;
+  prev_ref_pic_order_cnt_msb_ = -1;
+  prev_ref_pic_order_cnt_lsb_ = -1;
+  prev_ref_field_ = H264Picture::FIELD_NONE;
+
+  pending_slice_bufs_ = std::queue<VABufferID>();
+  pending_va_bufs_ = std::queue<VABufferID>();
+
+  ref_pic_list0_.clear();
+  ref_pic_list1_.clear();
+
+  for (POCToDecodeSurfaces::iterator it = poc_to_decode_surfaces_.begin();
+       it != poc_to_decode_surfaces_.end(); ) {
+    int poc = it->second->poc();
+    // Must be incremented before UnassignSurfaceFromPoC as this call
+    // invalidates |it|.
+    ++it;
+    DecodeSurface *dec_surface = UnassignSurfaceFromPoC(poc);
+    if (dec_surface) {
+      dec_surface->Release();
+      ++num_available_decode_surfaces_;
+    }
+  }
+  DCHECK(poc_to_decode_surfaces_.empty());
+
+  dpb_.Clear();
+  parser_.Reset();
+
+  // Still initialized and ready to decode, unless called from constructor,
+  // which will change it back.
+  state_ = kAfterReset;
+}
+
+void VaapiH264Decoder::Destroy() {
+  VAStatus va_res;
+
+  if (state_ == kUninitialized)
+    return;
+
+  switch (state_) {
+    case kDecoding:
+    case kAfterReset:
+    case kError:
+      DestroyVASurfaces();
+      // fallthrough
+    case kInitialized:
+      va_res = VAAPI_DestroyConfig(va_display_, va_config_id_);
+      VA_LOG_ON_ERROR(va_res, "vaDestroyConfig failed");
+      va_res = VAAPI_Terminate(va_display_);
+      VA_LOG_ON_ERROR(va_res, "vaTerminate failed");
+      // fallthrough
+    case kUninitialized:
+      break;
+  }
+
+  state_ = kUninitialized;
+}
+
+// Maps Profile enum values to VaProfile values.
+bool VaapiH264Decoder::SetProfile(media::VideoCodecProfile profile) {
+  switch (profile) {
+    case media::H264PROFILE_BASELINE:
+      profile_ = VAProfileH264Baseline;
+      break;
+    case media::H264PROFILE_MAIN:
+      profile_ = VAProfileH264Main;
+      break;
+    case media::H264PROFILE_HIGH:
+      profile_ = VAProfileH264High;
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+
+class ScopedPtrXFree {
+ public:
+  void operator()(void* x) const {
+    ::XFree(x);
+  }
+};
+
+bool VaapiH264Decoder::InitializeFBConfig() {
+  const int fbconfig_attr[] = {
+    GLX_DRAWABLE_TYPE, GLX_PIXMAP_BIT,
+    GLX_BIND_TO_TEXTURE_TARGETS_EXT, GLX_TEXTURE_2D_BIT_EXT,
+    GLX_BIND_TO_TEXTURE_RGB_EXT, GL_TRUE,
+    GLX_Y_INVERTED_EXT, GL_TRUE,
+    GL_NONE,
+  };
+
+  int num_fbconfigs;
+  scoped_ptr_malloc<GLXFBConfig, ScopedPtrXFree> glx_fb_configs(
+      glXChooseFBConfig(x_display_, DefaultScreen(x_display_), fbconfig_attr,
+                        &num_fbconfigs));
+  if (!glx_fb_configs.get())
+    return false;
+  if (!num_fbconfigs)
+    return false;
+
+  fb_config_ = glx_fb_configs.get()[0];
+  return true;
+}
+
+bool VaapiH264Decoder::Initialize(media::VideoCodecProfile profile,
+                                  Display* x_display,
+                                  GLXContext glx_context,
+                                  const OutputPicCB& output_pic_cb) {
+  DCHECK_EQ(state_, kUninitialized);
+
+  output_pic_cb_ = output_pic_cb;
+
+  x_display_ = x_display;
+  parent_glx_context_ = glx_context;
+
+  if (!SetProfile(profile)) {
+    DVLOG(1) << "Unsupported profile";
+    return false;
+  }
+
+  if (!AreVaapiFunctionPointersInitialized()) {
+    DVLOG(1) << "Could not load libva";
+    return false;
+  }
+
+  if (!InitializeFBConfig()) {
+    DVLOG(1) << "Could not get a usable FBConfig";
+    return false;
+  }
+
+  va_display_ = VAAPI_GetDisplayGLX(x_display_);
+  if (!VAAPI_DisplayIsValid(va_display_)) {
+    DVLOG(1) << "Could not get a valid VA display";
+    return false;
+  }
+
+  int major_version, minor_version;
+  VAStatus va_res;
+  va_res = VAAPI_Initialize(va_display_, &major_version, &minor_version);
+  VA_SUCCESS_OR_RETURN(va_res, "vaInitialize failed", false);
+  DVLOG(1) << "VAAPI version: " << major_version << "." << minor_version;
+
+  VAConfigAttrib attrib;
+  attrib.type = VAConfigAttribRTFormat;
+
+  VAEntrypoint entrypoint = VAEntrypointVLD;
+  va_res = VAAPI_GetConfigAttributes(va_display_, profile_, entrypoint,
+                                     &attrib, 1);
+  VA_SUCCESS_OR_RETURN(va_res, "vaGetConfigAttributes failed", false);
+
+  if (!(attrib.value & VA_RT_FORMAT_YUV420)) {
+    DVLOG(1) << "YUV420 not supported";
+    return false;
+  }
+
+  va_res = VAAPI_CreateConfig(va_display_, profile_, entrypoint,
+                              &attrib, 1, &va_config_id_);
+  VA_SUCCESS_OR_RETURN(va_res, "vaCreateConfig failed", false);
+
+  state_ = kInitialized;
+  return true;
+}
+
+void VaapiH264Decoder::ReusePictureBuffer(int32 picture_buffer_id) {
+  DecodeSurfaces::iterator it = decode_surfaces_.find(picture_buffer_id);
+  if (it == decode_surfaces_.end() || it->second->available()) {
+    DVLOG(1) << "Asked to reuse an invalid/already available surface";
+    return;
+  }
+  it->second->Release();
+  ++num_available_decode_surfaces_;
+}
+
+bool VaapiH264Decoder::AssignPictureBuffer(int32 picture_buffer_id,
+                                           uint32 texture_id) {
+  DCHECK_EQ(state_, kDecoding);
+
+  if (decode_surfaces_.size() >= GetRequiredNumOfPictures()) {
+    DVLOG(1) << "Got more surfaces than required";
+    return false;
+  }
+
+  // This will not work if we start using VDA.DismissPicture()
+  linked_ptr<DecodeSurface> dec_surface(new DecodeSurface(
+      fb_config_, x_display_, va_display_,
+      va_surface_ids_[decode_surfaces_.size()], picture_buffer_id, texture_id,
+      pic_width_, pic_height_));
+  if (!dec_surface->available()) {
+    DVLOG(1) << "Error creating a decoding surface (binding to texture?)";
+    return false;
+  }
+
+  DVLOG(2) << "New picture assigned, texture id: " << dec_surface->texture_id()
+           << " pic buf id: " << dec_surface->picture_buffer_id()
+           << " will use va surface " << dec_surface->va_surface_id();
+
+  bool inserted = decode_surfaces_.insert(std::make_pair(picture_buffer_id,
+                                                         dec_surface)).second;
+  DCHECK(inserted);
+  ++num_available_decode_surfaces_;
+
+  return true;
+}
+
+bool VaapiH264Decoder::CreateVASurfaces() {
+  DCHECK_NE(pic_width_, -1);
+  DCHECK_NE(pic_height_, -1);
+  DCHECK_EQ(state_, kInitialized);
+
+  // Allocate VASurfaces in driver.
+  VAStatus va_res = VAAPI_CreateSurfaces(va_display_, pic_width_,
+                                         pic_height_, VA_RT_FORMAT_YUV420,
+                                         GetRequiredNumOfPictures(),
+                                         va_surface_ids_);
+  VA_SUCCESS_OR_RETURN(va_res, "vaCreateSurfaces failed", false);
+
+  DCHECK(decode_surfaces_.empty());
+
+  // And create a context associated with them.
+  va_res = VAAPI_CreateContext(va_display_, va_config_id_,
+                               pic_width_, pic_height_, VA_PROGRESSIVE,
+                               va_surface_ids_, GetRequiredNumOfPictures(),
+                               &va_context_id_);
+  VA_SUCCESS_OR_RETURN(va_res, "vaCreateContext failed", false);
+
+  return true;
+}
+
+void VaapiH264Decoder::DestroyVASurfaces() {
+  DCHECK(state_ == kDecoding || state_ == kError || state_ == kAfterReset);
+
+  decode_surfaces_.clear();
+
+  VAStatus va_res = VAAPI_DestroyContext(va_display_, va_context_id_);
+  VA_LOG_ON_ERROR(va_res, "vaDestroyContext failed");
+
+  va_res = VAAPI_DestroySurfaces(va_display_, va_surface_ids_,
+                                 GetRequiredNumOfPictures());
+  VA_LOG_ON_ERROR(va_res, "vaDestroySurfaces failed");
+}
+
+// Fill |va_pic| with default/neutral values.
+static void InitVAPicture(VAPictureH264* va_pic) {
+  memset(va_pic, 0, sizeof(*va_pic));
+  va_pic->picture_id = VA_INVALID_ID;
+  va_pic->flags = VA_PICTURE_H264_INVALID;
+}
+
+void VaapiH264Decoder::FillVAPicture(VAPictureH264 *va_pic, H264Picture* pic) {
+  POCToDecodeSurfaces::iterator iter = poc_to_decode_surfaces_.find(
+      pic->pic_order_cnt);
+  if (iter == poc_to_decode_surfaces_.end()) {
+    DVLOG(1) << "Could not find surface with POC: " << pic->pic_order_cnt;
+    // Cannot provide a ref picture, will corrupt output, but may be able
+    // to recover.
+    InitVAPicture(va_pic);
+    return;
+  }
+
+  va_pic->picture_id = iter->second->va_surface_id();
+  va_pic->frame_idx = pic->frame_num;
+  va_pic->flags = 0;
+
+  switch (pic->field) {
+    case H264Picture::FIELD_NONE:
+      break;
+    case H264Picture::FIELD_TOP:
+      va_pic->flags |= VA_PICTURE_H264_TOP_FIELD;
+      break;
+    case H264Picture::FIELD_BOTTOM:
+      va_pic->flags |= VA_PICTURE_H264_BOTTOM_FIELD;
+      break;
+  }
+
+  if (pic->ref) {
+    va_pic->flags |= pic->long_term ? VA_PICTURE_H264_LONG_TERM_REFERENCE
+                                    : VA_PICTURE_H264_SHORT_TERM_REFERENCE;
+  }
+
+  va_pic->TopFieldOrderCnt = pic->top_field_order_cnt;
+  va_pic->BottomFieldOrderCnt = pic->bottom_field_order_cnt;
+}
+
+int VaapiH264Decoder::FillVARefFramesFromDPB(VAPictureH264 *va_pics,
+                                             int num_pics) {
+  H264DPB::Pictures::reverse_iterator rit;
+  int i;
+
+  // Return reference frames in reverse order of insertion.
+  // Libva does not document this, but other implementations (e.g. mplayer)
+  // do it this way as well.
+  for (rit = dpb_.rbegin(), i = 0; rit != dpb_.rend() && i < num_pics; ++rit) {
+    if ((*rit)->ref)
+      FillVAPicture(&va_pics[i++], *rit);
+  }
+
+  return i;
+}
+
+// Can only be called when all surfaces are already bound
+// to textures (cannot be run at the same time as AssignPictureBuffer).
+bool VaapiH264Decoder::AssignSurfaceToPoC(int poc) {
+  // Find a surface not currently holding data used for reference and/or
+  // to be displayed and mark it as used.
+  DecodeSurfaces::iterator iter = decode_surfaces_.begin();
+  for (; iter != decode_surfaces_.end(); ++iter) {
+    if (iter->second->available()) {
+      --num_available_decode_surfaces_;
+      DCHECK_GE(num_available_decode_surfaces_, 0);
+
+      // Associate with input id and poc and mark as unavailable.
+      iter->second->Acquire(curr_input_id_, poc);
+      DVLOG(4) << "Will use surface " << iter->second->va_surface_id()
+               << " for POC " << iter->second->poc()
+               << " input ID: " << iter->second->input_id();
+      bool inserted = poc_to_decode_surfaces_.insert(std::make_pair(poc,
+          iter->second.get())).second;
+      DCHECK(inserted);
+      return true;
+    }
+  }
+
+  // Could not find an available surface.
+  return false;
+}
+
+// Can only be called when all surfaces are already bound
+// to textures (cannot be run at the same time as AssignPictureBuffer).
+VaapiH264Decoder::DecodeSurface* VaapiH264Decoder::UnassignSurfaceFromPoC(
+    int poc) {
+  DecodeSurface* dec_surface;
+  POCToDecodeSurfaces::iterator it = poc_to_decode_surfaces_.find(poc);
+  if (it == poc_to_decode_surfaces_.end()) {
+    DVLOG(1) << "Asked to unassign an unassigned POC";
+    return NULL;
+  }
+  dec_surface = it->second;
+  DVLOG(4) << "POC " << poc << " no longer using surface "
+           << dec_surface->va_surface_id();
+  poc_to_decode_surfaces_.erase(it);
+  return dec_surface;
+}
+
+// Fill a VAPictureParameterBufferH264 to be later sent to the HW decoder.
+bool VaapiH264Decoder::SendPPS() {
+  const H264PPS* pps = parser_.GetPPS(curr_pps_id_);
+  DCHECK(pps);
+
+  const H264SPS* sps = parser_.GetSPS(pps->seq_parameter_set_id);
+  DCHECK(sps);
+
+  DCHECK(curr_pic_.get());
+
+  VAPictureParameterBufferH264 pic_param;
+  memset(&pic_param, 0, sizeof(VAPictureParameterBufferH264));
+
+#define FROM_SPS_TO_PP(a) pic_param.a = sps->a;
+#define FROM_SPS_TO_PP2(a, b) pic_param.b = sps->a;
+  FROM_SPS_TO_PP2(pic_width_in_mbs_minus1, picture_width_in_mbs_minus1);
+  // This assumes non-interlaced video
+  FROM_SPS_TO_PP2(pic_height_in_map_units_minus1,
+                  picture_height_in_mbs_minus1);
+  FROM_SPS_TO_PP(bit_depth_luma_minus8);
+  FROM_SPS_TO_PP(bit_depth_chroma_minus8);
+#undef FROM_SPS_TO_PP
+#undef FROM_SPS_TO_PP2
+
+#define FROM_SPS_TO_PP_SF(a) pic_param.seq_fields.bits.a = sps->a;
+#define FROM_SPS_TO_PP_SF2(a, b) pic_param.seq_fields.bits.b = sps->a;
+  FROM_SPS_TO_PP_SF(chroma_format_idc);
+  FROM_SPS_TO_PP_SF2(separate_colour_plane_flag,
+                     residual_colour_transform_flag);
+  FROM_SPS_TO_PP_SF(gaps_in_frame_num_value_allowed_flag);
+  FROM_SPS_TO_PP_SF(frame_mbs_only_flag);
+  FROM_SPS_TO_PP_SF(mb_adaptive_frame_field_flag);
+  FROM_SPS_TO_PP_SF(direct_8x8_inference_flag);
+  pic_param.seq_fields.bits.MinLumaBiPredSize8x8 = (sps->level_idc >= 31);
+  FROM_SPS_TO_PP_SF(log2_max_frame_num_minus4);
+  FROM_SPS_TO_PP_SF(pic_order_cnt_type);
+  FROM_SPS_TO_PP_SF(log2_max_pic_order_cnt_lsb_minus4);
+  FROM_SPS_TO_PP_SF(delta_pic_order_always_zero_flag);
+#undef FROM_SPS_TO_PP_SF
+#undef FROM_SPS_TO_PP_SF2
+
+#define FROM_PPS_TO_PP(a) pic_param.a = pps->a;
+  FROM_PPS_TO_PP(num_slice_groups_minus1);
+  pic_param.slice_group_map_type = 0;
+  pic_param.slice_group_change_rate_minus1 = 0;
+  FROM_PPS_TO_PP(pic_init_qp_minus26);
+  FROM_PPS_TO_PP(pic_init_qs_minus26);
+  FROM_PPS_TO_PP(chroma_qp_index_offset);
+  FROM_PPS_TO_PP(second_chroma_qp_index_offset);
+#undef FROM_PPS_TO_PP
+
+#define FROM_PPS_TO_PP_PF(a) pic_param.pic_fields.bits.a = pps->a;
+#define FROM_PPS_TO_PP_PF2(a, b) pic_param.pic_fields.bits.b = pps->a;
+  FROM_PPS_TO_PP_PF(entropy_coding_mode_flag);
+  FROM_PPS_TO_PP_PF(weighted_pred_flag);
+  FROM_PPS_TO_PP_PF(weighted_bipred_idc);
+  FROM_PPS_TO_PP_PF(transform_8x8_mode_flag);
+
+  pic_param.pic_fields.bits.field_pic_flag = 0;
+  FROM_PPS_TO_PP_PF(constrained_intra_pred_flag);
+  FROM_PPS_TO_PP_PF2(bottom_field_pic_order_in_frame_present_flag,
+                pic_order_present_flag);
+  FROM_PPS_TO_PP_PF(deblocking_filter_control_present_flag);
+  FROM_PPS_TO_PP_PF(redundant_pic_cnt_present_flag);
+  pic_param.pic_fields.bits.reference_pic_flag = curr_pic_->ref;
+#undef FROM_PPS_TO_PP_PF
+#undef FROM_PPS_TO_PP_PF2
+
+  pic_param.frame_num = curr_pic_->frame_num;
+
+  InitVAPicture(&pic_param.CurrPic);
+  FillVAPicture(&pic_param.CurrPic, curr_pic_.get());
+
+  // Init reference pictures' array.
+  for (int i = 0; i < 16; ++i)
+    InitVAPicture(&pic_param.ReferenceFrames[i]);
+
+  // And fill it with picture info from DPB.
+  FillVARefFramesFromDPB(pic_param.ReferenceFrames,
+                         arraysize(pic_param.ReferenceFrames));
+
+  pic_param.num_ref_frames = sps->max_num_ref_frames;
+
+  // Allocate a buffer in driver for this parameter buffer and upload data.
+  VABufferID pic_param_buf_id;
+  VAStatus va_res = VAAPI_CreateBuffer(va_display_, va_context_id_,
+                                       VAPictureParameterBufferType,
+                                       sizeof(VAPictureParameterBufferH264),
+                                       1, &pic_param, &pic_param_buf_id);
+  VA_SUCCESS_OR_RETURN(va_res, "Failed to create a buffer for PPS", false);
+
+  // Queue its VA buffer ID to be committed on HW decode run.
+  pending_va_bufs_.push(pic_param_buf_id);
+
+  return true;
+}
+
+// Fill a VAIQMatrixBufferH264 to be later sent to the HW decoder.
+bool VaapiH264Decoder::SendIQMatrix() {
+  const H264PPS* pps = parser_.GetPPS(curr_pps_id_);
+  DCHECK(pps);
+
+  VAIQMatrixBufferH264 iq_matrix_buf;
+  memset(&iq_matrix_buf, 0, sizeof(VAIQMatrixBufferH264));
+
+  if (pps->pic_scaling_matrix_present_flag) {
+    for (int i = 0; i < 6; ++i) {
+      for (int j = 0; j < 16; ++j)
+        iq_matrix_buf.ScalingList4x4[i][j] = pps->scaling_list4x4[i][j];
+    }
+
+    for (int i = 0; i < 2; ++i) {
+      for (int j = 0; j < 64; ++j)
+        iq_matrix_buf.ScalingList8x8[i][j] = pps->scaling_list8x8[i][j];
+    }
+  } else {
+    const H264SPS* sps = parser_.GetSPS(pps->seq_parameter_set_id);
+    DCHECK(sps);
+    for (int i = 0; i < 6; ++i) {
+      for (int j = 0; j < 16; ++j)
+        iq_matrix_buf.ScalingList4x4[i][j] = sps->scaling_list4x4[i][j];
+    }
+
+    for (int i = 0; i < 2; ++i) {
+      for (int j = 0; j < 64; ++j)
+        iq_matrix_buf.ScalingList8x8[i][j] = sps->scaling_list8x8[i][j];
+    }
+  }
+
+  // Allocate a buffer in driver for this parameter buffer and upload data.
+  VABufferID iq_matrix_buf_id;
+  VAStatus va_res = VAAPI_CreateBuffer(va_display_, va_context_id_,
+                                       VAIQMatrixBufferType,
+                                       sizeof(VAIQMatrixBufferH264), 1,
+                                       &iq_matrix_buf, &iq_matrix_buf_id);
+  VA_SUCCESS_OR_RETURN(va_res, "Failed to create a buffer for IQMatrix",
+                       false);
+
+  // Queue its VA buffer ID to be committed on HW decode run.
+  pending_va_bufs_.push(iq_matrix_buf_id);
+
+  return true;
+}
+
+bool VaapiH264Decoder::SendVASliceParam(H264SliceHeader* slice_hdr) {
+  const H264PPS* pps = parser_.GetPPS(slice_hdr->pic_parameter_set_id);
+  DCHECK(pps);
+
+  const H264SPS* sps = parser_.GetSPS(pps->seq_parameter_set_id);
+  DCHECK(sps);
+
+  VASliceParameterBufferH264 slice_param;
+  memset(&slice_param, 0, sizeof(VASliceParameterBufferH264));
+
+  slice_param.slice_data_size = slice_hdr->nalu_size;
+  slice_param.slice_data_offset = 0;
+  slice_param.slice_data_flag = VA_SLICE_DATA_FLAG_ALL;
+  slice_param.slice_data_bit_offset = slice_hdr->header_bit_size;
+
+#define SHDRToSP(a) slice_param.a = slice_hdr->a;
+  SHDRToSP(first_mb_in_slice);
+  slice_param.slice_type = slice_hdr->slice_type % 5;
+  SHDRToSP(direct_spatial_mv_pred_flag);
+
+  // TODO posciak: make sure parser sets those even when override flags
+  // in slice header is off.
+  SHDRToSP(num_ref_idx_l0_active_minus1);
+  SHDRToSP(num_ref_idx_l1_active_minus1);
+  SHDRToSP(cabac_init_idc);
+  SHDRToSP(slice_qp_delta);
+  SHDRToSP(disable_deblocking_filter_idc);
+  SHDRToSP(slice_alpha_c0_offset_div2);
+  SHDRToSP(slice_beta_offset_div2);
+
+  if (((slice_hdr->IsPSlice() || slice_hdr->IsSPSlice())
+        && pps->weighted_pred_flag)

[Ami GONE FROM CHROMIUM, 2012/05/07 16:38:05]

op goes on previous line

[Pawel Osciak, 2012/05/07 17:58:00]

Will I ever get used to this? ;) Sorry, done.

+      || (slice_hdr->IsBSlice() && pps->weighted_bipred_idc == 1)) {

[Ami GONE FROM CHROMIUM, 2012/05/07 16:38:05]

ditto

[Pawel Osciak, 2012/05/07 17:58:00]

Done.

+    SHDRToSP(luma_log2_weight_denom);
+    SHDRToSP(chroma_log2_weight_denom);
+
+    SHDRToSP(luma_weight_l0_flag);
+    SHDRToSP(luma_weight_l1_flag);
+
+    SHDRToSP(chroma_weight_l0_flag);
+    SHDRToSP(chroma_weight_l1_flag);
+
+    for (int i = 0; i <= slice_param.num_ref_idx_l0_active_minus1; ++i) {
+      slice_param.luma_weight_l0[i] =
+          slice_hdr->pred_weight_table_l0.luma_weight[i];
+      slice_param.luma_offset_l0[i] =
+          slice_hdr->pred_weight_table_l0.luma_offset[i];
+
+      for (int j = 0; j < 2; ++j) {
+        slice_param.chroma_weight_l0[i][j] =
+            slice_hdr->pred_weight_table_l0.chroma_weight[i][j];
+        slice_param.chroma_offset_l0[i][j] =
+            slice_hdr->pred_weight_table_l0.chroma_offset[i][j];
+      }
+    }
+
+    if (slice_hdr->IsBSlice()) {
+      for (int i = 0; i <= slice_param.num_ref_idx_l1_active_minus1; ++i) {
+        slice_param.luma_weight_l1[i] =
+            slice_hdr->pred_weight_table_l1.luma_weight[i];
+        slice_param.luma_offset_l1[i] =
+            slice_hdr->pred_weight_table_l1.luma_offset[i];
+
+        for (int j = 0; j < 2; ++j) {
+          slice_param.chroma_weight_l1[i][j] =
+              slice_hdr->pred_weight_table_l1.chroma_weight[i][j];
+          slice_param.chroma_offset_l1[i][j] =
+              slice_hdr->pred_weight_table_l1.chroma_offset[i][j];
+        }
+      }
+    }
+  }
+
+  for (int i = 0; i < 32; ++i) {
+    InitVAPicture(&slice_param.RefPicList0[i]);
+    InitVAPicture(&slice_param.RefPicList1[i]);
+  }
+
+  int i;
+  H264Picture::PtrVector::iterator it;
+  for (it = ref_pic_list0_.begin(), i = 0; it != ref_pic_list0_.end();
+       ++it, ++i)
+    FillVAPicture(&slice_param.RefPicList0[i], *it);
+  for (it = ref_pic_list1_.begin(), i = 0; it != ref_pic_list1_.end();
+       ++it, ++i)
+    FillVAPicture(&slice_param.RefPicList1[i], *it);
+
+  // Allocate a buffer in driver for this parameter buffer and upload data.
+  VABufferID slice_param_buf_id;
+  VAStatus va_res = VAAPI_CreateBuffer(va_display_, va_context_id_,
+                                       VASliceParameterBufferType,
+                                       sizeof(VASliceParameterBufferH264),
+                                       1, &slice_param, &slice_param_buf_id);
+  VA_SUCCESS_OR_RETURN(va_res, "Failed creating a buffer for slice param",
+                       false);
+
+  // Queue its VA buffer ID to be committed on HW decode run.
+  pending_slice_bufs_.push(slice_param_buf_id);
+
+  return true;
+}
+
+bool VaapiH264Decoder::SendSliceData(const uint8* ptr, size_t size)
+{
+    // Can't help it, blame libva...
+    void* non_const_ptr = const_cast<uint8*>(ptr);
+
+    VABufferID slice_data_buf_id;
+    VAStatus va_res = VAAPI_CreateBuffer(va_display_, va_context_id_,
+                                         VASliceDataBufferType, size, 1,
+                                         non_const_ptr, &slice_data_buf_id);
+    VA_SUCCESS_OR_RETURN(va_res, "Failed creating a buffer for slice data",
+                         false);
+
+    pending_slice_bufs_.push(slice_data_buf_id);
+    return true;
+}
+
+bool VaapiH264Decoder::QueueSlice(H264SliceHeader* slice_hdr) {
+  DCHECK(curr_pic_.get());
+
+  if (!SendVASliceParam(slice_hdr))
+    return false;
+
+  if (!SendSliceData(slice_hdr->nalu_data, slice_hdr->nalu_size))
+    return false;
+
+  return true;
+}
+
+// TODO(posciak) start using vaMapBuffer instead of vaCreateBuffer wherever
+// possible.
+
+bool VaapiH264Decoder::DecodePicture() {
+  DCHECK(!frame_ready_at_hw_);
+  DCHECK(curr_pic_.get());
+
+  static const size_t kMaxVABuffers = 32;
+  DCHECK_LE(pending_va_bufs_.size(), kMaxVABuffers);
+  DCHECK_LE(pending_slice_bufs_.size(), kMaxVABuffers);
+
+  DVLOG(4) << "Pending VA bufs to commit: " << pending_va_bufs_.size();
+  DVLOG(4) << "Pending slice bufs to commit: " << pending_slice_bufs_.size();
+
+  // Find the surface associated with the picture to be decoded.
+  DCHECK(pending_slice_bufs_.size());
+  DecodeSurface* dec_surface =
+      poc_to_decode_surfaces_[curr_pic_->pic_order_cnt];
+  DVLOG(4) << "Decoding POC " << curr_pic_->pic_order_cnt
+           << " into surface " << dec_surface->va_surface_id();
+
+  // Get ready to decode into surface.
+  VAStatus va_res = VAAPI_BeginPicture(va_display_, va_context_id_,
+                                       dec_surface->va_surface_id());
+  VA_SUCCESS_OR_RETURN(va_res, "vaBeginPicture failed", false);
+
+  // Put buffer IDs for pending parameter buffers into buffers[].
+  VABufferID buffers[kMaxVABuffers];
+  size_t num_buffers = pending_va_bufs_.size();
+  for (size_t i = 0; i < num_buffers && i < kMaxVABuffers; ++i) {
+    buffers[i] = pending_va_bufs_.front();
+    pending_va_bufs_.pop();
+  }
+
+  // And send them to the HW decoder.
+  va_res = VAAPI_RenderPicture(va_display_, va_context_id_, buffers,
+                               num_buffers);
+  VA_SUCCESS_OR_RETURN(va_res, "vaRenderPicture for va_bufs failed", false);
+
+  DVLOG(4) << "Committed " << num_buffers << "VA buffers";
+
+  // Put buffer IDs for pending slice data buffers into buffers[].
+  num_buffers = pending_slice_bufs_.size();
+  for (size_t i = 0; i < num_buffers && i < kMaxVABuffers; ++i) {
+    buffers[i] = pending_slice_bufs_.front();
+    pending_slice_bufs_.pop();
+  }
+
+  // And send them to the Hw decoder.
+  va_res = VAAPI_RenderPicture(va_display_, va_context_id_, buffers,
+                               num_buffers);
+  VA_SUCCESS_OR_RETURN(va_res, "vaRenderPicture fo slices failed", false);
+
+  DVLOG(4) << "Committed " << num_buffers << "slice buffers";
+
+  // Instruct HW decoder to start processing committed buffers (decode this
+  // picture). This does not block until the end of decode.
+  va_res = VAAPI_EndPicture(va_display_, va_context_id_);
+  VA_SUCCESS_OR_RETURN(va_res, "vaEndPicture failed", false);
+
+  // Used to notify clients that we had sufficient data to start decoding
+  // a new frame.
+  frame_ready_at_hw_ = true;
+  return true;
+}
+
+
+bool VaapiH264Decoder::InitCurrPicture(H264SliceHeader* slice_hdr) {
+  DCHECK(curr_pic_.get());
+
+  memset(curr_pic_.get(), 0, sizeof(H264Picture));
+
+  curr_pic_->idr = slice_hdr->idr_pic_flag;
+
+  if (slice_hdr->field_pic_flag) {
+    curr_pic_->field = slice_hdr->bottom_field_flag ? H264Picture::FIELD_BOTTOM
+                                                    : H264Picture::FIELD_TOP;
+  } else {
+    curr_pic_->field = H264Picture::FIELD_NONE;
+  }
+
+  curr_pic_->ref = slice_hdr->nal_ref_idc != 0;
+  // This assumes non-interlaced stream.
+  curr_pic_->frame_num = curr_pic_->pic_num = slice_hdr->frame_num;
+
+  if (!CalculatePicOrderCounts(slice_hdr))
+    return false;
+
+  // Try to get an empty surface to decode this picture to.
+  if (!AssignSurfaceToPoC(curr_pic_->pic_order_cnt)) {
+    DVLOG(1) << "Failed getting a free surface for a picture";
+    return false;
+  }
+
+  curr_pic_->long_term_reference_flag = slice_hdr->long_term_reference_flag;
+  curr_pic_->adaptive_ref_pic_marking_mode_flag =
+      slice_hdr->adaptive_ref_pic_marking_mode_flag;
+
+  // If the slice header indicates we will have to perform reference marking
+  // process after this picture is decoded, store required data for that
+  // purpose.
+  if (slice_hdr->adaptive_ref_pic_marking_mode_flag) {
+    COMPILE_ASSERT(sizeof(curr_pic_->ref_pic_marking) ==
+                   sizeof(slice_hdr->ref_pic_marking),
+                   ref_pic_marking_array_sizes_do_not_match);
+    memcpy(curr_pic_->ref_pic_marking, slice_hdr->ref_pic_marking,
+           sizeof(curr_pic_->ref_pic_marking));
+  }
+
+  return true;
+}
+
+bool VaapiH264Decoder::CalculatePicOrderCounts(H264SliceHeader* slice_hdr) {
+  DCHECK_NE(curr_sps_id_, -1);
+
+  int pic_order_cnt_lsb = slice_hdr->pic_order_cnt_lsb;
+  curr_pic_->pic_order_cnt_lsb = pic_order_cnt_lsb;
+  if (parser_.GetSPS(curr_sps_id_)->pic_order_cnt_type != 0) {
+    DVLOG(1) << "Unsupported pic_order_cnt_type";
+    return false;
+  }
+
+  // See spec 8.2.1.1.
+  int prev_pic_order_cnt_msb, prev_pic_order_cnt_lsb;
+  if (slice_hdr->idr_pic_flag) {
+    prev_pic_order_cnt_msb = prev_pic_order_cnt_lsb = 0;
+  } else {
+    if (prev_ref_has_memmgmnt5_) {
+      if (prev_ref_field_ != H264Picture::FIELD_BOTTOM) {
+        prev_pic_order_cnt_msb = 0;
+        prev_pic_order_cnt_lsb = prev_ref_top_field_order_cnt_;
+      } else {
+        prev_pic_order_cnt_msb = 0;
+        prev_pic_order_cnt_lsb = 0;
+      }
+    } else {
+      prev_pic_order_cnt_msb = prev_ref_pic_order_cnt_msb_;
+      prev_pic_order_cnt_lsb = prev_ref_pic_order_cnt_lsb_;
+    }
+  }
+
+  DCHECK_NE(max_pic_order_cnt_lsb_, 0);
+  if ((pic_order_cnt_lsb < prev_pic_order_cnt_lsb) &&
+      (prev_pic_order_cnt_lsb - pic_order_cnt_lsb >=
+       max_pic_order_cnt_lsb_ / 2)) {
+    curr_pic_->pic_order_cnt_msb = prev_pic_order_cnt_msb +
+        max_pic_order_cnt_lsb_;
+  } else if ((pic_order_cnt_lsb > prev_pic_order_cnt_lsb) &&
+      (pic_order_cnt_lsb - prev_pic_order_cnt_lsb >
+       max_pic_order_cnt_lsb_ / 2)) {
+    curr_pic_->pic_order_cnt_msb = prev_pic_order_cnt_msb -
+        max_pic_order_cnt_lsb_;
+  } else {
+    curr_pic_->pic_order_cnt_msb = prev_pic_order_cnt_msb;
+  }
+
+  if (curr_pic_->field != H264Picture::FIELD_BOTTOM) {
+    curr_pic_->top_field_order_cnt = curr_pic_->pic_order_cnt_msb +
+        pic_order_cnt_lsb;
+  }
+
+  if (curr_pic_->field != H264Picture::FIELD_TOP) {
+    // TODO posciak: perhaps replace with pic->field?
+    if (!slice_hdr->field_pic_flag) {
+      curr_pic_->bottom_field_order_cnt = curr_pic_->top_field_order_cnt +
+          slice_hdr->delta_pic_order_cnt_bottom;
+    } else {
+      curr_pic_->bottom_field_order_cnt = curr_pic_->pic_order_cnt_msb +
+          pic_order_cnt_lsb;
+    }
+  }
+
+  switch (curr_pic_->field) {
+    case H264Picture::FIELD_NONE:
+      curr_pic_->pic_order_cnt = std::min(curr_pic_->top_field_order_cnt,
+                                          curr_pic_->bottom_field_order_cnt);
+      break;
+    case H264Picture::FIELD_TOP:
+      curr_pic_->pic_order_cnt = curr_pic_->top_field_order_cnt;
+      break;
+    case H264Picture::FIELD_BOTTOM:
+      curr_pic_->pic_order_cnt = curr_pic_->bottom_field_order_cnt;
+      break;
+  }
+
+  return true;
+}
+
+void VaapiH264Decoder::UpdatePicNums() {
+  for (H264DPB::Pictures::iterator it = dpb_.begin(); it != dpb_.end(); ++it) {
+    H264Picture* pic = *it;
+    DCHECK(pic);
+    if (!pic->ref)
+      continue;
+
+    // Below assumes non-interlaced stream.
+    DCHECK_EQ(pic->field, H264Picture::FIELD_NONE);
+    if (pic->long_term) {
+      pic->long_term_pic_num = pic->long_term_frame_idx;
+    } else {
+      if (pic->frame_num > frame_num_)
+        pic->frame_num_wrap = pic->frame_num - max_frame_num_;
+      else
+        pic->frame_num_wrap = pic->frame_num;
+
+      pic->pic_num = pic->frame_num_wrap;
+    }
+  }
+}
+
+struct PicNumDescCompare {
+  bool operator()(const H264Picture* a, const H264Picture* b) const {
+    return a->pic_num > b->pic_num;
+  }
+};
+
+struct LongTermPicNumAscCompare {
+  bool operator()(const H264Picture* a, const H264Picture* b) const {
+    return a->long_term_pic_num < b->long_term_pic_num;
+  }
+};
+
+void VaapiH264Decoder::ConstructReferencePicListsP(H264SliceHeader* slice_hdr) {
+  // RefPicList0 (8.2.4.2.1) [[1] [2]], where:
+  // [1] shortterm ref pics sorted by descending pic_num,
+  // [2] longterm ref pics by ascending long_term_pic_num.
+  DCHECK(ref_pic_list0_.empty() && ref_pic_list1_.empty());
+  // First get the short ref pics...
+  dpb_.GetShortTermRefPicsAppending(ref_pic_list0_);
+  size_t num_short_refs = ref_pic_list0_.size();
+
+  // and sort them to get [1].
+  std::sort(ref_pic_list0_.begin(), ref_pic_list0_.end(), PicNumDescCompare());
+
+  // Now get long term pics and sort them by long_term_pic_num to get [2].
+  dpb_.GetLongTermRefPicsAppending(ref_pic_list0_);
+  std::sort(ref_pic_list0_.begin() + num_short_refs, ref_pic_list0_.end(),
+            LongTermPicNumAscCompare());
+
+  // Cut off if we have more than requested in slice header.
+  ref_pic_list0_.resize(slice_hdr->num_ref_idx_l0_active_minus1 + 1);
+}
+
+struct POCAscCompare {
+  bool operator()(const H264Picture* a, const H264Picture* b) const {
+    return a->pic_order_cnt < b->pic_order_cnt;
+  }
+};
+
+struct POCDescCompare {
+  bool operator()(const H264Picture* a, const H264Picture* b) const {
+    return a->pic_order_cnt > b->pic_order_cnt;
+  }
+};
+
+void VaapiH264Decoder::ConstructReferencePicListsB(H264SliceHeader* slice_hdr) {
+  // RefPicList0 (8.2.4.2.3) [[1] [2] [3]], where:
+  // [1] shortterm ref pics with POC < curr_pic's POC sorted by descending POC,
+  // [2] shortterm ref pics with POC > curr_pic's POC by ascending POC,
+  // [3] longterm ref pics by ascending long_term_pic_num.
+  DCHECK(ref_pic_list0_.empty() && ref_pic_list1_.empty());
+  dpb_.GetShortTermRefPicsAppending(ref_pic_list0_);
+  size_t num_short_refs = ref_pic_list0_.size();
+
+  // First sort ascending, this will put [1] in right place and finish [2].
+  std::sort(ref_pic_list0_.begin(), ref_pic_list0_.end(), POCAscCompare());
+
+  // Find first with POC > curr_pic's POC to get first element in [2]...
+  H264Picture::PtrVector::iterator iter;
+  iter = std::upper_bound(ref_pic_list0_.begin(), ref_pic_list0_.end(),
+                          curr_pic_.get(), POCAscCompare());
+
+  // and sort [1] descending, thus finishing sequence [1] [2].
+  std::sort(ref_pic_list0_.begin(), iter, POCDescCompare());
+
+  // Now add [3] and sort by ascending long_term_pic_num.
+  dpb_.GetLongTermRefPicsAppending(ref_pic_list0_);
+  std::sort(ref_pic_list0_.begin() + num_short_refs, ref_pic_list0_.end(),
+            LongTermPicNumAscCompare());
+
+  // RefPicList1 (8.2.4.2.4) [[1] [2] [3]], where:
+  // [1] shortterm ref pics with POC > curr_pic's POC sorted by ascending POC,
+  // [2] shortterm ref pics with POC < curr_pic's POC by descending POC,
+  // [3] longterm ref pics by ascending long_term_pic_num.
+
+  dpb_.GetShortTermRefPicsAppending(ref_pic_list1_);
+  num_short_refs = ref_pic_list1_.size();
+
+  // First sort by descending POC.
+  std::sort(ref_pic_list1_.begin(), ref_pic_list1_.end(), POCDescCompare());
+
+  // Find first with POC < curr_pic's POC to get first element in [2]...
+  iter = std::upper_bound(ref_pic_list1_.begin(), ref_pic_list1_.end(),
+                          curr_pic_.get(), POCDescCompare());
+
+  // and sort [1] ascending.
+  std::sort(ref_pic_list1_.begin(), iter, POCAscCompare());
+
+  // Now add [3] and sort by ascending long_term_pic_num
+  dpb_.GetShortTermRefPicsAppending(ref_pic_list1_);
+  std::sort(ref_pic_list1_.begin() + num_short_refs, ref_pic_list1_.end(),
+            LongTermPicNumAscCompare());
+
+  // If lists identical, swap first two entries in RefPicList1 (spec 8.2.4.2.3)
+  if (ref_pic_list1_.size() > 1 &&
+      std::equal(ref_pic_list0_.begin(), ref_pic_list0_.end(),
+                 ref_pic_list1_.begin()))
+    std::swap(ref_pic_list1_[0], ref_pic_list1_[1]);
+
+  // Per 8.2.4.2 it's possible for num_ref_idx_lX_active_minus1 to indicate
+  // there should be more ref pics on list than we constructed.
+  // Those superfluous ones should be treated as non-reference.
+  ref_pic_list0_.resize(slice_hdr->num_ref_idx_l0_active_minus1 + 1);
+  ref_pic_list1_.resize(slice_hdr->num_ref_idx_l1_active_minus1 + 1);
+}
+
+// See 8.2.4
+int VaapiH264Decoder::PicNumF(H264Picture *pic) {
+  if (!pic)
+      return -1;
+
+  if (!pic->long_term)
+      return pic->pic_num;
+  else
+      return max_pic_num_;
+}
+
+// See 8.2.4
+int VaapiH264Decoder::LongTermPicNumF(H264Picture *pic) {
+  if (pic->ref && pic->long_term)
+    return pic->long_term_pic_num;
+  else
+    return 2 * (max_long_term_frame_idx_ + 1);
+}
+
+// Shift elements on the |v| starting from |from| to |to|, inclusive,
+// one position to the right and insert pic at |from|.
+static void ShiftRightAndInsert(H264Picture::PtrVector& v,
+                                int from,
+                                int to,
+                                H264Picture* pic) {
+  DCHECK(pic);
+  for (int i = to + 1; i > from; --i)
+    v[i] = v[i - 1];
+
+  v[from] = pic;
+}
+
+bool VaapiH264Decoder::ModifyReferencePicList(H264SliceHeader *slice_hdr,
+                                              int list) {
+  int num_ref_idx_lX_active_minus1;
+  H264Picture::PtrVector* ref_pic_listx;
+  H264ModificationOfPicNum* list_mod;
+
+  // This can process either ref_pic_list0 or ref_pic_list1, depending on
+  // the list argument. Set up pointers to proper list to be processed here.
+  if (list == 0) {
+    if (!slice_hdr->ref_pic_list_modification_flag_l0)
+      return true;
+
+    list_mod = slice_hdr->ref_list_l0_modifications;
+    num_ref_idx_lX_active_minus1 = ref_pic_list0_.size() - 1;
+
+    ref_pic_listx = &ref_pic_list0_;
+  } else {
+    if (!slice_hdr->ref_pic_list_modification_flag_l1)
+      return true;
+
+    list_mod = slice_hdr->ref_list_l1_modifications;
+    num_ref_idx_lX_active_minus1 = ref_pic_list1_.size() - 1;
+
+    ref_pic_listx = &ref_pic_list1_;
+  }
+
+  DCHECK_GT(num_ref_idx_lX_active_minus1, 0);
+
+  // Spec 8.2.4.3:
+  // Reorder pictures on the list in a way specified in the stream.
+  int pic_num_lx_pred = curr_pic_->pic_num;
+  int ref_idx_lx = 0;
+  int pic_num_lx_no_wrap;
+  int pic_num_lx;
+  H264Picture *pic ;
+  for (int i = 0; i < H264SliceHeader::kRefListModSize; ++i) {
+    switch (list_mod->modification_of_pic_nums_idc) {
+      case 0:
+      case 1:
+        // Modify short reference picture position.
+        if (list_mod->modification_of_pic_nums_idc == 0) {
+          // Subtract given value from predicted PicNum.
+          pic_num_lx_no_wrap = pic_num_lx_pred -
+              (static_cast<int>(list_mod->abs_diff_pic_num_minus1) + 1);
+          // Wrap around max_pic_num_ if it becomes < 0 as result
+          // of subtraction.
+          if (pic_num_lx_no_wrap < 0)
+            pic_num_lx_no_wrap += max_pic_num_;
+        } else {
+          // Add given value to predicted PicNum.
+          pic_num_lx_no_wrap = pic_num_lx_pred +
+              (static_cast<int>(list_mod->abs_diff_pic_num_minus1) + 1);
+          // Wrap around max_pic_num_ if it becomes >= max_pic_num_ as result
+          // of the addition.
+          if (pic_num_lx_no_wrap >= max_pic_num_)
+            pic_num_lx_no_wrap -= max_pic_num_;
+        }
+
+        // For use in next iteration.
+        pic_num_lx_pred = pic_num_lx_no_wrap;
+
+        if (pic_num_lx_no_wrap > curr_pic_->pic_num)
+          pic_num_lx = pic_num_lx_no_wrap - max_pic_num_;
+        else
+          pic_num_lx = pic_num_lx_no_wrap;
+
+        DCHECK_LT(num_ref_idx_lX_active_minus1 + 1,
+                  H264SliceHeader::kRefListModSize);
+        pic = dpb_.GetShortRefPicByPicNum(pic_num_lx);
+        if (!pic) {
+          DVLOG(1) << "Malformed stream, no pic num " << pic_num_lx;
+          return false;
+        }
+        ShiftRightAndInsert(*ref_pic_listx, ref_idx_lx,
+                            num_ref_idx_lX_active_minus1, pic);
+        ref_idx_lx++;
+
+        for (int src = ref_idx_lx, dst = ref_idx_lx;
+             src <= num_ref_idx_lX_active_minus1 + 1; ++src) {
+          if (PicNumF((*ref_pic_listx)[src]) != pic_num_lx)
+            (*ref_pic_listx)[dst++] = (*ref_pic_listx)[src];
+        }
+        break;
+
+      case 2:
+        // Modify long term reference picture position.
+        DCHECK_LT(num_ref_idx_lX_active_minus1 + 1,
+                  H264SliceHeader::kRefListModSize);
+        pic = dpb_.GetLongRefPicByLongTermPicNum(list_mod->long_term_pic_num);
+        if (!pic) {
+          DVLOG(1) << "Malformed stream, no pic num " << pic_num_lx;
+          return false;
+        }
+        ShiftRightAndInsert(*ref_pic_listx, ref_idx_lx,
+                            num_ref_idx_lX_active_minus1, pic);
+        ref_idx_lx++;
+
+        for (int src = ref_idx_lx, dst = ref_idx_lx;
+             src <= num_ref_idx_lX_active_minus1 + 1; ++src) {
+          if (LongTermPicNumF((*ref_pic_listx)[src])
+              != static_cast<int>(list_mod->long_term_pic_num))
+            (*ref_pic_listx)[dst++] = (*ref_pic_listx)[src];
+        }
+        break;
+
+      case 3:
+        // End of modification list.
+        return true;
+
+      default:
+        // May be recoverable.
+        DVLOG(1) << "Invalid modification_of_pic_nums_idc="
+                 << list_mod->modification_of_pic_nums_idc
+                 << " in position " << i;
+        break;
+    }
+
+    ++list_mod;
+  }
+
+  return true;
+}
+
+bool VaapiH264Decoder::PutPicToTexture(int32 picture_buffer_id) {
+  DecodeSurfaces::iterator it = decode_surfaces_.find(picture_buffer_id);
+  if (it == decode_surfaces_.end()) {
+    DVLOG(1) << "Asked to put an invalid buffer";
+    return false;
+  }
+
+  DVLOG(3) << "Will output from VASurface " << it->second->va_surface_id()
+           << " to texture id " << it->second->texture_id();
+
+  return it->second->Sync();
+}
+
+bool VaapiH264Decoder::OutputPic(H264Picture* pic) {
+  // No longer need to keep POC->surface mapping, since for decoder this POC
+  // is finished with. When the client returns this surface via
+  // ReusePictureBuffer(), it will be marked back as available for use.
+  DecodeSurface* dec_surface = UnassignSurfaceFromPoC(pic->pic_order_cnt);
+  if (!dec_surface)
+    return false;
+
+  // Notify the client that a picture can be output. The decoded picture may
+  // not be synced with texture contents yet at this point. The client has
+  // to use PutPicToTexture() to ensure that.
+  DVLOG(4) << "Posting output task for input_id: " << dec_surface->input_id()
+           << "output_id: " << dec_surface->picture_buffer_id();
+  output_pic_cb_.Run(dec_surface->input_id(),
+                     dec_surface->picture_buffer_id());
+  return true;
+}
+
+bool VaapiH264Decoder::Flush() {
+  // Output all pictures that are waiting to be outputted.
+  H264Picture::PtrVector to_output;
+  dpb_.GetNotOutputtedPicsAppending(to_output);
+  // Sort them by ascending POC to output in order.
+  std::sort(to_output.begin(), to_output.end(), POCAscCompare());
+
+  H264Picture::PtrVector::iterator it;
+  for (it = to_output.begin(); it != to_output.end(); ++it) {
+    if (!OutputPic(*it)) {
+      DVLOG(1) << "Failed to output pic POC: " << (*it)->pic_order_cnt;
+      return false;
+    }
+  }
+
+  // And clear DPB contents.
+  dpb_.Clear();
+
+  return true;
+}
+
+bool VaapiH264Decoder::StartNewFrame(H264SliceHeader* slice_hdr) {
+// TODO posciak: add handling of max_num_ref_frames per spec.
+
+  // If the new frame is an IDR, output what's left to output and clear DPB
+  if (slice_hdr->idr_pic_flag) {
+    // (unless we are explicitly instructed not to do so).
+    if (!slice_hdr->no_output_of_prior_pics_flag) {
+      // Output DPB contents.
+      if (!Flush())
+        return false;
+    }
+    dpb_.Clear();
+  }
+
+  // curr_pic_ should have either been added to DPB or discarded when finishing
+  // the last frame. DPB is responsible for releasing that memory once it's
+  // not needed anymore.
+  DCHECK(!curr_pic_.get());
+  curr_pic_.reset(new H264Picture);
+  CHECK(curr_pic_.get());
+
+  if (!InitCurrPicture(slice_hdr))
+    return false;
+
+  DCHECK_GT(max_frame_num_, 0);
+
+  UpdatePicNums();
+
+  // Prepare reference picture lists if required (B and S/SP slices).
+  ref_pic_list0_.clear();
+  ref_pic_list1_.clear();
+  if (slice_hdr->IsPSlice() || slice_hdr->IsSPSlice()) {
+    ConstructReferencePicListsP(slice_hdr);
+    if (!ModifyReferencePicList(slice_hdr, 0))
+      return false;
+  } else if (slice_hdr->IsBSlice()) {
+    ConstructReferencePicListsB(slice_hdr);
+    if (!ModifyReferencePicList(slice_hdr, 0))
+      return false;
+    if (!ModifyReferencePicList(slice_hdr, 1))
+      return false;
+  }
+
+  // Send parameter buffers before each new picture, before the first slice.
+  if (!SendPPS())
+    return false;
+
+  if (!SendIQMatrix())
+    return false;
+
+  if (!QueueSlice(slice_hdr))
+    return false;
+
+  return true;
+}
+
+bool VaapiH264Decoder::HandleMemoryManagementOps() {
+  // 8.2.5.4
+  for (unsigned int i = 0; i < arraysize(curr_pic_->ref_pic_marking); ++i) {
+    // Code below does not support interlaced stream (per-field pictures).
+    H264DecRefPicMarking* ref_pic_marking = &curr_pic_->ref_pic_marking[i];
+    H264Picture* to_mark;
+    int pic_num_x;
+
+    switch (ref_pic_marking->memory_mgmnt_control_operation) {
+      case 0:
+        // Normal end of operations' specification.
+        return true;
+
+      case 1:
+        // Mark a short term reference picture as unused so it can be removed
+        // if outputted.
+        pic_num_x = curr_pic_->pic_num -
+            (ref_pic_marking->difference_of_pic_nums_minus1 + 1);
+        to_mark = dpb_.GetShortRefPicByPicNum(pic_num_x);
+        if (to_mark) {
+          to_mark->ref = false;
+        } else {
+          DVLOG(1) << "Invalid short ref pic num to unmark";
+          return false;
+        }
+        break;
+
+      case 2:
+        // Mark a long term reference picture as unused so it can be removed
+        // if outputted.
+        to_mark = dpb_.GetLongRefPicByLongTermPicNum(
+            ref_pic_marking->long_term_pic_num);
+        if (to_mark) {
+          to_mark->ref = false;
+        } else {
+          DVLOG(1) << "Invalid long term ref pic num to unmark";
+          return false;
+        }
+        break;
+
+      case 3:
+        // Mark a short term reference picture as long term reference.
+        pic_num_x = curr_pic_->pic_num -
+            (ref_pic_marking->difference_of_pic_nums_minus1 + 1);
+        to_mark = dpb_.GetShortRefPicByPicNum(pic_num_x);
+        if (to_mark) {
+          DCHECK(to_mark->ref && !to_mark->long_term);
+          to_mark->long_term = true;
+          to_mark->long_term_frame_idx = ref_pic_marking->long_term_frame_idx;
+        } else {
+          DVLOG(1) << "Invalid short term ref pic num to mark as long ref";
+          return false;
+        }
+        break;
+
+      case 4: {
+        // Unmark all reference pictures with long_term_frame_idx over new max.
+        max_long_term_frame_idx_
+            = ref_pic_marking->max_long_term_frame_idx_plus1 - 1;
+        H264Picture::PtrVector long_terms;
+        dpb_.GetLongTermRefPicsAppending(long_terms);
+        for (size_t i = 0; i < long_terms.size(); ++i) {
+          H264Picture* pic = long_terms[i];
+          DCHECK(pic->ref && pic->long_term);
+          // Ok to cast, max_long_term_frame_idx is much smaller than 16bit.
+          if (pic->long_term_frame_idx >
+              static_cast<int>(max_long_term_frame_idx_))
+            pic->ref = false;
+        }
+        break;
+      }
+
+      case 5:
+        // Unmark all reference pictures.
+        dpb_.MarkAllUnusedForRef();
+        max_long_term_frame_idx_ = -1;
+        curr_pic_->mem_mgmt_5 = true;
+        break;
+
+      case 6: {
+        // Replace long term reference pictures with current picture.
+        // First unmark if any existing with this long_term_frame_idx...
+        H264Picture::PtrVector long_terms;
+        dpb_.GetLongTermRefPicsAppending(long_terms);
+        for (size_t i = 0; i < long_terms.size(); ++i) {
+          H264Picture* pic = long_terms[i];
+          DCHECK(pic->ref && pic->long_term);
+          // Ok to cast, long_term_frame_idx is much smaller than 16bit.
+          if (pic->long_term_frame_idx ==
+              static_cast<int>(ref_pic_marking->long_term_frame_idx))
+            pic->ref = false;
+        }
+
+        // and mark the current one instead.
+        curr_pic_->ref = true;
+        curr_pic_->long_term = true;
+        curr_pic_->long_term_frame_idx = ref_pic_marking->long_term_frame_idx;
+        break;
+      }
+
+      default:
+        // Would indicate a bug in parser.
+        NOTREACHED();
+    }
+  }
+
+  return true;
+}
+
+// This method ensures that DPB does not overflow, either by removing
+// reference pictures as specified in the stream, or using a sliding window
+// procedure to remove the oldest one.
+// It also performs marking and unmarking pictures as reference.
+// See spac 8.2.5.1.
+void VaapiH264Decoder::ReferencePictureMarking() {
+  if (curr_pic_->idr) {
+    // If current picture is an IDR, all reference pictures are unmarked.
+    dpb_.MarkAllUnusedForRef();
+
+    if (curr_pic_->long_term_reference_flag) {
+      curr_pic_->long_term = true;
+      curr_pic_->long_term_frame_idx = 0;
+      max_long_term_frame_idx_ = 0;
+    } else {
+      curr_pic_->long_term = false;
+      max_long_term_frame_idx_ = -1;
+    }
+  } else {
+    if (!curr_pic_->adaptive_ref_pic_marking_mode_flag) {
+      // If non-IDR, and the stream does not indicate what we should do to
+      // ensure DPB doesn't overflow, discard oldest picture.
+      // See spec 8.2.5.3.
+      if (curr_pic_->field == H264Picture::FIELD_NONE) {
+        DCHECK_LE(dpb_.CountRefPics(),
+            std::max<int>(parser_.GetSPS(curr_sps_id_)->max_num_ref_frames,
+                          1));
+        if (dpb_.CountRefPics() ==
+            std::max<int>(parser_.GetSPS(curr_sps_id_)->max_num_ref_frames,
+                          1)) {
+          // Max number of reference pics reached,
+          // need to remove one of the short term ones.
+          // Find smallest frame_num_wrap short reference picture and mark
+          // it as unused.
+          H264Picture* to_unmark = dpb_.GetLowestFrameNumWrapShortRefPic();
+          if (to_unmark == NULL) {
+            DVLOG(1) << "Couldn't find a short ref picture to unmark";
+            return;
+          }
+          to_unmark->ref = false;
+        }
+      } else {
+        // Shouldn't get here.
+        DVLOG(1) << "Interlaced video not supported.";
+      }
+    } else {
+      // Stream has instructions how to discard pictures from DPB and how
+      // to mark/unmark existing reference pictures. Do it.
+      // Spec 8.2.5.4.
+      if (curr_pic_->field == H264Picture::FIELD_NONE) {
+        HandleMemoryManagementOps();
+      } else {
+        // Shouldn't get here.
+        DVLOG(1) << "Interlaced video not supported.";
+      }
+    }
+  }
+}
+
+bool VaapiH264Decoder::FinishPicture() {
+  DCHECK(curr_pic_.get());
+
+  // Finish processing previous picture.
+  // Start by storing previous reference picture data for later use,
+  // if picture being finished is a reference picture.
+  if (curr_pic_->ref) {
+    ReferencePictureMarking();
+    prev_ref_has_memmgmnt5_ = curr_pic_->mem_mgmt_5;
+    prev_ref_top_field_order_cnt_ = curr_pic_->top_field_order_cnt;
+    prev_ref_pic_order_cnt_msb_ = curr_pic_->pic_order_cnt_msb;
+    prev_ref_pic_order_cnt_lsb_ = curr_pic_->pic_order_cnt_lsb;
+    prev_ref_field_ = curr_pic_->field;
+  }
+
+  // Remove unused (for reference or later output) pictures from DPB.
+  dpb_.RemoveUnused();
+
+  DVLOG(4) << "Finishing picture, DPB entries: " << dpb_.size()
+           << " Num available dec surfaces: "
+           << num_available_decode_surfaces_;
+
+  if (dpb_.IsFull()) {
+    // DPB is full, we have to make space for the new picture.
+    // Get all pictures that haven't been outputted yet.
+    H264Picture::PtrVector not_outputted;
+    dpb_.GetNotOutputtedPicsAppending(not_outputted);
+    std::sort(not_outputted.begin(), not_outputted.end(), POCAscCompare());
+    H264Picture::PtrVector::iterator output_candidate = not_outputted.begin();
+
+    // Keep outputting pictures until we can either output the picture being
+    // finished and discard it (if it is not a reference picture), or until
+    // we can discard an older picture that was just waiting for output and
+    // is not a reference picture, thus making space for the current one.
+    while (dpb_.IsFull()) {
+      // Maybe outputted enough to output current picture.
+      if (!curr_pic_->ref && (output_candidate == not_outputted.end() ||
+          curr_pic_->pic_order_cnt < (*output_candidate)->pic_order_cnt)) {
+        // curr_pic_ is not a reference picture and no preceding pictures are
+        // waiting for output in DPB, so it can be outputted and discarded
+        // without storing in DPB.
+        if (!OutputPic(curr_pic_.get()))
+          return false;
+        goto no_store;
+      }
+
+      // Couldn't output current picture, so try to output the lowest PoC
+      // from DPB.
+      if (output_candidate != not_outputted.end()) {
+        if (!OutputPic(*output_candidate))
+          return false;
+
+        // If outputted picture wasn't a reference picture, it can be removed.
+        if (!(*output_candidate)->ref)
+          dpb_.RemoveByPOC((*output_candidate)->pic_order_cnt);
+      } else {
+        // Couldn't output current pic and couldn't do anything
+        // with existing pictures in DPB, so we can't make space.
+        // This should not happen.
+        DVLOG(1) << "Could not free up space in DPB!";
+        return false;
+      }
+    }
+    ++output_candidate;
+  }
+
+  // Store current picture for later output and/or reference (ownership now
+  // with the DPB).
+  dpb_.StorePic(curr_pic_.release());
+
+no_store:
+  return true;
+}
+
+bool VaapiH264Decoder::ProcessSPS(int sps_id) {
+  const H264SPS* sps = parser_.GetSPS(sps_id);
+  DCHECK(sps);
+
+  if (sps->frame_mbs_only_flag == 0) {
+    // Fields/interlaced video not supported.
+    DVLOG(1) << "frame_mbs_only_flag != 1 not supported";
+    return false;
+  }
+
+  if (sps->gaps_in_frame_num_value_allowed_flag) {
+    DVLOG(1) << "Gaps in frame numbers not supported";
+    return false;
+  }
+
+  if (sps->pic_order_cnt_type != 0) {
+    DVLOG(1) << "Unsupported pic_order_cnt_type";
+    return false;
+  }
+
+  curr_sps_id_ = sps->seq_parameter_set_id;
+
+  // Calculate picture height/width (spec 7.4.2.1.1, 7.4.3).
+  int width = 16 * (sps->pic_width_in_mbs_minus1 + 1);
+  int height = 16 * (2 - sps->frame_mbs_only_flag) *
+      (sps->pic_height_in_map_units_minus1 + 1);
+
+  if ((pic_width_ != -1 || pic_height_ != -1) &&
+      (width != pic_width_ || height != pic_height_)) {
+    DVLOG(1) << "Picture size changed mid-stream";
+    return false;
+  }
+
+  pic_width_ = width;
+  pic_height_ = height;
+  DVLOG(1) << "New picture size: " << pic_width_ << "x" << pic_height_;
+
+  max_pic_order_cnt_lsb_ = 1 << (sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
+  max_frame_num_ = 1 << (sps->log2_max_frame_num_minus4 + 4);
+
+  return true;
+}
+
+bool VaapiH264Decoder::ProcessPPS(int pps_id) {
+  const H264PPS* pps = parser_.GetPPS(pps_id);
+  DCHECK(pps);
+
+  curr_pps_id_ = pps->pic_parameter_set_id;
+
+  return true;
+}
+
+bool VaapiH264Decoder::FinishPrevFrameIfPresent() {
+  // If we already have a frame waiting to be decoded, decode it and finish.
+  if (curr_pic_ != NULL) {
+    if (!DecodePicture())
+      return false;
+    return FinishPicture();
+  }
+
+  return true;
+}
+
+bool VaapiH264Decoder::ProcessSlice(H264SliceHeader* slice_hdr) {
+  prev_frame_num_ = frame_num_;
+  frame_num_ = slice_hdr->frame_num;
+
+  if (prev_frame_num_ > 0 && prev_frame_num_ < frame_num_ - 1) {
+    DVLOG(1) << "Gap in frame_num!";
+    return false;
+  }
+
+  if (slice_hdr->field_pic_flag == 0)
+    max_pic_num_ = max_frame_num_;
+  else
+    max_pic_num_ = 2 * max_frame_num_;
+
+  // TODO posciak: switch to new picture detection per 7.4.1.2.4.
+  if (curr_pic_ != NULL && slice_hdr->first_mb_in_slice != 0) {
+    // This is just some more slice data of the current picture, so
+    // just queue it and return.
+    QueueSlice(slice_hdr);
+    return true;
+  } else {
+    // A new frame, so first finish the previous one before processing it...
+    if (!FinishPrevFrameIfPresent())
+      return false;
+
+    // and then start a new one.
+    return StartNewFrame(slice_hdr);
+  }
+}
+
+#define SET_ERROR_AND_RETURN()             \
+  do {                                     \
+    DVLOG(1) << "Error during decode";     \
+    state_ = kError;                       \
+    return VaapiH264Decoder::kDecodeError; \
+  } while (0)
+
+VaapiH264Decoder::DecResult VaapiH264Decoder::DecodeInitial(int32 input_id) {
+  // Decode enough to get required picture size (i.e. until we find an SPS),
+  // if we get any slice data, we are missing the beginning of the stream.
+  H264NALU nalu;
+  H264Parser::Result res;
+
+  DCHECK_NE(state_, kUninitialized);
+
+  curr_input_id_ = input_id;
+
+  while (1) {
+    // Get next NALU looking for SPS or IDR if after reset.
+    res = parser_.AdvanceToNextNALU(&nalu);
+    if (res == H264Parser::kEOStream) {
+      DVLOG(1) << "Could not find SPS before EOS";
+      return kNeedMoreStreamData;
+    } else if (res != H264Parser::kOk) {
+      SET_ERROR_AND_RETURN();
+    }
+
+    DVLOG(4) << " NALU found: " << static_cast<int>(nalu.nal_unit_type);
+
+    switch (nalu.nal_unit_type) {
+      case H264NALU::kSPS:
+        res = parser_.ParseSPS(&curr_sps_id_);
+        if (res != H264Parser::kOk)
+          SET_ERROR_AND_RETURN();
+
+        if (!ProcessSPS(curr_sps_id_))
+          SET_ERROR_AND_RETURN();
+
+        // Just got information about the video size from SPS, so we can
+        // now allocate surfaces and let the client now we are ready to
+        // accept output buffers and decode.
+        if (!CreateVASurfaces())
+          SET_ERROR_AND_RETURN();
+
+        state_ = kDecoding;
+        return kReadyToDecode;
+
+      case H264NALU::kIDRSlice:
+        // If after reset, should be able to recover from an IDR.
+        if (state_ == kAfterReset) {
+          H264SliceHeader slice_hdr;
+
+          res = parser_.ParseSliceHeader(&nalu, &slice_hdr);
+          if (res != H264Parser::kOk)
+            SET_ERROR_AND_RETURN();
+
+          if (!ProcessSlice(&slice_hdr))
+            SET_ERROR_AND_RETURN();
+
+          state_ = kDecoding;
+          return kReadyToDecode;
+        }  // else fallthrough
+      case H264NALU::kNonIDRSlice:
+      case H264NALU::kPPS:
+        // Non-IDR slices cannot be used as resume points, as we may not
+        // have all reference pictures that they may require.
+        // fallthrough
+      default:
+        // Skip everything unless it's PPS or an IDR slice (if after reset).
+        DVLOG(4) << "Skipping NALU";
+        break;
+    }
+  }
+}
+
+void VaapiH264Decoder::SetStream(uint8* ptr, size_t size) {
+  DCHECK(ptr);
+  DCHECK(size);
+
+  // Got new input stream data from the client.
+  DVLOG(4) << "New input stream chunk at " << (void*) ptr
+           << " size:  " << size;
+  parser_.SetStream(ptr, size);
+}
+
+VaapiH264Decoder::DecResult VaapiH264Decoder::DecodeOneFrame(int32 input_id) {
+  // Decode until one full frame is decoded or return it or until end
+  // of stream (end of input data is reached).
+  H264Parser::Result par_res;
+  H264NALU nalu;
+
+  curr_input_id_ = input_id;
+
+  if (state_ != kDecoding) {
+    DVLOG(1) << "Decoder not ready: error in stream or not initialized";
+    return kDecodeError;
+  } else if (num_available_decode_surfaces_ < 1) {
+    DVLOG(4) << "No output surfaces available";
+    return kNoOutputAvailable;
+  }
+
+  // All of the actions below might result in decoding a picture from
+  // previously parsed data, but we still have to handle/parse current input
+  // first.
+  // Note: this may drop some already decoded frames if there are errors
+  // further in the stream, but we are OK with that.
+  while (1) {
+    par_res = parser_.AdvanceToNextNALU(&nalu);
+    if (par_res == H264Parser::kEOStream)
+      return kNeedMoreStreamData;
+    else if (par_res != H264Parser::kOk)
+      SET_ERROR_AND_RETURN();
+
+    DVLOG(4) << "NALU found: " << static_cast<int>(nalu.nal_unit_type);
+
+    switch (nalu.nal_unit_type) {
+      case H264NALU::kNonIDRSlice:
+      case H264NALU::kIDRSlice: {
+        H264SliceHeader slice_hdr;
+
+        par_res = parser_.ParseSliceHeader(&nalu, &slice_hdr);
+        if (par_res != H264Parser::kOk)
+          SET_ERROR_AND_RETURN();
+
+        if (!ProcessSlice(&slice_hdr))
+          SET_ERROR_AND_RETURN();
+        break;
+      }
+
+      case H264NALU::kSPS:
+        int sps_id;
+
+        if (!FinishPrevFrameIfPresent())
+          SET_ERROR_AND_RETURN();
+
+        par_res = parser_.ParseSPS(&sps_id);
+        if (par_res != H264Parser::kOk)
+          SET_ERROR_AND_RETURN();
+
+        if (!ProcessSPS(sps_id))
+          SET_ERROR_AND_RETURN();
+        break;
+
+      case H264NALU::kPPS:
+        int pps_id;
+
+        if (!FinishPrevFrameIfPresent())
+          SET_ERROR_AND_RETURN();
+
+        par_res = parser_.ParsePPS(&pps_id);
+        if (par_res != H264Parser::kOk)
+          SET_ERROR_AND_RETURN();
+
+        if (!ProcessPPS(pps_id))
+          SET_ERROR_AND_RETURN();
+        break;
+
+      default:
+        // skip NALU
+        break;
+    }
+
+    // If the last action resulted in decoding a frame, possibly from older
+    // data, return. Otherwise keep reading the stream.
+    if (frame_ready_at_hw_) {
+      frame_ready_at_hw_ = false;
+      return kDecodedFrame;
+    }
+  }
+}
+
+// static
+size_t VaapiH264Decoder::GetRequiredNumOfPictures() {
+  return kNumReqPictures;
+}
+
+}  // namespace content
+