Blackmagic Forum

Hello Guys,

I have a very strange issue with my new video assist 12g. It works fine on all my camera's, no problems at all. But when I use it in combination with my bmpcc 6K the screenof my video assist 12G starts to glitch and makes a strange crispy kind of sound.

The glitching of the monitor starts when I shoot on 50 fps or higher. When I shoot on 25fps there is no glitchting at all.

Does anyone know what this problem can be? I've tried out several HDMI cables, but the problem remains.

Kind regards,

Davey Gans

Dave’s, are you only using the monitor function or also recording? What codec and resolution and frame rates are you sending that cause problems.

I’d call BMD Support.

This is interesting, as the Pocket 6K only outputs a HD/1080p signal. So when shooting 50 FPS or up, the monitor is getting 1080p50 or higher FPS. What is the top line (left side) on the monitor showing for camera output when you set the camera at 50 or 60 FPS? If 50fps is glitching and not 60fps, you might have a 50 vs 60 hZ sync issue.

It might also be a HDMI cable issue, not having enough bandwidth to support the higher frame rates. Try getting a new high bandwidth HDMI cable, most of the time camera/monitor issues is down to the cable.
Cheers

rick.lang wrote:Dave’s, are you only using the monitor function or also recording? What codec and resolution and frame rates are you sending that cause problems.

I’d call BMD Support.

Hi Rick,

Thanks for your reply.

I'm only using the monitor function. I'm shooting on pro res 422 on 4k 60 fps. But basically every codec and resolution is causing the monitor to start glitching on 50 fps or higher. Under 50 fps the monitor does not gltich at all. Very strange.

Kind regards,

Davey

Denny Smith wrote:This is interesting, as the Pocket 6K only outputs a HD/1080p signal. So when shooting 50 FPS or up, the monitor is getting 1080p50 or higher FPS. What is the top line (left side) on the monitor showing for camera output when you set the camera at 50 or 60 FPS? If 50fps is glitching and not 60fps, you might have a 50 vs 60 hZ sync issue.

It might also be a HDMI cable issue, not having enough bandwidth to support the higher frame rates. Try getting a new high bandwidth HDMI cable, most of the time camera/monitor issues is down to the cable.
Cheers

Hi Denny,

Indeed! So you'd expect there to be no problems. On the left side I see 1080p 50 fps. 50 fps and 60 fps are both glitching. On every resolution. This is only with my bmpcc 6k, My sony A7III gives no problems at every high frame rate.

I've bought the fastest hdmi cable I could find. And I've used this cable before on my blackmagic pocket 6k in combination with an atomos monitor. And there where no problems at all. So I doubt that would be the issue. What I did not pay attention to when buying the hdmi cable, is buying a HDMI 2.0A. So I could try buying a hdmi cable that supports HDR.

Thanks for your reply!

Kind regards,

Davey Gans

1080p60 has been supported since HDMI 1.0.

Is off speed recording enabled? The camera shifts gears in this mode and sync becomes a secondary priority.

Good Luck

Camera resolution does not matter, as HDMI output is constant HD/1080P, only real variable is frame rate.
Howard has a good suggestion, make sure off speed recording is off.
Cheers

True, Denny. I was thinking about determining the camera activity, in case the shooter was pushing the boundaries and the camera was exhibiting problems managing the overall workload. I think we’ve eliminated that as a source of the problem.

Now I think it’s a faulty (underpowered) cable or a bad copy of the video assist.

For many years I’m aware of the advice to only buy HDMI cables that specify they are to be used for HDTV. When I bought mine several years back there were two different prices and labeling on the packaging: one identified for high speed HD and one not. I’ve never had an issue with the high speed cable. Perhaps that was a scam but I have my doubts.

I only buy high bandwidth cables, after getting a cable that would not pass 108059.94/60 frame rate, and this was a well known brand cable too. The more I think about this, I will bet it is the HDMI cable also, not enough bandwidth for the high frame rate and audio pass through, so the audio starts to glitch.
Cheers

Howard Roll wrote:1080p60 has been supported since HDMI 1.0.

Is off speed recording enabled? The camera shifts gears in this mode and sync becomes a secondary priority.

Good Luck

Hi Howard,

Off speed recording was not enabled when the glitching was happening. Once I enabled it, I could record in slowmotion, but the slowmotion was baked in. And I don't really like that. I prefer to have the option to have all the frames.

Thanks for your reply!

Kind regards,

Davey Gans

Denny Smith wrote:Camera resolution does not matter, as HDMI output is constant HD/1080P, only real variable is frame rate.
Howard has a good suggestion, make sure off speed recording is off.
Cheers

Hi Denny,

The HDMI cable should do the trick. I've used this cable for all kinds of monitors and camera's, also in combination with 4K 60. So I can't imagine that the cable is not good enough. Especially with an 1080 output.

Off speed recording was indeed turned off.

Kind regards,

Davey

Hi guys,

Thanks for all the replies! Great that you are all thinking with me to help me solve the problem.

I have tried every single option, but I could not fix the problem. So I've decided to send the monitor back for repair. Because I think it's a faulty monitor.

I will keep you guys updated.

Regards,

Davey

Well when all other possibilities are not the issue, then a RMA it is...
Cheers

Hey Davey,

did you found out what the problem was? i have the same problem on my Pocket 4k with the Video Assist 4K. If i go higher than 30fps its starts to glitch my VA


best regards,

Alex