am 972af221: FastMixer compensates for SRC jitter in audio HAL (16f07fb7) · Commits · e / os / android_frameworks_av

services/audioflinger/FastMixer.cpp

+14 −6

Original line number	Diff line number	Diff line
		@@ -65,6 +65,7 @@ bool FastMixer::threadLoop()
		long periodNs = 0; // expected period; the time required to render one mix buffer
		long underrunNs = 0; // underrun likely when write cycle is greater than this value
		long overrunNs = 0; // overrun likely when write cycle is less than this value
		long forceNs = 0; // if overrun detected, force the write cycle to take this much time
		long warmupNs = 0; // warmup complete when write cycle is greater than to this value
		FastMixerDumpState dummyDumpState, *dumpState = &dummyDumpState;
		bool ignoreNextOverrun = true; // used to ignore initial overrun and first after an underrun
		@@ -221,11 +222,14 @@ bool FastMixer::threadLoop()
		periodNs = (frameCount * 1000000000LL) / sampleRate; // 1.00
		underrunNs = (frameCount * 1750000000LL) / sampleRate; // 1.75
		overrunNs = (frameCount * 250000000LL) / sampleRate; // 0.25
		forceNs = (frameCount * 750000000LL) / sampleRate; // 0.75
		warmupNs = (frameCount * 500000000LL) / sampleRate; // 0.50
		} else {
		periodNs = 0;
		underrunNs = 0;
		overrunNs = 0;
		forceNs = 0;
		warmupNs = 0;
		}
		mixBufferState = UNDEFINED;
		#if !LOG_NDEBUG
		@@ -468,6 +472,8 @@ bool FastMixer::threadLoop()
		dumpState->mWarmupCycles = warmupCycles;
		}
		}
		sleepNs = -1;
		if (isWarm) {
		if (sec > 0 \|\| nsec > underrunNs) {
		#if defined(ATRACE_TAG) && (ATRACE_TAG != ATRACE_TAG_NEVER)
		ScopedTrace st(ATRACE_TAG, "underrun");
		@@ -476,7 +482,6 @@ bool FastMixer::threadLoop()
		ALOGV("underrun: time since last cycle %d.%03ld sec",
		(int) sec, nsec / 1000000L);
		dumpState->mUnderruns++;
		sleepNs = -1;
		ignoreNextOverrun = true;
		} else if (nsec < overrunNs) {
		if (ignoreNextOverrun) {
		@@ -487,14 +492,17 @@ bool FastMixer::threadLoop()
		(int) sec, nsec / 1000000L);
		dumpState->mOverruns++;
		}
		// Code for non blocking audio HAL. Sleep time must be tuned to allow
		// catching up after an underrun
		// sleepNs = periodNs - overrunNs;
		sleepNs = -1;
		// This forces a minimum cycle time. It:
		// - compensates for an audio HAL with jitter due to sample rate conversion
		// - works with a variable buffer depth audio HAL that never pulls at a rate
		// < than overrunNs per buffer.
		// - recovers from overrun immediately after underrun
		// It doesn't work with a non-blocking audio HAL.
		sleepNs = forceNs - nsec;
		} else {
		sleepNs = -1;
		ignoreNextOverrun = false;
		}
		}
		#ifdef FAST_MIXER_STATISTICS
		// advance the FIFO queue bounds
		size_t i = bounds & (FastMixerDumpState::kSamplingN - 1);