Title: [102888] trunk/Source/WebCore
- Revision
- 102888
- Author
- [email protected]
- Date
- 2011-12-14 22:14:11 -0800 (Wed, 14 Dec 2011)
Log Message
fast path to accelerate processing in AudioBus::processWithGainFromMonoStereo
https://bugs.webkit.org/show_bug.cgi?id=74054
Patch by Wei James <[email protected]> on 2011-12-14
Reviewed by Kenneth Russell.
Avoid de-zippering when the gain has converged on the targetGain.
It can get about 75% performance gain at most when all frames don't need
de-zippering.
* platform/audio/AudioBus.cpp:
(WebCore::AudioBus::processWithGainFromMonoStereo):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (102887 => 102888)
--- trunk/Source/WebCore/ChangeLog 2011-12-15 06:14:08 UTC (rev 102887)
+++ trunk/Source/WebCore/ChangeLog 2011-12-15 06:14:11 UTC (rev 102888)
@@ -1,3 +1,17 @@
+2011-12-14 Wei James <[email protected]>
+
+ fast path to accelerate processing in AudioBus::processWithGainFromMonoStereo
+ https://bugs.webkit.org/show_bug.cgi?id=74054
+
+ Reviewed by Kenneth Russell.
+
+ Avoid de-zippering when the gain has converged on the targetGain.
+ It can get about 75% performance gain at most when all frames don't need
+ de-zippering.
+
+ * platform/audio/AudioBus.cpp:
+ (WebCore::AudioBus::processWithGainFromMonoStereo):
+
2011-12-14 Adam Klein <[email protected]>
Optimize MutationObserverInterestGroup construction
Modified: trunk/Source/WebCore/platform/audio/AudioBus.cpp (102887 => 102888)
--- trunk/Source/WebCore/platform/audio/AudioBus.cpp 2011-12-15 06:14:08 UTC (rev 102887)
+++ trunk/Source/WebCore/platform/audio/AudioBus.cpp 2011-12-15 06:14:11 UTC (rev 102888)
@@ -231,15 +231,76 @@
}
}
+// Slowly change gain to desired gain.
+#define GAIN_DEZIPPER \
+ gain += (totalDesiredGain - gain) * DezipperRate; \
+ gain = DenormalDisabler::flushDenormalFloatToZero(gain);
+
+// De-zipper for the first framesToDezipper frames and skip de-zippering for the remaining frames
+// because the gain is close enough to the target gain.
+#define PROCESS_WITH_GAIN(OP) \
+ for (k = 0; k < framesToDezipper; ++k) { \
+ OP \
+ GAIN_DEZIPPER \
+ } \
+ gain = totalDesiredGain; \
+ for (; k < framesToProcess; ++k) \
+ OP
+
+#define STEREO_SUM \
+ { \
+ float sumL = DenormalDisabler::flushDenormalFloatToZero(*destinationL + gain * *sourceL++); \
+ float sumR = DenormalDisabler::flushDenormalFloatToZero(*destinationR + gain * *sourceR++); \
+ *destinationL++ = sumL; \
+ *destinationR++ = sumR; \
+ }
+
+// Mono -> stereo (mix equally into L and R)
+// FIXME: Really we should apply an equal-power scaling factor here, since we're effectively panning center...
+#define MONO2STEREO_SUM \
+ { \
+ float scaled = gain * *sourceL++; \
+ float sumL = DenormalDisabler::flushDenormalFloatToZero(*destinationL + scaled); \
+ float sumR = DenormalDisabler::flushDenormalFloatToZero(*destinationR + scaled); \
+ *destinationL++ = sumL; \
+ *destinationR++ = sumR; \
+ }
+
+#define MONO_SUM \
+ { \
+ float sum = DenormalDisabler::flushDenormalFloatToZero(*destinationL + gain * *sourceL++); \
+ *destinationL++ = sum; \
+ }
+
+#define STEREO_NO_SUM \
+ { \
+ float sampleL = *sourceL++; \
+ float sampleR = *sourceR++; \
+ *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleL); \
+ *destinationR++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleR); \
+ }
+
+// Mono -> stereo (mix equally into L and R)
+// FIXME: Really we should apply an equal-power scaling factor here, since we're effectively panning center...
+#define MONO2STEREO_NO_SUM \
+ { \
+ float sample = *sourceL++; \
+ *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sample); \
+ *destinationR++ = DenormalDisabler::flushDenormalFloatToZero(gain * sample); \
+ }
+
+#define MONO_NO_SUM \
+ { \
+ float sampleL = *sourceL++; \
+ *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleL); \
+ }
+
void AudioBus::processWithGainFromMonoStereo(const AudioBus &sourceBus, double* lastMixGain, double targetGain, bool sumToBus)
{
// We don't want to suddenly change the gain from mixing one time slice to the next,
// so we "de-zipper" by slowly changing the gain each sample-frame until we've achieved the target gain.
// FIXME: optimize this method (SSE, etc.)
- // FIXME: Need fast path here when gain has converged on targetGain. In this case, de-zippering is no longer needed.
- // FIXME: Need fast path when this==sourceBus && lastMixGain==targetGain==1.0 && sumToBus==false (this is a NOP)
-
// FIXME: targetGain and lastMixGain should be changed to floats instead of doubles.
// Take master bus gain into account as well as the targetGain.
@@ -262,82 +323,45 @@
const float DezipperRate = 0.005f;
int framesToProcess = length();
+ // If the gain is within epsilon of totalDesiredGain, we can skip dezippering.
+ // FIXME: this value may need tweaking.
+ const float epsilon = 0.001f;
+ float gainDiff = fabs(totalDesiredGain - gain);
+
+ // Number of frames to de-zipper before we are close enough to the target gain.
+ int framesToDezipper = (gainDiff < epsilon) ? 0 : framesToProcess;
+
+ int k = 0;
+
if (sumToBus) {
// Sum to our bus
if (sourceR && destinationR) {
// Stereo
- while (framesToProcess--) {
- float sumL = DenormalDisabler::flushDenormalFloatToZero(*destinationL + gain * *sourceL++);
- float sumR = DenormalDisabler::flushDenormalFloatToZero(*destinationR + gain * *sourceR++);
- *destinationL++ = sumL;
- *destinationR++ = sumR;
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ PROCESS_WITH_GAIN(STEREO_SUM)
} else if (destinationR) {
- // Mono -> stereo (mix equally into L and R)
- // FIXME: Really we should apply an equal-power scaling factor here, since we're effectively panning center...
- while (framesToProcess--) {
- float scaled = gain * *sourceL++;
- float sumL = DenormalDisabler::flushDenormalFloatToZero(*destinationL + scaled);
- float sumR = DenormalDisabler::flushDenormalFloatToZero(*destinationR + scaled);
-
- *destinationL++ = sumL;
- *destinationR++ = sumR;
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ // Mono -> stereo
+ PROCESS_WITH_GAIN(MONO2STEREO_SUM)
} else {
// Mono
- while (framesToProcess--) {
- float sum = DenormalDisabler::flushDenormalFloatToZero(*destinationL + gain * *sourceL++);
- *destinationL++ = sum;
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ PROCESS_WITH_GAIN(MONO_SUM)
}
} else {
// Process directly (without summing) to our bus
+ // If it is from the same bus and no need to change gain, just return
+ if (this == &sourceBus && *lastMixGain == targetGain && targetGain == 1.0)
+ return;
+
+ // FIXME: if (framesToDezipper == 0) and DenormalDisabler::flushDenormalFloatToZero() is a NOP (gcc vs. Visual Studio)
+ // then we can further optimize the PROCESS_WITH_GAIN codepaths below using vsmul().
if (sourceR && destinationR) {
// Stereo
- while (framesToProcess--) {
- float sampleL = *sourceL++;
- float sampleR = *sourceR++;
- *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleL);
- *destinationR++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleR);
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ PROCESS_WITH_GAIN(STEREO_NO_SUM)
} else if (destinationR) {
- // Mono -> stereo (mix equally into L and R)
- // FIXME: Really we should apply an equal-power scaling factor here, since we're effectively panning center...
- while (framesToProcess--) {
- float sample = *sourceL++;
- *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sample);
- *destinationR++ = DenormalDisabler::flushDenormalFloatToZero(gain * sample);
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ // Mono -> stereo
+ PROCESS_WITH_GAIN(MONO2STEREO_NO_SUM)
} else {
// Mono
- while (framesToProcess--) {
- float sampleL = *sourceL++;
- *destinationL++ = DenormalDisabler::flushDenormalFloatToZero(gain * sampleL);
-
- // Slowly change gain to desired gain.
- gain += (totalDesiredGain - gain) * DezipperRate;
- gain = DenormalDisabler::flushDenormalFloatToZero(gain);
- }
+ PROCESS_WITH_GAIN(MONO_NO_SUM)
}
}
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