Sound file formats and sound quality

[ANMB]

Good Afternoon,

I am wondering if when copying a segment or a clip of a track, does the copied clip have a reduction in sound quality? Or when saving a copy of a mp3 file, is there a reduction in the quality from the original?

I found this thread:

http://forum.audacityteam.org/viewtopic ... ty#p208473

and I wonder what is the best format to work with and edit in audacity that will save quality of sound? I have access to a few flac files or .rm or mp3 files. Or would converting a mp3 to flac or wav work?

Thank you.

Ayesha Nicole

[steve]

I am wondering if when copying a segment or a clip of a track, does the copied clip have a reduction in sound quality?

There is not normally reduction in sound quality when copying / pasting within Audacity.

Or when saving a copy of a mp3 file

There is always loss of sound quality when exporting as MP3.

and I wonder what is the best format to work with

WAV, AIFF or FLAC

and edit in audacity

Audacity always works with high quality uncompressed PCM audio internally.

Or would converting a mp3 to flac or wav work?

Converting from MP3 to WAV or FLAC does not improve the sound quality. It's a one way street - converting to MP3 (or other lossy compressed format) reduces sound quality.

[DVDdoug]

One more thing in case it's not clear...

Audacity (like all "regular" audio editors*) decompresses the audio when you open the file. If you open and edit an MP3 (or other lossy file) and then re-export it as MP3 (or other lossy format) it's going through a 2nd generation of lossy compression.

If you save to WAV or FLAC, there is no additional quality loss.

Ideally, you should compress ONCE as the final step if you want a lossy format. Otherwise, try to minimize the number of times the data is lossy-compressed.




*There are some specialized editors (such as MP3DirectCut) that can do some limited MP3 editing without decompressing first.

[ANMB]

Thank you. When I download a mp3 file and work with it, and then export it again as an mp3, does it lose another 'layer' of sound quality? Similar to making a copy of a copy of a copy of an image?

I have a very large personal project, that will eventually be shared with many others, and it will become the norm for this particular usage; and there are many mp3 files available; but I am thinking that if I can actually locate and purchase the studio quality cd's, and rip them and edit in audacity, it may be the best for sound quality, in the long run. I am trying to plan very well before I start, and streamline the process to train others to help with it, because it is extremely labor intensive.

[steve]

When I download a mp3 file and work with it, and then export it again as an mp3, does it lose another 'layer' of sound quality? Similar to making a copy of a copy of a copy of an image?

Yes.

The amount of loss depends on the MP3 encoding settings. Higher "kbps" loose less than low "kbps" but at the cost of greater file size - that's the trade-off "quality:file size".

Exporting as FLAC. WAV or AIFF will reduce the loss to almost nothing. This is like having a near perfect photocopier.

Exporting as 32-bit float WAV will reduce the loss to zero. This is like having a perfect photocopier, but the down side is that 32-bit float WAV files are huge (double the size of a normal WAV file), and not many applications support 32-bit float WAV. Normal 16-bit WAV (or FLAC) is good enough for just about everything (except perhaps scientific research).