[Steven Sullivan]

Legaldeejay wrote:
I've always wanted to know whether there is any true quality loss in the
following circumstances:

1. I burn a 192 kbps mp3 file to CD as a .wav file so that it can play on
a CD player. If I re-create an mp3 file at 192 kbps from that same CD, is
there any quality loss?

Could be. An ABX coparison will tell you if there is any audible losss.
The mp3 codec will attempt to remove data again, it doesn't 'know'
that the file has already been lossy compressed once before. However, your're safer doing
two rounds of 192 kbps than if you had started with, say, a 128 kbps mp3.

2. I open a 192 kbps mp3 file in Soundforge to edit. Soundforge creates a
temporary file for editing. Once I edit the file, I save the new file as a
a 192 kbps mp3 file. Is there any quality loss in this process?

the temporary file is likely a .wav, so the same applies.


3. I run a 192 kbps mp3 file through a normalizing program like Mptrim. If
the program makes changes to the file, such as eliminating silence at the
beginning of the file and normalizing the volume, is there any quality loss?

Possibly. Again, an ABX is the way to 'prove' it to yourself.

4. When zipping and unzipping mp3 files in Winzip and WinRar, is there any
quality loss?

No. THis is purely data compression, not lossy compression.




--
-S
A wise man, therefore, proportions his belief to the evidence. -- David Hume, "On Miracles"
(1748)