MediaStream: Adding VideoTrackRecorder class and unittests

media/capture/webm_muxer.h

 // Copyright 2015 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.
 
 #ifndef MEDIA_FILTERS_LIBWEBM_MUXER_H_
 #define MEDIA_FILTERS_LIBWEBM_MUXER_H_
 
 #include <set>
 
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
+#include "base/memory/weak_ptr.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/string_piece.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 #include "third_party/libwebm/source/mkvmuxer.hpp"
 #include "ui/gfx/geometry/size.h"
 
 namespace media {
 
 // Adapter class to manage a WebM container [1], a simplified version of a
 // Matroska container [2], composed of an EBML header, and a single Segment
 // including at least a Track Section and a number of SimpleBlocks each
 // containing a single encoded video frame. WebM container has no Trailer.
-// Clients will push encoded VPx video frames one by one via OnEncodedVideo()
-// with indication of the Track they belong to, and libwebm will eventually ping
+// Clients will push encoded VPx video frames one by one via the
+// OnEncodedVideoCB() returned by AddVideoTrack(). libwebm will eventually ping
 // the WriteDataCB passed on contructor with the wrapped encoded data. All
 // operations must happen in a single thread, where WebmMuxer is created and
 // destroyed.
 // [1] http://www.webmproject.org/docs/container/
 // [2] http://www.matroska.org/technical/specs/index.html
 // TODO(mcasas): Add support for Audio muxing.
 class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
  public:
   // Callback to be called when WebmMuxer is ready to write a chunk of data,
   // either any file header or a SingleBlock. The chunk is described as a byte
   // array and a byte length.
   using WriteDataCB = base::Callback<void(const base::StringPiece&)>;
 
   explicit WebmMuxer(const WriteDataCB& write_data_callback);
   ~WebmMuxer() override;
 
-  // Creates and adds a new video track. Called before receiving the first
+  // Creates and adds a new video track. Called upon receiving the first
   // frame of a given Track, adds |frame_size| and |frame_rate| to the Segment
   // info, although individual frames passed to OnEncodedVideo() can have any
-  // frame size. Returns the track_index to be used for OnEncodedVideo().
-  uint64_t AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
+  // frame size. Returns OnEncodedVideo() callback with a |track_number| bound
+  // in the callback.
+  using OnEncodedVideoCB = base::Callback<void(const base::StringPiece& data,
+                                               base::TimeDelta timestamp,
+                                               bool is_key_frame)>;
+  OnEncodedVideoCB AddVideoTrack(const gfx::Size& frame_size,
+                                 double frame_rate);
+
+ private:
+  friend class WebmMuxerTest;
 
   // Adds a frame with |encoded_data.data()| to WebM Segment. |track_number| is
-  // a caller-side identifier and must have been provided by AddVideoTrack().
+  // a caller-side identifier and must have been returned by AddVideoTrack().
   // TODO(mcasas): Revisit how |encoded_data| is passed once the whole recording
   // chain is setup (http://crbug.com/262211).
   void OnEncodedVideo(uint64_t track_number,
                       const base::StringPiece& encoded_data,
                       base::TimeDelta timestamp,
                       bool keyframe);
 
- private:
-  friend class WebmMuxerTest;
-
   // IMkvWriter interface.
   mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
   mkvmuxer::int64 Position() const override;
   mkvmuxer::int32 Position(mkvmuxer::int64 position) override;
   bool Seekable() const override;
   void ElementStartNotify(mkvmuxer::uint64 element_id,
                           mkvmuxer::int64 position) override;
 
   // Used to DCHECK that we are called on the correct thread.
   base::ThreadChecker thread_checker_;
 
   // Callback to dump written data as being called by libwebm.
   const WriteDataCB write_data_callback_;
 
   // Rolling counter of the position in bytes of the written goo.
   base::CheckedNumeric<mkvmuxer::int64> position_;
 
   // The MkvMuxer active element.
   mkvmuxer::Segment segment_;
 
+  base::WeakPtrFactory<WebmMuxer> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(WebmMuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_LIBWEBM_MUXER_H_