Alpha channel in ProRes 4444 quicktime video files no longer works
I have been successfully using animated credits made in Apple Motion and exported as prores 4444 and displayed as a series of video clips in a playlist. They sit in a layer above the main output layer, and it has always just worked. Clean background with animated titles.
Invested in a new fully loaded macbook pro M1 running Monterey 12.1 and in exactly the same setup, with a new copy of Wirecast Pro 14.3.4 and a new licence, the alpha channel no longer is recognised. It all works fine on a new mac mini M1, where the only difference is Monterey is 12.0.1 and it doesn't have as much memory as the MBP. Obviously I can workaround using a chroma-key background, but I wonder if anyone else has experienced this. Ticket has been raised, and I await a result.
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Is there another program you can test the alpha channel file in as well?
Let's see if it's a more general 12.1 issue not limited to Wirecast.
Would you be able to link to the file so I can test as well on a 12.1 system? -
Good evening Craig. I'll come back with an example in the morning. I suppose I can instal OBS and see if the alpha channel works in that on the new laptop. It's brand new, but has iMovie. I've also had a response from tech support, so well on our way (I hope)
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Glen Collie said:
Invested in a new fully loaded macbook pro M1 running Monterey 12.1I tested my own ProRes with Alpha file on 13" M1 Monterey 12.1 and the alpha works without issue in Wirecast 14.3.4. 14" and 16" MBP are M1Pro or M1Max, not M1 (as used in 13" MBP) so that might be significant.
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Glen Collie said:
It's brand new, but has iMovie.That would be a good test to see if it works in Apple's own software.
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This is the M1 Max (£3,000) sigh. I'll also raise the issue with Apple tech support in the morning.
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Glen Collie There's a related discussion in the Apple Discussion forum. The version of Apple Motion might be a factor as well. Make sure you update Apple Motion and export the file again.
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Glen Collie said:
This is the M1 MaxSince it's working with 12.1 on 13" MBP it might be specific to the new Pro and/or Max chips rather than Wirecast. iMovie test might reveal that.
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CraigS Update from further tests.
Good morning. I have now done several things. First was to try the ProRes file as a key in iMovie. Same result as in WireCast. Repeated the test on the Mac Mini, where it worked perfectly in iMovie. Beginning to think it was either a OS version problem or an interaction between the max hardware and the OS.
I then downloaded OBS onto the MacBook Pro Max. Same test with OBS using the same files. OBS works exactly as it should.
So my conclusion, at the moment, is that both Wirecast and Apple have a bug in the software that does not allow ProRes 4444 transparency to be recognised. I will next install Final Cut on the MBP and see if it recognises the ProRes transparency.
In passing, a PNG file with a transparent background works in WireCast on the MBP.
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Glen Collie We're not seeing the issue in M1 Monterey 12.1 so we believe it's related to M1Max/M1Pro models. We likely follow Apple's guidelines so Apple may need to fix this for developers who follow their protocols. It may be related to other "Video toolbox" issues we're seeing specific to M1Max/M1Pro chips.
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I worked on this issue last night and discovered something pretty interesting. It seems that higher resolution color space of ProRes 4444 XQ QT MOV files (32 bit alpha channel) is not compatible with Wirecast presenter playback (the alpha channels are not respected, files are flattened) but if you export your ProRes 4444 MOV file with 8 bit alpha channels, the alpha channels are respected and work like a charm. This really boggled my mind for over a year.
Glen Collie - give ProRes 4444 QT MOV with 8 bit alpha channels a shot
CraigS can you comment about the support for 8 bit alpha channels vs 32 bit?-
Stephen Collins We're working on this issue WIRE-19830. We're certainly trying to get this to work.
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CraigS ProRes 4444 8 bit alpha channels do work so please provide this as temp workaround
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Stephen Collins Thanks for noting that.
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CraigS no worries, happy to help
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Stephen Collins 👍
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CraigS To confirm. With M1 Max it doesn't work even with ProRes 4444 8 bit files. Works with 15 Beta 2, but I have to make sure everything else I need works also.
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Stephen Collins Glen Collie
Wirecast 15 Beta 2 released yesterday for testing should fix this issue. -
Thanks Craig I will download and give it a try. Best wishes Glen
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Glen Collie 👍
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Brett Sherman said:
Works with 15 Beta 2The issue is fixed in the next release. Thanks for confirming.