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      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_RECEIVER_AUDIO_DECODER_H_
      6 #define MEDIA_CAST_RECEIVER_AUDIO_DECODER_H_
      7 
      8 #include "base/callback.h"
      9 #include "base/memory/ref_counted.h"
     10 #include "media/base/audio_bus.h"
     11 #include "media/cast/cast_config.h"
     12 #include "media/cast/cast_environment.h"
     13 #include "media/cast/transport/cast_transport_config.h"
     14 
     15 namespace media {
     16 namespace cast {
     17 
     18 class AudioDecoder {
     19  public:
     20   // Callback passed to DecodeFrame, to deliver decoded audio data from the
     21   // decoder.  The number of samples in |audio_bus| may vary, and |audio_bus|
     22   // can be NULL when errors occur.  |is_continuous| is normally true, but will
     23   // be false if the decoder has detected a frame skip since the last decode
     24   // operation; and the client should take steps to smooth audio discontinuities
     25   // in this case.
     26   typedef base::Callback<void(scoped_ptr<AudioBus> audio_bus,
     27                               bool is_continuous)> DecodeFrameCallback;
     28 
     29   AudioDecoder(const scoped_refptr<CastEnvironment>& cast_environment,
     30                int channels,
     31                int sampling_rate,
     32                transport::AudioCodec codec);
     33   virtual ~AudioDecoder();
     34 
     35   // Returns STATUS_AUDIO_INITIALIZED if the decoder was successfully
     36   // constructed from the given FrameReceiverConfig.  If this method returns any
     37   // other value, calls to DecodeFrame() will not succeed.
     38   CastInitializationStatus InitializationResult() const;
     39 
     40   // Decode the payload in |encoded_frame| asynchronously.  |callback| will be
     41   // invoked on the CastEnvironment::MAIN thread with the result.
     42   //
     43   // In the normal case, |encoded_frame->frame_id| will be
     44   // monotonically-increasing by 1 for each successive call to this method.
     45   // When it is not, the decoder will assume one or more frames have been
     46   // dropped (e.g., due to packet loss), and will perform recovery actions.
     47   void DecodeFrame(scoped_ptr<transport::EncodedFrame> encoded_frame,
     48                    const DecodeFrameCallback& callback);
     49 
     50  private:
     51   class ImplBase;
     52   class OpusImpl;
     53   class Pcm16Impl;
     54 
     55   const scoped_refptr<CastEnvironment> cast_environment_;
     56   scoped_refptr<ImplBase> impl_;
     57 
     58   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
     59 };
     60 
     61 }  // namespace cast
     62 }  // namespace media
     63 
     64 #endif  // MEDIA_CAST_RECEIVER_AUDIO_DECODER_H_
     65