Blackmagic capture



  • I recently went to switch my capture setup to 1080p25, I had not really checked it out recently, I was pretty surprised to see no option for grabbing at this rate, I was coding with qtkit and quicktime grabbers. I did see some progressive settings but only for 23.976 and 24 framerates. After a little tinkering I tried it with avfoundation and sure enough I get access to all the supported rates of the card.

    There is a thread on the forum here about this but it is not resolved with a firmware update and it is nothing to do with blackmagic per se it is just a problem with software using outdated capture libraries.
    http://troikatronix.com/troikatronixforum/discussion/comment/5268#Comment_5268
    I had a further tinker and found that although I could get the input with avfoundation, using the blackmagic SDK directly gave me total control over the input preset (if you have a card with multiple types of hardware input you can also set that from the SDK which is pretty handy).
    The blackmagic SDK also gives me much much less latency around a frame I think to get the image on my laptop screen in 1080p as well as what I think is better quality colour space conversion.
    Those of you looking to get the 1080p functions working in Isadora will not be able to unless you use the SDK (someone can make an Isadora plugin for it) or if Isadora changes to a more up to date capture library. I believe gstreamer is looking like a good cross platform option for other coders.

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