There is quite a number of people here who value sound quality above all else (e.g. tanstaafl's quote:
My ultimate plans are to put my really "important" music in uncompressed -- Rob says that eventually the empeg will be able to play .wav files directly, if I understand him correctly -- so my IASCA competition disk and a few individual tracks I use to impress unsuspecting onlookers will not go in as MP3's at all.)

Are there any plans to include support for some of lossless compression formats (I have heard of several, but at the moment can only find a reference to this proprietary one: http://www.softsound.com/Shorten.html)?

Cheers!

Dragi "Bonzi" Raos
Zagreb, Croatia
#5196

Another academic site with two lossless algorithms: http://www-ft.ee.tu-berlin.de/~liebchen/lac.html....

Dragi "Bonzi" Raos
Zagreb, Croatia
#5196

How can you compress sound without losing something? I guess ill have to read the websites you have posted.

Term

How can you compress sound without losing something? I guess ill have to read the websites you have posted.

I haven't read those websites, but I can compress a .WAV file simply by running PKZip on the thing. Not by much, but it's still compression. I'm assuming that those websites have lossless compression algorithms that are somehow tweaked for audio data and can do better than PKZip or Rar?

The only reason for lossy compression is to significantly reduce the file size or the required data bandwidth. There are hard mathematical limits to just how much you can compress something using lossless methods. But when you use a lossy algorithm, you trade loss of quality for compression, and the amount of compression you can achieve becomes a sliding scale between 0% and 100%.



Tony Fabris
Empeg #144

I haven't read those websites, but I can compress a .WAV file simply by running PKZip on the thing. Not by much, but it's still compression. I'm assuming that those websites have lossless compression algorithms that are somehow tweaked for audio data and can do better than PKZip or Rar?

Of course. While gzip will give compression factor of 1.15 or so, specialised algorithms achieve as much as 2 (more typically 1.7). See here for comparison. I think that cutting space taken but losslessly compressed files by almost half is worth the trouble.

Cheers!

Dragi "Bonzi" Raos
Zagreb, Croatia
#5196

How can you compress sound without losing something?

All man-made (and most natural) signals are at least a bit redundant (i.e. contain less information than they take up bits, so to speak :)

On one end of the range are text files: say that the file contains only 1000 different words, on average 4 letters each. We can code 1000 different symbols in 10 bits, and 4 8-bit characters take up 32 bits. Hence the room for compression. Most popular algorithms (Huffmann, LZW etc) differ mostly in details such as whether they need a dictionary or not, do they use fixed or variable lenght symbols etc.

On the other end are signals like audio, where we must use our knowledge about it (e.g. the fact that the difference between two consecutive samples will in most cases be relatively small). But see those academic papers for details.

Of course, sometimes a signal that does not seem redundant at all actually is. For example, white noise one gets by recording, say, cosmic radiation seems as random as output from linear congruence generator, and yet the later's output can be described by just three numbers: seed, factor and modulus (one can find more on this on cryptography sites).

Sorry for being boring.

Cheers!

Dragi "Bonzi" Raos
Zagreb, Croatia
#5196