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Standards Conversion 23.976 to 29.97

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Jack BonnettStandards Conversion 23.976 to 29.97
by on Jun 10, 2013 at 1:26:18 pm

Hi all, I'd just like to check something with the Cow Mind about standards conversion in After Effects if I may.

Although I am in PAL land I am currently working on a loop for someone that is primarily 29.97 footage. Although it looks progressive it is flagged as interlaced so I am working in the final project in FCP with an interlaced timeline.

The issue is that two of the clips we have been sent as premium content are at 23.976fps and again although they appear progressive are flagged as interlaced.

I believe therefore for times sake I am better off converting the two 23.976 clips to match the majority of the footage at 29.97. (Although I also understand that converting 29.97 footage to 23.98 will give better results correct?)

Although I expect a hardware encoder will give better results too there is no budget for this so AE or Compressor it is. In AE I have imported the clip and checked it's interpretation as 23.98 and no field dominance. This I have placed in a it's own composition with the same settings. On export I have chosen my output as Prores HQ and Changed the render settings to upper field first and turned on 3:2 pull down to export to 29.97fps. I have also exported it as a progressive video without the 3:2 pulldown thereby duplicating every 4th frame.

The client so far isn't particularly happy with either result. They don't like the occasional blended frame on the interlaced version and they don't like the slightly choppy movement on the repeated frame version. There is sync sound that is mixed so simply retiming it in Cinema tools isn't an option either. I think the final file needs to be delivered as a high bit rate progressive .ts or .tp file. Is the deinterlacing after the 3:2 pulldown causing some of the problems with this version?

Any advice on anything else to try or anything I may have done wrong with this?

Sorry long post hope someone has a suggestion and thanks again for the help.

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Dave LaRondeRe: Standards Conversion 23.976 to 29.97
by on Jun 10, 2013 at 2:20:45 pm

This is a classic example of why you shouldn't mix frame rates. If you can't afford to do it in hardware, you'll have to invest in frame rate conversion software like Twixtor to convert the 23.976 footage to 29.97... and I guess it would be 29.97p. If you're certain it's 29.97p.

Do the 23.976 clips independently of the 29.97 footage.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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Jack BonnettRe: Standards Conversion 23.976 to 29.97
by on Jun 10, 2013 at 2:31:51 pm

Thanks Dave,

That's as I feared I'll have to talk to the boss man about software etc. Just to confirm though have I followed the correct steps above to achieve my unsatisfactory end result.

Do the Natress filters work well?

Ta again

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Kevin CampRe: Standards Conversion 23.976 to 29.97
by on Jun 10, 2013 at 5:09:29 pm

[Jack Bonnett] " Just to confirm though have I followed the correct steps above to achieve my unsatisfactory end result."

yep... if the 29.97 footage is interlaced, then mixing in the 23.976 with a pulldown added to conform it to 29.97 would be typical way to go.

since that was unsatisfactory, another way could be to conform the 29.97 to 23.976.

if the 29.976 is interlaced, i've found this quick-and-dirty method to be fairly effective...

bring the 29.97i footage into ae, use the interpret footage settings and choose separate fields (with correct field order) and enable the smooth edges option. this will effectively turn the 29.97i into 59.94p.

drop that footage into a 23.976 comp, enable frame blending for the footage layer (frame mix) and enable frame blending for the preview. preview a portion and see how that looks. then turn the frame blending toggle for preview off and preview again to see which looks better, then render whichever looks best... or render both and see which looks better with the original 24p clips. (remember to disable the frame blending on the layer before rendering the non-frame blended version - or override the option in the render settings).

typically the frame blended method will have more normal looking motion blur and closer to what 24p would look like with a normal shutter angle. the non-frame blended version will have less motion blur, like the footage was shot with a tight shutter angle, but that might work with the other 24p footage.

Kevin Camp
Senior Designer

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Keith SlavinRe: Standards Conversion 23.976 to 29.97
by on Jun 24, 2013 at 10:20:18 pm

Hi Jack,

Have you established for sure your 29.97 footage is interlaced or progressive? If it is interlaced, the best solution is to use 3:2 interlace pulldown (NOT duplicated frames!) to convert the 23.976 footage to 29.97 to match the other. If the 29.97 is progressive, you need to frame-rate convert one to match the other. Cleaner (lower noise) footage will frame-rate convert better, and a higher input frame rate will also help (so 29.97->23.976 would be easier, all other things being equal), but it also depends on the degree of motion. Have you had any luck getting good results yet? We have high quality tools for all of these approaches. If you want, send me email at, with a link to a short test clip, and we could convert it for you.

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