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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_MEDIA_MULTI_CHANNEL_RESAMPLER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_MEDIA_MULTI_CHANNEL_RESAMPLER_H_
#include <memory>
#include "base/functional/callback.h"
#include "media/base/multi_channel_resampler.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/functional.h"
namespace media {
class AudioBus;
} // namespace media
namespace blink {
class AudioBus;
// This is a simple wrapper around the MultiChannelResampler provided by the
// media layer.
class PLATFORM_EXPORT MediaMultiChannelResampler final {
USING_FAST_MALLOC(MediaMultiChannelResampler);
// 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 WTF::CrossThreadRepeatingFunction<void(int frame_delay,
blink::AudioBus*)>
ReadCB;
public:
// 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|.
MediaMultiChannelResampler(int channels,
double io_sample_rate_ratio,
uint32_t request_frames,
ReadCB read_cb);
MediaMultiChannelResampler(const MediaMultiChannelResampler&) = delete;
MediaMultiChannelResampler& operator=(const MediaMultiChannelResampler&) =
delete;
// Resamples |frames| of data from |read_cb_| into a blink::AudioBus, this
// requires creating a wrapper for the media::AudioBus on each call and so
// resampling directly into a media::AudioBus using ResampleInternal() is
// preferred if possible.
void Resample(int frames, blink::AudioBus* resampler_input_bus);
// Resamples |frames| of data from |read_cb_| into a media::AudioBus by
// directly calling Resample() on the underlying
// media::MultiChannelResampler.
void ResampleInternal(int frames, media::AudioBus* resampler_input_bus);
private:
// Wrapper method used to provide input to the media::MultiChannelResampler
// with a media::AudioBus rather than a blink::AudioBus.
void ProvideResamplerInput(int resampler_frame_delay,
media::AudioBus* resampler_output_bus);
// The resampler being wrapped by this class.
std::unique_ptr<media::MultiChannelResampler> resampler_;
// An intermediary storage (wrapper) for buffers from Web Audio.
const std::unique_ptr<media::AudioBus> resampler_input_bus_wrapper_;
// An intermediary storage (wrapper) for providing the resampler's output.
const scoped_refptr<AudioBus> resampler_output_bus_wrapper_;
// The callback using a blink::AudioBus that will be called by
// ProvideResamplerInput().
ReadCB read_cb_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_MEDIA_MULTI_CHANNEL_RESAMPLER_H_
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