Demux

[ydekmekji]

Can anyone give a concise definition of demux and whether i should do it/use it (i think there is a .bat file by someone)?

[reven]

its only for use with the "my videos" plugin, and only then if you want to burn your videos to dvd on a regular basis. it just fixes every recorded file once a day so they can be burnt to dvd quicker. otherwise another process has to take place when burning a dvd, adding about 10-20mins to the burning time.

[colin]

A mpeg file consists of 2 stream, a video and an audio stream. The process of demuxing splits the the mpeg out into its 2 streams. Unless you need to do any work on the video or audio stream then you have no need to do this.

Occassionly, if your audio is either ahead or behind the video, then demuxing and remuxing sometimes will help this problem (ie, the audio timestamps in the original are maybe corrupted so this fixes the problem). In the case of a DVD, the vob is really an mpeg consisting of video and ac3 audio. You can demux this, convert the audio stream to mpa audio, mux it together again and this will play nicely on a device like the MVP. DVD2Mpeg plugin does this.

Cheers,
Colin.

[reven]

the demux file does a demux then a remux of the file, just so its good for burning (yeah it was a poor name for the file) i think ydekmekji is talking about the "demux.exe" file found at the wiki. if ydekmekji is talking about that disregard colins post as its the technical side of "demuxing" and it has very little to do with "demux.exe".

[colin]

so what does "demux.exe" do if it does not split the mpeg into audio/video streams?

cheers,
Colin.

[reven]

the demux.exe file i made, uses PVAs... (something, i forget the name, its a wierd one) to demux the mpeg2 file, so you get temp.mpv and temp.mpa, then it uses mplex to put the mpv and mpa file back together, and replaces the orignal mpeg2 file, thus fixing it and allowing it to be burned with dvdauthor. its a demux/remux.

[colin]

probably PVAinstrumento. I would be curious to know whether muxman would be of any use to in the remux process. I have yet to try it, so might have a play with it and see if it could be used in preparation for DVD authoring,

Cheers,
Colin.

[reven]

yeah i think its PVAinstrumento, just a name i always forget. there is a problem with it however, it requires a demux.ajb (i think its .ajb) file to run, it cant take the something like:
pva.exe originalmpg.mpg temp.mpv temp.mpa
and do it that way, it needs a complete file, so that can be annoying. other than that its pretty good, mplex does a good job at putting the pieces back together.

[colin]

An alternative to PVA would be rejig. And i believe this can be used as a command line like so

ReJig -level 65 -o "e:\rip\big_small.m2v" -i "e:\rip\big.vob"

(for no transcoding change the level to 100). I will try later if

ReJig -o "e:\rip\big_small.mpa" -i "e:\rip\big.vob"

will extract the audio, but this may make things easier as additional files like PVA. Oh, and it can do mpegs so just change the .vob to the mpeg postfix.

Cheers,
Colin.

[reven]

colin dont worry about it, it does what its suppose to do quickly enough, and its not suppose to be a big advance thing, it just takes does one of the dvd burning steps once a day instead of when the dvd is about to be burned. its nothing fancy.