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On Wed, Jun 16, 2004 at 09:33:09PM -0400, andrew lattis wrote:> i'm sure everyone else with a need has written there own script, but > i didn't see any in the archives, so here's mine > > basically it take an existing ogg, decodes it to a wav, grabs the > comments and re-encodes at a new quality setting and appends the comments. > > the script looks in your current directory and finds all *.ogg files > recursively, it then recreates the directory structure as > quality-$x/blah/blah/blah.ogg > > its not perfect, and its not real peeling but everything seems to be > working fine so far, i've got it running through 230 albums layed out as > band/album/song.ogg and recreating as quality-4/band/album/song.ogg > > my current name for it is hap, half ass peeler > > why? > 40gb of high quality oggs, and a 20gb rio karma... >Just curious question: will there be some quality loss?> _______________________________________________ > Vorbis mailing list > Vorbis@xiph.org > http://lists.xiph.org/mailman/listinfo/vorbis-- Petr Tomasek, http://www.etf.cuni.cz/~tomasek/
<20040617091314.GA28476@ebed.etf.cuni.cz> Message-ID: <20040617141946.GA18688@naranek.org> On 2004/06/17 11:13:14AM +0200, Thu, Petr Tomasek wrote:> > basically it take an existing ogg, decodes it to a wav, grabs the > > comments and re-encodes at a new quality setting and appends the comments. > > Just curious question: will there be some quality loss? >i don't know enough about the encoding to say 100% but i wouldn't think so, in theory the wav should contain all the information that was in the original ogg, so your only loss will be whatever would have been cut out in going to the lower quality, i haven't been able to hear any defects atleast. andrew -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: not available Url : http://westfish.xiph.org/pipermail/vorbis/attachments/20040617/43c1a294/attachment.pgp
<20040617091314.GA28476@ebed.etf.cuni.cz> <20040617141946.GA18688@naranek.org> Message-ID: <0C459B15-C0A5-11D8-A9B7-000A95CD704C@kungfoocoder.org> On Jun 17, 2004, at 16:19, andrew lattis wrote:> On 2004/06/17 11:13:14AM +0200, Thu, Petr Tomasek wrote: >>> basically it take an existing ogg, decodes it to a wav, grabs the >>> comments and re-encodes at a new quality setting and appends the >>> comments. >> >> Just curious question: will there be some quality loss? >> > > i don't know enough about the encoding to say 100% but i wouldn't think > so, in theory the wav should contain all the information that was in > the > original ogg, so your only loss will be whatever would have been cut > out > in going to the lower quality, i haven't been able to hear any defects > atleast.This is not strictly speaking true... this can be trivially tested by just doing a ogg-encode/decode cycle on a given file for about 10 times... You will notice the difference, particularly at lower bitrates. The problem is that what you get back is not what you put in "minus some", it is a reconstruction that sounds similar. The distinction is important, this would not be true if we were able to use real real numbers (float and double don't cut it ;-) since the reconstruction could pick up exactly the same information, but since we are decoding into a discrete space, then our nice smooth curves aren't anymore... and that is what makes it hard to re-encode them. Cheers, Paul -------------- next part -------------- A non-text attachment was scrubbed... Name: PGP.sig Type: application/pgp-signature Size: 186 bytes Desc: This is a digitally signed message part Url : http://westfish.xiph.org/pipermail/vorbis/attachments/20040617/eb4149e3/PGP.pgp