media/filters/ffmpeg_h264_to_annex_b_bitstream_converter.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_FILTERS_FFMPEG_H264_TO_ANNEX_B_BITSTREAM_CONVERTER_H_
   6 #define MEDIA_FILTERS_FFMPEG_H264_TO_ANNEX_B_BITSTREAM_CONVERTER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "media/base/media_export.h"
  10 #include "media/filters/ffmpeg_bitstream_converter.h"
  11 #include "media/filters/h264_to_annex_b_bitstream_converter.h"
  12
  13 // Forward declarations for FFmpeg datatypes used.
  14 struct AVCodecContext;
  15 struct AVPacket;
  16
  17 namespace media {
  18
  19 // Bitstream converter that converts H.264 bitstream based FFmpeg packets into
  20 // H.264 Annex B bytestream format.
  21 class MEDIA_EXPORT FFmpegH264ToAnnexBBitstreamConverter
  22     : public FFmpegBitstreamConverter {
  23  public:
  24   // The |stream_codec_context| will be used during conversion and should be the
  25   // AVCodecContext for the stream sourcing these packets. A reference to
  26   // |stream_codec_context| is retained, so it must outlive this class.
  27   explicit FFmpegH264ToAnnexBBitstreamConverter(
  28       AVCodecContext* stream_codec_context);
  29
  30   ~FFmpegH264ToAnnexBBitstreamConverter() override;
  31
  32   // FFmpegBitstreamConverter implementation.
  33   // Converts |packet| to H.264 Annex B bytestream format. This conversion is
  34   // on single NAL unit basis which is contained within the |packet| with the
  35   // exception of the first packet which is prepended with the AVC decoder
  36   // configuration record information. For example:
  37   //
  38   //    NAL unit #1 ==> bytestream buffer #1 (AVC configuraion + NAL unit #1)
  39   //    NAL unit #2 ==> bytestream buffer #2 (NAL unit #2)
  40   //    ...
  41   //    NAL unit #n ==> bytestream buffer #n (NAL unit #n)
  42   //
  43   // Returns true if conversion succeeded. In this case, the output will be
  44   // stored into the |packet|. But user should be aware that this conversion can
  45   // free and reallocate the |packet|, if it needs to do so to fit it in.
  46   // FFmpeg allocation methods will be used for buffer allocation to ensure
  47   // compatibility with FFmpeg's memory management.
  48   //
  49   // Returns false if conversion failed. In this case, the |packet| will not
  50   // be changed.
  51   bool ConvertPacket(AVPacket* packet) override;
  52
  53  private:
  54   // Actual converter class.
  55   H264ToAnnexBBitstreamConverter converter_;
  56
  57   // Flag for indicating whether global parameter sets have been processed.
  58   bool configuration_processed_;
  59
  60   // Variable to hold a pointer to memory where we can access the global
  61   // data from the FFmpeg file format's global headers.
  62   AVCodecContext* stream_codec_context_;
  63
  64   DISALLOW_COPY_AND_ASSIGN(FFmpegH264ToAnnexBBitstreamConverter);
  65 };
  66
  67 }  // namespace media
  68
  69 #endif  // MEDIA_FILTERS_FFMPEG_H264_TO_ANNEX_B_BITSTREAM_CONVERTER_H_