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// Copyright (c) 2009 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.
// Software adjust volume of samples, allows each audio stream its own
// volume without impacting master volume for chrome and other applications.
#include "base/basictypes.h"
#include "base/logging.h"
#include "media/audio/audio_util.h"
namespace media {
// Done as C for future assembly optimization and/or to move to different class.
// TODO(fbarchard): add channels_in to allow number of channels to be reduced.
template<class Format>
void AdjustVolumeInternal(Format* buf_out,
int sample_count,
float volume) {
for (int i = 0; i < sample_count; ++i) {
buf_out[i] = static_cast<Format>(buf_out[i] * volume);
}
}
// AdjustVolume() does an in place audio sample change.
bool AdjustVolume(void* buf,
size_t buflen,
int channels,
int bytes_per_sample,
float volume) {
DCHECK(buf);
DCHECK(volume >= 0.0f && volume <= 1.0f);
if (volume == 1.0f) {
return true;
} else if (volume == 0.0f) {
memset(buf, 0, buflen);
return true;
}
if (channels > 0 && channels <= 6 && bytes_per_sample > 0) {
int sample_count = buflen / bytes_per_sample;
if (bytes_per_sample == 1) {
AdjustVolumeInternal(reinterpret_cast<uint8*>(buf),
sample_count,
volume);
return true;
} else if (bytes_per_sample == 2) {
AdjustVolumeInternal(reinterpret_cast<int16*>(buf),
sample_count,
volume);
return true;
} else if (bytes_per_sample == 4) {
AdjustVolumeInternal(reinterpret_cast<int32*>(buf),
sample_count,
volume);
return true;
}
}
return false;
}
} // namespace media
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