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_RENDERER_H_ 6 #define MEDIA_BASE_AUDIO_RENDERER_H_ 7 8 #include "base/callback.h" 9 #include "base/memory/ref_counted.h" 10 #include "base/time/time.h" 11 #include "media/base/media_export.h" 12 #include "media/base/pipeline_status.h" 13 14 namespace media { 15 16 class DemuxerStream; 17 18 class MEDIA_EXPORT AudioRenderer { 19 public: 20 // First parameter is the current time that has been rendered. 21 // Second parameter is the maximum time value that the clock cannot exceed. 22 typedef base::Callback<void(base::TimeDelta, base::TimeDelta)> TimeCB; 23 24 AudioRenderer(); 25 virtual ~AudioRenderer(); 26 27 // Initialize an AudioRenderer with |stream|, executing |init_cb| upon 28 // completion. 29 // 30 // |statistics_cb| is executed periodically with audio rendering stats. 31 // 32 // |underflow_cb| is executed when the renderer runs out of data to pass to 33 // the audio card during playback. ResumeAfterUnderflow() must be called 34 // to resume playback. Pause(), Preroll(), or Stop() cancels the underflow 35 // condition. 36 // 37 // |time_cb| is executed whenever time has advanced by way of audio rendering. 38 // 39 // |ended_cb| is executed when audio rendering has reached the end of stream. 40 // 41 // |disabled_cb| is executed when audio rendering has been disabled due to 42 // external factors (i.e., device was removed). |time_cb| will no longer be 43 // executed. TODO(scherkus): this might not be needed http://crbug.com/234708 44 // 45 // |error_cb| is executed if an error was encountered. 46 virtual void Initialize(DemuxerStream* stream, 47 const PipelineStatusCB& init_cb, 48 const StatisticsCB& statistics_cb, 49 const base::Closure& underflow_cb, 50 const TimeCB& time_cb, 51 const base::Closure& ended_cb, 52 const base::Closure& disabled_cb, 53 const PipelineStatusCB& error_cb) = 0; 54 55 // Start audio decoding and rendering at the current playback rate, executing 56 // |callback| when playback is underway. 57 virtual void Play(const base::Closure& callback) = 0; 58 59 // Temporarily suspend decoding and rendering audio, executing |callback| when 60 // playback has been suspended. 61 virtual void Pause(const base::Closure& callback) = 0; 62 63 // Discard any audio data, executing |callback| when completed. 64 virtual void Flush(const base::Closure& callback) = 0; 65 66 // Start prerolling audio data for samples starting at |time|, executing 67 // |callback| when completed. 68 // 69 // Only valid to call after a successful Initialize() or Flush(). 70 virtual void Preroll(base::TimeDelta time, 71 const PipelineStatusCB& callback) = 0; 72 73 // Stop all operations in preparation for being deleted, executing |callback| 74 // when complete. 75 virtual void Stop(const base::Closure& callback) = 0; 76 77 // Updates the current playback rate. 78 virtual void SetPlaybackRate(float playback_rate) = 0; 79 80 // Sets the output volume. 81 virtual void SetVolume(float volume) = 0; 82 83 // Resumes playback after underflow occurs. 84 virtual void ResumeAfterUnderflow() = 0; 85 86 private: 87 DISALLOW_COPY_AND_ASSIGN(AudioRenderer); 88 }; 89 90 } // namespace media 91 92 #endif // MEDIA_BASE_AUDIO_RENDERER_H_ 93
