On Thu, 2005-04-07 at 20:42 +0300, Peter wrote:
> At what data rate ? A mp3 needs to be beyond 256kBps to sound 
> reasonable. If you compress 44.1kHz (=705.6kBps) cd quality audio 2:1 
> (easy) using something lossless you get something like 350kBps lossless 
> cd quality data. Thus if a 256kBps mp3 does sound as good as a cd then 
> the size gain from using mp3 is only 350/256 ~= 36%. And a 256kBps mp3 
> does *not* sound like a cd, at least not to me, although I have to 
> listen carefully to a part I know well to discern them. And there are 
> lossless sound compression algorythms that go way beyond 2:1. Oh, and 
> usually the non-mp3 compressors (that I know of) require a peanut-sized 
> integer dsp as opposed to the pentium-class processing required to do 
> mp3 decompression in real time.

I think you've confused some numbers.

First off you are listing kBps when I think you mean kbps.

Also, you quote CD audio at 705.6kbps, I think you've forgotten that
almost everything music wise you listen to is in stereo, so that number
should be 1411200bps.

Now, what sounds "reasonable" to someone's ears is a debate that would
NEVER be resolved. For many people 128kbps sounds good enough. For me I
usually encode at 192kbps if space is important. For areas where I want
max quality I encode at 384kbps. But there's more to this then just a
raw bit rate.

MP3 (and other formats) give you the ability to use VBR. Often music
doesn't NEED a high encoding number for certain times (i.e. very loud
sections of a song can drop info about quieter stuff), this allows MP3
to become much more efficient then raw numbers would indicate. Another
good example is correlation between channels, a good amount of data in a
song is common on both channels (i.e. the singer's voice).

There's no doubt that lossy techniques "cost" more in other areas, but
the market has pretty much decided that it's worth it. And to top things
off, you are talking mp3, some of the newer compression formats out
there VASTLY outperform MP3 (MP3 being a REALLY old technology in the
grand scheme of things). TTYL



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