media/cast/sender/video_frame_factory.h

   1 // Copyright 2014 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_CAST_SENDER_VIDEO_FRAME_FACTORY_H_
   6 #define MEDIA_CAST_SENDER_VIDEO_FRAME_FACTORY_H_
   7
   8 #include "base/memory/scoped_ptr.h"
   9 #include "base/time/time.h"
  10
  11 namespace gfx {
  12 class Size;
  13 }
  14
  15 namespace media {
  16
  17 class VideoFrame;
  18
  19 namespace cast {
  20
  21 // Interface for an object capable of vending video frames. There is no
  22 // requirement for a |VideoFrameFactory| to be concurrent but it must not be
  23 // pinned to a specific thread. Indeed, |VideoFrameFactory| implementations are
  24 // created by cast on the main cast thread then used by unknown client threads
  25 // via the |VideoFrameInput| interface.
  26 //
  27 // Clients are responsible for serialzing access to a |VideoFrameFactory|.
  28 // Generally speaking, it is expected that a client will be using these objects
  29 // from a rendering thread or callback (which may execute on different threads
  30 // but never concurrently with itself). Forcing every implementation to take a
  31 // lock, even with no contention, is an unnecessary cost, especially on mobile
  32 // platforms.
  33 class VideoFrameFactory {
  34  public:
  35   virtual ~VideoFrameFactory() {}
  36
  37   // Creates a |VideoFrame| suitable for input via |InsertRawVideoFrame|. Frames
  38   // obtained in this manner may provide benefits such memory reuse and affinity
  39   // with the encoder. The format is guaranteed to be I420 or NV12.
  40   //
  41   // This can transiently return null if the encoder is not yet initialized or
  42   // is re-initializing.
  43   virtual scoped_refptr<VideoFrame> MaybeCreateFrame(
  44       const gfx::Size& frame_size, base::TimeDelta timestamp) = 0;
  45 };
  46
  47 }  // namespace cast
  48 }  // namespace media
  49
  50 #endif  // MEDIA_CAST_SENDER_VIDEO_FRAME_FACTORY_H_