[vorbis] Ogg to SPDIF

[Kenneth Arnold]

On Tue, Jan 01, 2002 at 10:01:09AM -0500, Ross Vandegrift wrote:
> > > Can't do this with emu10k1 cards.  They don't do sample accurate transfer
> > > for rates other than 48kHz.
> > 
> > But unless I am mistaken, you can bypass all of the soundcards processing
> > and stream directly out of the SPDIF socket.
> 
> I've heard it resamples it.

IIRC, SPDIF allows sampling rates other than 48kHz, but emu10k1 will
resample everything passing through it. Whether or not this can be
bypassed with loadable DSP microcode I don't know; I would suspect
so.

> > Otherwise, how else would you
> > be able to output AC3 directly from a DVD?
> 
> Dunno.  But the ALSA pages talk about straying from SBLives for just this
> reason.

For this and the above, check out the CVS from
opensource.creative.com. There's an ac3 pass-through module in there,
as well as the devel tools and microcode source for a lot of the
processing. I doubt you would want to do it, but transcoding Vorbis to
(high quality setting) AC3 and using the ac3 pass-through should
accomplish the same end result. Unfortunately I lack SPDIF speakers at
the moment so can't really poke too much into this myself.


-- 
Kenneth Arnold <ken at arnoldnet.net>
- "Know thyself."

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