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when trying to get mplayer to play back a dts audio CD via spdif passthrough, I fail miserably with "mplayer -ac dtscd cdda://1" or "mplayer -ao alsa:device=spdif -ac dtscd cdda://1":

There's no such -ac in current CVS code. It must've been patched by the packager.

Fair enough - I found mention of that -ac dtscd on this mailing list, so that must be code that obviously didn't make it into cvs... Irrespectively, there then is the issue why "mplayer -rawaudio on:format=0x2001 cdda://1" doesn't properly switch to dts?

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MPlayer dev-CVS--4.0.2 (C) 2000-2005 MPlayer Team

Unknown MPlayer version. Unsupported.

Sorry for that, it's Ubuntu's 1:1.0-pre7cvs20050716-0.1ubuntu9.1 by Christian Marillat <marillat@debian.org>. Don't know why they messed with the version info. Guess the next response will be to build the latest cvs... <sigh> Thanks anyway, Lars