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/channel_layout.h" 11 #include "media/base/pipeline_status.h" 12 #include "media/base/media_export.h" 13 14 namespace media { 15 16 class AudioBuffer; 17 class DemuxerStream; 18 19 class MEDIA_EXPORT AudioDecoder { 20 public: 21 // Status codes for read operations. 22 enum Status { 23 kOk, 24 kAborted, 25 kDecodeError, 26 }; 27 28 AudioDecoder(); 29 virtual ~AudioDecoder(); 30 31 // Initialize an AudioDecoder with the given DemuxerStream, executing the 32 // callback upon completion. 33 // statistics_cb is used to update global pipeline statistics. 34 virtual void Initialize(DemuxerStream* stream, 35 const PipelineStatusCB& status_cb, 36 const StatisticsCB& statistics_cb) = 0; 37 38 // Request samples to be decoded and returned via the provided callback. 39 // Only one read may be in flight at any given time. 40 // 41 // Implementations guarantee that the callback will not be called from within 42 // this method. 43 // 44 // Non-NULL sample buffer pointers will contain decoded audio data or may 45 // indicate the end of the stream. A NULL buffer pointer indicates an aborted 46 // Read(). This can happen if the DemuxerStream gets flushed and doesn't have 47 // any more data to return. 48 typedef base::Callback<void(Status, const scoped_refptr<AudioBuffer>&)> 49 ReadCB; 50 virtual void Read(const ReadCB& read_cb) = 0; 51 52 // Reset decoder state, dropping any queued encoded data. 53 virtual void Reset(const base::Closure& closure) = 0; 54 55 // Returns various information about the decoded audio format. 56 virtual int bits_per_channel() = 0; 57 virtual ChannelLayout channel_layout() = 0; 58 virtual int samples_per_second() = 0; 59 60 private: 61 DISALLOW_COPY_AND_ASSIGN(AudioDecoder); 62 }; 63 64 } // namespace media 65 66 #endif // MEDIA_BASE_AUDIO_DECODER_H_ 67