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Alpha channel not working in DNX HD QT
I have made some short graphic overlays in After Effects and wanted to export them to Avid Media Composer. Since the background footage is DNX HD120 I wanted to export the footage as DNX HD 185X to get the best quality and selected RGB+Alpha to give me a real-time matte for Avid.
However when I imported the clip I couldn’t get the the alpha to work. When I exported the clip using uncompressed avi the alpha worked fine, but was five times the file-size.
Is there any reason why clips exported using DNX HD clips don’t work? I tried Straight/Pre-matted and the import settings are correct in the Avid. The source material is fine (as proved by the AVI file working).
I also tried other DNX HD options with no success.
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2 Replies
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When did you download the DNxHD codecs? Avid made some adjustments to the codec a couple of versions back.
https://avid.custkb.com/avid/app/selfservice/search.jsp?DocId=372311
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Thanks Gary.
Downloaded them and they work fine. I had downloaded the trial of Media Composer 5 and assumed I had a recent set.
They all key perfectly although I am surprised that I don’t have to invert the key during import – seems unnatural somehow after years of doing it!
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