Why Does One Mpg Jitter and One Doesn't? And Why The Jitter?

[abrogard]

Does anyone have idea why two 'parameter-wise' alike mpg files play differently - one with smooth video and one with jerky frames, like vibrating ?

What I mean by 'parameter-wise', I guess you know, is that they were produced exactly the same way, have all the same parameters but are different movies.

For anyone interested they were produced this way: The avi was fed into virtualdub and the brightening filter invoked. Then the frameserver started and frames served to TMPGPro which made an mpg from each.

Neither has a picture in winamp, just sound. Both play with both video and sound in Nero and Media Player Classic but the first one plays with 'vibrating' video.

GSpot says they have these parameters: DVDVOB. MP2Prog. 10080 kbs AC3 sound. Video MPEG2 Codec NOT installed. pic: 23.97, fps 2997, fld/s 59.93 Src: 4:3 NTSC 4:3 DVD

The original avi files were movie files with a frame rate of 23.97.

It is almost certain I have made some mistake in configuring TMPG or VirtualDub because I'm very much a novice. But I'm very sure I processed the two of them exactly the same - so why does only one 'jitter' ?

There is a difference in the sources inasmuch as one file gives a 'Warning Nothing to Output Bframe Decoder Lag' message when first loaded into VDub. That's the one with the jitter.


regards,

ab

[gadgetguy]

Probably a field order problem. May not be your fault. Problem could exist in the avi and wouldn't be noticeable on the PC.

[DB83]

The answer may well be here

"The original avi files were movie files with a frame rate of 23.97"

If this is correct then in your conversion you have added 6 frames - 23.97 to 29.97 - for every second of video. Or 1/4 of the original video has been duplicated.

The original video should be 29.97 frames per second to avoid any duplicate frames.

But I also see that you are in a PAL system country so why not convert to 25 frames per second if the source is 23.97. Less duplication and, maybe, less stutter.

[abrogard]

I did try to change to PAL but as I remember I didn't have any clear options to do such. I remember at one stage trying to input frame rate and being constrained to preset values amongst which 25fps did not appear.

I'm very much a novice.

Wasting my time really, I think. My t.v. can handle ntsc or pal, I believe. Anyway I'm going to try encoding again without changing from ntsc and see what I finish up with.

these mpg files I'm talking about have not been burned to dvd, have therefore not been played through my dvd player or on the tv, they've only been looked at on the computer. I'm not going to burn them until this jittering thing is fixed.

regards,

ab

[guns1inger]

Open the mpg that 'jitters' in Rejig and demux to elementary streams (video and audio files). Use Restream to change the field order, then test play the video and see if it fixed. try both field orders until you get the right one. If changing the field order doesn't fix the problem, at least you have ruled it out. If it does, you can author with the fixed video and original audio.

[manono]

If this is correct then in your conversion you have added 6 frames - 23.97 to 29.97 - for every second of video. Or 1/4 of the original video has been duplicated.

The original video should be 29.97 frames per second to avoid any duplicate frames.

You're from a PAL country so you can be forgiven your ignorance. But you shouldn't really make statements about things you don't understand. The GSpot statement shows everything to be in order; encoded as progressive 23.976fps with 3:2 pulldown applied to output interlaced 29.97fps.

As both gadgetguy and guns1inger mentioned, it's almost certainly a field order problem.

[abrogard]

Guys, DB83 was only trying to help and I appreciate any such attempts, misleading as they quite often are with the best intentions and previous expertise... it's just the nature of the beast I think.

Anyway... thanks for the input about the two utilities. I have downloaded, installed and used them both. I now have a file: "rejigfile.0.m2v" which was made by restream from the rejig product.

I've changed the field order, I hope, I simply unchecked the 'top field first' box - is that right?

And now I'm wondering what to do with this file. This unmuxed file. To what do I feed it to get it muxed up again back to an mpg so's I can test it and holler with success?

regards,

ab

[manono]

is that right?

Yes. I hope that works, but I've never changed the field order of a pulled down M2V. Maybe you'll have to strip out the flags and reapply pulldown (DGPulldown with the Top Field First box unchecked). I just don't know. Hope for the best.

To what do I feed it to get it muxed up again back to an mpg so's I can test it and holler with success?

For freeware, try ImagoMPEG-Muxer.

[guns1inger]

You can play the video stream back with VLC or Media Player Classic before you go to the trouble of muxing. if it hasn't worked you will know immediately, and will save you time.

[abrogard]

Yes, it didn't work. I used mpc, thanks for the tip.

So first thing is I'll go back to the beginning and make sure I processed them correctly with virtualdub from the original .avi

I've been thinking about it and there was one place there - i think in vdub - where you input the source type and I think I might have input ntsc - whereas actually it was a movie and they're neither ntsc nor pal, are they? they've something else again, that's why the 23. something frame rate.

I'll go back to the beginning.

This is turning into quite a learning curve. And I've got a dir devoted to tools for this task and it's beginning to look quite full......

[guns1inger]

NTSC has two possible framerates. 23.976 for film sourced material, and 29.970 for video sourced material. Pulldown is used to allow smooth playback of 23.976 fps material at 29.970 fps.