623427c522
This CL breaks out the output sample rate calculation from
webrtc::AudioMixerImpl. A new OutputRateCalculator interface is added
to make the sample rate configurable. There are at least three reasons
for this change:
1. The mixer will be used for an internal project, in which no
resampling is done after the mixing. There the sample rate should
be static. Currently, it can differ across mix iterations and
depends on the number of audio sources. If there are no sources,
the WebRTC mixer behavior is to produce silence at 48 kHz.
2. A planned change to WebRTC will make audio processing steps
happen at constant sample rates. A configurable sample rate
calculator will make the transition simpler for the mixer.
3. The current mixer design is a single large file. Behavior is not
always simple to change (e.g. as in this case to mix at a
constant rate), unrelated behavior can be broken, reusing the
mixer in internal projects is tricky. Using DI for the sample
rate calculation solves parts of these issues.
Changes:
The protected mixer c-tor now takes
unique_ptr<OutputRateCalculator>. The current output rate calculation
is moved to DefaultOutputRateCalculator. A new factory method
AudioMixerImpl::CreateWithOutputRateCalculator is added. The old
factory method passes the default rate calculator.
BUG=webrtc:6346
Review-Url: https://codereview.webrtc.org/2557713006
Cr-Commit-Position: refs/heads/master@{#15472}
30 lines
938 B
C++
30 lines
938 B
C++
/*
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* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_MODULES_AUDIO_MIXER_OUTPUT_RATE_CALCULATOR_H_
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#define WEBRTC_MODULES_AUDIO_MIXER_OUTPUT_RATE_CALCULATOR_H_
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#include <vector>
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namespace webrtc {
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// Decides the sample rate of a mixing iteration given the preferred
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// sample rates of the sources.
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class OutputRateCalculator {
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public:
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virtual int CalculateOutputRate(
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const std::vector<int>& preferred_sample_rates) = 0;
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virtual ~OutputRateCalculator() {}
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};
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} // namespace webrtc
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#endif // WEBRTC_MODULES_AUDIO_MIXER_OUTPUT_RATE_CALCULATOR_H_
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