Add a Vp9Parser implementation

media/filters/vp9_parser.cc

+// Copyright 2015 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.
+//
+// This file contains an implementation of a VP9 bitstream parser.
+
+#include "media/filters/vp9_parser.h"
+
+#include "base/logging.h"
+
+namespace {
+
+// Helper function for Vp9Parser::ReadTiles. Defined as get_min_log2_tile_cols
+// in spec.
+int GetMinLog2TileCols(int sb64_cols) {
+  const int kMaxTileWidthB64 = 64;
+  int min_log2 = 0;
+  while ((kMaxTileWidthB64 << min_log2) < sb64_cols)
+    min_log2++;
+  return min_log2;
+}
+
+// Helper function for Vp9Parser::ReadTiles. Defined as get_max_log2_tile_cols
+// in spec.
+int GetMaxLog2TileCols(int sb64_cols) {
+  const int kMinTileWidthB64 = 4;
+  int max_log2 = 1;
+  while ((sb64_cols >> max_log2) >= kMinTileWidthB64)
+    max_log2++;
+  return max_log2 - 1;
+}
+
+}  // namespace
+
+namespace media {
+
+Vp9Parser::Vp9Parser() : stream_(nullptr), size_(0) {
+  memset(&ref_slots_, 0, sizeof(ref_slots_));
+}
+
+uint8_t Vp9Parser::ReadProfile() {
+  uint8_t profile = 0;
+
+  // LSB first.
+  profile |= reader_.ReadBit();
+  profile |= reader_.ReadBit() << 1;
+  if (profile > 2)
+    profile += reader_.ReadBit();
+  return profile;
+}
+
+bool Vp9Parser::VerifySyncCode() {
+  const int kSyncCode = 0x498342;
+  if (reader_.ReadLiteral(8 * 3) != kSyncCode) {
+    DVLOG(1) << "Invalid frame sync code";
+    return false;
+  }
+  return true;
+}
+
+bool Vp9Parser::ReadBitDepthColorSpaceSampling(Vp9FrameHeader* fhdr) {
+  if (fhdr->profile == 2 || fhdr->profile == 3) {
+    fhdr->bit_depth = reader_.ReadBit() ? 12 : 10;
+  } else {
+    fhdr->bit_depth = 8;
+  }
+
+  fhdr->color_space = static_cast<Vp9ColorSpace>(reader_.ReadLiteral(3));
+  if (fhdr->color_space != Vp9ColorSpace::SRGB) {
+    fhdr->yuv_range = reader_.ReadBit();
+    if (fhdr->profile == 1 || fhdr->profile == 3) {
+      fhdr->subsampling_x = reader_.ReadBit();
+      fhdr->subsampling_y = reader_.ReadBit();
+      if (fhdr->subsampling_x == 1 && fhdr->subsampling_y == 1) {
+        DVLOG(1) << "4:2:0 color not supported in profile 1 or 3";
+        return false;
+      }
+      bool reserved = reader_.ReadBit();
+      if (reserved) {
+        DVLOG(1) << "reserved bit set";
+        return false;
+      }
+    } else {
+      fhdr->subsampling_x = fhdr->subsampling_y = 1;
+    }
+  } else {
+    if (fhdr->profile == 1 || fhdr->profile == 3) {
+      fhdr->subsampling_x = fhdr->subsampling_y = 0;
+
+      bool reserved = reader_.ReadBit();
+      if (reserved) {
+        DVLOG(1) << "reserved bit set";
+        return false;
+      }
+    } else {
+      DVLOG(1) << "4:4:4 color not supported in profile 0 or 2";
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void Vp9Parser::ReadFrameSize(Vp9FrameHeader* fhdr) {
+  fhdr->width = reader_.ReadLiteral(16) + 1;
+  fhdr->height = reader_.ReadLiteral(16) + 1;
+}
+
+bool Vp9Parser::ReadFrameSizeFromRefs(Vp9FrameHeader* fhdr) {
+  for (size_t i = 0; i < kVp9NumRefsPerFrame; i++) {
+    if (reader_.ReadBit()) {
+      fhdr->width = ref_slots_[i].width;
+      fhdr->height = ref_slots_[i].height;
+
+      const int kMaxDimension = 1 << 16;
+      if (fhdr->width < 1 || fhdr->width > kMaxDimension || fhdr->height < 1 ||

[Pawel Osciak, 2015/08/05 07:46:32]

Oh sorry, we should say if fhdr->width == 0 not < 1 actually since it's a uint.
Same for height.

[kcwu, 2015/08/05 08:42:40]

Done.

+          fhdr->height > kMaxDimension) {
+        DVLOG(1) << "The size of referenced frame is out of range: "

[Pawel Osciak, 2015/08/05 07:46:32]

s/referenced/reference/

[kcwu, 2015/08/05 08:42:40]

Done.

+                 << ref_slots_[i].width << "," << ref_slots_[i].height;
+        return false;
+      }
+      return true;
+    }
+  }
+
+  fhdr->width = reader_.ReadLiteral(16) + 1;
+  fhdr->height = reader_.ReadLiteral(16) + 1;
+  return true;
+}
+
+void Vp9Parser::ReadDisplayFrameSize(Vp9FrameHeader* fhdr) {
+  if (reader_.ReadBit()) {
+    fhdr->display_width = reader_.ReadLiteral(16) + 1;
+    fhdr->display_height = reader_.ReadLiteral(16) + 1;
+  } else {
+    fhdr->display_width = fhdr->width;
+    fhdr->display_height = fhdr->height;
+  }
+}
+
+Vp9InterpFilter Vp9Parser::ReadInterpFilter() {
+  if (reader_.ReadBit())
+    return Vp9InterpFilter::INTERP_FILTER_SELECT;
+
+  // The mapping table for next two bits.
+  const Vp9InterpFilter table[] = {
+      Vp9InterpFilter::EIGHTTAP_SMOOTH, Vp9InterpFilter::EIGHTTAP,
+      Vp9InterpFilter::EIGHTTAP_SHARP, Vp9InterpFilter::BILINEAR,
+  };
+  return table[reader_.ReadLiteral(2)];
+}
+
+void Vp9Parser::ReadLoopFilter(Vp9LoopFilter* loop_filter) {
+  loop_filter->filter_level = reader_.ReadLiteral(6);
+  loop_filter->sharpness_level = reader_.ReadLiteral(3);
+
+  loop_filter->mode_ref_delta_enabled = reader_.ReadBit();
+  if (loop_filter->mode_ref_delta_enabled) {
+    loop_filter->mode_ref_delta_update = reader_.ReadBit();
+    if (loop_filter->mode_ref_delta_update) {
+      for (size_t i = 0; i < Vp9LoopFilter::kNumRefDeltas; i++) {
+        loop_filter->update_ref_deltas[i] = reader_.ReadBit();
+        if (loop_filter->update_ref_deltas[i])
+          loop_filter->ref_deltas[i] = reader_.ReadSignedLiteral(6);
+      }
+
+      for (size_t i = 0; i < Vp9LoopFilter::kNumModeDeltas; i++) {
+        loop_filter->update_mode_deltas[i] = reader_.ReadBit();
+        if (loop_filter->update_mode_deltas[i])
+          loop_filter->mode_deltas[i] = reader_.ReadLiteral(6);
+      }
+    }
+  }
+}
+
+void Vp9Parser::ReadQuantization(Vp9QuantizationParams* quants) {
+  quants->base_qindex = reader_.ReadLiteral(8);
+
+  if (reader_.ReadBit())
+    quants->y_dc_delta = reader_.ReadSignedLiteral(4);
+
+  if (reader_.ReadBit())
+    quants->uv_ac_delta = reader_.ReadSignedLiteral(4);
+
+  if (reader_.ReadBit())
+    quants->uv_dc_delta = reader_.ReadSignedLiteral(4);
+}
+
+void Vp9Parser::ReadSegmentationMap(Vp9Segmentation* segment) {
+  for (size_t i = 0; i < Vp9Segmentation::kNumTreeProbs; i++) {
+    segment->tree_probs[i] =
+        reader_.ReadBit() ? reader_.ReadLiteral(8) : kVp9MaxProb;
+  }
+
+  for (size_t i = 0; i < Vp9Segmentation::kNumPredictionProbs; i++)
+    segment->pred_probs[i] = kVp9MaxProb;
+
+  segment->temporal_update = reader_.ReadBit();
+  if (segment->temporal_update) {
+    for (size_t i = 0; i < Vp9Segmentation::kNumPredictionProbs; i++) {
+      if (reader_.ReadBit())
+        segment->pred_probs[i] = reader_.ReadLiteral(8);
+    }
+  }
+}
+
+void Vp9Parser::ReadSegmentationData(Vp9Segmentation* segment) {
+  segment->abs_delta = reader_.ReadBit();
+
+  const int kFeatureDataBits[] = {7, 6, 2, 0};
+  const bool kFeatureDataSigned[] = {true, true, false, false};
+
+  for (size_t i = 0; i < Vp9Segmentation::kNumSegments; i++) {
+    for (size_t j = 0; j < Vp9Segmentation::kNumFeatures; j++) {
+      int8_t data = 0;
+      segment->feature_enabled[i][j] = reader_.ReadBit();
+      if (segment->feature_enabled[i][j]) {
+        data = reader_.ReadLiteral(kFeatureDataBits[j]);
+        if (kFeatureDataSigned[j])
+          if (reader_.ReadBit())
+            data = -data;
+      }
+      segment->feature_data[i][j] = data;
+    }
+  }
+}
+
+void Vp9Parser::ReadSegmentation(Vp9Segmentation* segment) {
+  segment->enabled = reader_.ReadBit();
+
+  if (!segment->enabled) {
+    return;
+  }
+
+  segment->update_map = reader_.ReadBit();
+  if (segment->update_map)
+    ReadSegmentationMap(segment);
+
+  segment->update_data = reader_.ReadBit();
+  if (segment->update_data)
+    ReadSegmentationData(segment);
+}
+
+void Vp9Parser::ReadTiles(Vp9FrameHeader* fhdr) {
+  int sb64_cols = (fhdr->width + 63) / 64;
+
+  int min_log2_tile_cols = GetMinLog2TileCols(sb64_cols);
+  int max_log2_tile_cols = GetMaxLog2TileCols(sb64_cols);
+
+  int max_ones = max_log2_tile_cols - min_log2_tile_cols;
+  fhdr->log2_tile_cols = min_log2_tile_cols;
+  while (max_ones-- && reader_.ReadBit())
+    fhdr->log2_tile_cols++;
+
+  if (reader_.ReadBit())
+    fhdr->log2_tile_rows = reader_.ReadLiteral(2) - 1;
+}
+
+bool Vp9Parser::ParseUncompressedHeader(Vp9FrameHeader* fhdr) {
+  reader_.Initialize(stream_, size_);
+
+  // frame marker
+  if (reader_.ReadLiteral(2) != 0x2)
+    return false;
+
+  fhdr->profile = ReadProfile();
+  if (fhdr->profile >= kVp9MaxProfile) {
+    DVLOG(1) << "Unsupported bitstream profile";
+    return false;
+  }
+
+  fhdr->show_existing_frame = reader_.ReadBit();
+  if (fhdr->show_existing_frame) {
+    fhdr->frame_to_show = reader_.ReadLiteral(3);
+    fhdr->show_frame = true;
+
+    if (!reader_.IsValid()) {

[Pawel Osciak, 2015/08/05 07:46:32]

I'm wondering, why this check here specifically? We have one at the end of the
method...

[kcwu, 2015/08/05 08:42:40]

Here is a "return true".

+      DVLOG(1) << "parser reads beyond the end of buffer";
+      return false;
+    }
+    fhdr->uncompressed_header_size = reader_.GetBytesRead();
+    return true;
+  }
+
+  fhdr->frame_type = static_cast<Vp9FrameHeader::FrameType>(reader_.ReadBit());
+  fhdr->show_frame = reader_.ReadBit();
+  fhdr->error_resilient_mode = reader_.ReadBit();
+
+  if (fhdr->IsKeyframe()) {
+    if (!VerifySyncCode())
+      return false;
+
+    if (!ReadBitDepthColorSpaceSampling(fhdr))
+      return false;
+
+    for (size_t i = 0; i < kVp9NumRefFrames; i++)
+      fhdr->refresh_flag[i] = true;
+
+    ReadFrameSize(fhdr);
+    ReadDisplayFrameSize(fhdr);
+  } else {
+    if (!fhdr->show_frame)
+      fhdr->intra_only = reader_.ReadBit();
+
+    if (!fhdr->error_resilient_mode)
+      fhdr->reset_context = reader_.ReadLiteral(2);
+
+    if (fhdr->intra_only) {
+      if (!VerifySyncCode())
+        return false;
+
+      if (fhdr->profile > 0) {
+        if (!ReadBitDepthColorSpaceSampling(fhdr))
+          return false;
+      } else {
+        fhdr->bit_depth = 8;
+        fhdr->color_space = Vp9ColorSpace::BT_601;
+        fhdr->subsampling_x = fhdr->subsampling_y = 1;
+      }
+
+      for (size_t i = 0; i < kVp9NumRefFrames; i++)
+        fhdr->refresh_flag[i] = reader_.ReadBit();
+      ReadFrameSize(fhdr);
+      ReadDisplayFrameSize(fhdr);
+    } else {
+      for (size_t i = 0; i < kVp9NumRefFrames; i++)
+        fhdr->refresh_flag[i] = reader_.ReadBit();
+
+      for (size_t i = 0; i < kVp9NumRefsPerFrame; i++) {
+        fhdr->frame_refs[i] = reader_.ReadLiteral(kVp9NumRefFramesLog2);
+        fhdr->ref_sign_biases[i] = reader_.ReadBit();
+      }
+
+      if (!ReadFrameSizeFromRefs(fhdr))
+        return false;
+      ReadDisplayFrameSize(fhdr);
+
+      fhdr->allow_high_precision_mv = reader_.ReadBit();
+      fhdr->interp_filter = ReadInterpFilter();
+    }
+  }
+
+  if (fhdr->error_resilient_mode) {
+    fhdr->frame_parallel_decoding_mode = true;
+  } else {
+    fhdr->refresh_frame_context = reader_.ReadBit();
+    fhdr->frame_parallel_decoding_mode = reader_.ReadBit();
+  }
+
+  fhdr->frame_context_idx = reader_.ReadLiteral(2);
+
+  ReadLoopFilter(&fhdr->loop_filter);
+  ReadQuantization(&fhdr->quant_params);
+  ReadSegmentation(&fhdr->segment);
+
+  ReadTiles(fhdr);
+
+  fhdr->first_partition_size = reader_.ReadLiteral(16);
+  if (fhdr->first_partition_size == 0) {
+    DVLOG(1) << "invalid header size";
+    return false;
+  }
+
+  if (!reader_.IsValid()) {
+    DVLOG(1) << "parser reads beyond the end of buffer";
+    return false;
+  }
+  fhdr->uncompressed_header_size = reader_.GetBytesRead();
+
+  return true;
+}
+
+void Vp9Parser::UpdateSlots(const Vp9FrameHeader* fhdr) {
+  for (int i = 0; i < kVp9NumRefFrames; i++) {

[Pawel Osciak, 2015/08/05 07:46:32]

s/int/size_t/

[kcwu, 2015/08/05 08:42:40]

Done.

+    if (fhdr->refresh_flag[i]) {
+      ref_slots_[i].width = fhdr->width;
+      ref_slots_[i].height = fhdr->height;
+    }
+  }
+}
+
+bool Vp9Parser::ParseFrame(const uint8_t* stream,
+                           size_t frame_size,
+                           Vp9FrameHeader* fhdr) {
+  DCHECK(stream);
+  stream_ = stream;
+  size_ = frame_size;
+  memset(fhdr, 0, sizeof(*fhdr));
+
+  if (!ParseUncompressedHeader(fhdr))
+    return false;
+
+  UpdateSlots(fhdr);
+
+  return true;
+}
+
+}  // namespace media