Greg Wooledge
2002-Nov-15 15:24 UTC
[vorbis] Re: [MP3 ENCODER] Re: Quality problem reencoding
Dan Nelson (dnelson@allantgroup.com) wrote:> I guess the problem might be oggenc's option parser, then. Given a > stereo 22050hz input file, I can't seem to get oggenc to encode less > than 22kbits. The lowest bitrate it will allow on the commandline (for > 22050hz/2ch input) is -b 30, but if you also add -M 1, it will generate > a file with an average bitrate of 22.$ sox -V War\ -\ Low\ Rider.wav -r 22050 foo.wav [...] sox: Finished writing Wave file, 17102568 data bytes 8551284 samples $ oggenc -b 16 -M 16 --downmix foo.wav foo.ogg Enabling bitrate management engine Opening with wav module: WAV file reader Downmixing stereo to mono Encoding "foo.wav" to "foo.ogg" at average bitrate 16 kbps (no min, max 16 kbps), using full bitrate management engine [100.0%] [ 0m00s remaining] - Done encoding file "foo.ogg" File length: 3m 13.0s Elapsed time: 0m 22.2s Rate: 8.7477 Average bitrate: 15.7 kb/s Of course, the resulting file sounds pretty bad. (It's actually not as bad as I expected it to be, but it has horrible artifacts in the mid-range frequencies, and the high frequencies are gone. A lowpass might help a bit.) Are you sure you're using Vorbis 1.0? -- Greg Wooledge | "Truth belongs to everybody." greg@wooledge.org | - The Red Hot Chili Peppers http://wooledge.org/~greg/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: part Type: application/pgp-signature Size: 188 bytes Desc: not available Url : http://lists.xiph.org/pipermail/vorbis/attachments/20021115/3b550741/part-0001.pgp
In the last episode (Nov 15), Greg Wooledge said:> Dan Nelson (dnelson@allantgroup.com) wrote: > > I guess the problem might be oggenc's option parser, then. Given a > > stereo 22050hz input file, I can't seem to get oggenc to encode less > > than 22kbits. The lowest bitrate it will allow on the commandline (for > > 22050hz/2ch input) is -b 30, but if you also add -M 1, it will generate > > a file with an average bitrate of 22. > > $ sox -V War\ -\ Low\ Rider.wav -r 22050 foo.wav > [...] > sox: Finished writing Wave file, 17102568 data bytes 8551284 samples > > $ oggenc -b 16 -M 16 --downmix foo.wav foo.ogg[...]> at average bitrate 16 kbps (no min, max 16 kbps), > using full bitrate management engine > Done encoding file "foo.ogg" > Average bitrate: 15.7 kb/s > > Of course, the resulting file sounds pretty bad. (It's actually not > as bad as I expected it to be, but it has horrible artifacts in the > mid-range frequencies, and the high frequencies are gone. A lowpass > might help a bit.) > > Are you sure you're using Vorbis 1.0?Yes, but I was using stereo 22Khz input. With mono, oggenc lets you use -b 16, which on my test wav actually generated an avg 24kbit file. I had to add -M 16 to force it to generate an avg 16kbit file. Is there an oggenc flag that does what lame's --abr ## flag does? i.e. "I want an output file with this average bitrate". So far -b consistently gives me a bitrate up to 50% higher than what I asked for. Time to move this thread to a vorbis list? Oh wait. I see the CC. Nevermind :) -- Dan Nelson dnelson@allantgroup.com --- >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.