media/capture/webm_muxer.h

   1 // Copyright 2015 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_LIBWEBM_MUXER_H_
   6 #define MEDIA_FILTERS_LIBWEBM_MUXER_H_
   7
   8 #include <set>
   9
  10 #include "base/callback.h"
  11 #include "base/gtest_prod_util.h"
  12 #include "base/numerics/safe_math.h"
  13 #include "base/strings/string_piece.h"
  14 #include "base/threading/thread_checker.h"
  15 #include "base/time/time.h"
  16 #include "media/base/media_export.h"
  17 #include "third_party/libwebm/source/mkvmuxer.hpp"
  18 #include "ui/gfx/geometry/size.h"
  19
  20 namespace media {
  21
  22 // Adapter class to manage a WebM container [1], a simplified version of a
  23 // Matroska container [2], composed of an EBML header, and a single Segment
  24 // including at least a Track Section and a number of SimpleBlocks each
  25 // containing a single encoded video frame. WebM container has no Trailer.
  26 // Clients will push encoded VPx video frames one by one via OnEncodedVideo()
  27 // with indication of the Track they belong to, and libwebm will eventually ping
  28 // the WriteDataCB passed on contructor with the wrapped encoded data. All
  29 // operations must happen in a single thread, where WebmMuxer is created and
  30 // destroyed.
  31 // [1] http://www.webmproject.org/docs/container/
  32 // [2] http://www.matroska.org/technical/specs/index.html
  33 // TODO(mcasas): Add support for Audio muxing.
  34 class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
  35  public:
  36   // Callback to be called when WebmMuxer is ready to write a chunk of data,
  37   // either any file header or a SingleBlock. The chunk is described as a byte
  38   // array and a byte length.
  39   using WriteDataCB = base::Callback<void(const base::StringPiece&)>;
  40
  41   explicit WebmMuxer(const WriteDataCB& write_data_callback);
  42   ~WebmMuxer() override;
  43
  44   // Creates and adds a new video track. Called before receiving the first
  45   // frame of a given Track, adds |frame_size| and |frame_rate| to the Segment
  46   // info, although individual frames passed to OnEncodedVideo() can have any
  47   // frame size. Returns the track_index to be used for OnEncodedVideo().
  48   uint64_t AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
  49
  50   // Adds a frame with |encoded_data.data()| to WebM Segment. |track_number| is
  51   // a caller-side identifier and must have been provided by AddVideoTrack().
  52   // TODO(mcasas): Revisit how |encoded_data| is passed once the whole recording
  53   // chain is setup (http://crbug.com/262211).
  54   void OnEncodedVideo(uint64_t track_number,
  55                       const base::StringPiece& encoded_data,
  56                       base::TimeDelta timestamp,
  57                       bool keyframe);
  58
  59  private:
  60   friend class WebmMuxerTest;
  61
  62   // IMkvWriter interface.
  63   mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
  64   mkvmuxer::int64 Position() const override;
  65   mkvmuxer::int32 Position(mkvmuxer::int64 position) override;
  66   bool Seekable() const override;
  67   void ElementStartNotify(mkvmuxer::uint64 element_id,
  68                           mkvmuxer::int64 position) override;
  69
  70   // Used to DCHECK that we are called on the correct thread.
  71   base::ThreadChecker thread_checker_;
  72
  73   // Callback to dump written data as being called by libwebm.
  74   const WriteDataCB write_data_callback_;
  75
  76   // Rolling counter of the position in bytes of the written goo.
  77   base::CheckedNumeric<mkvmuxer::int64> position_;
  78
  79   // The MkvMuxer active element.
  80   mkvmuxer::Segment segment_;
  81
  82   DISALLOW_COPY_AND_ASSIGN(WebmMuxer);
  83 };
  84
  85 }  // namespace media
  86
  87 #endif  // MEDIA_FILTERS_LIBWEBM_MUXER_H_