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CubebUtils.cpp
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CubebUtils.cpp
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <stdint.h>
#include <algorithm>
#include "mozilla/Preferences.h"
#include "mozilla/StaticMutex.h"
#include "CubebUtils.h"
#include "nsAutoRef.h"
#include "prdtoa.h"
#define PREF_VOLUME_SCALE "media.volume_scale"
#define PREF_CUBEB_LATENCY "media.cubeb_latency_ms"
namespace mozilla {
namespace {
// This mutex protects the variables below.
StaticMutex sMutex;
cubeb* sCubebContext;
double sVolumeScale;
uint32_t sCubebLatency;
bool sCubebLatencyPrefSet;
// Prefered samplerate, in Hz (characteristic of the hardware, mixer, platform,
// and API used).
//
// sMutex protects *initialization* of this, which must be performed from each
// thread before fetching, after which it is safe to fetch without holding the
// mutex because it is only written once per process execution (by the first
// initialization to complete). Since the init must have been called on a
// given thread before fetching the value, it's guaranteed (via the mutex) that
// sufficient memory barriers have occurred to ensure the correct value is
// visible on the querying thread/CPU.
uint32_t sPreferredSampleRate;
} // anonymous namespace
extern PRLogModuleInfo* gAudioStreamLog;
static const uint32_t CUBEB_NORMAL_LATENCY_MS = 100;
namespace CubebUtils {
void PrefChanged(const char* aPref, void* aClosure)
{
if (strcmp(aPref, PREF_VOLUME_SCALE) == 0) {
nsAdoptingString value = Preferences::GetString(aPref);
StaticMutexAutoLock lock(sMutex);
if (value.IsEmpty()) {
sVolumeScale = 1.0;
} else {
NS_ConvertUTF16toUTF8 utf8(value);
sVolumeScale = std::max<double>(0, PR_strtod(utf8.get(), nullptr));
}
} else if (strcmp(aPref, PREF_CUBEB_LATENCY) == 0) {
// Arbitrary default stream latency of 100ms. The higher this
// value, the longer stream volume changes will take to become
// audible.
sCubebLatencyPrefSet = Preferences::HasUserValue(aPref);
uint32_t value = Preferences::GetUint(aPref, CUBEB_NORMAL_LATENCY_MS);
StaticMutexAutoLock lock(sMutex);
sCubebLatency = std::min<uint32_t>(std::max<uint32_t>(value, 1), 1000);
}
}
bool GetFirstStream()
{
static bool sFirstStream = true;
StaticMutexAutoLock lock(sMutex);
bool result = sFirstStream;
sFirstStream = false;
return result;
}
double GetVolumeScale()
{
StaticMutexAutoLock lock(sMutex);
return sVolumeScale;
}
cubeb* GetCubebContext()
{
StaticMutexAutoLock lock(sMutex);
return GetCubebContextUnlocked();
}
void InitPreferredSampleRate()
{
StaticMutexAutoLock lock(sMutex);
if (sPreferredSampleRate == 0 &&
cubeb_get_preferred_sample_rate(GetCubebContextUnlocked(),
&sPreferredSampleRate) != CUBEB_OK) {
// Query failed, use a sensible default.
sPreferredSampleRate = 44100;
}
}
cubeb* GetCubebContextUnlocked()
{
sMutex.AssertCurrentThreadOwns();
if (sCubebContext ||
cubeb_init(&sCubebContext, "CubebUtils") == CUBEB_OK) {
return sCubebContext;
}
NS_WARNING("cubeb_init failed");
return nullptr;
}
uint32_t GetCubebLatency()
{
StaticMutexAutoLock lock(sMutex);
return sCubebLatency;
}
bool CubebLatencyPrefSet()
{
StaticMutexAutoLock lock(sMutex);
return sCubebLatencyPrefSet;
}
void InitLibrary()
{
#ifdef PR_LOGGING
gAudioStreamLog = PR_NewLogModule("AudioStream");
#endif
PrefChanged(PREF_VOLUME_SCALE, nullptr);
Preferences::RegisterCallback(PrefChanged, PREF_VOLUME_SCALE);
PrefChanged(PREF_CUBEB_LATENCY, nullptr);
Preferences::RegisterCallback(PrefChanged, PREF_CUBEB_LATENCY);
}
void ShutdownLibrary()
{
Preferences::UnregisterCallback(PrefChanged, PREF_VOLUME_SCALE);
Preferences::UnregisterCallback(PrefChanged, PREF_CUBEB_LATENCY);
StaticMutexAutoLock lock(sMutex);
if (sCubebContext) {
cubeb_destroy(sCubebContext);
sCubebContext = nullptr;
}
}
uint32_t MaxNumberOfChannels()
{
cubeb* cubebContext = GetCubebContext();
uint32_t maxNumberOfChannels;
if (cubebContext &&
cubeb_get_max_channel_count(cubebContext,
&maxNumberOfChannels) == CUBEB_OK) {
return maxNumberOfChannels;
}
return 0;
}
uint32_t PreferredSampleRate()
{
MOZ_ASSERT(sPreferredSampleRate,
"sPreferredSampleRate has not been initialized!");
return sPreferredSampleRate;
}
#if defined(__ANDROID__) && defined(MOZ_B2G)
cubeb_stream_type ConvertChannelToCubebType(dom::AudioChannel aChannel)
{
switch(aChannel) {
case dom::AudioChannel::Normal:
/* FALLTHROUGH */
case dom::AudioChannel::Content:
return CUBEB_STREAM_TYPE_MUSIC;
case dom::AudioChannel::Notification:
return CUBEB_STREAM_TYPE_NOTIFICATION;
case dom::AudioChannel::Alarm:
return CUBEB_STREAM_TYPE_ALARM;
case dom::AudioChannel::Telephony:
return CUBEB_STREAM_TYPE_VOICE_CALL;
case dom::AudioChannel::Ringer:
return CUBEB_STREAM_TYPE_RING;
case dom::AudioChannel::Publicnotification:
return CUBEB_STREAM_TYPE_SYSTEM_ENFORCED;
default:
NS_ERROR("The value of AudioChannel is invalid");
return CUBEB_STREAM_TYPE_MAX;
}
}
#endif
} // namespace CubebUtils
} // namespace mozilla