Hi,

I'm working on a cross platform mobile OS media player and doing some research into Realtime audio playback on Android at the moment. It seems there is a fairly small amount of info online and a lot less fully fledged code examples than available for the iPhone platform. For example I have already implemented my demo app in objective-C but it looks like it is going to be significantly more effort to do the same for Android.

I have found a couple of interesting posts and articles about the current state things. Maybe people round here would like to comment on the situation?

Here's what I have found so far:

1: There are three main API's - mediaPlayer, SoundPool, AutdioTrack with openSL ES in the works for release sometime in the near future.

2: All of the Android API's do not provide true low latency support and have varying bugs that need to be worked around with native code. The pd team have made some progress on the workarounds based on jack style callback wrapper classes.

3: There is no standard library for decoding audio file formats at the lower level. Although several options exist including native java implementations for mp3 (JLayer), and custom code from developers like Ivan Memruk from mindtherobot.com

4: There is no native midi or OSC support and it looks like there is no LV2 or ladspa port at this point either. There are very few open source demo apps available which provide a complete solution for media playback and recording at low latency. It seems that the pd implementation is the only one.

Overview:

http://www.wiseandroid.com/post/2010/07/13/Intro-to-the-three-Android-Audio-APIs.aspx
http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-and-o <http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-and-opensl-es/>pensl-es/ <http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-and-opensl-es/>

Sample code:

http://mobiledeviceprogramming.blogspot.com/2010/10/fun-with-android-audiotrack.html
http://mindtherobot.com/blog/580/android-audio-play-a-wav-file-on-an-audiotrack/
http://mindtherobot.com/blog/624/android-audio-play-an-mp3-file-on-an-audiotrack/
http://blog.pocketjourney.com/2008/04/04/tutorial-custom-media-streaming-for-androids-mediaplayer/

Workarounds / Middleware:

http://gitorious.org/pdlib
http://www.typhon4android.org/



Cheers.


--
Patrick Shirkey
Boost Hardware Ltd.

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