Add VaapiVideoEncodeAccelerator for HW-accelerated video encode.

media/filters/h264_bitstream_buffer.h

+// Copyright 2014 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 H264BitstreamBuffer class for
+// constructing raw bitstream buffers containing NAL units in
+// H.264 Annex-B stream format.
+// See H.264 spec Annex B and chapter 7for more details.
+
+#ifndef MEDIA_FILTERS_H264_BITSTREAM_BUFFER_H_
+#define MEDIA_FILTERS_H264_BITSTREAM_BUFFER_H_
+
+#include "base/gtest_prod_util.h"
+#include "base/numerics/safe_conversions.h"
+#include "media/base/media_export.h"
+#include "media/base/video_frame.h"
+#include "media/filters/h264_parser.h"
+
+namespace media {
+
+// Holds one or more NALUs as a raw bitstream buffer in H.264 Annex-B format.
+// Note that this class currently does NOT insert emulation prevention
+// three-byte sequences (spec 7.3.1).
+class MEDIA_EXPORT H264BitstreamBuffer {
+ public:
+  H264BitstreamBuffer();
+  ~H264BitstreamBuffer();
+
+  // Discard all data and reset the buffer for reuse.
+  void Reset();
+
+  // Append |num_bits| bits to the stream from |val|.
+  // |val| is interpreted in the host endianness.
+  template <typename T>
+  void AppendBits(size_t num_bits, T val) {
+    DCHECK_GE(val, 0);
+    AppendU64(num_bits, static_cast<uint64>(val));
+  }
+
+  void AppendBits(size_t num_bits, bool val) {
+    DCHECK_EQ(num_bits, 1);
+    AppendBool(val);
+  }
+
+  // Append a one-bit bool/flag value |val| to the stream.
+  void AppendBool(bool val);
+
+  // Append a signed value in |val| in Exp-Golomb code.
+  void AppendSE(int val);
+
+  // Append an unsigned value in |val| in Exp-Golomb code.
+  void AppendUE(unsigned int val);
+
+  // Start a new NALU of type |nalu_type| and with given |nal_ref_idc|
+  // (see spec). Note, that until FinishNALU() is called, some of the bits
+  // may not be flushed into the buffer and the data will not be correctly
+  // aligned with trailing bits.
+  void BeginNALU(H264NALU::Type nalu_type, int nal_ref_idc);
+
+  // Finish current NALU. This will flush any cached bits and correctly align
+  // the buffer with RBSP trailing bits. This MUST be called for the stream
+  // returned by data() to be correct.
+  void FinishNALU();
+
+  // Return number of full bytes in the stream. Note that FinishNALU() has to
+  // be called to flush cached bits, or the return value will not include them.
+  size_t BytesInBuffer();
+
+  // Return a pointer to the stream. FinishNALU() must be called before
+  // accessing the stream, otherwise some bits may still be cached and not
+  // in the buffer.
+  uint8* data();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(H264BitstreamBufferAppendBitsTest,
+                           AppendAndVerifyBits);
+
+  // Allocate additional memory (kGrowBytes bytes) for the buffer.
+  void Grow();
+
+  // Append |num_bits| bits from U64 value |val| (in host endianness).
+  void AppendU64(size_t num_bits, uint64 val);
+
+  // Flush any cached bits in the reg with byte granularity, i.e. enough
+  // bytes to flush all pending bits, but not more.
+  void FlushReg();
+
+  typedef uint64 RegType;
+  enum {
+    // Sizes of reg_.
+    kRegByteSize = sizeof(RegType),
+    kRegBitSize = kRegByteSize * 8,
+    // Amount of bytes to grow the buffer by when we run out of
+    // previously-allocated memory for it.
+    kGrowBytes = 4096,
+  };
+
+  COMPILE_ASSERT(kGrowBytes >= kRegByteSize,
+                 kGrowBytes_must_be_larger_than_kRegByteSize);
+
+  // Unused bits left in reg_.
+  size_t bits_left_in_reg_;
+
+  // Cache for appended bits. Bits are flushed to data_ with kRegByteSize
+  // granularity, i.e. when reg_ becomes full, or when an explicit FlushReg()
+  // is called.
+  RegType reg_;
+
+  // Current capacity of data_, in bytes.
+  size_t capacity_;
+
+  // Current byte offset in data_ (points to the start of unwritten bits).
+  size_t pos_;
+
+  // Buffer for stream data.
+  uint8* data_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_H264_BITSTREAM_BUFFER_H_