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 Stop() or Reset().
  29     kNotEnoughData,  // Not enough data to produce a video frame.
  30     kDecodeError,  // A decoding error occurred.
  31     kDecryptError  // Decrypting error happened.
  32   };
  33
  34   AudioDecoder();
  35   virtual ~AudioDecoder();
  36
  37   // Initializes an AudioDecoder with the given DemuxerStream, executing the
  38   // callback upon completion.
  39   // statistics_cb is used to update global pipeline statistics.
  40   virtual void Initialize(const AudioDecoderConfig& config,
  41                           const PipelineStatusCB& status_cb) = 0;
  42
  43   // Requests samples to be decoded and returned via the provided callback.
  44   // Only one decode may be in flight at any given time.
  45   //
  46   // Implementations guarantee that the callback will not be called from within
  47   // this method.
  48   //
  49   // Non-NULL sample buffer pointers will contain decoded audio data or may
  50   // indicate the end of the stream. A NULL buffer pointer indicates an aborted
  51   // Decode().
  52   typedef base::Callback<void(Status, const scoped_refptr<AudioBuffer>&)>
  53       DecodeCB;
  54   virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
  55                       const DecodeCB& decode_cb) = 0;
  56
  57   // Some AudioDecoders will queue up multiple AudioBuffers from a single
  58   // DecoderBuffer, if we have any such queued buffers this will return the next
  59   // one. Otherwise we return a NULL AudioBuffer.
  60   virtual scoped_refptr<AudioBuffer> GetDecodeOutput();
  61
  62   // Resets decoder state, dropping any queued encoded data.
  63   virtual void Reset(const base::Closure& closure) = 0;
  64
  65   // Stops decoder, fires any pending callbacks and sets the decoder to an
  66   // uninitialized state. An AudioDecoder cannot be re-initialized after it has
  67   // been stopped.
  68   // Note that if Initialize() is pending or has finished successfully, Stop()
  69   // must be called before destructing the decoder.
  70   virtual void Stop() = 0;
  71
  72  private:
  73   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
  74 };
  75
  76 }  // namespace media
  77
  78 #endif  // MEDIA_BASE_AUDIO_DECODER_H_