what is muxing and demuxing...

[monkeyhair]

hi,

this must be a real newbie question, but what is muxing and demuxing? like what does it do to the movie file? why would you do it?

-m

[khelms]

They're short for multiplexing and demultiplexing. Multiplexing means combining different types of data in a single stream or file. On this board, they're talking about combining the video and audio data in a single file. Demultiplexing means splitting the video and audio out into separate files.

As I understand it, the MPEG1/2 streams on VCDs and SVCDs contain multiplexed audio and video, so if your capture process creates separate files, you could combine them before you do your MPEG encoding. I suppose you might demultiplex an a/v file if you wanted to extract just the audio portion of the data. I've also seen some postings saying the xyz encoder works better with separate audio and video files.

[Vejita-sama]

You've got it. As for why do it? A lot of people like to encode their audio w/ tooLame instead of TMPGenc's. Also have TMPGenc just encode the video speeds up the encoding (slightly).

Also if you're making (x)SVCD you can encode more than one audio track, then mux it with the video.

For example, for no good reason I made a xSVCD of an anime:
480x480 MPEG2
Video=2488kbit/s
Audio1 = Japanese; Audio2 = English both at 128kbit/s
Selectable subtitles in English and French
Motion menu (TSCV) with chapters, THX intro clip, etc. etc.