Jay Epperson
Forum Replies Created
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After continued headaches using Blackmagic cards for streaming, we decided to go the ViewCast Osprey route. Their HD-SDI offering (the Osprey 700e HD) is 4x more expensive than the Blackmagic Intensity/Decklink SDI cards but it has been an absolute solid performer with auto locking to any SDI signal given to it, test pattern fallback upon signal loss and ability to be used by multiple software at once. We are using an HDMI2SDI converter box to feed the signal into it.
Blackmagic cards are great, but they’re just not meant for streaming like the Ospreys. Blackmagic could really tap that market if it wanted to as it’s all really a matter of proper firmware and driver support, they already have the hardware. I sure hope they do so I don’t have to spend $2000 on an SDI streaming card.
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Standard definition digital video does not use square pixels and encodes everything at either 720×486 (NTSC) or 720×576 (PAL). Depending on the content stored, the video is “resized” to square pixels during playback using either 4:3 or 16:9 ratios (essentially an anamorphic squeeze). Certain containers like QuickTime MOV support flags inside the stream that allows you to specify what kind of content you are indeed storing (but it’s still stored as 720×576). AVI, however, does not support such flags so the playback is always 1:1. What you are seeing in Windows Media player is the raw 720×576 video, without any kind of square pixel correction applied, and if it’s anamorphic 16:9 content, everything should appear much much skinnier. You are not seeing 4:3, however, as 720×576 viewed as square pixels actually has a ratio of 5:4.
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We have been experiencing the exact same thing and not just with the Intensity but with the DeckLink SDI as well. Everything is flawless for the first couple of minutes and then drops down to 5-10fps.
I suspected that perhaps the input processing of these cards may have something to do with this, especially the Intensity’s, as afaik its done in software (and the DeckLink’s in hardware?) but ruled this out as even with 480i input the same thing happens.
Btw, I can confirm that 1080i/720p input works in FMLE 3.1 (which isn’t out yet but I’m a beta tester), however it doesn’t mean much with these horrible frame drops. An FMLE developer in the Adobe beta forum mentioned that these issues may be due to a problem with Timestamps. I do not know how this carries over to the Windows side of things as DirectShow and QuickTime are two different animals, but it’s worth a mention.
I would really like for someone from Blackmagic to shed some light on this. Thanks in advance!