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    <p>SoundPool is the lowest-latency interface on most devices, because the pool is stored in the audio process. All of the other audio paths require inter-process communication. OpenSL is the best choice if SoundPool doesn't meet your needs.</p> <p>Why OpenSL? AudioTrack and OpenSL have similar latencies, with one important difference: AudioTrack buffer callbacks are serviced in Dalvik, while OpenSL callbacks are serviced in native threads. The current implementation of Dalvik isn't capable of servicing callbacks at extremely low latencies, because there is no way to suspend garbage collection during audio callbacks. This means that the minimum size for AudioTrack buffers has to be larger than the minimum size for OpenSL buffers to sustain glitch-free playback.</p> <p>On most Android releases this difference between AudioTrack and OpenSL made no difference at all. But with Jellybean, Android now has a low-latency audio path. The actual latency is still device dependent, but it can be considerably lower than previously. For instance, <a href="http://code.google.com/p/music-synthesizer-for-android/" rel="noreferrer">http://code.google.com/p/music-synthesizer-for-android/</a> uses 384-frame buffers on the Galaxy Nexus for a total output latency of under 30ms. This requires the audio thread to service buffers approximately once every 8ms, which was not feasible on previous Android releases. It is still not feasible in a Dalvik thread.</p> <p>This explanation assumes two things: first, that you are requesting the smallest possible buffers from OpenSL and doing your processing in the buffer callback rather than with a buffer queue. Second, that your device supports the low-latency path. On most current devices you will not see much difference between AudioTrack and OpenSL ES. But on devices that support Jellybean+ and low-latency audio, OpenSL ES will give you the lowest-latency path.</p>
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    1. POAndroid: sound API (deterministic, low latency)
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    1. COIan, I actually performed tests and it looks that OpenSL performs worse.
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    2. COCan you describe the tests you performed? There are a number of ways you can set up OpenSL ES so that its latency is higher than AudioTrack. See my answer to http://stackoverflow.com/questions/14842803/low-latency-audio-playback-on-android/16205370#16205370 for details on how to set up OpenSL to be low latency.
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    3. COI used Android's OpenSL waveout code from WebRTC for playing audio. The idea of my test was simple: I generate two distinctive short burst of noise from loudspeaker and I pick it up on the microphone of the same device. Then I measure the time from when I wrote these bursts of noise to waveout and the time when I detected it on wavein. We need lowest possible waveout latency for real-time VoIP calls, we also need all kinds of controls available for AudioTrack, like switching earpiece/loudspeaker, switching automatic gain or acoustic echo cancellation; Is all of that unavailable with OpenSL?
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