MP2, MP3 as soundtrack?

[JosephTocco]

I see in some archived movies something strange, namely MP2 or MP3 as soundtracks.
If MP3 is well known format, how about MP2? This was apparently used in radio stations due to a smaller size than MP3, but similar quality.

But in movies? Is it good idea to convert it to something cinema-related, like AC3 or AAC? And what parameters?
Most of these strange things are in MP2 at 48kHz 192kbps.

[ProWo]

mp2 and mp3 are older codecs than ac3 or aac.
The quality at the same bitrate is much higher with ac3 and aac than with mp3 or even mp2.
Therefore it is not a good idea to convert video audio tracks from aac or ac3 to mp3 or mp2.

[JosephTocco]

Not TO Mpeg, but FROM
In practice I never saw before MP2, but on Wikipedia is written that both are from 1993

So MP2 → AC3 with the same parameters will be okay?

[ProWo]

It is a recoding and will only bring you a reduction in quality, but a smaller file.

[jagabo]

MP2 is one of the formats supported by DVD. So some files sourced from DVD will contain MP2 audio.

[JosephTocco]

MP2 tracks arrived to me from Russia. I really didn't saw it before. Could it be dependened on country?
More over, I have recording from Russian version of international channel, directly from DVB-T decoder, and what it is inside? MP2!

How to compare audios, because I don't hear differences?

[Cornucopia]

Depends on the bitrate, on the type of content, and the codec's efficiency. For general reference, let's say for a certain audio file MP2 at 320kbps ~= MP3 at 256kbps ~= AC3 at 220kbps ~= AAC at 192kbps, assuming they're all 1st gen conversions sourced from an original master LPCM wav. That's a good assumption of comparing efficiencies of the various codecs, at least to start with.

MP2 is not as common as it used to be, but it used to be VERY common. DVD, VCD, SVCD, HDV, Musicam transmissions (esp. in live interview audio feeds)...

Scott

[Skiller]

MP2 is widely used (even madatory) in standard def DVB-S and DVB-T broadcasts and DVB-S radio in Europe, as decoders are not required to be able to decode AC3.

The quality at the same bitrate is much higher with ac3 and aac than with mp3 or even mp2.

Albeit I do not have scientific proof, I cannot confirm this. No question about AAC but AC3, even when encoded with commercial software, is not per se better than MP2 (and especially not MP3), at least at 192 KBit/s and up for stereo. AC3 is not good at keeping quality at low bitrates – neither is MP2 – and at the mentioned bitrates both start to sound good, well, they both sound the same (to me anyways, and I tried hard).
192 KBit/s is the magic number. At 160 and below both start to sound quite bad. Hence, AC3 cannot be vastly superior.