media/base/audio_decoder.h

   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
  16 namespace media {
  17
  18 class AudioBuffer;
  19 class DemuxerStream;
  20
  21 class 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 Reset() or destruction.
  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
  44   // Fires any pending callbacks, stops and destroys the decoder.
  45   // Note: Since this is a destructor, |this| will be destroyed after this call.
  46   // Make sure the callbacks fired from this call doesn't post any task that
  47   // depends on |this|.
  48   virtual ~AudioDecoder();
  49
  50   // Initializes an AudioDecoder with the given DemuxerStream, executing the
  51   // callback upon completion.
  52   //  |statistics_cb| is used to update global pipeline statistics.
  53   //  |output_cb| is called for decoded audio buffers (see Decode()).
  54   virtual void Initialize(const AudioDecoderConfig& config,
  55                           const PipelineStatusCB& status_cb,
  56                           const OutputCB& output_cb) = 0;
  57
  58   // Requests samples to be decoded. Only one decode may be in flight at any
  59   // given time. Once the buffer is decoded the decoder calls |decode_cb|.
  60   // |output_cb| specified in Initialize() is called for each decoded buffer,
  61   // before or after |decode_cb|.
  62   //
  63   // Implementations guarantee that the callbacks will not be called from within
  64   // this method.
  65   //
  66   // If |buffer| is an EOS buffer then the decoder must be flushed, i.e.
  67   // |output_cb| must be called for each frame pending in the queue and
  68   // |decode_cb| must be called after that.
  69   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  70                       const DecodeCB& decode_cb) = 0;
  71
  72   // Resets decoder state. All pending Decode() requests will be finished or
  73   // aborted before |closure| is called.
  74   virtual void Reset(const base::Closure& closure) = 0;
  75
  76  private:
  77   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
  78 };
  79
  80 }  // namespace media
  81
  82 #endif  // MEDIA_BASE_AUDIO_DECODER_H_