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After Effects: prores 422 conversion codec for best results in removing green screen and expotr to FLV alpha
Hello to you all!
Recently I came to case when videographer used Prores 422 for filming model in front of green screen. Result is great image but enormous file size for 30 second clip ( around 1 GB ). For file transfer we should use Dropbox or Google drive and I would like to ask for help about best codec to convert from Prores 422 which should result in significantly smaller file size and still be able to have high quality video that I can put in AE and export in .FLV 720p without detoriated image quality.
I’m very new to Prores so is videographer and would appreciate simplest solution. We tried to convert one file for test and used H.264 with 8 bit depth and 65,000 mbit/s for 1920x1080p. Result was .mp4 file with 14 MB size, very good quality image but when imported to AE and exported to .FLV, image was completely detoriated with pixelated artefacts…
So my Q is is there any good solution when downgrading prores 422 to another codec and what should be the best bit depth and bit rate?
Thank you all,
Haris
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4 Replies
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You don’t really want to compress green-screen footage too heavily. Using compressed footage makes it much harder to pull a clean key with good edges.
ProRes is a good choice in terms of quality. You will not be able to retain that level of quality without some file size.
If Dropbox is too slow, you might consider shipping a drive with the footage.
Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive | RenderBreak [blog] | Profile [LinkedIn] -
Tnx for reply but unfortunately shipping of drive is not an option, because of continental distance and we need to find a way how to save enough quality for removing green screen and puting it in smaller file size…let’s say around 200-300MB for 30 second clip.
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[Haris Berbić] “Tnx for reply but unfortunately shipping of drive is not an option, because of continental distance and we need to find a way how to save enough quality for removing green screen and puting it in smaller file size…let’s say around 200-300MB for 30 second clip.”
A single uncompressed HD frame is about 8 MB. 30 seconds of uncompressed HD at 24 fps — 720 frames at 8 MB each — is about 5.5 GB.
You’ve already cut that down 5:1 with a ProRes file that’s ony 1 GB.
Further reduction will eliminate important visual information, making keying significantly more difficult — and then another generation of compression after that will exaggerate the compression artifacts.
You mentioned that you were working on Dropbox. What about using an image sequence? You could use a JPEG sequence which can achieve similar compression to ProRes, but because it’s a sequence — many smaller files instead of one large one — you could start working right away on the beginning of the sequence while files continue downloading.
Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive | RenderBreak [blog] | Profile [LinkedIn] -
Tnx Walter for your proposed solution, I am not that familiar with JPEG sequence workflow, I have to look into some documentation but we made new compressed file that was also great looking and I managed to pull out the image and remove that nasty flickers on models suit and as you said edges came very hard to straighten but with a help of refine matte pluggin that was corrected. Overall I am not very happy with result yet again it is far better than it was in previous tests. My conclusion is that it is possible to downgrade ProRes to signifficantly smaler file size and after rendering out from AE quality can be acceptable if final clip is for web video not for broadcast. Now I am challenged with another type of nastyness called BANDING on models suit, effect that looks like areas of suit are ringing, so I tryed to add noise, grain, and I can’t reduce it at all…
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