Hi. I've been browsing the archive on this topic and only found a few notes, all dating from a year ago (almost too precisely :) ) -- hope I haven't skipped the mails on that matter, sorry if I did. <p>Basically, I will get in the next few months a MOTU 896, that have 8 i/os in 24/96. I do pro sound recording, so it's more or less my business to have such a piece. Of course, everyone knows the files will be huge, at least uncompressed (3x the size of a conventional CD, and that's for stereo). I'll remix in full quality. But once I have finished a track, I am look ing for a way to archive all the source files without a lot of loss. I'd be willing to live up with some degradation, I would more or less compress the files to the point where they can fit on a CD, so it'd mean 2-8x compression of mono/stereo files. That would still be much better than any standard CD so I'd be happy with the result. Here comes ogg format. Other than enabling a 24bit-integer format and adding 88.2/96KHz formats to the supported list, what is missing? If I read well the 24/96 post of last year, there were mentions of checking the result quality of the compression & tweaking the compression parameters. I'd be more than willing to do that, once I get my hardware piece. My other possibility is to use DVD-Audio format and put that on a CD... but I'd prefer a open source system over anything else. <p>On subnote, the fabulous HD192 (still by MOTU) just came on the marketplace. I have no requirement for 192KHz nor grade-A 120db dynamic range... even if it is tempting :P But it's good to make my point anyways: with the release of "affordable" gear that can do better than DAT, I guess it would be the time Ogg starts to look on higher resolution than what has been available for the last 15 years on computers. <p>Have a nice day Mike --- >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.
Michel Donais wrote:> Here comes ogg format. Other than enabling a 24bit-integer format and > adding 88.2/96KHz formats to the supported list, what is missing? If IInternally, Vorbis uses floating point numbers only, i.e. you always have 32bit float resolution - it's up to the player to reduce that to 24/16/8bit integer so the respective soundcard eats it. (Somebody please correct me if I got that wrong.) It depends on the encoding software that you choose to get your .ogg files from ... and it's getting trickier here. AFAIK even oggenc supports only 8 or 16bit integer or 32bit IEEE float input files. Mike mentioned on IRC that he planned to add support for 24bit int input files, but I don't know when this is going to happen. However, since more-than-16bit support is natural for Vorbis by design, maybe there already is an implementation that takes 24bit input without the unnecessary step of converting to 16bit first. (You could also convert to 32bit floats yourself and feed those to oggenc, but that'd mean quite some time and diskspace effort.) About the sample rate ... well, getting a tuned mode for >48kHz could take really long, since that's way off normal use. You say that you accept quality degration; why not "degrade" quality to 48kHz and compress the whole thing with something lossless? If you want to make another remix some day, a losslessly compressed source resampled back up to 96kHz should give you better quality, especially since 96 = 2 * 48 ... resampling would be pretty exact. E.g. if you play one of those sources at a different pitch, previously inaudible differences made by the psychoacoustic model might suddenly become audible, even at high bitrates. A lossy Codec like Vorbis would discard/reduce most of the information above 24kHz anyways, because inaudible audio information is considered "not important". A nice and free lossless Codec is FLAC (flac.sf.net). <p>Moritz --- >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.
> -----Original Message----- > From: owner-vorbis@xiph.org [mailto:owner-vorbis@xiph.org] On BehalfOf> gtgbr@gmx.net > Sent: 30 décembre, 2002 06:14 > To: vorbis@xiph.org > Subject: Re: [vorbis] YA-2496 > > It depends on the encoding software that you choose to get your .ogg > files from ... and it's getting trickier here. AFAIK even oggenc > supports only 8 or 16bit integer or 32bit IEEE float input files. MikeI wouldn't care converting to 32bit IEEE floats.... If it's all it takes. That part is properly covered even if (like you pointed out) it takes some time and HD space. HD is not a (too big) problem and time, well, if that's what it takes... <p>> About the sample rate ... well, getting a tuned mode for >48kHz could> take really long, since that's way off normal use. You say that you > accept quality degration; why not "degrade" quality to 48kHz and > compress the whole thing with something lossless? If you want to makeThat would mean cut off half the quality and get a lot more quantization problems at higher frequencies, exactly what I'm trying to avoid. Some of my work would directly be at 88.2KHz to accommodate CD halving of the quality. But most of the sources will still be 96KHz to have the best possible quality before the application of any filters and before mixdown. <p>> ... resampling would be pretty exact. E.g. if you play one of those> sources at a different pitch, previously inaudible differences made by > the psychoacoustic model might suddenly become audible, even at high > bitrates. A lossy Codec like Vorbis would discard/reduce most of the > information above 24kHz anyways, because inaudible audio informationis> considered "not important".That's basically the part I am afraid of. I do not care much on 24KHz cutoff, as with the original I will probably get only a dozen "true" frequencies on that upper range and everything else will get biased toward these values due to quantization... and the lower 24KHz will be much richer than on a CD/DAT source with much less quantization problems... but I am afraid of the psychoacoustic model and what it might do to the soundtrack, even at highest bitrate. And then, I probably won't play the samples 4x slower than they should... I do not do downtempo (yet). If I continue forward with my 192KHz example, it would then be a real loss of quality, and the model should be biased toward 48KHz or even more (basically IMHO it should be variable with the resulting bitrate - a 192KHz source @ 64Kbps should still be cutoff'ed @ 20 or so KHz), even if the human ear can't perceive these frequencies at a correct rate. <p><p>> A nice and free lossless Codec is FLAC (flac.sf.net). This codec was also mentioned in the original 1-year-old discussion thread. Even if lossless is a good idea for perfect archival, the biggest problem here is the potential range of compressibility of the source. If I have a source which consists of a few gated kick-drums to the left or to the right, this is god-sent. But if I have a big heavy guitar with lots of fuzz distortion and everything, and my sample is pretty much normalized, I am afraid I won't have a lot of success with FLAC. Or the overheads for the cymbals during a cymbal solo... Worse comes to worst, I will fall back on this format anyways, as these are special cases anyways. <p><p>Have a nice day Mike <p>--- >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.