Determining if MPG has sequence header before Demux.

[Shaba1]

I have read some of the articles by Micheal Tam at the vcdimager site. Also have read vitalus' post here. What I want to know is BEFORE I start to demux and insert closed GOPs to a mpeg. Is there any way or any software that will tell me if the file already has sequece headers and thus can be chaptered with something like VCDImager or VCDEasy.

I guess I should explain. I have several cds with raw video streams of things that I have shot myself with an analog camcorder and converted to avi with my ATI all in wonder card. I then converted these to mpg-1 with TMPENC and burned them onto cd using EZ CD recorder. They play just fine in both my computer and DVD Stand alone player. I also have a lot of mpeg files that I have downloaded from the internet and that I either converted to vcd format(mpg-1) I or came that way already. No problem playing them in the computer or DVD.

Now I would like to make real VCD's with chapters and menus e.t.c I understand how to do this. I have read the guides from VCDEasy, here at this site and at Micheal Tam's site. The thing is, from reading all that stuff I have determined that that mpeg has to have sequence header(regular or otherwise) in order to be chaptered. I know I can use MPEGSEQUENCE maker OR TMPENC to do that, but I would hate to go thru that if they file already had the headers in it. Is there anyway to tell?

[SaSi]

Easy.

MPEG1 files don't have GOPs at all because GOPs are part of MPEG2 specification.

[petar]

Not sure what SaSi meant but the GOP structure in MPEG1 is (almost) the same as in MPEG2 (MPEG2 is a superset of MPEG1).
If you had the "Output interval of sequence header" (under GOP structure) set to 1 when encoding with TMPGEnc then you have a sequence header for each GOP.
If you're not sure, run the video through an MPEG parser (DVD-Lab has one) and you'll see.

[SaSi]

Not sure what SaSi meant but the GOP structure in MPEG1 is (almost) the same as in MPEG2 (MPEG2 is a superset of MPEG1).

What I meant is that (I could almost swear) that MPEG 1 doesn't have a GOP sequence header structure.

Well, I am wrong. Yesterday was a bad day to post replies. It's been a year since I read the MPEG1 specs and I forgot that MPEG-1 has GOP headers as well in the stream.

Well, what I meant, (if I understand myself correctly), is that any encoder encoding MPEG1 would most likely avoid placing GOP headers as GOP headers are only required for DVD.

Same like encoding for SVCD. Video typically doesn't include GOP headers making the video invalid for DVD (apart from the frame size which can be defeated by programs that modify the sequence header).

In any case, ignore my posting

[petar]

It's the heat .
I'm too in Southern Europe (Spain) it's over 30 degrees here in the morning.