[vorbis-dev] Vorbis packet sizes

[Michael Smith]

On Friday 06 June 2003 01:15, David Etherton wrote:
> > Yes, the more huffman code bits are there, the longer it takes to decode
> > them, but the real time consuming component is IMHO the iMDCT. I'm not
> > aware of the performances of the libVorbis components, but in my own
> > vorbis decoder implementation the iMDCT takes about 90% of the overall
> > decoding time. (tested on a 112kbps-44kHz stereo sample)
>
> Is the amount of of time spent in iMDCT linear in the output sample rate at
> all?  Or is it constant-time independent of the data rate?

Yes - higher sample rates give you more data in total. So although (for 
libvorbis 1.0, ignoring the very lowest bitrate modes) all the modes use the 
same block sizes, and so it takes just as much cpu to decode each block, 
there will be fewer blocks (per second, or whatever time period you want) for 
lower sample rates.

Mike

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