media/cast/sender/video_encoder.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_ENCODER_H_
   6 #define MEDIA_CAST_SENDER_VIDEO_ENCODER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/time/time.h"
  12 #include "media/base/video_frame.h"
  13 #include "media/cast/cast_config.h"
  14 #include "media/cast/cast_environment.h"
  15 #include "media/cast/sender/sender_encoded_frame.h"
  16 #include "media/cast/sender/video_frame_factory.h"
  17
  18 namespace media {
  19 namespace cast {
  20
  21 // All these functions are called from the main cast thread.
  22 class VideoEncoder {
  23  public:
  24   // Callback used to deliver an encoded frame on the Cast MAIN thread.
  25   using FrameEncodedCallback =
  26       base::Callback<void(scoped_ptr<SenderEncodedFrame>)>;
  27
  28   // Creates a VideoEncoder instance from the given |video_config| and based on
  29   // the current platform's hardware/library support; or null if no
  30   // implementation will suffice.  The instance will run |status_change_cb| at
  31   // some point in the future to indicate initialization success/failure.
  32   //
  33   // All VideoEncoder instances returned by this function support encoding
  34   // sequences of differently-size VideoFrames.
  35   //
  36   // TODO(miu): Remove the CreateVEA callbacks.  http://crbug.com/454029
  37   static scoped_ptr<VideoEncoder> Create(
  38       const scoped_refptr<CastEnvironment>& cast_environment,
  39       const VideoSenderConfig& video_config,
  40       const StatusChangeCallback& status_change_cb,
  41       const CreateVideoEncodeAcceleratorCallback& create_vea_cb,
  42       const CreateVideoEncodeMemoryCallback& create_video_encode_memory_cb);
  43
  44   virtual ~VideoEncoder() {}
  45
  46   // If true is returned, the Encoder has accepted the request and will process
  47   // it asynchronously, running |frame_encoded_callback| on the MAIN
  48   // CastEnvironment thread with the result.  If false is returned, nothing
  49   // happens and the callback will not be run.
  50   virtual bool EncodeVideoFrame(
  51       const scoped_refptr<media::VideoFrame>& video_frame,
  52       const base::TimeTicks& reference_time,
  53       const FrameEncodedCallback& frame_encoded_callback) = 0;
  54
  55   // Inform the encoder about the new target bit rate.
  56   virtual void SetBitRate(int new_bit_rate) = 0;
  57
  58   // Inform the encoder to encode the next frame as a key frame.
  59   virtual void GenerateKeyFrame() = 0;
  60
  61   // Inform the encoder to only reference frames older or equal to frame_id;
  62   virtual void LatestFrameIdToReference(uint32 frame_id) = 0;
  63
  64   // Creates a |VideoFrameFactory| object to vend |VideoFrame| object with
  65   // encoder affinity (defined as offering some sort of performance benefit).
  66   // This is an optional capability and by default returns null.
  67   virtual scoped_ptr<VideoFrameFactory> CreateVideoFrameFactory();
  68
  69   // Instructs the encoder to finish and emit all frames that have been
  70   // submitted for encoding. An encoder may hold a certain number of frames for
  71   // analysis. Under certain network conditions, particularly when there is
  72   // network congestion, it is necessary to flush out of the encoder all
  73   // submitted frames so that eventually new frames may be encoded. Like
  74   // EncodeVideoFrame(), the encoder will process this request asynchronously.
  75   virtual void EmitFrames();
  76 };
  77
  78 }  // namespace cast
  79 }  // namespace media
  80
  81 #endif  // MEDIA_CAST_SENDER_VIDEO_ENCODER_H_