media/cast/receiver/audio_decoder.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_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/net/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                Codec codec);
  33   virtual ~AudioDecoder();
  34
  35   // Returns STATUS_INITIALIZED if the decoder was successfully constructed from
  36   // the given FrameReceiverConfig.  If this method returns any other value,
  37   // calls to DecodeFrame() will not succeed.
  38   OperationalStatus 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<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_