Windows > Third Party Plug-ins, Programs, and Skins
Blackmagic decklink Capture Filter Testing
mattkhan:
thanks for testing
--- Quote from: jmone on April 21, 2025, 05:32:27 pm ---- HDR 10 0 nits: Something is stripping out the static HDR Meta Data as I only get "HDR 10 0 nits" on the HDR Test Clips through this chain, but when played natively it is "HDR10 1000 nits"
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this one is a small bug on my side but, to the best of my knowledge, it's only impacting the OSD (as JRVR ignores this when tone mapping as far as I know
--- Quote from: jmone on April 21, 2025, 05:32:27 pm ---- Audio Channel Mapping: Missing Center & wrong Sub Channel. The UltraStudio is seen by my laptop as a "normal" HDMI connection supporting up to 8ch. If I pick any of the 5.1 / 7.1 config options I don't get any center channel, and the sub is mixed to the center channel on my Desktop. It seems like a channel mapping issue but I'm not sure if it is in the capture code or with the config of either/and/or the Laptop / Ultrastudio
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in my magewell filter, I have full support for all possible channel mappings because I have access to the HDMI infoframe that contains this info. The Blackmagic SDK doesn't provide any such info so I probably have to pick what look like the most sensible default option and use that? If you have a better idea, do lmk!
you can see all the possible mappings from CEA-861-E Table 28 in https://github.com/3ll3d00d/ezcapture/blob/main/mwcapture/mwcapture.cpp#L1614 (I guess the comments should make it clear what's what)
probably the one marked as KSAUDIO_SPEAKER_7POINT1_SURROUND is the only one that really makes sense (NB: you can see that C and LFE are swapped on the wire but not sure if blackmagic sdk remaps this or passes it through)
jmone:
- Audio: Does not look like the UltraStudio supports bitstreaming. Windows does not report that it has any compressed format support.
- Display Rate Change: Not unexpected (given the filter is already built) but changing the frame rate (eg MC's Display Rate change option) does not work, you have the frame rate that the filter was created sticking, even though the UltraStudio itself dynamically changes to the new frame rate.
mattkhan:
--- Quote from: jmone on April 21, 2025, 05:34:52 pm ---I've also only been testing the Audio being decoded, I'd need to test if Bit streaming works?
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the decklink sdk says it only supports PCM, I asked about it on https://forum.blackmagicdesign.com/viewtopic.php?f=12&t=218498 but seems like they don't really answer Qs so no clue what would get passed through if you send encoded audio
all the code to support this (detection of the codec in the bitstream, extraction of the databurst, negotiation of audio formats with MC) is present in my magewell filter so can give it a try once I get everything else working
for a pure bitstream passthrough, I believe MC would need to support this (not sure if it does, I don't think so but Hendrik would have to comment)
mattkhan:
--- Quote from: jmone on April 21, 2025, 05:57:15 pm ---- Display Rate Change: Not unexpected (given the filter is already built) but changing the frame rate (eg MC's Display Rate change option) does not work, you have the frame rate that the filter was created sticking, even though the UltraStudio itself dynamically changes to the new frame rate.
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it's an MC limitation, refresh rate switching does not work for capture cards so you have to do it manually until MC supports that
jmone:
- On the Audio, I've just been testing with the Windows Audio Config, where you click on different speakers to see where it goes. I tried it with both the 5.1 mapping option in the UltraStudio on and off (see pic). That looks like the only option from their GUI. Apart from that I don't really have any insight to what would work best, as the BMD device are just designed to pass through audio eg take Ch1 --> Ch1 etc as the cameras let you map the Mics to any Audio Channel, and you then assign them in the editing SW to the layout you want.
- Bitstreaming: I just don't think it supports it as compressed audio not really a "thing" in their space. It would be interesting to see what it does if you did force though a Bitstream. It would be kind of irrelevant however, as most devices would only see what the UltraStudio is advertising, and it is blank for Bitstreaming so that would need to be spoofed in the driver?
- Frame Rate Switching: Yup, I remember the convo many years ago about this limitation (discussion having gapless playback of multiple video files like you can with audio)
- HDR 10 0 nits: Nice. I don't see any obvious differences anyway in my testing
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