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Pro res puzzle???

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Samantha Hatton
Pro res puzzle???
on Jun 20, 2013 at 4:50:08 pm

I have been editing in pro res but I have found the oddest thing to happen on strap lines that that are on top of footage (motion templates) or to footage that does not have a filter on it but sits on top on footage that does. Just before it gets to the the start or the end of the template or footage without a filter the footage underneath has a dark colour shift to it which lasts for a few frames but can be noticed. It can only be noticed when the time time is rendered and exported as a self contained .mov. The weird thing is when I leave the timeline unrendered and export as a self contained .mov the problem does not happen.

I was just wondering if anyone knew what could be coursing the problem, any feedback would be great.

Thanks in advance

Sam :)


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Michael Gissing
Re: Pro res puzzle???
on Jun 20, 2013 at 11:00:24 pm

ProRes describes a family of codecs (Proxy, LT,422, HQ or 4444). What exactly is the codec of the original footage, the footage once converted to ProRes and your sequence settings.

If you are converting footage to ProRes, how are you doing that? Compressor?, Log & Transfer etc??


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Samantha Hatton
Re: Pro res puzzle???
on Jun 21, 2013 at 8:09:07 am

Thanks for you reply here is the info about my workflow

The original footage was from a Canon 7D camera so it was H:264 files. I converted to pro pres using compressor using the following settings

File Extension: mov
Estimated file size: 525 MB
Audio: multi-track passthrough
Video Encoder
Format: QT
Width: (100% of source)
Height: (100% of source)
Selected: 1920 x 1080
Pixel aspect ratio: Square
Crop: None
Padding: None
Frame rate: (100% of source)
Selected: 25
Frame Controls: Automatically selected: Off
Codec Type: Apple ProRes 422 (HQ)
Multi-pass: Off, frame reorder: Off
Progressive
Pixel depth: 24
Spatial quality: 50
Min. Spatial quality: 0
Temporal quality: 0
Min. temporal quality: 0

I also had the Enabled 4:4:4 chroma filtering disabled

Thanks

Sam


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Rafael Amador
Re: Pro res puzzle???
on Jun 21, 2013 at 11:35:30 am

That's smells to some gamma shifting.
Make sure that your Prores sequence is set to render in "10b YUV" or "High Precision YUV".
In Motion, go to File > Project Properties > Bit Depth and make sure is set to 16b or 32b Floating Point.
rafael


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Samantha Hatton
Re: Pro res puzzle???
on Jun 21, 2013 at 12:43:51 pm

Hi rafael,

Thanks for your reply.

After some trial and a lot or error experimenting I found that the problem lay with the way I was converting the H264 files in compressor. With the Pro res files I was editing with when I was converting them in compressor I unticked Enable 4:4:4 chroma filtering. So I have just exported to sample files with the Enable 4:4:4 chroma filtering ticked, then I used the end of the same time line I had been editing in to do a test. I placed one clip on the the bottom track and added a filter then I placed the other clip over the top as if a cut away. then I rendered and exported this session of the timeline as a self contained movie and the problem of the color shift had gone.

Sam


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Rafael Amador
Re: Pro res puzzle???
on Jun 22, 2013 at 2:00:11 pm

Hi Samantha,
Great that you found the reason of that problem.
The truth is that the "Enable 4:4:4 chroma filtering" makes no sense on a 444 codec, most of all when codec can be YUV or RGB and you can't even choose the flavor.

BTW, its makes no much sense to convert H264 to Prores 444 in Compressor.
The only app (as long as I know) that would take any advantage of the codec is 5DtoRGB, that applies real "Chroma Filtering" when resampling.
Prores422 or HQ would be OK.
The best codec for the conversion would be Apple 6b Uncompressed, but makes files too big.
rafael


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Samantha Hatton
Re: Pro res puzzle???
on Jun 22, 2013 at 8:18:42 pm

Hi Rafael!

Thanks for your advice. I converted my H:264 files to Apple ProRes 422 (HQ), would your advice be to use 5DtoRGB to do this convention.

Thanks again for your help

Sam


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Rafael Amador
Re: Pro res puzzle???
on Jun 23, 2013 at 10:55:15 am

[Samantha Hatton] "Thanks for your advice. I converted my H:264 files to Apple ProRes 422 (HQ), would your advice be to use 5DtoRGB to do this convention."
The process takes longer than with most other options, but if you can afford the extra time, a highly recommend you to do it.
420 codecs (H264, DV, XDCAM,..) have only one Chroma sample for every 4 pixels.
When converting to a 422 or 444, we have to recreate the Chroma that has been discharged on compression. Most applications (QT, FC, compressor, AE,..) will just average the existing values to calculate the missed information.
5DtoRGB uses a more intelligent algorithm to try to rebuild the Chroma as it was before downsampling.
The results are visible.
Rafael


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Samantha Hatton
Re: Pro res puzzle???
on Jun 23, 2013 at 2:31:16 pm

Thanks again Rafael for your advice much appreciated.

Sam


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