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why dual-channel ?

I saw somewhere in this forum this kwag's post:

Quote:

Originally Posted by kwag

(...)
Dual channel
In this mode, the 2 channels will be totally independently encoded. Each channel will have exactly half of the bitrate. This mode is designed for applications like dual languages encoding (ex: English in one channel an French in the other). Using this encoding mode for regular stereo files will result in a lower quality encoding.
Joint stereo
In this mode, the encoder will make use of a correlation between both channels in order to achieve higher compression. This will enhance the quality of constant bitrate recordings, and reduce the size of variable bitrate recordings. (...)

kwag

So why kvds templates uses dual channel if the joint stereo method gives more quality and higher compression ?

Re: why dual-channel ?

Quote:

Originally Posted by muaddib

I saw somewhere in this forum this kwag's post:

Quote:

Originally Posted by kwag

So why kvds templates uses dual channel if the joint stereo method gives more quality and higher compression ?

Because if you use "Joint Stereo", you loose Dolby Surround information.
The original templates were encoded as joint. That's why I changed to "Dual Channel". And I believe there is a correction to be made in the statement above, which I had taken from a quote in another site.
Dual Channel is exactly the same as stereo, as far as bit rate and quality. But in dual channel, each channel is 100% completely independent. It's actually two mono channels. One left, one right. In stereo, there are some Left Right differences that "bleed" from channel to channel or "cross talk". Not so in Dual Channel mode.

kwag

Re: why dual-channel ?

Quote:

Originally Posted by kwag

Thanks for the answer!
So, if I don't want dolby surround information, it would be better to use joint stereo?
This way I will get more quality (+ bit rate) with the same size, but loose the dolby surround.
Is that right?

Just one more newbie question...
Whem I decode ac3 --> wav, did't I loose the dolby surround information? :roll:

Re: why dual-channel ?

Quote:

Originally Posted by muaddib

Quote:

Originally Posted by kwag

You're right. If you don't want surround sound, go ahead and encode joint stereo.
If you use DVD2AVI, and select "downmix", you'll get your surround in the WAV file. If you use something like "headac3he", you'll also preserve your surround sound. Any Dolby Pro logic receiver will decode the surround sound in your encoded (xyzK)VCD. :wink:

kwag

Kwag,
Where can I select the "downmix" option in DVD2AVI, all I can see is under "audio" tap, under "Dobly Digital" tap, there are options like demux, demux all tracks and decode. Which one is to preserve the surround sound effect in WAV file??

Sorry, I found it. Should I select "demux" or "decode" then??

Select decode.

kwag