Demux

[Deltron]

What exactly does de-muxing do and when should I use it?

I convert my .avi's to .mpg's in TMPGEnc and then go straight to Nero. Why do I have to demux?

Please clear this up for me.

Laters,
Deltron.

[Shabubu]

Demux seperates the audio and video to 2 different files. You then remux them back together. TMPGEnc seems to have problems putting the audio and video together (according to the mpeg scan in VCDEasy), so lots of people including me demux, then remux with bbMPEG, which makes a very compliant MPEG.

It's not something to worry about if your only getting started, you only really bother when you've been doing it a while and get picky

[vulture]

Shabubu,

This is probably a stupid question, but at what point do you demux and then remux? Demux before encoding to MPEG? If you could give the order you do things, that would be great. Thanks

[Shabubu]

Demux is for encoded MPEG's. Again it's only used to fix problems in an encoded mpeg. If the mpeg's you make work you don't need to do it. follow the flow chart below to see how mpeg's are encoded (roughly).

http://www.greenfieldsstudios.com/Stuff/muxing.gif

Now if your not happy how your encoder MUXED the two streams (audio and video) together you can take them apart again and put them back together (DEMUX & REMUX).

So short answer to your question is after encoding. But try and see how it all fits together. Again if your don't understand it and your mpeg's work, you don't need to worry about it.

[Deltron]

I have Memento as an .avi right now, and when I load it into TMPGEnc it tells me an error occured when loading the audio. So I make a .wav out of the audio, then load that with Memento.avi to get my .mpg right.

I encode it for 30 secs, stop it, and check how the output looks, and the video is out of sync with the audio, so would demux and muxing help me in this situation? Would it align the audio with video?

Laters,
Deltron

[Shabubu]

If the audio is consistantly a certain time off sync then yes, when you mux with bbMpeg you can change the startup delays for audio and video seperately, so that you can have the video start before or after the audio, fixing your async. Also, try frameserving to tmpgenc using virtualdub (set the audio to full processing mode) and get tooLame and SSRC and set them upo as external tools in tmpgenc.