I want to convert a big number of AAC music files to mp3. The bitrates I will meet in AAC are in the range of 96,128,152,192 kbps. The available bitrates to mp3 from my converter are 96,128,152,192,256,320 kbps.

Since I know that AAC generally provides better quality at the same bitrate when compared to mp3, I need to choose the suitable mp3 bitrate for each mp3 file I will be converting. I spontaneously decided to move the quality two "steps" up for each conversion, e.g. if the AAC is 96 kbps, I move to 152 kbps MP3, if its 192, I move to 320 kbps MP3.

However I'm not sure if that's the optimal choice, since I would like to save as much space as possible by choosing the lowest mp3 bitrate necessary to avoid loss of quality.

So, what I am asking for, is someone who has good knowledge of the relative technical aspects to recommend the best choice I should make about the bitrates while converting from AAC to MP3, ideally for each one of the choices listed above.

1 Answer 1


You will lose quality due to second generation loss. Even if AAC and MP3 were identical in quality for a given bitrate, the transcode from one to the other would result in a loss because the information each discard is different. It wouldn't surprise me if converting from a 96kbps AAC to even a 320kbps MP3 would be unsatisfactory quality due to the additional loss.

It's really up to you to come up with a scheme that matches your quality and space needs. If I had to do a conversion like that, I'd probably try using higher quality MP3s for the lower quality AACs to minimize additional loss and then have a it balance out in the middle and then use high quality for the high quality.

Your best bet is really to do some trials and adjust for your personal tastes though. Try taking a couple of files of each quality level, encode them in a few different quality levels and listen to them. Decide what the trade off between quality and size that is ok to you is and setup your guide that way.

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