Help me understand some basic encoding concepts.

[royrose]

I am not entirely sure what happens during the encoding process. I have taken VOBs and demuxed them using VOBedit. This results in an audio and a video file. The video file ends in .m2v. If I remux using TMPGEnc, I get a file ending in .mpg

My question is what is the difference between an mpg file and an m2v file. Also. what changes in the remuxing?

The VOB was already encoded using mpeg compression settings. Why do I have to remux or reencode it to then use it in an authoring program? Does demuxing undo any mpeg settings that then have to be redetermined?

These questions came up after I captured video into my Panasonic HS2 video recorder, created a DVD, then copied the VOBs into my computer so I could demux them and reedit the video and create new menus. I found that simple demuxing and remuxing degrades the video but complete reencoding at high quality levels produces high quality video. I would like to simply demux while keeping the original high quality compression.

Any help would be appreciated.

Roy

[SIRCOOKS]

https://www.videohelp.com/glossary .. please refer here to find out terms, use dvd2avi to demux your vobs, then use whatever you use to turn the .mpa file into wav, and your ready to encode, .m2v i think without checking the glossary myself, mpeg 2 format...useful for a svcd..but after you demux it as i said you can do whatever you want with the file... it doesn't undo any mpeg settings...to my knowledge it just turns mpegs to compatible .avi's for encoding...also that does not necessarily decrease the quality of the overall picture of the feature, its your encoder and your process leading up to encoding..holla if you need help

[royrose]

Actually, I think I need to rephrase my question. I am satisfied with the demux done by VOBedit. I also have learned how to convert the AC3 audio from the demux to wav.

What I want to do is unite the m2v video from the demux with the wav file without changing the compression of the m2v video file in any way. Programs like TMPGEnc seem to reencode using new compression settings. I would like to find an encode program that has a box where you check "keep current compression fromat".

Thanks for the tip on the glossary.

Roy

[Hardcoreruss]

Not being rude but why would you want to do this ?.

Is your aim not to transfer the film onto a cd to watch on a standalone

[tompearson]

wont Vdub do what u want, ie join the wave and video together? and save as avi?

[bugster]

First thing I want to say is that the use of file extensions is only convention, you can't guarntee a file types contents just by the filename extension.

Having said that:-

.m2v - mpeg-2 video, no audio
.mpg - mpeg program stream, audio and video interleaved or 'multiplexed'

When you 'demultiplex' a set of vobs, it is extracting the video information and storing it into a .m2v file. It also extracts the audio data and stores it into a .wav (uncompressed PCM audio) or a .ac3 (Dolby Digital multichannel audio) file. The actual video and audio data is not changed during this process, only the way it is stored with the files. One thing that does change is the file headers that describe the data format used to any programs that may require it. This isn't normall a problem.


OK, so you have a .m2v file and a matching audio file and want to use these to author a DVD. You don't say what authoring app you want to use. Some apps require program streams (video and audio together), som require seperate streams and some will take either.

re-multiplexing is only necessary if your authoring app requires it. This can be done using TmpGenc. Go to file->mpeg tools and select the simple multiplex option. You should be able to work out the rest of the process yourself.


From your descriiption it looks like you were re-encoding with TmpGenc, which would reduce the quality and should be avoided if at all possible.

Hope this helps