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// 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.
#include "base/logging.h"
#include "media/audio/audio_input_stream_impl.h"
namespace media {
static const int kMinIntervalBetweenVolumeUpdatesMs = 1000;
AudioInputStreamImpl::AudioInputStreamImpl()
: agc_is_enabled_(false),
max_volume_(0.0),
normalized_volume_(0.0) {
}
AudioInputStreamImpl::~AudioInputStreamImpl() {}
void AudioInputStreamImpl::SetAutomaticGainControl(bool enabled) {
agc_is_enabled_ = enabled;
}
bool AudioInputStreamImpl::GetAutomaticGainControl() {
return agc_is_enabled_;
}
void AudioInputStreamImpl::UpdateAgcVolume() {
base::AutoLock lock(lock_);
// We take new volume samples once every second when the AGC is enabled.
// To ensure that a new setting has an immediate effect, the new volume
// setting is cached here. It will ensure that the next OnData() callback
// will contain a new valid volume level. If this approach was not taken,
// we could report invalid volume levels to the client for a time period
// of up to one second.
if (agc_is_enabled_) {
GetNormalizedVolume();
}
}
void AudioInputStreamImpl::QueryAgcVolume(double* normalized_volume) {
base::AutoLock lock(lock_);
// Only modify the |volume| output reference if AGC is enabled and if
// more than one second has passed since the volume was updated the last time.
if (agc_is_enabled_) {
base::Time now = base::Time::Now();
if ((now - last_volume_update_time_).InMilliseconds() >
kMinIntervalBetweenVolumeUpdatesMs) {
GetNormalizedVolume();
last_volume_update_time_ = now;
}
*normalized_volume = normalized_volume_;
}
}
void AudioInputStreamImpl::GetNormalizedVolume() {
if (max_volume_ == 0.0) {
// Cach the maximum volume if this is the first time we ask for it.
max_volume_ = GetMaxVolume();
}
if (max_volume_ != 0.0) {
// Retrieve the current volume level by asking the audio hardware.
// Range is normalized to [0.0,1.0] or [0.0, 1.5] on Linux.
normalized_volume_ = GetVolume() / max_volume_;
}
}
} // namespace media
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