GOP Values & DGPulldown

[Island_Dweller]

Hey folks!

I'm wondering if there is any way to calculate the M, N/M values to input in CCE depending on source material's frame rate and the final output. Sometimes, TMPGEnc Authoring Works complains about the GOP length being too long.

What values are recommended when encoding with CCE and applying pulldown afterwards with DGPulldown?

1) 23.976 fps -> DGPulldown -> 29.97 fps
2) 24 fps -> DGPulldown -> 29.97 fps
3) 25 fps -> DGPulldown -> 29.97 fps

4) 24 fps -> DGPulldown -> 25 fps

I know case 1 doesn't require DGPulldown, as CCE can readily apply the necessary pulldown, but TMPGEnc Authoring Works likes to complain about the bitrate being too high or something, and running the mpg file through dgpulldown gets rids of that.

[manono]

Sometimes, TMPGEnc Authoring Works complains about the GOP length being too long.

That's when you open your video in TMPGEnc Authoring Works, right? What values have you been using? I'd ignore it. Now, if it aborts during the authoring, then you might have something to worry about.

For your first three I use M=3, N/M=4. Those are safe values. Never done the fourth. I would guess M=3, N/M=5 would be OK.

...but TMPGEnc Authoring Works likes to complain about the bitrate being too high or something...

A well-known TMPGEnc Authoring Works bug. CCE might set the Max Bitrate at 9800 in the header no matter what it really is, and that 9800 plus the audio bitrate causes it to throw a warning. It can't possibly know about any actual buffer underflows until doing the authoring.

[Island_Dweller]

That's when you open your video in TMPGEnc Authoring Works, right? What values have you been using? I'd ignore it. Now, if it aborts during the authoring, then you might have something to worry about.

For your first three I use M=3, N/M=4. Those are safe values. Never done the fourth. I would guess M=3, N/M=5 would be OK.

It's actually when you try a simulation or if you click on "start output". I have ignored it in the past and it didn't create any problems during playback on my DVD player, but sometimes I get some 24 fps footage sent to me and they ask for a PAL or NTSC DVD. I just want to be thorough and be absolutely sure it won't cause any problems.

I just tried those values you suggested, M=3, N/M=4 works perfectly for the first three.

However, M=3, N/M=5 doesn't work for 24 -> 25 pulldown, I get the same GOP length message.
But M=3, N/M=4 works perfectly on this last one.

A well-known TMPGEnc Authoring Works bug. CCE might set the Max Bitrate at 9800 in the header no matter what it really is, and that 9800 plus the audio bitrate causes it to throw a warning. It can't possibly know about any actual buffer underflows until doing the actual authoring.

I didn't realise that, but your explanation seems logical, I never use a Max Bitrate that high, I usually set it to 8000.


Thank you very much for your kind help, it is much appreciated