re: Lossey compression & quality degradation

[JeffB]

Is some sound quality lost every time a lossey file is copied/saved/moved?

If one were to import a non-lossey file and save it in a lossey format such as .mp3 some data & quality would be lost. If that mp3 file were later opened, edited and saved again the file would then be re-compressed and addtional data & quality lost. If it were not edited, but was opened and then saved again would more data & quality be lost this time? ie. if you saved a copy to another drive would there be some degradation of quality? and again if it were burned to a CD or DVD?

If so, is there a way to avoid this short of saving it in a non-lossey format?

[kozikowski]

People have designed extensive tricks to minimize the damage, but no, every time you change something in the file however slight, the quality of the performance degrades. The problem comes from the inability to edit in most compression schemes, so they have to be decompressed back down to "real audio", edited, and then recompressed. And yes, the only way to avoid that completely is to edit in an uncompressed medium--and the highest quality one you can manage.

Many audiophiles consider CD 44100 quality to be barely tolerable. If you starting doing special effects in 44100, the errors crop up almost instantly. 48000 is considered the minimum production quality (television is mostly 48000) and some go higher.

<<<copied/saved/moved?>>>

Copy and move are free, but "save" assumes importing into an audio program and that one can be a problem. The only way you get away with that one is if the clips, the project/timeline and the export all match and they're all at very high quality. If you capture something on-line from an MPEG4 stream, do effects and edit it on a 44100 timeline and export as MP3, There could be extensive damage to the show.

Koz

[JeffB]

Thanks for the info. I'll certainly keep that in mind.