i recently took a store bought cd and made some different bitrate mp3s out of it. i picked a various track from the cd and made it into three different bitrates. one 128, one 192 and one 256. they all were different sizes of course but when i decompressed them they all ended up being around 50mb. my question is this, how does the sound quailty compare between the three? i know when you listen to a 128 bitrate versus a 256 bitrate mp3 through a mp3 player you can tell the difference. if you happen to decompress them for a cd they end up being the same size. if i decompress a 128 bitrate will it be the same quailty if i decompress a 256 for a cd? are they cd quailty once decompressed even though they are different bitrates? hope you understand my question. thanks.

No, mp3 is a lossy format so when you convert a file into an mp3 some information is lost forever. The more you compress it the more information is lost, and thus the worse it will sound. They will be the same size when you convert them back into a wav file regardless of the sound quality. 30 seconds of static and hissing takes up as much room as 30 seconds of orchestra as far as raw audio is concerned.

A 256K MP3 when decompressed will sound better than a 128K MP3 when decompressed. If that's what you're asking.

Once decompressed they will sound the same as they did when they were in mp3 format.

CD Quality is 128Kbps, so I'd say it's best to compress at this rate, although as it is lossey, compressing to 256Kbps will retain the most quality. 128 is really the most practical, as the difference is so marginal, it is barely noticable. When decompressed, it will also retain the same quality as the compressed file.