[vorbis-dev] Re: Optimizing Vorbis for a DSP

[Adam D. Moss]

Johannes Sandvall wrote:
> On Sun 28 Mar 2004 23:23:46 CEST, Graham Mitchell wrote:
> 
>>>I have recently ported Vorbis to a Texas instruments DSP (TMS320C5510),
>>>The problem I have is that it is not decoding the audio in real time(
>>>about 50% of real time). Could any one give me a clue in which area I
>>>could start to optimize the code.
>>
>>Well, a few weeks ago Johannes Sandvall posted to the list about "replacing 
>>the IMDCT with a N/4 FFT", which I seem to recall gave a large speedup; his 
>>report is here:
>>	http://www.sandvall.nu/thesis.pdf
>>
>>And my crufty brain seems to recall that profiling has determined that more 
>>time is spent in the function "mdct_backward" than any other, but I could be 
>>way off base.
>>
>>Others on the list are much more qualified than I am, but sometimes a faster, 
>>mediocre response is better than a slower, perfect one.  At least that's 
>>what I'm banking on, anyway.
> 
> Here is maybe a patch of the code. Should include both optimized TI
> assembler and reference c code. Patch available at:
> http://www.sandvall.nu/patch

Anyone been able to take a look at this patch?  I haven't had an
opportunity yet, myself...

--Adam

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