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FLAC Joins The Xiph Family
Ancipital writes "Xiph.org (of Ogg Vorbis fame) have today announced that the FLAC (Free Lossless Audio Codec) project has joined the Xiph rebel alliance. The full story and press release can be found at the Xiph site. (FLAC is nice, because it gives you pristine lossless audio at roughtly 50% size reduction over uncompressed WAVs- you can store them on your hard drive/wherever and then transcode down to a lossy format when you need portability, yum!)"
"Lossless compression" means that the compression algorythm allows for the compressed file to be reconstructed exactly as it was before compression. You do remove data in compression, but you do it in a way that you can reconstuct the data you lost.
Bork Bork Bork!!
However, the compression mostly happens for highly idealized data (such as written text); binary files or music/image files where the randomness of successive bits is very high, and thus lossless compression can't happen.
I don't disagree that a lossless compression scheme that gets 50% compression is highly questionable, but it's definitely not out of the realm of possibility.
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
'Physics Genius' - you obviously have no clue about compression formats! So you loose data when you use a zip/gzip/bzip file? Then why does anyone use them?
OK, if you are arguing semantics, then yes the compressed file has 'lost' some information, but the compression algorithm can recreate that information.
Very simple example: a file that contained 20 'a' s (aaaaaaaaaaaaaaaaaaaa) could be compressed by recording in the compressed file that the file is 20 x the letter 'a'. The decompressor can recognise this and write out the contents of the original file.
You're either trying to be a troll or a know anything about compression - whichever it is, don't bother posting!
" To steal ideas from one person is plagiarism; to steal from many is research. "
While I believe the parent post to be nothing more than a troll/flamebait, I'll bite.
Either you never studied compression or never fully understood it. There are two basic types of compression: lossy and lossless. Lossless means that none of the original data is lost. This doesn't mean that the compressed version is -identical- to the original. It simply means that by following a predetermined algorithm, the original can be fully restored. Compression schemes look for repeating patterns. The more common a pattern is, the better a compression ratio you will acheive. Common repeating patters are replaced by some sort of symbol or mapping (which is saved with the compressed file). To reverse this you simply replace the symbol or mapping with the original sequence of characters.
If you take a file, make a copy, compress it using lossless compression, and decompress it to a different filename the computer will find no differences between the two. The compressed/decompressed copy will look -identical- to the orignal. That's what's meant by lossless encoding.
By claiming " There's no such thing as 'lossless compression' by definition" you are only showing your ignorance.
To add this this...using an extremely simplified example but:
ABABABABCDCDCDCDGHGHGH (22 chars)
4AB4CD4GH (9 chars)
The second line is a different representation of the first, but the same data can be extrapolated. Compression works in a similar fashion, finding patterns and reducing them.
You can get the first sample from the second, and have the same data. Visibly, data is less, but there is no real loss, only a change in representation that gives a smaller filesize
Are you saying that the CD's people are encoding to mp3 have "inaudible" sounds on them?
I didn't think so.
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Actually, that is what I'm saying. I did dumb it down a little, but if you'd like to learn how mp3 compression works, check out this site.
A quote from this site:
To make a good compression algorithm for sound, a technique called perceptual noise shaping is used. It is "perceptual" part because the MP3 format uses characteristics of the human ear to design the compression algorithm. For example:
* There are certain sounds that the human ear cannot hear.
* There are certain sounds that the human ear hears much better than others.
* If there are two sounds playing simultaneously, we hear the louder one but cannot hear the softer one.
Using facts like these, certain parts of a song can be eliminated without significantly hurting the quality of the song for the listener.
That is to say, parts of the audio signal (the parts that are inaudible to the human ear) are removed to save space.
After that is done, a regular compression algorithm is applied to the file, further reducing the size.
Some of the major dissidents of the mp3 format claim that these so-called "inaudible sounds", when removed, can affect the overall quality of the audio. I guess that's why they wanted a lossless compression algorithm in the first place. Actually, a lot of these people don't like digital transfers of music at all. They prefer an analog technology like vinyl.
For most people, though, the difference in quality is negligible, at best - especially when compared to the savings in data space.
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Disclaimer: The above statement probably includes half-truths, because real truth is too complicated.