Android sound synthesis

Question

I am trying to play a synthesized sound (basically 2 sine waves and some noise) using the AudioTrack class. It doesn't seem to be any different than the SourceDataLine in javax.sound.sampled, BUT the synthesis is REALLY SLOW. Even for ARM standards, it's unrealistic to think that 32768 samples (16 bit, stereo, for a total of 65536) take over 1 second to render on a Nexus 4 (measured with System.nanotime(), write to AudioTrack excluded). The synthesis part is almost identical to this http://audioprograming.wordpress.com/2012/10/18/a-simple-synth-in-android-step-by-step-guide-using-the-java-sdk/, the only difference is that I play stereo sound (I can't reduce it to mono because it's a binaural tone).

Any ideas? what can I do?

Thanks in advance

Answer 1

Marko's answer seems very good. But if you're still in the experimental/investigational phase of your project, you might want to consider using Pure Data, which already is implemented as a combination Android library/NDK library and which would allow you to synthesize many sounds and interact with them in a relatively simple manner.

The libpd distribution is the Android implementation of Pure Data. Some good starting references can be found at the SoundOnSound site and also at this site.

Addendum: I found a basic but functional implementation of an Android Midi Driver through this discussion link. The relevant code can be found here (github, project by billthefarmer, named mididriver).

You can view how I use it in my Android app (imSynt link leads you to Google Play), or on YouTube.