I noticed that clipping occurs in lossy audio compression even if there is no clipping in the original file (though the original file has peaks that are just below the maximum). I know that this happens due to all the filtering involved during compression, but I'm wondering just how audible this clipping is because I don't hear anything wrong. I mean, as things are now, is it safe to say that the clipping introduced in Vorbis will not be audible if, of course, the input file doesn't have clipped parts? Is it possible to avoid clipping at all (if the source isn't clipped)? On the other hand, using samples that are already clipped, clipping can't be avoided so the encoder only has to take care that it doesn't sound worse... Greetings, Aleksandar --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
On Sun, 25 Feb 2001, Aleksandar Dovnikovic wrote:> I noticed that clipping occurs in lossy audio compression even > if there is no clipping in the original file (though the original > file has peaks that are just below the maximum). I know > that this happens due to all the filtering involved during compression, > but I'm wondering just how audible this clipping is because I don't > hear anything wrong.Do you have some numerical observertions? I'd be interested to know. It is expectable that this can occur, so I always try to limit (by scaling the volume to the minimum of 98%-max-sample and 0.15-RMS which I have on most my songs) my input files to 98% of the maximum assuming that this is enough - but I never checked that it really is. It is possible that the decoder can change the volume during decoding before clipping can occur, thus avoiding it if the volume is below maximum. Winamp's mp3 input plugin can do fast EQ which I assume is done before the conversion to pcm domain. Vorbis can't do it now afaik - maybe it'd be useful to add a volume scaling parameter to the decoder (encoder too?) that will allow one to decode a vorbis files that represents >100% samples without clipping.> [snipped]-- Beni Cherniavsky <cben@crosswinds.net> (also scben@t2,cben@tx in Technion) (/bin/ch x)^2 = (/bin/sh x)^2 + 1 --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
Aleksandar Dovnikovic <aldov@EUnet.yu> wrote: : I noticed that clipping occurs in lossy audio compression even : if there is no clipping in the original file (though the original : file has peaks that are just below the maximum). I know : that this happens due to all the filtering involved during compression, : but I'm wondering just how audible this clipping is because I don't : hear anything wrong. I mean, as things are now, is it safe to say : that the clipping introduced in Vorbis will not be audible if, : of course, the input file doesn't have clipped parts? Is it : possible to avoid clipping at all (if the source isn't clipped)? : On the other hand, using samples that are already clipped, : clipping can't be avoided so the encoder only has to take : care that it doesn't sound worse... A lot of professional mastering companies nowadays in the ultra-blanket-compression trend will intentionally clip a track as long as it doesn't sound bad. -- andrew michael greenburg ! a m g @ b e w l e y . n e t ---------------------------------------------------------------------------- --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.