CCE:2.67 What does "Close all GOPs" do?

[ou8thisSN]

I was burning some home video DV files using DVD-Lab after encoding to DVD video in CCE. Then i upgraded DVD-Lab Pro to the latest version on their website. Now whenever I import new CCE-Encoded video, DVD-Lab Pro gives me a warning saying

"this video file does not have a closed GOP. You can author this file and most players will play it, however your chapter times may be off"


I am paraphrasing the warning. Anyway, with the older version of DVD lab, i never got this warning, and all my DVDRs turned out just fine on my Console DVD players. I also burned the DVDs after the warning, and they played fine as well.

I am encoding 4 video files tonight using CCE, and this time I did check the "Close all GOPs" option. Will this have any adverse effects to what I am trying to achieve?

I am a newB at thist stuff and am basically following the DV => DVD guide using CCE on the Doom9 main page. If you guys can help, thanks.

[fccHandler]

Basically, a GOP is a small "Group Of Pictures" which is part of the larger sequence (your movie), and it typically consists of 15 to 18 pictures. If the group of pictures is "closed", it means it can be decoded independantly of any other such groups. If the GOP is not closed, it will need information from some other group of pictures to be decoded correctly.

Myself, I've read a lot of conflicting statements about GOPs and DVDs. Some say that to be DVD compliant, ALL GOPs must be closed. But I know for a fact I have commercial DVDs where many GOPs are not closed. Some say that chapter breaks MUST refer to closed GOPs, but I know I've seen exceptions to that too.

In theory, allowing GOPs to borrow information from other GOPs can save on bits and improve the overall quality. So, forcing all GOPs to be closed may adversely affect quality. A little. (Honestly, I doubt it would be noticeable to a human.)

[Archimedes]

Ignore the warnings. Use "Close all GOPs" only, if you have really problems with dvd authoring software.

CCE generates closed GOPs automaticly when necessary (i. e. on scene change).

Josef

[kolak]

If you use CCE create chapter list, and use open Gops.
I'm not sure but if you have open gops then you'll have problems with chapater positions.
If some know this please correct me, but
"Chapter points can be set in I frames, that's mean at the begining of gops (but only closed gops)"

edit: sorry but cchandler unswered on my question. I didn't see that:)

[JonRead]

Thanks for pointing me to this thread, I asked the same question (near identical in wording, and I am using DVD Lab Pro too) in another forum section. There seems to be a mixed message really. I guess I will just have to experiment.

[Archimedes]

Here’s an original quote (directly from CCE Headquarters) i’v found on another forum:


<Quote>

Closed GOP is self-contained, that is, all frames in a closed
GOP can be decoded without referencing previous GOP. On the
other hand, open GOP references previous GOP so it is not
suitable for random access. Especially, if you want to set a
chapter to a particular frame, the frame should be the first
frame of a closed GOP. Otherwize, some of the B frames (2 frames,
at most) in the GOP cannot be decoded properly when you skipped
previous GOP, that is the only problem of open GOP when creating
DVD.

In the default setting, CCE outputs open GOP only if there is no
scene change. At scene change point (or if you manually set
chapter to a particular frame), CCE automatically generates
closed GOP to avoid the problem mentioned above.

In short, CCE generates closed GOP when necessary so you don't
need to select "Close all GOPs."

</Quote>


Hope this helps.

Best regards
Josef

[ou8thisSN]

well i made 4 dvds today from the "Closed ALL GOPs" options checked on CCE. Burned with DVD Lab, and tested... no problems or noticable differences between checking and unchecking the option (besides not getting a warning in DLP). So, i guess its whatever...

[Archimedes]

In general, only use „Close all GOPs“ if you have problems with authoring software etc. You will become better results without this option.

Best regards
Josef

[Amnon82]

In general, only use „Close all GOPs“ if you have problems with authoring software etc. You will become better results without this option.

Thats right. I use also DVDLabPro for authoring my DVDs. I encode the M2V with my program AutoQ which is a addon to CCE. Since 1.5.6 I added Closed GOPs - Option. I'll encode today my first film with CGOPs. Lets see if this change the Chapter-Problems with DVDLabPro. I can tell You: If You use open GOPs it will work. Till now I had no problems with GOPs. If You can life with almost right Chapter points use open GOPs, if not close them. Open GOPs will give You better Quality ...

Now here the Result of my Test with CGOPs in AutoQ:

DVDLABPro don't give me the message cos all GOPs are closed, but the chapterpoints bug isn't gone. So I'll encode with open GOPs as I did in the past ;)