Merge 279733 "Revert 279650 "Add VaapiVideoEncodeAccelerator for..."

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) {
-    AppendU64(num_bits, static_cast<uint64>(val));
-  }
-
-  void AppendBits(size_t num_bits, bool val) {
-    DCHECK_EQ(num_bits, 1ul);
-    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_