Telecine problems with Progressive File

[jweathers7]

I have joined together three MPEG2 files where the middle MPEG2 is a re-encoded transition. All three files are Progressive frame MPEG2 with Pulldown flags. When I join them together, the result appears to have problem near the point of joining in terms of applying the pulldown flags.

If I use DGIndex to create a d2v file of the result file telling DGIndex to honor the pulldown flags and then step through the file in VirtualDub, I find that the nice 3 progressive frames, 2 interlaced frames pattern breaks down at the place where the two clips were joined and I see a few places with 3P:7I and 3P:6I.

What's causing the pulldown flags to get all out of wack?

Is there some way I can remove all the telecine flags and then have them added back in properly so that that the film looks right when shown on an interlaced TV?

[Guest]

Naively joining pulled-down MPEG2 fragments is fraught with peril.

Suppose you have a first clip that is:

3 0 1 2 3 0 1 2 ... 3 0 [EOF]

and the second is:

3 0 1 2 3 0 1 2 ... 3 0 1 2 [EOF]

When you join them, you get:

3 0 1 2 3 0 1 2 ... 3 0 3 0 1 2 3 0 1 2 ... 3 0 1 2 [EOF]

The transition 0 -> 3 changes the field order.

The best thing is to edit such that no field order transitions result.

You can use DGPulldown to reflag the stream. But if there is irregular pulldown in the original stream, then you may get audio desync. It's worth a try if you don't have the option of re-editing the cuts.

[jweathers7]

Thanks for this information and description and all those wonderful DG tools!

So are you suggesting that I -might- be able to fix my problem by using DGPulldown to remove the flags from each of the clips (using 29.97 -> 23.976), join the clips together in Womble, and then use to DGPulldown to add the flags back into the picture (using 23.976 -> 29.97)?

If I wish to give the reediting option a try, is there a tool that I can use to let me know which type of frame I'm dealing with (0, 1, 2, 3)?

Thanks again!

[Guest]

So are you suggesting that I -might- be able to fix my problem by using DGPulldown to remove the flags from each of the clips (using 29.97 -> 23.976), join the clips together in Womble, and then use to DGPulldown to add the flags back into the picture (using 23.976 -> 29.97)? No. Just run 23.976 -> 29.97 using DGPulldown on the merged stream. The old flags will be replaced. You'll have to demux to ES streams and remux, because DGPulldown acts only on ES.

If I wish to give the reediting option a try, is there a tool that I can use to let me know which type of frame I'm dealing with (0, 1, 2, 3)? DGIndex. I'm afraid this is an advanced operation and I'm time-challenged for bringing you up to speed on it. Maybe someone else will jump in.

[jweathers7]

No. Just run 23.976 -> 29.97 using DGPulldown on the merged stream. The old flags will be replaced. You'll have to demux to ES streams and remux, because DGPulldown acts only on ES.
:thanks: You just fixed my problem! I tried it out and verified it on my TV. Now I can finally be satisfied with my re-edit!

DGIndex. I'm afraid this is an advanced operation and I'm time-challenged for bringing you up to speed on it. Maybe someone else will jump in.
Well, thanks for the pointer anyway. If someone else jumps in about it that will be cool. If not, maybe I can figure it out on my own. It seems like a better approach for future projects.

[jweathers7]

I spoke too soon.

Indeed, just as I was warned above, I now have an audio/video sync problem that I described here: http://forum.doom9.org/showthread.php?t=107801

I posted the above message to the other forum mainly because I wasn't sure if my question still applied to this forum and didn't know where audio/video sync best fit in on the forums.