Lag on DVD playback

[andrewgerm]

Good day all

I'm busy putting together some feedback on a commercially pressed DVD. The disc lags on both a set-top player, and when played back on my PC. The video looks like it's somewhere between 15 and 20 FPS, instead of the intended 25 for PAL.

I've checked the VOB files with MediaInfo, and they come back as 25FPS, with an average bitrate of 6mbps.

The disc behaves the same on all players I use. And all other discs work normally, and smoothly.
What I'm now trying to do, is find a way to prove that is an issue, other than to subjectivly view the disc itself.

My thoughts are, that the actual disc would pass a cursory check, but that there was likely an issue with the source material, or in the telecine process.

Any suggestions would be greatly appreciated!

[jagabo]

Step through the video frame by frame in an editor. Does the picture change with each frame? If not, you need to figure out what went wrong in your editing and authoring.

[andrewgerm]

Thank you!
DVDinfo says the disc doesn't have CSS so will try one of the VOB files

Thanks for the suggestion!

[andrewgerm]

Some quick feedback. When stepping forward frame by frame, every third frame seems repeated
Seems they used a 24 @ 25 Repeat pulldown method

Would I be correct in assuming this would have been caused at a point during the conversion from 24 FPS to PAL 25?
Either way, it becomes far more obvious when stepping through motion (especially large objects)

[jagabo]

Some quick feedback. When stepping forward frame by frame, every third frame seems repeated

Like ABCCDEFFGHII ? That implies a 25*3/4 = 18.75 fps frame rate. Or do you mean ABBCDDEFF ? That indicates 25*2/3 = 16.7 fps.

Seems they used a 24 @ 25 Repeat pulldown method

2:2:2:2:2:2:2:2:2:2:2:3 pulldown would not give you repeats every 3 frames. 24 fps film is usually just sped up to 25 fps (resulting in a ~4% shorter running time).

Would I be correct in assuming this would have been caused at a point during the conversion from 24 FPS to PAL 25?

What was your source? 8mm film? That's typically 16 to 18 fps.