Fix race condition in initializing downmix
The code that initializes downmix GUID searches for an effect of
the right type. If two or more AudioMixers are created, there is a
possibility that the GUID will temporarily have the wrong value.
Now the initialization is only done once, regardless of how many
AudioMixers there are.
Other minor changes:
- use naming convention of leading 's' for static member variables
- log message for no downmix effect is now a warning instead of an error,
since it is not an error until there is actual content to downmix
without a downmix effect
Change-Id: I33ab0e51cf9d24ecaf8ae868883736b0772178c4
diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index 91aedbb..5fe5fcb 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -90,9 +90,9 @@
// ----------------------------------------------------------------------------
-bool AudioMixer::isMultichannelCapable = false;
+bool AudioMixer::sIsMultichannelCapable = false;
-effect_descriptor_t AudioMixer::dwnmFxDesc;
+effect_descriptor_t AudioMixer::sDwnmFxDesc;
// Ensure mConfiguredNames bitmask is initialized properly on all architectures.
// The value of 1 << x is undefined in C when x >= 32.
@@ -136,27 +136,6 @@
t++;
}
- // find multichannel downmix effect if we have to play multichannel content
- uint32_t numEffects = 0;
- int ret = EffectQueryNumberEffects(&numEffects);
- if (ret != 0) {
- ALOGE("AudioMixer() error %d querying number of effects", ret);
- return;
- }
- ALOGV("EffectQueryNumberEffects() numEffects=%d", numEffects);
-
- for (uint32_t i = 0 ; i < numEffects ; i++) {
- if (EffectQueryEffect(i, &dwnmFxDesc) == 0) {
- ALOGV("effect %d is called %s", i, dwnmFxDesc.name);
- if (memcmp(&dwnmFxDesc.type, EFFECT_UIID_DOWNMIX, sizeof(effect_uuid_t)) == 0) {
- ALOGI("found effect \"%s\" from %s",
- dwnmFxDesc.name, dwnmFxDesc.implementor);
- isMultichannelCapable = true;
- break;
- }
- }
- }
- ALOGE_IF(!isMultichannelCapable, "unable to find downmix effect");
}
AudioMixer::~AudioMixer()
@@ -276,13 +255,13 @@
DownmixerBufferProvider* pDbp = new DownmixerBufferProvider();
int32_t status;
- if (!isMultichannelCapable) {
+ if (!sIsMultichannelCapable) {
ALOGE("prepareTrackForDownmix(%d) fails: mixer doesn't support multichannel content",
trackName);
goto noDownmixForActiveTrack;
}
- if (EffectCreate(&dwnmFxDesc.uuid,
+ if (EffectCreate(&sDwnmFxDesc.uuid,
pTrack->sessionId /*sessionId*/, -2 /*ioId not relevant here, using random value*/,
&pDbp->mDownmixHandle/*pHandle*/) != 0) {
ALOGE("prepareTrackForDownmix(%d) fails: error creating downmixer effect", trackName);
@@ -1459,6 +1438,28 @@
{
LocalClock lc;
sLocalTimeFreq = lc.getLocalFreq();
+
+ // find multichannel downmix effect if we have to play multichannel content
+ uint32_t numEffects = 0;
+ int ret = EffectQueryNumberEffects(&numEffects);
+ if (ret != 0) {
+ ALOGE("AudioMixer() error %d querying number of effects", ret);
+ return;
+ }
+ ALOGV("EffectQueryNumberEffects() numEffects=%d", numEffects);
+
+ for (uint32_t i = 0 ; i < numEffects ; i++) {
+ if (EffectQueryEffect(i, &sDwnmFxDesc) == 0) {
+ ALOGV("effect %d is called %s", i, sDwnmFxDesc.name);
+ if (memcmp(&sDwnmFxDesc.type, EFFECT_UIID_DOWNMIX, sizeof(effect_uuid_t)) == 0) {
+ ALOGI("found effect \"%s\" from %s",
+ sDwnmFxDesc.name, sDwnmFxDesc.implementor);
+ sIsMultichannelCapable = true;
+ break;
+ }
+ }
+ }
+ ALOGW_IF(!sIsMultichannelCapable, "unable to find downmix effect");
}
// ----------------------------------------------------------------------------
diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index 43aeb86..a15bdca 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -256,9 +256,9 @@
state_t mState __attribute__((aligned(32)));
// effect descriptor for the downmixer used by the mixer
- static effect_descriptor_t dwnmFxDesc;
+ static effect_descriptor_t sDwnmFxDesc;
// indicates whether a downmix effect has been found and is usable by this mixer
- static bool isMultichannelCapable;
+ static bool sIsMultichannelCapable;
// Call after changing either the enabled status of a track, or parameters of an enabled track.
// OK to call more often than that, but unnecessary.