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 class VideoFrame;
  23
  24 // Adapter class to manage a WebM container [1], a simplified version of a
  25 // Matroska container [2], composed of an EBML header, and a single Segment
  26 // including at least a Track Section and a number of SimpleBlocks each
  27 // containing a single encoded video frame. WebM container has no Trailer.
  28 // Clients will push encoded VPx video frames one by one via the
  29 // OnEncodedVideo(). libwebm will eventually ping the WriteDataCB passed on
  30 // contructor with the wrapped encoded data.
  31 // WebmMuxer is created/destroyed on a thread, usually the Main Render thread,
  32 // and receives OnEncodedVideo()s on another thread, usually Render IO.
  33 // [1] http://www.webmproject.org/docs/container/
  34 // [2] http://www.matroska.org/technical/specs/index.html
  35 // TODO(mcasas): Add support for Audio muxing.
  36 class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
  37  public:
  38   // Callback to be called when WebmMuxer is ready to write a chunk of data,
  39   // either any file header or a SingleBlock. The chunk is described as a byte
  40   // array and a byte length.
  41   using WriteDataCB = base::Callback<void(const base::StringPiece&)>;
  42
  43   explicit WebmMuxer(const WriteDataCB& write_data_callback);
  44   ~WebmMuxer() override;
  45
  46   // Adds a |video_frame| with |encoded_data.data()| to WebM Segment.
  47   // TODO(mcasas): Revisit how |encoded_data| is passed once the whole recording
  48   // chain is setup (http://crbug.com/262211).
  49   void OnEncodedVideo(const scoped_refptr<VideoFrame>& video_frame,
  50                       const base::StringPiece& encoded_data,
  51                       base::TimeTicks timestamp,
  52                       bool is_key_frame);
  53
  54  private:
  55   friend class WebmMuxerTest;
  56
  57   // Creates and adds a new video track. Called upon receiving the first
  58   // frame of a given Track, adds |frame_size| and |frame_rate| to the Segment
  59   // info, although individual frames passed to OnEncodedVideo() can have any
  60   // frame size.
  61   void AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
  62
  63   // IMkvWriter interface.
  64   mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
  65   mkvmuxer::int64 Position() const override;
  66   mkvmuxer::int32 Position(mkvmuxer::int64 position) override;
  67   bool Seekable() const override;
  68   void ElementStartNotify(mkvmuxer::uint64 element_id,
  69                           mkvmuxer::int64 position) override;
  70
  71   // Used to DCHECK that we are called on the correct thread (usually IO)
  72   base::ThreadChecker thread_checker_;
  73
  74   // A caller-side identifier to interact with |segment_|, initialised upon
  75   // first frame arrival by AddVideoTrack().
  76   uint64_t track_index_;
  77
  78   // Origin of times for frame timestamps.
  79   base::TimeTicks first_frame_timestamp_;
  80
  81   // Callback to dump written data as being called by libwebm.
  82   const WriteDataCB write_data_callback_;
  83
  84   // Rolling counter of the position in bytes of the written goo.
  85   base::CheckedNumeric<mkvmuxer::int64> position_;
  86
  87   // The MkvMuxer active element.
  88   mkvmuxer::Segment segment_;
  89
  90   DISALLOW_COPY_AND_ASSIGN(WebmMuxer);
  91 };
  92
  93 }  // namespace media
  94
  95 #endif  // MEDIA_FILTERS_LIBWEBM_MUXER_H_