[vorbis-dev] How many MIPS for Vorbis Decoder?

[Johannes Sandvall]

On Fri 19 Mar 2004 19:20:34 CET, John Ripley wrote:
> > From: Jens Prüfer [mailto:jens.pruefer at gmx.de]
> > Sent: 19 March 2004 17:31
> > To: vorbis-dev at xiph.org
> > Subject: Re: [vorbis-dev] How many MIPS for Vorbis Decoder?
> > 
> > > What's this intended for anyway - low power, small form 
> > factor, or low
> > > cost?
> > 
> > Ultra-Low-Cost! Definately. Low power would also be nice. I 
> > was thinking of 
> > one of the TI MSP430's maybe? But when I read "200 MHz Strong 
> > ARM" my heart 
> > skips. But more MHz does not necessarily mean more Speed. The 
> > MSP430F169 has 
> > a MAC unit as well, making those nasty multiplications cheap 
> > (1 cycle only). But it only does 8 MIPS :(
> 
> Yikes. That's really low. I can't actually find any MDCT or FFT references
> on TI's site... so I don't know how efficient it would be. A brief scan of
> the user guide reveals that it's also restricted to a 16 bit address space,
> but if that means 128KB, it's probably going to fit. Sounds like a lot of
> porting is required, though, if it will actually work.
> 
> If you're looking for ultra-low-cost that probably rules out anything ARM
> based. (Grumble - ARM cores are great but they're always too damn
> expensive). You don't need anything as powerful (or expensive) as a
> StrongARM, but there's plenty of other microcontrollers around that might do
> the job a bit less marginally. Don't forget development time when you
> compare these things for cost :)
> 
> If you can find a figure for how fast that DSP performs MDCTs (i.e number of
> clocks for a block size), that would help.

Our TI implementation takes around 8 MIPS for the MDCT using the
normal window lengths.

The 44 MIPS in my thesis is still a little high since a more efficient
huffman probably would bring decoding of 128kBit Ogg/Vorbis under 20
MIPS on a TI 55xx.

Regards Johannes Sandvall
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