Question about converting mp3's

Yes, if the mp3s get decoded and encoded to mp3 again there will be a decrease in quality. See transcoding.

I transcoded AAC 256 VBR ten times from AAC to AIFF to AAC to AIFF to AAC... etc. The difference between the original AIFF and the tenth generation AIFF was VERY small. Transcoding high bitrate lossy isn't really a problem.

I doubt that the difference between your MP3s is audible.

Quote:

Originally Posted by bigshot 

I transcoded AAC 256 VBR ten times from AAC to AIFF to AAC to AIFF to AAC... etc. The difference between the original AIFF and the tenth generation AIFF was VERY small. Transcoding high bitrate lossy isn't really a problem.

 

I doubt that the difference between your MP3s is audible.

The .mp3 coded is VERY different from AAC.  I would think multiple passes through .mp3 and back would fare much worse.  

If you want to try something really wild, transcode between AAC > mp3 > AAC (different rate) > mp3 (different rate).  

I found a set of conditions once, .mp3 > Dolby AC3 that actually sounded better than either alone!  I don't recall the bit rates, but something about that combination was complimentary.  I doubt this would happen very often though.  It was in a broadcast situation, music stored on HDD as mp3 files, then sent over a Dolby STL to a transmitter site, about 15 years back. Unlikely this is an issue anymore.

Maybe for most tracks there is no difference if you transcode from mp3 V0 to V0 once, but it is still a lossy process.

Using lower bitrates (128 kbps) there definitely is a difference when using an mp3 as source instead of the original.

You'd think that the software would have a simple check to see whether the file to-be-transferred is already at the desired encoding scheme.

Quote:

Originally Posted by anetode 

You'd think that the software would have a simple check to see whether the file to-be-transferred is already at the desired encoding scheme.

I know with dbpoweramp's batch convert you can specify which file types you would like to convert. Very nifty tool. I don't think the batch convert is part of the free version but you can get a free trial, and it's the fastest converter that I know of(especially if you have a lot of cores) so the trial should be plenty enough time to get the job done. 

Yes, I use dbpoweramp and its batch-processing is a wonder to behold from behind a four core hyperthreaded processor. What I was referring to was the OP's software, which I presume is iTunes given the stated purpose. Does itunes indiscriminately re-encode each file or does it check whether the file already uses the prescribed encoding scheme?

There should be an option to only convert a certain filetype in the batch converter.

I was doing pretty much the same thing as you before, and what I did is converted all FLAC files to MP3, and then did a search in foobar for .mp3 and copied and pasted those into the converted folder.