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Two DeckLink BlackMagic Cards (Can be Studio, Quad, Intensity, Extreme 3D) and DirectShow Fitlers

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Fernando Tirelli
Two DeckLink BlackMagic Cards (Can be Studio, Quad, Intensity, Extreme 3D) and DirectShow Fitlers
on Aug 4, 2011 at 8:17:59 pm

Hello, i' am having a serious problem with two decklink cards in one pc and a graphedit. I will be very grateful if someone can help with this problem. To reproduce the problem do the following.

1. Put two Decklink Cards with any driver version.

2. Meake a graph like the following:

"Decklink Video Capture (1)" -> "Render Decklink Video (2) [clock set]"
"Decklink Audio Capture (1)" -> "Render Audio Decklink (2) [clock set]"


3. Configure Decklink Video Capture in 720p 60 frames 8 bits and the Audio Capture in 2 channels 48Khz 16 bits.

4. Connect a Video source to the SDI input of the Decklink (1) and connect the SDI output to a monitor to see the image.

5. Start the graph and leave it for 4 or more hours until you experience a lost of video frames or lost of audio. Other way to reproduce the problem is when you have the graph started unplugged and plugged again the live video feed.

Regards.


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Fernando Tirelli
Re: Two DeckLink BlackMagic Cards (Can be Studio, Quad, Intensity, Extreme 3D) and DirectShow Fitlers
on Aug 9, 2011 at 4:10:15 pm

Anyone can help me with my problem?.


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Reuben Martin
Re: Two DeckLink BlackMagic Cards (Can be Studio, Quad, Intensity, Extreme 3D) and DirectShow Fitlers
on Aug 11, 2011 at 8:30:50 pm

Well, you described how to reproduce the problem, but never actually described what is going wrong.

I'm assuming you are loosing sync? Remember that SDI is not always perfect. Frames get lost, time code has jitter or can jump around quite a bit. Especially when using crappy hardware in the signal chain. If your software does not have an effective way to deal with this, when it encounters errors or anomalies it may cut the sync loose between video and audio and let them run free, and in that mode the drift can get off very quickly. I had that happen to me and after about 2 hours the audio sync was off by almost 30 min! Your software has to be smart enough to insert black frames, or drop frames in order to keep sync. The guy developing the software I use added that functionality in and it fixed a whole mess of problems with poor SDI signals. But that was on a linux system. Not sure that helps or if that is even the issue you are encountering.


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Fernando Tirelli
Re: Two DeckLink BlackMagic Cards (Can be Studio, Quad, Intensity, Extreme 3D) and DirectShow Fitlers
on Aug 12, 2011 at 3:44:10 pm

I fix the problem with a reference signal. It seems that without a ref signal the video and the audio of the input card gets out of sync after running the graph for several hours.


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