Android Audio Latency Workarounds

Question

So anybody worth their salt in the android development community knows about issue 3434 relating to low latency audio in Android. For those who don't, you can educate yourself here. http://code.google.com/p/android/issues/detail?id=3434

I'm looking for any sort of temporary workaround for my personal project. I've heard tell of exposing private interfaces to the NDK by rolling your own build of android and modifying the NDK.

All I need is a way to access the low level alsa drivers which are already packaged with the standard 2.2 build. I'd like to have the ability to send PCM directly to the audio hardware on my device. I don't care that the resulting app won't be distributable over the marketplace, and likely won't run with any other device than mine.

Anybody have any useful ideas?

-Griff

EDIT: I should mention, I know AudioTrack provides this functionality, but I'd like much lower latency -- AudioTrack sits around 300ms, I'd like somewhere around 20-30 ms.

Answer 1

Griff, that's just the problem, NDK wil not improve the known latency issue (that's even documented). The hardware abstraction layer in native code is currently adding to the latency, so it's not just about access to the low level drivers (btw you shouldn't rely on alsa drivers being there anyway).

Answer 2

Android: sound API (deterministic, low latency) covers the tradeoffs pretty well. TL;DR: NDK gives you a minor benefit because the threads can run at higher priority, but this benefit is meaningless pre-Jellybean because the entire audio system is tuned for Java.

The Galaxy Nexus running 4.1 can get fairly close to 30ms of output latency.