HydrogenAudio

Lossy Audio Compression => MP3 => Topic started by: BFG on 2019-11-20 02:08:03

Title: MPEG-2.5 Layer 3 to MPEG-1 Layer 3 using LAME
Post by: BFG on 2019-11-20 02:08:03
I have some old recordings that were encoded as MPEG-2.5 MP3s, 32kbps, several years ago.  I'd like to convert them to MPEG-1 MP3s for maximum compatibility.  I recognize this will require upsampling, but what else would be necessary?

I'm only willing to do this if it can be done "losslessly" (or, more accurately, without further loss of data).  From what I've read and seen of LAME, it appears that the stream would have to be decoded into WAV, upsampled, and then reencoded as MPEG-1 which definitely would be lossy.  Am I wrong about this?
Title: Re: MPEG-2.5 Layer 3 to MPEG-1 Layer 3 using LAME
Post by: DVDdoug on 2019-11-20 03:15:26
I'm pretty sure you'll have to transcode/re-encode and that's technically lossy.   But, if you increase the sample rate you may not hear the quality loss.   I suggest you just go-ahead and try it.

I don't think you have to decompress to WAV, but it will "internally" decoded to uncompressed PCM (the underlying WAV format).
Title: Re: MPEG-2.5 Layer 3 to MPEG-1 Layer 3 using LAME
Post by: saratoga on 2019-11-20 03:21:58
I recognize this will require upsampling, but what else would be necessary?

Decode to wav, upsample, encode to new format.  This will not be lossless obviously.
Title: Re: MPEG-2.5 Layer 3 to MPEG-1 Layer 3 using LAME
Post by: BFG on 2019-11-20 03:25:20
Gotcha.  OK, thanks both.
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