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MP2 to MP3 without loss?, converter desired
bugbear
post Oct 23 2012, 09:15
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I have some audio capture from Freeview transmissions in the UK (DVB)

I can demux the Audio out using Project X, but that gives me MP2.

My goal is to generate an MP3, for better software/equipment compatibility. I (obviously... rolleyes.gif ) do not wish to incur any degradation in the conversion.

I note the existence of Jpegtran, a set of routines that perform limited manipulation of JPEG image without performing a decode-recode pair.

I wish a similar transform, from mp2 to mp3 (if it is possible).

Given the existence of mp3repacker, a VERY rough (but lossless) mp2 to mp3 implementation would serve, since the output mp3 could be retrospectively tidied.

BugBear

This post has been edited by bugbear: Oct 23 2012, 09:18
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darkbyte
post Oct 23 2012, 09:20
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I dont think it's possible. MP2 encodes audio in the time domain, MP3 does it frequency domain so although they have the same MPEG file format the two codecs are different.
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2Bdecided
post Oct 23 2012, 10:25
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darkbyte is right, in that mp3 uses (and any valid mp3 file must use) an MDCT - which is entirely absent from mp2. So there's no way of putting the mp2 data into an mp3 file without loss. It's a different, lossy, representation of the audio signal.

Just renaming something.mp2 to something.mp3 (or something.mp2.mp3 so you know what it really is) is a handy workaround for lots of equipment - often the front end only looks for ".mp3" files and can be tricked into letting mp2 audio through by the simple renaming. Mp3 decoders are supposed to decode mp2, and many will if you can force the front end to pass them through. Doesn't always work though.


I just transcode using fb2k/lame if I need mp3s. I pick a higher target quality/bitrate than normal to try to minimise transcoding artefacts. I only transcode if I have to. Where space is less important than compatibility and sound quality, I just go to FLAC. If I want to keep the recording long term, I just keep the mp2 version.

Cheers,
David.
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bugbear
post Oct 23 2012, 11:16
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QUOTE (2Bdecided @ Oct 23 2012, 10:25) *
darkbyte is right, in that mp3 uses (and any valid mp3 file must use) an MDCT - which is entirely absent from mp2. So there's no way of putting the mp2 data into an mp3 file without loss. It's a different, lossy, representation of the audio signal.

Just renaming something.mp2 to something.mp3 (or something.mp2.mp3 so you know what it really is) is a handy workaround for lots of equipment - often the front end only looks for ".mp3" files and can be tricked into letting mp2 audio through by the simple renaming. Mp3 decoders are supposed to decode mp2, and many will if you can force the front end to pass them through. Doesn't always work though.


I just transcode using fb2k/lame if I need mp3s. I pick a higher target quality/bitrate than normal to try to minimise transcoding artefacts. I only transcode if I have to. Where space is less important than compatibility and sound quality, I just go to FLAC. If I want to keep the recording long term, I just keep the mp2 version.

Cheers,
David.


Thanks for that - it's a really good answer to my question, even if it's not the answer I was hoping for.

BugBear
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Maggi
post Oct 23 2012, 13:13
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just like 2Bdecided said, you could try and just rename the mp2 extension to mp3 ...

I did so quite a while back with recorded satellite radio streams (mp2) and those played back just fine on my Philips eXpanium 511 CD/MP3 player back then

This post has been edited by Maggi: Oct 23 2012, 13:14
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