PGC...data rate too high

Question

Hallo,
message
nunew33, "Mpeg not valid error message" #4, 31 Jan 2006 3:29 pm describes a certain error message. The user had problems with an imported MPEG movie.
Now I receive the same message, but the MPEG that is causing the problem is created by Encore DVD itself!?
I am working with the german version, but here is a rough translation of the message:
"PGC 'Weitere Bilder' has an error at 00:36:42:07.
The data rate of this file is too high for DVD. You must replace the file with one of a lower data rate. - PGC Info: Name = Weitere Bilder, Ref = SApgc, Time = 00:36:42:07"
My test project has two menus and a slide show with approx. 25 slides and blending as transition. The menus are ok, I verified that before.
First I thought it was a problem with the audio I use in the slide show. Because I am still in the state of learning how to use the application, I use some test data. The audio tracks are MP3s. I learned already that it is better to convert the MP3s to WAV files with certain properties.
I did that, but still the DVD generation was not successful.
Then I deleted all slides from the slide show but the first. Now the generation worked!? As far as a single slide (an image file) can not have a bitrate per second, and there was no sound any more, and as far as the error message appears AFTER the slide shows are generated, while Encore DVD is importing video and audio just before the burning process, I think that the MPEG that is showing the slide show is the problem.
But this MPEG is created by Encore DVD itself. Can Encore DVD create Data that is not compliant to the DVD specs?
The last two days I had to find out the cause for a "general error". Eventually I found out that image names must not be too long. Now there is something else, and I still have to just waste time for finding solutions for apparent bugs in Encore DVD. Why doesn't the project check find and tell me such problems? Problem is that the errors appear at the end of the generation process, so I always have to wait for - in my case - approx. 30 minutes.
If the project check would have told me before that there are files with file names that are too long, I wouldn't have had to search or this for two days.
Now I get this PGC error (what is PGC by the way?), and still have no clue, cause again the project check didn't mention anything.
Any help would be greatly appreciated.
Regards,
Christian Kirchhoff

Answer 1

Hallo,
thanks, Ruud and Jeff, for your comments.
The images are all scans of ancient paintings. And they are all rather dark. They are not "optimized", meaning they are JPGs right now (RGB), and they are bigger then the resolution for PAL 3:4 would require. I just found out that if I choose "None" as scaling, there is no error, and the generation of the DVD is much, much faster.
A DVD with a slide show containing two slides and a 4 second transition takes about 3 minutes to generate when the scaling is set to something other than "None". Without scaling it takes approx. 14 seconds. The resulting movies size is the same (5,35 MB).
I wonder why the time differs so much. Obviously the images have to be scaled to the target size. But it seems that the images are not scaled only once, that those scaled versions of the source images are cached, and those cached versions are used to generate then blend effect, but for every frame the source images seem to be scaled again.
So I presume that the scaling - unfortunately - has an effect on the resulting movie, too, and thus influences the success of the process of DVD generation.
basic situation:
good image > 4 secs blend > bad image => error
variations:
other blend times don't cause an error:
good image > 2 secs blend > bad image => success
good image > 8 secs blend > bad image => success
other transitions cause an error, too:
good image > 4 secs fade to black > bad image => error
good image > 4 secs page turn > bad image => error
changing the image order prevents the error:
bad image > 4 secs blend > good image => success
changing the format of the bad image to TIFF doesn't prevent the error.
changing colors/brightness of the bad image: a drastic change prevents the error. I adjusted the histogram and made everything much lighter.
Just a gamma correction with values between 1.2 and 2.0 didn't help.
changing the image size prevents the error. I decreased the size. The resulting image was still bigger than the monitor area, thus it still had to be scaled a bit by Encore DVD, but with this smaller version the error didn't occur. The original image is approx. 2000 px x 1400 px. Decreasing the size by 50% helped. Less scaling (I tried 90%, 80%, 70% and 60%, too) didn't help.
using a slightly blurred version (gaussian blur, 2 px, in Photoshop CS) of the bad image prevents the error.
My guess is that the error depends on rather subtle image properties. The blur doesn't change the images average brightness, the balance of colors or the size of the image, but still the error was gone afterwards.
The problem is that I will work with slide shows that contain more images than two. It would be too time consuming to try to generate the DVD over and over again, look at which slide an error occurs, change that slide, and then generate again. Even the testing I am doing right now already "ate" a couple of days of my working time.
Only thing I can do is to use a two image slide show and test image couple after image couple. If n is the number of images, I will spend (n - 1) times 3 minutes (which is the average time to create a two slides slide how with a blend). But of course I will try to prepare the images and make them as big as the monitor resolution, so Encore DVD doesn't have to scale the images any more. That'll make the whole generation process much shorter.
If I use JPGs or TIFFs, the pixel aspect ratio is not preserved when the image is imported. I scaled one of the images in Photoshop, using a modified menu file that was installed with Encore DVD, because it already has the correct size for PAL, the pixel aspect ratio and the guides for the save areas. I saved the image as TIFF and as PSD and imported both into Encore DVD. The TIFF is rendered with a 1:1 pixel aspect ratio and NOT with the D1/DV PAL aspect ration that is stored in the TIFF. Thus the image gets narrowed and isn't displayed the way I wanted it any more. Only the PSD looks correct. But I think I saw this already in another thread...
I cannot really understand why the MPEG encoding engine would produce bit rates that are illegal and that are not accepted afterwards, when Encore DVD is putting together all the stuff. Why is the MPEG encoding engine itself not throwing an error during the encoding process? This would save the developer so much time. Instead they have to wait until the end, thinking everything went right, and find out then that there was a problem.
Still, if sometime somebody finds out more about the whole matter I would be glad about further explanations.
Best regards,
Christian