stereo or dual channel mp2?

[t0nito]

What's the difference between stereo and dual channel audio? In Tmpgenc's audio settings there is a dual channel option. Which setting is better? I've heard that dual channel can preserve dolby prologic surround.

[vitualis]

There are three ways of encoding stereo in MPEG-1 audio:
Stereo
For ordinary "stereo" for MPEG-1 encoded audio, the bitrate of each channel (L and R) can change depending of the "demand" of the audio in each channel.

For example, say the left channel is silent and there is audio in the right channel. The MPEG encoder can then allocate most of the bitrate to the right channel.

MS stereo (mid-side) or Joint stereo
In this mode, the audio is encode as L+R and L-R (i.e., middle and side). The decoder then processes them back to ordinary L and R. The benefit of this scheme is that it takes into account the redundancy between channels. For example, in most audio, the left channel and right channel are quite similar. The method of encoding audio will be able to exploit this redundancy and effectively boost the bitrate of the encoded audio.

This works especially well for low bitrate MPEG audio.

BTW, I in previous posts mistaken referred to ordinary stereo as MS stereo. It is not!

Dual channel
This allocates exactly half of the bitrate to the left and half to the right all the time.

Now, I would suggest that you don't use joint stereo with VCDs. The bitrate is high enough that you probably can't hear the difference anyway, and there is generally some degree of loss of separation in JS encoding (which *may* affect Dolby Surround reproduction).

I personally advocate that you use standard stereo as the encoding is more efficient than dual channel. I don't think (to my ears) that it has any detrimental effect on Dolby Surround when compared to dual channel.

However, Sefy (another moderator on this forum) thinks that dual channel is better.

I suggest that you try it out yourself and test it with your own ears.

Regards.

[t0nito]

ok I'll try thanks a lot for explaining.

[Ethelred]

And some VCD players, such as the NAPA 310 can't play Joint Stereo VCD's, which is fair enough really when the spec says stereo.

[SatStorm]

Not exactly in the subject, but it is related somehow:
Most of DVB/s transmissions in europe, are Stereo and Join Stereo. There are no dual sound transmittions, exept some SCPC feed channels, not for cormecial use. Those pro transmissions include the TV sound on one audio channel and a radio on the other one. You hear both audio channels, and only manually you can choose what to listen. The same is happening with the Swiss channels on Hotbird satellite series.

For the record, Most of Movie channels are using stereo, but most of music channels are using joing stereo.