Video on DVD is "jerky"

[t0lik]

Hey guys,
anybody can help me out with this problem: I made DVD from my home movies, and everything works and plays fine, until camera in the video starts panning around, or somebody moving in front of the camera - at that point, video becomes very "jerky".. how to explain it... images basicaly "double" as they move - it's like there is no smooth motion or something.. Very weird. I made several DVDs with no problems before. The only thing I made different this time is when i made the movie in Studio 7, I export it as MPEG file, not AVI as before. Then I split the mpg file into video (m2v) and audio (mp2) file. Then I encoded audio into ac3 file, then created project in Sonic Fusion, and imported both ac3 and m2v files. DVD creation went with no problems. When I play these video files on my computer, everything is fine - video is not jerky on motion scenes, it only happens on regular DVD player. Any ideas?

Thanks

[jrdallas]

Possibly the field order in your encoded mpeg file is wrong. Normally when encoding to mpeg2 you should check 'upper field first' in your mpeg2 encoding program.

[t0lik]

Well... It doesn't look like it the case of the incorrect field setting... If I chose the wrong setting, the video would be "jerky" from the very beginning, right? In my case, video is very stable all the way through, except when something moves on the screen , or camera pans around - at that moment, objects in the video have "double vision" effect - it's like they all have "ghost" afterimage right next to them. When something is more or less static on the screen, it looks fine. It's only when the object starts to move, then instead of smooth motion, the object starts to "multiply" - it "doubles" and "triples" with ghost images. Almost like strobe effect. Any ideas?

[Arky]

This could also be caused by one or more of the following:

I must say that my first instinct was exactly the same as jrDallas's - this is a very common symptom of incorrect field order. However, since you state that you have eliminated this possibility, there are others:

1) Bitrate too HIGH (data cannot be read fast enough from the disk - this is a rotational velocity / data density issue - because the data is not as densely packed on a CDR as it is on a DVD, the CDR cannot spin fast enough for enough bits to be read when a high data-rate MPEG file demands it, during playback).


2) LACK of bitrate - scene changes require insertion of I-frames (if you want to know more about this, read up on the fundamentals of MPEG encoding-THEORY). I frames use the most Bitrate of all the frame types, and if there ain't enough bitrate to go round, scene changes will suffer in your final MPEG files.

3) Lack of Scene-detected I-Frame insertion - some decoders require that this be specifically enabled by the user. If I-frames are not inserted at scene changes, or fast pans, etc, then you will get extremely poor results, with jerkiness being just one of the possible symptoms.

4) Inadequate CPU processing power to playback high datarate footage.

5) I don't know what your source footage is, but I have had problems CAPTURING DV-cam footage, with symptoms exactly the same as you describe. This turned out to be a CARDBUS (PCMCIA) bandwidth problem on my laptop, which I have since resolved, through more efficient resource management, and disabling preview during capture, using Premiere6. Of course, encoding these faultily-captured DV files into MPEG2 simply carried the problem across into the final result.


I hope one of the above will solve your problem. If not, get back to me!

Good luck.


Arky ;o)