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