audio_decoder.h revision 6d86b77056ed63eb6871182f42a9fd5f07550f90 
1// Copyright (c) 2012 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_BASE_AUDIO_DECODER_H_
6#define MEDIA_BASE_AUDIO_DECODER_H_
7
8#include "base/callback.h"
9#include "base/memory/ref_counted.h"
10#include "media/base/audio_decoder_config.h"
11#include "media/base/channel_layout.h"
12#include "media/base/decoder_buffer.h"
13#include "media/base/media_export.h"
14#include "media/base/pipeline_status.h"
15
16namespace media {
17
18class AudioBuffer;
19class DemuxerStream;
20
21class MEDIA_EXPORT AudioDecoder {
22 public:
23  // Status codes for decode operations.
24  // TODO(rileya): Now that both AudioDecoder and VideoDecoder Status enums
25  // match, break them into a decoder_status.h.
26  enum Status {
27    kOk,  // We're all good.
28    kAborted,  // We aborted as a result of Stop() or Reset().
29    kDecodeError,  // A decoding error occurred.
30    kDecryptError  // Decrypting error happened.
31  };
32
33  // Callback for AudioDecoder to return a decoded frame whenever it becomes
34  // available. Only non-EOS frames should be returned via this callback.
35  typedef base::Callback<void(const scoped_refptr<AudioBuffer>&)> OutputCB;
36
37  // Callback for Decode(). Called after the decoder has completed decoding
38  // corresponding DecoderBuffer, indicating that it's ready to accept another
39  // buffer to decode.
40  typedef base::Callback<void(Status)> DecodeCB;
41
42  AudioDecoder();
43  virtual ~AudioDecoder();
44
45  // Initializes an AudioDecoder with the given DemuxerStream, executing the
46  // callback upon completion.
47  //  |statistics_cb| is used to update global pipeline statistics.
48  //  |output_cb| is called for decoded audio buffers (see Decode()).
49  virtual void Initialize(const AudioDecoderConfig& config,
50                          const PipelineStatusCB& status_cb,
51                          const OutputCB& output_cb) = 0;
52
53  // Requests samples to be decoded. Only one decode may be in flight at any
54  // given time. Once the buffer is decoded the decoder calls |decode_cb|.
55  // |output_cb| specified in Initialize() is called for each decoded buffer,
56  // before or after |decode_cb|.
57  //
58  // Implementations guarantee that the callbacks will not be called from within
59  // this method.
60  //
61  // If |buffer| is an EOS buffer then the decoder must be flushed, i.e.
62  // |output_cb| must be called for each frame pending in the queue and
63  // |decode_cb| must be called after that.
64  virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
65                      const DecodeCB& decode_cb) = 0;
66
67  // Resets decoder state. All pending Decode() requests will be finished or
68  // aborted before |closure| is called.
69  virtual void Reset(const base::Closure& closure) = 0;
70
71  // Stops decoder, fires any pending callbacks and sets the decoder to an
72  // uninitialized state. An AudioDecoder cannot be re-initialized after it has
73  // been stopped. DecodeCB and OutputCB may still be called for older buffers
74  // if they were scheduled before this method is called.
75  // Note that if Initialize() is pending or has finished successfully, Stop()
76  // must be called before destructing the decoder.
77  virtual void Stop() = 0;
78
79 private:
80  DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
81};
82
83}  // namespace media
84
85#endif  // MEDIA_BASE_AUDIO_DECODER_H_
86