[LAD] Realtime Audio on Android

[Patrick Shirkey]

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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