[vorbis-dev] Argh, preecho mistriggers

[Robert Hegemann]

Monty schrieb am Fre, 16 Jun 2000:
> In case people on the list don't know it, A Vorbis tester (who's email I've 
> lost!  If you're on the list, speak up!) is maintaining a vorbis audio quality 
> test page:
> 
> http://hem.passagen.se/ingets1/vorbis.htm
> 
> He's doing us the great service of hunting down samples that break Vorbis (so
> we don't have to :-)
> 
> In any case, it turns out that the trumpets in the dr4 sample are reliably mistriggering the preecho detector (which implies either a large bug in the detector, or general borkkenness which must be fixed).  The artifacts in the sample are due entirely to Vorbis trying to encode the trumpets entirely in short blocks (which will suck for strongly periodic/harmonic waveforms, as produced by brass instruments).
> 
> Just a heads up; if someone else runs across this artifact (it manifests as
> 'wayyy to much noise/rasp'), you know that I knwo about it. 
> 
> Monty

ome files vorbizing doesn't do well,
hmm I think you are aware of these testcases already:

60.wav, frer07_1.wav	very audible distortions
applaud.wav         	clipping problems in nearly all frames
fatboy.wav          	sounds bad as with most encoders
gspi35_2.wav        	doesn't sound right imho

frer* and gspi* are SQAM tracks:
        http://sound.media.mit.edu/mpeg4/audio/sqam

the rest you can find at sulaco.org

Ciao Robert

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