OPen GOP problem

[bendernz]

Hi everyone, I have a problem that is driving me nuts. An "Open GOPs problem”

I know its quite common and I have searched extensively through these forums and, I think I’m probably suffering info overload because I’m just plain confused.

Background: I’m using Sonic Foundry Video Factory to edit a whole bunch of footage into AVI and then decode to mpeg. It supports mpeg 1 and 2, and that seems to be OK.
I’ve recently looked at the trial version of DVlab, which I like a lot. However when I open the mpeg file with DVlab it tells me there are open gops and some of the chapter points will not start accurately. This turns out to be the case.

The movie plays OK, but there are problems with sections playing from the menu at the beginning.

Can anyone give me some info about how I am getting open GOPs, and what I can do to solve the problem?

Thanks.

Shane (posting from New Zealand)

[jimmalenko]

The open GOPs are coming from when you encode to MPEG.

[bendernz]

jimmalenko - any ideas how to fix it? I can find a setting in the software or even a mention in the help section.

[bendernz]

Sorry that should be can't

[Abond]

I would try to explain this open GOP mystery as this is the fifth post I have seen with such a question.
The open/closed GOP depend on the way your mpeg2 encoder handles scene changes. The correct way AFAIK is when an encoder hit the scene change (let say a night scene is changed with a day scene) it starts a new GOP and this GOP must be closed. If you have disabled scene detection in your encoder, then this GOP would stay open and you would have open GOP error from some authoring tools.
The open GOP means that the frames of the GOP can have references from previous GOP. Closed GOP has no such references. So, as the scene changes it can be so different as night and day and there is no sense to have the references from the GOP of previous scene.

[guns1inger]

It will be a setting in your encoder. Sonic Foundry Video factory is a very old package, given that they sold their video and audio packages to Sony more than 2 years ago, and had ditched video factory in favour of Vegas prior to that. Perhaps it doesn't have all the control you now need.

You might also look at the Debugmode Frameserver. It may support Video Factory, and may allow you to frameserve from the timeline to a better encoder.

[bendernz]

I don't have a setting for that in the encoder that I can find. However, when I am capturing the default is to have the scene detection disabled. Might that be the cause.

The MPEG encoder only seems to offer me choices for saving to hard drive, cd, dvd, tape and website so I don't think I can change the setting at the encode or render part.

Each bit of info adds to my sketchy knowledge, and will help me to get to the solution, so many thanks people.

[guns1inger]

I just had a look at the Debugmode site, and the Vegas version does support video factory. It might be worth installing it, and trying out an alternate encoder. CCE Basic or ProCoder express are well priced and powerful encoders. HCEnc is also very good, and free. It's not as fast CCE.

[bendernz]

Gunslinger Vegas started out as video factory and from what I can see, its still almost the same. However I think from this point, using a separate encoder is definitely worth a try so I'll give those suggestions a go. Many thanks to you all for helping. So far my amateur efforts have been very well received among my friends for whom I have made copies... albeit with some random results with the menu. It would be nice to sort it out.

Does anyone else rate dvd lab studio as a menu creation tool or is there something better. Its not that expensive and the results so far have been pretty good.

[guns1inger]

Vegas has come a long way since the video factory days, although the basics are still similar.

I use DVD Lab Pro a lot and like it. I use photoshop to create still menu templates then import them.

[pijetro]

Do you create new chapter points after dropping the video onto the timeline, or are you importing them??

[bendernz]

pijetro, soryy been away for a few days. I'm so new to this I'm not sure of the correct answer, but I think it is ... creating new chapter points using DVD Lab studio once the movie is rendered as an mpeg.

I'm editing the video as an AVI using sonic foundry (which, although its old, is pretty nice to use). I'm putting some words as general chapter headings (such as .. The Fishing Trip of 1994) as an overlay. Then I'm rendering into MPG. I can use MPG 1 or 2, two takes about 5 times as long, and still doesnt prevent the problem.

I am inserting chapter points using DVD Lab Studio. It is when I import the mpeg movie into DVD Lab studio that I get the message about open GOPs. I can't find any settings for closing gops in sounic foundry. The only place I can find scene detection settings is in the original capture from handycam to hard disc.

Hope that long winded explanation helps. I really am a newbie and it's got me stumped. I have downloaded DG Decode but all I have is a bunch of files and not sure how to install or set it up. There are two executables and they will open, but there's a countdown and I get spat out after about 20 seconds. They don't "install" or setup like any other computer program I've used. Don't know what I'm missing there.

[bendernz]

Bloody hell I'm ready to give up. I have established how to get HC Mpeg reader to open and start. But it won't "see" any of the mpeg, avi or dv2 files i have on disc. What the hell and I doing wrong?

[Abond]

dv2 - what's this?
HC Mpeg reader? You mean HC Encoder?
If it is so HC require avisynth script or d2v project file from DGIndex as input.

[bendernz]

Sorry, frustration is making me inaccurate. Yes I mean HC encoder. DV2 - I meant M2V, which is the file I get when I use MPEG2.

How do I get avisynth or dgindex files?

[Abond]

Avisynth.
Install avisynth. Install (unpack) FitCD. Launch FitCD. Click Source and load the .avi. Choose the destination. Click Save script. Load the saved script (the file with .avs extension) in HC. Set it and encode. You can specify a chapters in HC specifying a frame numbers - these would be encoded with closed GOP
DGIndex
Install (unpack) DGMPGDEC. Copy the dgdecode.dll to HC folder. Launch DGIndex. Open mpeg (or m2v) file. File-> Save project. Load the resulted d2v file in HC.
d2v files also can be frameserved to HC using avisynth. Load d2v file in FitCD and then use the routines for avs creation. You need to copy dgdecode.dll in avisynth plugins folder.
In the DGMPGDEC package exists Quick start guide. Read it.

[Bjs]

Open gop's are a right pain to fix ... and I have tried just about everything there is ... ulead video studio can handle them without causing other problem's .

Came in handy when dealing with my first stargate dvd ... it had open gop's ... drove me nutt's making a backup for a customer ...