[vorbis] questions

[Tom Uban]

My application is for games as well, so your information is right on track.

One additional question which I forgot to ask about is whether there is
any significant delay time from when an audio stream begins decoding to
when audio is first available at the output?

--tnx
--tom

At 01:30 PM 1/15/01 -0800, you wrote:
>We haven't attempted to create an embedded version, but we did examine some
>of these issues when seeing if it could be used in video games. I'll state
>here that I didn't actually do the work, I'm just relaying the results of
>our research.
>
>What we found was that the biggest problem was not the MIPS required
>(although that's always an issue too). The biggest problem was the memory
>footprint required. Apparently as of beta 2, it required about 1 megabyte of
>memory to perform decoding. We reduced that to about 500k by using shorts in
>the codebook expansion instead of ints. Of that 500k, about 250k could be
>shared among all instances if they used the same code book (they will be the
>same if using the same Vorbis encoding mode with the same encoder), and
>another 250k was required per instance.
>
>Compared to MP3, that is a lot of memory use. I think MP3 only requires a
>fraction of that amount of memory, and there is no such issue as separate
>code books. Of course Vorbis is superior in regards to compression, but it's
>an interesting observation nonetheless - perhaps the creators of MP3 saw
>memory footprint as an issue and designed that into it.
>
>I would be interested to hear if our figures are about right or way off base
>by anyone who knows better. Things may have changed since beta 2/3, or we
>may be overlooking some simple optimizations to the memory footprint. I know
>for our case (video games), we can't really afford that much memory use - it
>kind of defeats the purpose of the compression for us. 
>
>So if your embedded device doesn't have much memory, and I think many don't
>have that much (I'm not an expert on them), it may be a problem getting
>Vorbis implemented on them. I'm sure there are lots where it would fit
>though, and maybe there is a way to deal with looking through the code books
>on the fly instead of pre-decoding them.
>
>Thanks,
>Dave.
>
>
>-----Original Message-----
>From: Tom Uban [mailto:uban at ubanproductions.com]
>Sent: Monday, January 15, 2001 1:13 PM
>To: vorbis at xiph.org
>Subject: [vorbis] questions
>
>
>Has anyone made an attempt to create an embedded version yet?
>
>Is there a plan to have embedded examples as part of the open source?
>
>If I want to create four independent decode streams, is there any
>decode work which can be shared, or is it going to be four times the
>work?
>
>How many MIPS does it take to decode a single stream?
>
>--tnx
>--tom
>
>
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