| // 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 MEDIA_BASE_MULTI_CHANNEL_RESAMPLER_H_ |
| #define MEDIA_BASE_MULTI_CHANNEL_RESAMPLER_H_ |
| |
| #include <stddef.h> |
| |
| #include <memory> |
| #include <vector> |
| |
| #include "base/callback.h" |
| #include "base/macros.h" |
| #include "media/base/sinc_resampler.h" |
| |
| namespace media { |
| class AudioBus; |
| |
| // MultiChannelResampler is a multi channel wrapper for SincResampler; allowing |
| // high quality sample rate conversion of multiple channels at once. |
| class MEDIA_EXPORT MultiChannelResampler { |
| public: |
| // Callback type for providing more data into the resampler. 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 a MultiChannelResampler with the specified |read_cb|, which is |
| // used to acquire audio data for resampling. |io_sample_rate_ratio| is the |
| // ratio of input / output sample rates. |request_frames| is the size in |
| // frames of the AudioBus to be filled by |read_cb|. |
| MultiChannelResampler(int channels, |
| double io_sample_rate_ratio, |
| size_t request_frames, |
| const ReadCB& read_cb); |
| virtual ~MultiChannelResampler(); |
| |
| // Resamples |frames| of data from |read_cb_| into AudioBus. |
| void Resample(int frames, AudioBus* audio_bus); |
| |
| // Flush all buffered data and reset internal indices. Not thread safe, do |
| // not call while Resample() is in progress. |
| void Flush(); |
| |
| // Update ratio for all SincResamplers. SetRatio() will cause reconstruction |
| // of the kernels used for resampling. Not thread safe, do not call while |
| // Resample() is in progress. |
| void SetRatio(double io_sample_rate_ratio); |
| |
| // The maximum size in frames that guarantees Resample() will only make a |
| // single call to |read_cb_| for more data. |
| int ChunkSize() const; |
| |
| // See SincResampler::BufferedFrames. |
| double BufferedFrames() const; |
| |
| // See SincResampler::PrimeWithSilence. |
| void PrimeWithSilence(); |
| |
| private: |
| // SincResampler::ReadCB implementation. ProvideInput() will be called for |
| // each channel (in channel order) as SincResampler needs more data. |
| void ProvideInput(int channel, int frames, float* destination); |
| |
| // Source of data for resampling. |
| ReadCB read_cb_; |
| |
| // Each channel has its own high quality resampler. |
| std::vector<std::unique_ptr<SincResampler>> resamplers_; |
| |
| // Buffers for audio data going into SincResampler from ReadCB. |
| std::unique_ptr<AudioBus> resampler_audio_bus_; |
| |
| // To avoid a memcpy() on the first channel we create a wrapped AudioBus where |
| // the first channel points to the |destination| provided to ProvideInput(). |
| std::unique_ptr<AudioBus> wrapped_resampler_audio_bus_; |
| |
| // The number of output frames that have successfully been processed during |
| // the current Resample() call. |
| int output_frames_ready_; |
| |
| DISALLOW_COPY_AND_ASSIGN(MultiChannelResampler); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_BASE_MULTI_CHANNEL_RESAMPLER_H_ |