Close GOPs

[geohei]

Hi.

I might have a problem with Encore DVD, which (apparently ?!) only accepts streams with closed GOPs. I have a couple of streams, which have open GOPs. Is there any tool I can use, to reencode _only_ the open GOPs, or do I have to reencode the complete stream all over again?

BTW ... which tool can I use to detect open GOPs?

Thanks,

[AlanHK]

Womble MPEG-VCR has a tool called "MPEG GOP Fixer" which is worth a try.
You can get a time-limited demo at http://www.womble.com/.

For some reason this crashes for me if I do "All above: Scan and fix". But if I do scan, then fix, it works.

[geohei]

At a first glance, this seems to work. However (as you said), it't trial. Is there no alternative software (freeware, shareware, ...)?

Thanks,

[guns1inger]

I am surprised Encore doesn't allow open GOPs as this is a valid encoding technique and allowed within the DVD spec. Of course, Encore hasn't always allow fully compliant objects to be used anyway, so perhaps it isn't such a surprise.

[geohei]

Meanwhile, another odd value showed up in the original stream.

The VBV buffer value of 65 (= non-standard).

This could also be the reason why Encore insists to transcode.
https://forum.videohelp.com/viewtopic.php?t=307127

Also see:
http://www.adobeforums.com/cgi-bin/webx/.3bc1416c/22

Thanks.

[guns1inger]

The transcoding for no reason problem seems to be a major issue wit this release of Encore, along with the fact that compliant video specs are seen as non-compliant (eg 704 x 480 is not seen as compliant by Encore, nor it's main technical support). In fact, many of the responses by what appears to be an Adobe tech support person seems to be ill-informed, often rude, and trying to defend a flawed position.

If you still have DLP on your system, I would use that until Adobe understand what it they are doing.

[geohei]

@guns1inger

You might be right, but be aware that DLP is also messing around. I found numerous bugs! Oscar didn't correct any of them so far (even he confiormed bugy by other users), that's why I changed to Encore.

Back to the topic ... do you know whether open GOPs and/or a VBV != 112 creates transcoding (reencoding) of the stream? If I would know, there might be a workaround.

Regards,

[guns1inger]

From what I was reading in the Adobe forums, open GOPs will certainly force a transcode.

I know DLP has some issues, especially with the release of version 2.0, but at least it allows you to use anything encoded within the DVD specification. I have (touch wood) thankfully not come across any of the bugs and issues listed yet. Some of that is because I just don't use some of the troublesome features (slideshow builder etc), and perhaps don't push it as hard as some on the VM coding side of things.

If I was looking for a change, however, Encore would have been very low on my list simply because it has been wrong from version 1.0, and never been corrected. I would look at DVD Workshop 2 as a more viable alternative.

[pijetro]

I've used both open and closed GOP's with Encore..No issues at all. I would suggest you give us your encoding methods firstly...
I'm suspecting a flawed encode...

[geohei]

@pijetro

I test encoded 2 streams now, using open and closed GOPs. Indeed, Encore accepts both streams. Next I encoded a stream with VBV 112 (standard) and one with 50. Again, Encore accepted both.

Hence, there must be something else which is wrong with my mpeg-2 stream. No clue what this can be ... ?!?!

Here the one that doesn't work (a DVB-S recording)!
http://www.geohei.lu/downloads/temp/NavyCIS.m2v

Here the test encodings which all work fine:
http://www.geohei.lu/downloads/temp/opengop_vbv224.m2v
http://www.geohei.lu/downloads/temp/closedgop_vbv224.m2v
http://www.geohei.lu/downloads/temp/opengop_vbv100.m2v
http://www.geohei.lu/downloads/temp/closedgop_vbv100.m2v

Hence ... open GOPs and VBVs != 112 can't be the reason why Encore doesn't like my DVB-S stream.

Thanks.

[pijetro]

I think the very first frame is corrupted..Everything looks good..
Fantastic encode BTW..
Is that some sort of High Definition Broadcast or something??

[manono]

It authors fine in both Muxman and IFOEdit. As near as I can tell, there's nothing wrong with it. Except for the fact that I wouldn't encode anything that way, but I don't know how much was the broadcast and how much was you. But it's way below the quality of a decent DVD. I only looked at the one that was supposed to be funky.

[geohei]

I think the very first frame is corrupted..Everything looks good..

Could you please be more specific ...

VirtualDub tests it w/o error.
DLP accepts it as well w/o any error message
Pj.X doesn't report any error/warning.

Fantastic encode BTW..
Is that some sort of High Definition Broadcast or something??

Yes. It's part of HDTV demo.

[geohei]

It authors fine in both Muxman and IFOEdit. As near as I can tell, there's nothing wrong with it. ... I only looked at the one that was supposed to be funky.

You looked at the NavyCIS stream, right?

Any idea (other than open GOP, and VBV != 112) why Encore insists to retranscode the stream?

Thanks,

[manono]

Hi-

Yes, that's the one I tested. No, I don't know anything about Encore.

[geohei]

Hi.

Some more testing ...

I managed to pinpoint the problem inside the NavyCIS stream. The very weird thing is now, that when I use NavyCIS_tr-0-0.m2v, Encore transcodes. As soon as I cut the first OR the last GOP, Encore doesn't ranscode anymore?!

http://www.geohei.lu/downloads/temp/NavyCIS_tr-0-0.m2v
transcode

http://www.geohei.lu/downloads/temp/NavyCIS_nr-1-0.m2v
no transcode
first GOP cut

http://www.geohei.lu/downloads/temp/NavyCIS_nr-0-1.m2v
no transcode
last GOP cut

Here the Frames:

NavyCIS_tr-0-0.m2v: IBBPBBPBBPBBI ............................ IBBPBBPBBPBBI
NavyCIS_nr-1-0.m2v:             IBBPBBPBBPBBI ................ IBBPBBPBBPBBI
NavyCIS_nr-0-1.m2v: IBBPBBPBBPBBI ................ IBBPBBPBBPBBI

As you see, nothing wrong there.

I have no idea why Encore accepts the stream without transcoding as soon as I cut either the first or the last GOP.

Thanks,

[geohei]

More stuff ...

I found this tool:
http://www.geocities.com/gabrielgoc/MPEGValidator.zip

It reports 2 problems, which are common to all 3 streams.
# VBV Buffer Size = 65 -> (130 KB)
# DCT Type = Frame

Hence, this can't be the source of the issue since Encore only transcodes the first stream.

On top of that, I just received a message in another forum, that the first stream (which transcodes in Encore 2.0), doesn't transcode in Encore 1.5.1. I really start to believe that it's more Encore 2.0 the problem than my stream.

[geohei]

Hey guys ... it's x-mas

Look at this:
---- cut here ----
In repeat sequence headers all of the data elements ........shall have the same values as in the first sequence header.

The bitrate specified bounds the maximum rate of operation of the VBV as defined in C.3 of annex C. In all cases (both constant and variable bitrate operation) the bitrate specified shall be the upper bound of the rate at which the coded data is supplied to the input of the VBV.
---- cut here ----

The do this:
Take DVDPatcher, and read out the bitrate from the top part of the window. Patch the entire file with this value.

After that ... it works! It seems that Encore doesn't like the different bitrates inside the Sequence Headers.

I'd like to thank you all, for kicking me with ideas, downloading and testing my streams. Unfortunately, not every thread populates competent people which contribute to a solution.

Bye.