[gst-devel] building an AC3 decoder...

Darrell Berry darrell at ku24.com
Sun Jun 13 13:00:04 CEST 2004


I'm am absolutely new to gstreamer, although I've skimmed the 
documentation and have a fair understanding of audio issues in general. 

I am looking at the feasibilty of buiding a dedicated AC3 decoder box,
with professional audio cards for S/SPF input and analog output. The cards
I'm looking at (either digiram by preference, or RME) seem best-supported
under LSA, which probably means I need Jack for routing (or can gstreamer
talk directly to ALSA? I understand not?).

I have, at this point, no desire for any DSP other than AC3 decoding, 
which I need as low-latency, high-quality as possible. I want to do the 
AC3 decoding in software, and use the audiocards simply as high-quality 
DACs -- I don't want to use all-in-one DAC/decoder cards,as I want more 
flexibility and betetr quality than I can see currently on the market.

So, I'm wondering

a) has anyone already done the hard work of building a gstreamer-based 
patch which takes AC3 in and rects it out to 6 (5.1) or more (7.2?) 
discrete channels on a multi-port audio card using Jack?

b) is it possible on linux to get low enough latency that doing the above 
is bearable in conjunction with a dvd player doing its own video 
processing? obviously there' slittle point exploring the ac3 side of 
things, if there's no way to get latency down to a few milliseconds!

All help much appreciated


- darrell

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