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Ogg The Conqueror? RC2 Is Out
jonathan_ingram writes: "There has been a lot of discussion recently in Slashdot about sound compression formats. Much has been focused on
Ogg Vorbis, but the most recent version available has been a beta released in Feburary.
Today, RC2 of Vorbis
has been released. The most important of the
many changes
is
channel coupling,
which means that Vorbis can now encode bitsteams at a much lower
bitrate than before.
Try it out today!"
Unfortunately the poster didn't mention this, so I will.
This is a tuning release. Although all infrastructure like channel coupling is in place, the encoder itself is not ideally tuned yet. One of the goals of this release is to get people to test the new modes and report possible problems (samples were it goofs up). If you do this, be sure to try a blind test. Your mind _will_ play tricks on you otherwise.
Two known problems currently are pre/postecho on some really hard samples, and occasional 'hissing' in the low bitrate modes (< 160).
Both are known and will be fixed in the very near future. RC3 is already expected next week.
--
GCP
The only difference was that the low end was less impressive on the OGG than the CD. I put on a few songs and started them simultanously and switched the amp from CD to cassette in (which happened to be my computer). Although it is possible that the casette input amp is less accurate near the low end than the CD input amp, I doubt it. The speakers used were Bose 501s. Conclusion: at 256k/sec, OGG was fine at the high end, but strangely enough, not good enough at the low end.
You are comaring:
a) OGG -- decoded stream -- soundcard -- casette input -- amp -- speakers
b) CD -- decoded stream -- CD-D/A-converter -- CD-input -- amp -- speakers
If alternative a doesn't sound as good as b, this doesn't say anything about the ogg-encoding, because it isn't the only variable. Maybe the difference is caused by the different audio-characteristics of soundcard and CD-D/A-converter.
To get a valid comparison, rip the content of the CD as WAV. Then compare the WAV and the OGG, using the same soundcard and the same amp-input. Everything else is totally meaningless.
But even with this setting, there remains one additional variable: your psyche. If ogg and wav were bit-per-bit equal you will still recognize a difference when you know which one of the two you are hearing. So if you want to get meaningful results, you have to make a double-blind-test.
It's really sad how easy it is for the marketing guys to convince people that alternative codecs are inferior, because 95% don't understand anything about scientific methods or statistics. And they will do that, because they have the budget and we have not.
Channel coupling is a method of decreasing the bitrate while maintaining identical or similar quality. Vorbis supports multiple modes, from a "lossless stereo" to aggressive modes. The lossless mode produces greater compression with bit-for-bit identical output results to non-coupled modes. The more aggresive modes sacrifice some of the stereo separation in order to decrease the bitrate.
So, your question is a little silly. The whole point to having multiple bitrates is to allow the user to choose their preferred mix of quality and size. If an aggressive channel-coupling mode can provide significant size savings while having a minimal impact on quality, lots of people will find that worthwhile. And, as you would know if you read the link before posting, you don't have to sacrifice quality at all! Do you really need to ask why someone might want to encode in a mode which has a lower bitrate and identical quality?
I don't think there are any un-patented 5.1 channel codecs around.
Actually, if you look at the last answer on the Vorbis FAQ you'll see that Ogg Vorbis already supports encoding of up to 255 channels per stream, so, theoretically at least, it ought to be a cinch to use Vorbis for 5.1 audio.
This could be a real opportunity for Ogg to become the first mainstream audio codec to support 5.1 explicitly. It would be a real leg-up for Ogg's chances if it gets accepted as the choice of audiophiles, and having 5.1 supported before MP3 and WMA can only help with that. Those who have experimented with DVD Audio would finally have a format worth considering for ripping purposes, and it helps that Vorbis sounds very musical.