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