| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COBALT_MEDIA_BASE_AUDIO_PULL_FIFO_H_ |
| #define COBALT_MEDIA_BASE_AUDIO_PULL_FIFO_H_ |
| |
| #include <memory> |
| |
| #include "base/basictypes.h" |
| #include "base/callback.h" |
| #include "cobalt/media/base/media_export.h" |
| |
| namespace cobalt { |
| namespace media { |
| class AudioBus; |
| |
| // A FIFO (First In First Out) buffer to handle mismatches in buffer sizes |
| // between a producer and consumer. The consumer will pull data from this FIFO. |
| // If data is already available in the FIFO, it is provided to the consumer. |
| // If insufficient data is available to satisfy the request, the FIFO will ask |
| // the producer for more data to fulfill a request. |
| class MEDIA_EXPORT AudioPullFifo { |
| public: |
| // Callback type for providing more data into the FIFO. Expects AudioBus |
| // to be completely filled with data upon return; zero padded if not enough |
| // frames are available to satisfy the request. |frame_delay| is the number |
| // of output frames already processed and can be used to estimate delay. |
| typedef base::Callback<void(int frame_delay, AudioBus* audio_bus)> ReadCB; |
| |
| // Constructs an AudioPullFifo with the specified |read_cb|, which is used to |
| // read audio data to the FIFO if data is not already available. The internal |
| // FIFO can contain |channel| number of channels, where each channel is of |
| // length |frames| audio frames. |
| AudioPullFifo(int channels, int frames, const ReadCB& read_cb); |
| virtual ~AudioPullFifo(); |
| |
| // Consumes |frames_to_consume| audio frames from the FIFO and copies |
| // them to |destination|. If the FIFO does not have enough data, we ask |
| // the producer to give us more data to fulfill the request using the |
| // ReadCB implementation. |
| void Consume(AudioBus* destination, int frames_to_consume); |
| |
| // Empties the FIFO without deallocating any memory. |
| void Clear(); |
| |
| // Returns the size of the fifo in number of frames. |
| int SizeInFrames() const; |
| |
| private: |
| // Attempt to fulfill the request using what is available in the FIFO. |
| // Append new data to the |destination| starting at |write_pos|. |
| int ReadFromFifo(AudioBus* destination, int frames_to_provide, int write_pos); |
| |
| // Source of data to the FIFO. |
| const ReadCB read_cb_; |
| |
| // Temporary audio bus to hold the data from the producer. |
| std::unique_ptr<AudioBus> fifo_; |
| int fifo_index_; |
| |
| DISALLOW_COPY_AND_ASSIGN(AudioPullFifo); |
| }; |
| |
| } // namespace media |
| } // namespace cobalt |
| |
| #endif // COBALT_MEDIA_BASE_AUDIO_PULL_FIFO_H_ |