Subject:Does saving MP3 file to MP3 file degrade audio?

Posted by: telstar

Date:4/19/2001 11:28:55 AM

Several questions relating to saving audio files.
(reason: audio files come in all forms and most times need
adjusting/normalizing to coexist with other audio files in
one's library)

1. Does a MP3 file degrade with each save (i.e., 128kbps to
128kbps)?

2. Does a MP3 file degrade if it is saved at greater kbps
(i.e, 128kbps to 320kbps)? If degrades, is it audibly
noticeable?

3. Does an MP3 file degrade if saved as a .WAV file?

From a real estate point of view it is nice to save files
in MP3 format, however, if the audio is affected .WAV is
the likely alternative (real estate hog)???

Thanks for your assistance.

Subject:RE: Does saving MP3 file to MP3 file degrade audio?

Reply by: telstar

Date:4/27/2001 6:58:42 PM

Doesn't anyone have any answers for this. Thanks!

Subject:RE: Does saving MP3 file to MP3 file degrade audio?

Reply by: Micsound

Date:4/29/2001 6:14:23 AM

If you just save the MP3 file there will be no degredation.
But if you re encode the MP3 file it will degrade the file
as it basicly works by taking the bits out of the sound you
supposedly cannot hear.Like AC3 or any other heavy forms of
commpression, they cannot handle being de coded and re
encodded.So keep wave files as wave files and your MP3 files
as they are,just save them.

Subject:RE: Does saving MP3 file to MP3 file degrade audio?

Reply by: telstar

Date:4/29/2001 4:18:15 PM

Thanks Mike for the clarification!

Subject:RE: Does saving MP3 file to MP3 file degrade audio?

Reply by: nlamartina

Date:4/29/2001 4:53:33 PM

Telstar,

Let me add something:

1. Saving MP3 over and over and over again, CAN degrade the
quality, albeit very little (as Mike noted). The only thing
you'll possibly start to notice is a bit of compression
noise in the highs. After 3 or 4 saves, it'll start
sounding like a high bit-rate WMA file.

2. Saving a 128 Kbit file to a 320 Kbit file does degrade
the audio, since, after all, it's being recompressed.
However, the difference is most likely inaudible. Remember,
audio fidelity can never be added during a recompression,
regardless of the bit-rate difference. Fidelity can only be
lost (unless you're using zero loss compression like PCA,
but that's another story).

3. Saving an MP3 to a WAV will not degade the quality, so
long as you save it as a 44kHz, 16 bit, stereo file. The
WAV extension uses absolutely no compression. Think of it
like unfolding bedsheets. In the closet (hard disk), the
sheets (music) are all folded up, therefore taking up less
room (MP3), but they don't keep you very warm all folded up
(audio fidelity). Taking the sheets out and spreading them
out (decompressing) on the bed (hard disk) takes up more
room (WAV), but they'll keep you warmer (audio clarity). Do
you follow my rather unorthodox analogy?

Anyway, that's the way it is. Choose your storage method
and compressions wisely. Don't forget to have fun too.

Best wishes,
Nick LaMartina

Subject:RE: Does saving MP3 file to MP3 file degrade audio?

Reply by: telstar

Date:6/4/2001 4:27:43 PM

Thanks Nick for a more exacting response....GREATLY APPRECIATED!