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Downconvert from 1080 to 4:3 SD with pull-down looks awful

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Matt Riley
Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 10:08:53 pm

Source: 1080 @ 23.976 10 bit uncompressed (wiretap)
Output: letterboxed 720 x 480 @ 29.97 via 3:2 pull-down, H.264 codec

The pull-down is being inserted by the frame rate filter and the cadence looks correct. However, the frames that don't have pull-down have nasty jaggies in them, almost like they are interlaced (but they should be progressive, like the source). I've tried it with H.264, DV and DVCPRO 50 codecs so I don't think the codec is the problem.

I am basing my settings from the factory "StdConv 24p to NTSC TeleCine" setting and no matter what I fiddle with it seems to keep turning out the way I described. If you look at the embedded image, the left side is what I'm getting and the right side is what I *should* be getting (the right side was taken from a different Episode encode and is actually slightly scaled up for this comparison). Looks like the JPEG applied to the embedded image is pretty heavy, but the problem I'm describing is very easily seen along the edges of the text and the shirt edges.

I've tried turning on the lowpass scaling filter but it doesn't seem to help. Again, I've tried just using the StdConv 24p to NTSC TeleCine preset as-is and get these results so what am I misunderstanding here?

-Matt



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Jakub Mech
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 10:33:31 pm

Hi Matt,

Which version of Episode are you using?

have you checked your video on the output how many fps it has? is it 29,97 fixed ?

http://www.HardingTestOnline.com


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Matt Riley
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 10:49:51 pm

Episode v. 6.3.

Frame Rate filter
Filter mode: Fixed Frame Rate
Framerate Preset: Automatic
New Framerate: 29.97

These are settings unchanged from the factory sample setting I mentioned. I've also tried setting the Framerate Preset to "Telecine 23.976->29.97" without any difference in the output. I assume this is what the "Automatic" setting is picking based on my source material and desired framerate as that is exactly what I want.

-Matt



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Matt Riley
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 11:00:04 pm

It looks like all of the trouble is happening in the resize filter.

I can get better results if I set the Interlace Handling to Progressive but then it smashes the fields that are being inserted for pull-down. This feels like an image processing chain issue. For this (common) task the processing pipeline should look something like this:

source > scale/crop > insert pull-down (fielded frames) > output codec

It almost seems like Episode is putting the pull-down in first, then doing the scale/crop. If the filters are applied top-to-bottom in the list then this would seem to be the case. However, I don't know if that is entirely true - just making an educated guess.

The scale/crop stage should be applied first as you want to scale the progressive frames from the source rather than scaling interlaced frames. Much cleaner results that way. Can anyone chime in about the execution order of Episode's filter list?

-Matt



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Jakub Mech
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 11:28:51 pm

I think when you set the Interlace Handling to Progressive you probably get frame doubled on output, right?
For me, in this workflow I had no problem with execution order of Episode's filter list? In both cases the result was the same.

1). source > scale/crop > insert pull-down (fielded frames) > output codec

2).source >insert pull-down (fielded frames)>scale/crop > output codec

http://www.HardingTestOnline.com


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Matt Riley
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 17, 2012 at 2:18:06 pm

If I set the output to be progressive in the resize filter, I get the correct pull-down cadence inserted but the frames are not interlaced (because, of course, I told it to use progressive output). This isn't proper 3:2 pull-down.

It should be progressive/fielded/fielded/progressive/progressive and on and on for proper pull-down insertion.

Compressor can do this trick just fine. After Effects also does a pretty swell job of it. But I bought Episode to move all of my encoding tasks into one app so that I don't have to jump around so much. This *should* work but something is wrong.

-Matt



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Matt Riley
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 24, 2012 at 6:13:29 pm

Support just passed along information from the Engineering dept. that what I want isn't possible. Their workaround is to create an intermediate file that is scaled down, then run that file through to add pull-down.

For a professional product (performing a task pros do routinely) this is supremely disappointing to hear.

One day, I hope to use Episode without compromise/workarounds.

-Matt

PS--The filter order is not changeable, although the case remains open. If enough people complain, perhaps this will get moved up the list of to-dos.



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Matt Riley
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Aug 2, 2012 at 2:47:52 pm

Support recently sent me a settings file that *DOES* have the filter order changed (scale first, then apply pull-down). I was told one of their top software engineers made the file (which is really just an xml file that you can examine in a text editor). The trick is to apply the setting in Episode but to NOT examine it with the inspector panel, else it will be rewritten and the filter order set back to the current incorrect settings.

Anyway, I tried it and it seems to work perfectly. I fed it a 1080/24p clip and the setting scaled it to letterboxed NTSC SD with 3:2 pull-down and it looks great. No smashed fields, no scaling artifacts. Just like I expected.

So, there is a workaround and support is aware of it. If enough people bug them about it, perhaps a proper fix will be moved up the priority list so we can all benefit.

-Matt



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Jakub Mech
Re: Downconvert from 1080 to 4:3 SD with pull-down looks awful
on Jul 16, 2012 at 11:06:18 pm

OK,
And you are sure that your video on the output (playing back in quicktime) shows 29,97 fps (cmd+i), rigt?
I am asking, because I tried to do exatly what you. During first conversion I achived similar results as you -then when I was playing back in quicktime it showed me 14fps. Later when I changed a setting everything was fine. Maybe it's en episode bug?

Trying more ;)

http://www.HardingTestOnline.com


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