[maemo-developers] [maemo-developers] Audio on scratchbox and 770

From: Teemu Nikkilä tnikkila at cc.hut.fi
Date: Thu Feb 2 12:42:21 EET 2006
Hi all,

I've been trying to understand the audio (and multimedia) framework on the 
770, but with not much success. There seems to be a shortage on documentation 
on this subject, or maybe I just don't know how to find it.

So this far I've managed to figure out that on the 770 the multimedia stuff is 
built on gstreamer (GST) and esound (ESD) and that you can use SDL for low 
level access to audio and video output [1]. I've also tried to write 
to /dev/dsp on  scratchbox, which works just fine, so I'm led to believe that 
scratchbox is OSS enabled.

The problems I've encountered so far are: ESD unfortunately refuses to start 
on scratchbox because of missing /dev/dsptask/pcm1. And 770 OTOH is missing 
esddsp, which I believe could be used as a wrapper to allow all those 
applications, who use /dev/dsp, to work without modifications. Also missing 
on 770 are some gst-utilities like gst-inspect and gst-launch.

So my questions (for now) are: 
could someone, who knows the multimedia system well, write a small (or maybe 
even comprehensive) howto or a tutorial on the subject to Maemo Wiki?

What is osso-media-server?

Is using libSDL really the best way to write sound related applicatons for 770 
(like is done with OggPlay)? For me it looks like a work-around, unless you 
are into games development, while using ESD or GST directly would be the 
right thing(tm) to do.

How about making scratchbox 770 compatible in respect to ESD? Is this 
difficult to do yourself? This would make development and testing easier.

Quite a long post and lots of questions, but this seems to be surprisingly 
complicated subject.


[1] http://www.maemo.org/platform/docs/maemo_exec_whitepaper.html

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