HDTV 29.97 to 23.976 any difference?

[n3rdyguy]

I've lately taken an interest in encoding HDTV streams (.ts) to avi, and just noticed that all the other hdtv rips I've watched were 23.976 FPS. However ALL the .ts streams I've got are 29.97.
Anyone got an idea why this is? Is there any encoding speed increase or better quality in doing this?

I was just curious thats all, but if there is some sort of point in this, anyone mind telling me how to do this with gordian knot??


Regards,

[manono]

Hi-

Anyone got an idea why this is?

Yes, NTSC television standards require 29.97fps (actually 59.94 fields per second) output. If they're movies originally 23.976fps, then you apply IVTC in GKnot to bring them back down to 23.976fps. The advantage? Smoother playback, more efficient compression, better bitrate distribution, since you're encoding 20% fewer frames.

[n3rdyguy]

Hi-

Anyone got an idea why this is?

Yes, NTSC television standards require 29.97fps (actually 59.94 fields per second) output. If they're movies originally 23.976fps, then you apply IVTC in GKnot to bring them back down to 23.976fps. The advantage? Smoother playback, more efficient compression, better bitrate distribution, since you're encoding 20% fewer frames.

Thanks alot for the fine answer. :thanks:

[n3rdyguy]

I have now tested this method, and it seems to work. But I got a warning from Goridan Knot, saying that IVTC is the last thing to try, and that I should proberly try turning on Forced Film in DGIndex.

So I made a 3 minute clip with Womble (http://www.womble.com/products/), then back to DGIndex and turned on Forced Film under the Field Operations menu. And voila! Encoded the clip with GK, and it was 23.976 FPS, and the audio was in perfect sync.

So again, thanks alot for your help.


Regards,

[manono]

Hi-

Yes, Forced Film is easier when it can be used. The usual advice is to use it when the percentage of Film is greater than 95. IVTC after using Honor Pulldown Flags in DGIndex will do the same thing, just more slowly.

Either way the audio remains in synch. And either way, you've learned now how to get your captured movies back to their original 23.976fps with the resulting better quality for the same file size. Good going.