Mp3 formats

[kenshin_himura 0]

hmmm did a search within the forum archive.... and the net but i still have some prob...

wats the difference between lossless from apple and 320kbps and AIFF or FLAC.. still quite lost..

lossless data compression.. does it allow the original quality of the song to be constructed if i convert it using eg. apple's lossless.... for music files downloaded and ripped..

Edited September 8, 2006 by kenshin_himura

[scanfiend 0]

Here you go - some homework for you

 

http://wiki.hydrogenaudio.org/index.php?title=Lossless

[kenshin_himura 0]

thx

[kenshin_himura 0]

wahhahaha.. i am even more confused.....so eg the apple lossless codec ... can it restore the original quality of the mp3 i dled off the net or .... someone pls help me!

[scanfiend 0]

wahhahaha.. i am even more confused.....so eg the apple lossless codec ... can it restore the original quality of the mp3 i dled off the net or .... someone pls help me!

 

An mp3 is a lossy codec. What this means is that it discards data during the encoding process. That means the data that was discarded is gone forever. You cannot reconstruct something out of nothing -therefore you can never get the "original" uncompressed song, no matter which lossless codec you use to transcode.

Edited September 8, 2006 by scanfiend

[kenshin_himura 0]

An mp3 is a lossy codec. What this means is that it discards data during the encoding process. That means the data that was discarded is gone forever. You cannot reconstruct something out of nothing -therefore you can never get the "original" uncompressed song, no matter which lossless codec you use to transcode.

so ..hmm.. i can onli get back the uncompressed version of the song if it is encoded using lossless codecs?

[kenshin_himura 0]

' date='9 Sep 2006, 03:01 AM' post='77834']

That is correct, but not highly recommended because although it is theoretically perfect, I think FLAC to WAV isn't advisable too.. but you can try and tell us the differences..

I think FLAC to WAV isn't advisable too

hmm care to explain??? btw read in wiki that its like zip format.. so if music files are zipped and i dl those.. isit uncompressed?? or it onli applies for files in music CDs.

[aegisofrime 0]

' date='9 Sep 2006, 03:13 AM' post='77837']

Here you go...

 

Do read up...

 

You can do that theoretically, and it should sound the same as the original .WAV file that was encoded..but I'm not sure whether the quality is the same as the original CD..because there are some anomalies present here and there that you cant control, like maybe a few errors here and there..

 

I mean u imagine the file is downloaded from somewhere and it was moved here and there through different hands on different hard disks, I know I'm paranoid since digital data is stored in 0s and 1s so it shouldn't change.. but I have a feeling that it does, anyone confirm this?

 

Anyone wants to try it out?

 

 

It's true that the 1st generation lossless rip from the CD might not be the same, due to some read errors during the ripping process. This can be countered by using the right techniques (force re-read etc...).

 

However when transcoding between different lossless formats, the data should be the same. This applies to .Wav too, even though strictly speaking it is an uncompressed format rather than lossless, for those nitpicky ones out there

 

As for data being moved through different hands via P2P programs, I believe that these programs will perform some sort of CRC checking to ensure that what you downloaded is the same as the original.

 

If you really wanna confirm, you can share the same file between you and your friend about ten-times and do a bit-by-bit check against the original file. Bit-by-bit checks are the most stringent since it actually compares the actual 1s and 0s.

Edited September 9, 2006 by aegisofrime

[mashimaro 0]

For any zip file, there is error checking. If there is 1 bit change, it will report "file corrupted".

[mashimaro 0]

This part is interesting:

"Evidence that conversions really are lossless

 

To make sure that the audio stored in each lossless format really is the same as the original audio source, I used an uncompressed Wave file of Canon in D major from The Essential Classics Collection. This Wave file was examined using the handy HashTab Shell Extension, and the MD5, SHA1 and CRC-32 hash values for the file were noted down, as was the size of the Wave file in bytes. This Wave file was converted using dBpowerAMP into a FLAC file (using the same compression settings as used in the big comparison above), and the original Wave file was deleted. The FLAC file was converted into a Monkey's Audio file, which was converted into an OptimFROG file, which was converted into a Shorten file, which was converted into a WavPack file. Finally, the WavPack file was converted into an uncompressed Wave file.

 

The resulting Wave file was exactly the same size as the original Wave file, and the MD5, SHA1 and CRC-32 hash values matched exactly with the original. This is very strong evidence that each of the lossless formats tested preserves the original audio perfectly.

 

Note that this process only succeeds because Wave does not support meta tags, it only stores the audio in the track. The conversion process above will change meta tags (that describe the track name, year the track was released, etc), so these are not necessarily preserved exactly between lossless formats. This is because not all audio file formats support the same meta tags. However, as far as audio is concerned, these formats really are lossless."

[kenshin_himura 0]

wahaha this discussion is realli "chim" sia...can someone kind enuff to summarise wat has been discussed previously?

[replay 0]

Let's say you have a wav file ripped from a CD. You convert this wav to FLAC, then from FLAC to WavPack, then from WavPack to APE, then from this APE to a WAV file again. You should get exactly the same WAV file you started off with. This was checked by comparing the MD5 and CRC of the orginal WAV file. So if you are going LOSSLESS, you shld get back the same file if you uncompress it.

 

Or you can do this also (I did this before) =>

Wav -> FLAC

Wav -> APE -> FLAC

Wav -> WavPack -> FLAC

 

The resulting FLAC file should have the same MD5 or CRC hash check. So to sum it all up, there will be no loss of data if you are going lossless. It's similar to using ZIP or RAR, the compression format is different, but the data within is still the same.

 

Theoretically the above shld hold.. but of cos Windows OS can be weird sometimes. Pls correct me if I'm wrong. Hope this helps.