Dual Stereo, Joint stereo???

[Doohan99]

What´s the difference between dual, joint and normal stereo????

If I encoded with dolby surround should I use DUAL in TMPGenc?

Is dual with surround sound??
Joint some kind of compression or what?????

Thanx...

[vitualis]

Some correct me if I'm wrong, but my understanding of this is as follows:

MS stereo (normal stereo):
For MPEG audio, in this mode, the bitrate distribution can vary between the left and right channels depending on the "need" or "complexity" of the audio. For example, if the left channel was silent and the right channel had audio, then more of the combined audio bitrate (224 kbit/s MP2 for VCD) will go to the right channel compared to the left.

Joint stereo:
In this mode, the audio is encoded as L+R and L-R... That is, it also looks at the redundancy between the left and right channel. For example, if the left and right channels were very similar (most audio), then the relative bitrate for both would be higher (and thus higher quality). If there is a great degree of difference between the L and R channels, then under JS encoding, the encoder can switch back to MS as required.

For lower bitrates, JS yields better quality audio (as it is more efficient). However, JS encoding can lead to audio artifacts as well... there is a degree of loss of stereo separation, and apparently inappropriate switching between JS and MS encoding (by the encoder) can lead artifacts.

Dual channel:
This is when exactly half the combined audio bitrate is given to the left and right channels.

For VCDs where the audio bitrate is 224 kbit/s, I would suggest that you use just standard audio encoding (i.e., MS). If you create a dual language VCD (e.g., Cantonese mono on L and Mandarin mono on R), then dual channel may be a good idea.

Regards.

[dirk67]

Hi,

Dual: left and right channels are encoded separately. I use it to generate a (S)VCD containing two mono tracks (in one stereo track!), e.g. english on left, german on right channel

Stereo: just what you expect, use this for Dolby Surround

Joint Stereo: used to save bitrate for stereo signals, not recommended since it will not correctly reproduce Dolby Surround.

Please note that these are encode modes, i.e. we ALWAYS have a stereo signal, the modes only differ in the way the channels are used to generate the MP2.