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   };
  33
  34   // Callback for VideoDecoder initialization.
  35   typedef base::Callback<void(bool success)> InitCB;
  36
  37   // Callback for AudioDecoder to return a decoded frame whenever it becomes
  38   // available. Only non-EOS frames should be returned via this callback.
  39   typedef base::Callback<void(const scoped_refptr<AudioBuffer>&)> OutputCB;
  40
  41   // Callback for Decode(). Called after the decoder has completed decoding
  42   // corresponding DecoderBuffer, indicating that it's ready to accept another
  43   // buffer to decode.
  44   typedef base::Callback<void(Status)> DecodeCB;
  45
  46   AudioDecoder();
  47
  48   // Fires any pending callbacks, stops and destroys the decoder.
  49   // Note: Since this is a destructor, |this| will be destroyed after this call.
  50   // Make sure the callbacks fired from this call doesn't post any task that
  51   // depends on |this|.
  52   virtual ~AudioDecoder();
  53
  54   // Returns the name of the decoder for logging purpose.
  55   virtual std::string GetDisplayName() const = 0;
  56
  57   // Initializes an AudioDecoder with the given DemuxerStream, executing the
  58   // callback upon completion.
  59   //  |init_cb| is used to return initialization status.
  60   //  |output_cb| is called for decoded audio buffers (see Decode()).
  61   virtual void Initialize(const AudioDecoderConfig& config,
  62                           const InitCB& init_cb,
  63                           const OutputCB& output_cb) = 0;
  64
  65   // Requests samples to be decoded. Only one decode may be in flight at any
  66   // given time. Once the buffer is decoded the decoder calls |decode_cb|.
  67   // |output_cb| specified in Initialize() is called for each decoded buffer,
  68   // before or after |decode_cb|.
  69   //
  70   // Implementations guarantee that the callbacks will not be called from within
  71   // this method.
  72   //
  73   // If |buffer| is an EOS buffer then the decoder must be flushed, i.e.
  74   // |output_cb| must be called for each frame pending in the queue and
  75   // |decode_cb| must be called after that.
  76   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  77                       const DecodeCB& decode_cb) = 0;
  78
  79   // Resets decoder state. All pending Decode() requests will be finished or
  80   // aborted before |closure| is called.
  81   virtual void Reset(const base::Closure& closure) = 0;
  82
  83  private:
  84   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
  85 };
  86
  87 }  // namespace media
  88
  89 #endif  // MEDIA_BASE_AUDIO_DECODER_H_