feed SDI-in Decklink:X temp distort keyed SDI-out Decklink:Y

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Walter Sonius

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feed SDI-in Decklink:X temp distort keyed SDI-out Decklink:Y

PostSun May 07, 2017 5:41 pm

I'm having an issue with 2 inter-connected Decklink cards (SDI-out from Card X to SDI-in on Card Y) in the same machine which temporary severely interupts the SDI-output of Card Y (internal keyed SD-PAL signal) when the SDI-in on Card X is switched ON/OFF for feeding Card Y SDI-input with Card X SDI-output. Are you following me :?.
Its so bad that the whole frame jumps/resyncs almost in a analogue way, both video and sound are affected. All signals are same SD-pal 10bit uyvy 422 signals.

However this only happens in one direction when SDI-out of Card X is loop-feeding Card Y SDI-in with Card X its SDI-input, when swapping directions since both cards have the SAME SDI layout by (swapping cables) fixes this problem (this also requires roles to be swapped in software application). Sadly this workaround is not an option since these cards are different in audio mixing capability with internal keying and therefor the 4K Model must be at the end of the video chain/flow.

SDI Signal flow:

Card X = Decklink SDI(non-4K)
Card Y = Decklink SDI(4K)

"Card X" activate/stop SDI-in > SDI-out >> "Card Y" SDI-in >internal-keyer> SDI-out = Affected

"Card Y" activate/stop SDI-in > SDI-out >> "Card X" SDI-in >internal-keyer> SDI-out = good

Greater than sign > means feed direction, one sign ">" means internal signal flow inside a decklink card and double ">>" means the SDI loop cable between decklink cards.

It looks like the 4K model is not able to cleanly separate sync of input to output while keying?

Other people with similar experiance?

Hardware:
The setup consists of two Decklink SDI (4K) cards in the same system, notice that I'm mixing different models the 4K(pci-e 4x) and non 4K(pci-e 1x) version. This is sadly budget related. These two cards can be inter-connected in two way's, I tried both ways with SDI-out to SDI-in from one card to the other and the other way around. The good things is that only one way is affected by this distortion! The source of the SDI-in signal can be JVC cameara HDMI>SDI output or the output of SDI vbit data inserter which contains video/audio vbit vanc data.

Software:
Windows 10 prof x64 15063
CasparCG 2.07/2.10beta1(linux) controlling "internal keyer"
Melt 6.5 (mlt framework) controlling "playback of file/stream based video or SDI-in"
MediaExpress capture
Linux Ubuntu 16.04.1 4.4.x kernel
Desktop video driver 10.9
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decklink-sync-error.jpg
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Last edited by Walter Sonius on Wed May 17, 2017 9:55 am, edited 2 times in total.
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Walter Sonius

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Re: feed SDI-in Decklink:X temp distort keyed SDI-out Deckli

PostMon May 08, 2017 5:17 pm

The problem is probably not electronically, because a different software setup doesn't show the distortions.

For instance by disabling the "internal keyer" on the SDI 4K and let CasparCG only control its SDI-out, and add the SDI-in from the same 4K card (since its full duplex card) in CasparCG with following AMCP:

add 1-2 decklink 2

When feeding this SDI-in on the 4K card with the SDI-out of the first decklink non-4k card, being file/stream or even SDI-in to SDI-out loop from that card doesn't distort the picture on the SDI-out of the 4k card.

"Card X" activate/stop SDI-in > SDI-out >>"Card Y" SDI-in Cas.CG D.l.producer > SDI-out = good

Will a Decklink Duo2 solve or make this problem worse, the same for 2 Decklink SDI 4K or 2 Decklink SDI?
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Walter Sonius

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Re: feed SDI-in Decklink:X temp distort keyed SDI-out Deckli

PostWed May 17, 2017 10:15 am

In contact with BMD support BRS-669-15580, will try to test this setup with Decklink only software for ease of replicating by BMD.

CasparCG Server will be replaced by "BMD LiveKey" if that program is patched to select a other Decklink card in a system with multiple cards. Waiting for BMD support on this "Live Key" issue.

Melt can be replaced by "BMD Media Express" for file playback or recording mode(SDI-in to SDI-out passthrough). This has been a verified replacement of melt and gives the same distortion to debug.
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Walter Sonius

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Re: feed SDI-in Decklink:X temp distort keyed SDI-out Deckli

PostFri May 26, 2017 10:51 am

UPDATE
This issue is reproducible by using blackmagic only software, but since there is a bug/limitation in BM "LiveKey" (not able to select among Decklink cards in the same system) you may need two machines to host each decklink card with the cable layout I showed earlier.

System 1 uses the "BMD Livekey app" instead of "casparcg server" with a simple TGA PAL sd format "key above image" with the decklink sdi "4K" card. (sidenote: there is yet another bug with live key app and "4k" decklink dither/alpha error, but this has no effect on the sync issue that is still there!!!)

System 2 used "BMD media express app" and playback pre-recorded video's (which works fine) or start capturing SDI-in which passes live video through its SDI-out and distorts the image through the decklink 4K keyer in system!!!

Swapping the cables and software roles so the 4K sdi card is in the begin of the chain will not show this distortion.
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Walter Sonius

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Re: feed SDI-in Decklink:X temp distort keyed SDI-out Deckli

PostSat Jul 08, 2017 8:36 am

UPDATE
This issue is now reproducible by using blackmagic only software on a single machine, but since there is a bug/limitation in BM "LiveKey" (not able to select among Decklink cards in the same system) you need the following workaround

Disable the first Decklink (non 4k) in device manager and restart your PC. After PC restart, start BM LiveKey which will use the first and only available Decklink SDI 4K model for keying, than enable the older Decklink SDI in device manager and start Media express.
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Walter Sonius

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Re: feed SDI-in Decklink:X temp distort keyed SDI-out Deckli

PostSat Jul 08, 2017 8:49 am

Update: more Decklink/Intensity models tested

As suggested by the helpdesk, this distortion is intended behaviour on older non 4k Decklink models because of less advanced input circuitry. Further testing with older and newer Decklink/Intensity combinations on a different platform/OS, seems to partly strengthen this believe.

SDI Signal flow:

Card X = Decklink SDI
Card Y = Decklink SDI 4K
Card Z1 = Decklink Multibridge Pro 2
Card Z2 = Intensity 4K (with HDMI camera as input and HDMI > SDI converter as output to decklink)

"Card X" activate/stop SDI-in > SDI-out >> "Card Y" SDI-in >internal-keyer> SDI-out = Affected

"Card Y" activate/stop SDI-in > SDI-out >> "Card X" SDI-in >internal-keyer> SDI-out = good

"Card X" activate/stop SDI-in > SDI-out >> "Card Z1" SDI-in >internal-keyer> SDI-out = Affected

"Card Z1" activate/stop SDI-in > SDI-out >> "Card X" SDI-in >internal-keyer> SDI-out = Affected

"Card Z1" activate/stop SDI-in > SDI-out >> "Card Y" SDI-in >internal-keyer> SDI-out = Affected

"Card Y" activate/stop SDI-in > SDI-out >> "Card Z1" SDI-in >internal-keyer> SDI-out = Affected(not expected)

"Card Z2" activate/stop HDMI-in > (HDMI converted)SDI-out >> "Card Y" SDI-in >internal-keyer> SDI-out = good

Greater than sign > means feed direction, one sign ">" means internal signal flow inside a decklink card and double ">>" means the SDI loop cable between decklink cards. With "activate/stop" I mean toggle/switch in Media Express from playback(captured material) to live input(capture).

However I would still like to emphasize that by not using the internal keyer but just pass-through mode (media express to media express) or full duplex mode(in and out controlled independent by software) doesn't show this distortion which therefor still looks like a software/firmware issue.

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