Mpeg2TS - estimate duration for video frames.

media/formats/mp2t/es_adapter_video.h

+// Copyright 2014 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_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_
+#define MEDIA_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_
+
+#include <deque>
+#include <list>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/time/time.h"
+
+namespace media {
+class StreamParserBuffer;
+class VideoDecoderConfig;
+
+namespace mp2t {
+
+// Some constraints of the MSE spec are not necessarily met by video streams
+// inside an Mpeg2 TS stream.
+// The goal of the ES adapter is to modify the incoming buffers to meet these
+// constraints, e.g.
+// - get the frame duration,
+// - make sure the first video frame is a key frame.

[acolwell GONE FROM CHROMIUM, 2014/07/09 20:01:10]

This comment is a little misleading. The FrameProcessor should be taking care of
non-keyframes being passed in first. The code in this class is just replacing
those non-keyframes with the first frame to avoid a hole from being created in
the timeline if the video lags the audio significantly. Right? Does this still
apply with the new FrameProcessor.

[damienv1, 2014/07/10 16:00:54]

Right. The frame processor discards non key-frame. So the goal here is to
replace non key frames by the first key frame to avoid a hole in the video
source buffer (in that case, playback would stall).

+class EsAdapterVideo {
+ public:
+  typedef base::Callback<void(const VideoDecoderConfig&)> NewVideoConfigCB;
+  typedef base::Callback<void(scoped_refptr<StreamParserBuffer>)> EmitBufferCB;
+
+  EsAdapterVideo(
+      const NewVideoConfigCB& new_video_config_cb,
+      const EmitBufferCB& emit_buffer_cb);
+  ~EsAdapterVideo();
+
+  // Force the emission of the pending video buffers.
+  void Flush();

[acolwell GONE FROM CHROMIUM, 2014/07/09 20:01:11]

nit: s/Flush/EmitAllPendingBuffers/?

[damienv1, 2014/07/10 16:00:53]

I am using Flush in EsParser.
I'll keep the same naming here.

+
+  // Provide the configuration that applies to the upcoming video buffers.
+  void OnConfigChanged(const VideoDecoderConfig& video_decoder_config);
+
+  // Provide a new video buffer.
+  void OnNewBuffer(
+      const scoped_refptr<StreamParserBuffer>& stream_parser_buffer);
+
+ private:
+  typedef std::deque<scoped_refptr<StreamParserBuffer> > BufferQueue;
+  typedef std::pair<int64, VideoDecoderConfig> ConfigEntry;
+
+  void ProcessPendingBuffers(bool flush);
+
+  // Return the PTS of the frame that comes just after |current_pts| in
+  // presentation order. Return kNoTimestamp() if not found.
+  base::TimeDelta GetNextFramePts(base::TimeDelta current_pts);
+
+  void ReplaceDiscardedFrames(
+      const scoped_refptr<StreamParserBuffer>& stream_parser_buffer);
+
+  NewVideoConfigCB new_video_config_cb_;
+  EmitBufferCB emit_buffer_cb_;
+
+  bool has_valid_config_;
+  bool has_valid_frame_;
+
+  // Duration of the last video frame.
+  base::TimeDelta last_frame_duration_;
+
+  // Association between a video config and a buffer index.
+  std::list<ConfigEntry> config_list_;
+
+  // Index of the first buffer in |buffer_list_|.

[acolwell GONE FROM CHROMIUM, 2014/07/09 20:01:10]

nit: I think this comment may be missing something. I'd expect the "index of the
first buffer in |buffer_list_|" to always be 0. s/Index/Global index/ or
something like that since I believe this is tracking the that the first frame in
buffer_list_ is the n'th buffer passed to this class. 

[damienv1, 2014/07/10 16:00:53]

Agree. The comment should be more accurate. This is an absolute index of the
frame since the creation of the ES adapter.

+  int64 buffer_index_;
+
+  // List of buffer to be emitted and PTS of frames already emitted.
+  BufferQueue buffer_list_;
+  std::list<base::TimeDelta> emitted_pts_;
+
+  // - Minimum PTS of discarded frames.
+  // - DTS of discarded frames.
+  base::TimeDelta discarded_frames_min_pts_;
+  std::list<base::TimeDelta> discarded_frames_dts_;
+
+  DISALLOW_COPY_AND_ASSIGN(EsAdapterVideo);
+};
+
+}  // namespace mp2t
+}  // namespace media
+
+#endif  // MEDIA_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_