Delay in live capture with Panasonic gh5 and Elgato 4k capture card.

DCMP

Hi!

I am new to Isadora and have been testing some initial experiments with live capture. As of now I am using a Panasonic Gh5 (in 1920x1080p) with a Elgato 4k capture card and I am experiencing a delay with the live video feedback. I am wondering how to get the best performance and reduce any lag. I have tested live video playback in OBS and I haven't experienced any delay. Right now I have the target frame rate at 25fps in Isadora, matching that on the camera. I have a feeling that my computer may not have enough processing capabilities but I was wondering if anyone may have some further knowledge on this issue.

Thanks!!!

DusX

@dcmp

First It would be helpful to know about your Isadora system. This forum post will guide you through adding a signature to your profile which includes your system specs.
https://community.troikatronix...

Regarding latency, Each piece of hardware introduces at least 1 frame of latency. So best case scenario your Camera and Capture card will have 2 frames of delay. Isadora uses the OS media frameworks to interface capture cards on Mac and Windows, as well as, offers Black Magic Designs drivers for interfacing with Black Magic Designs devices. Black Magic devices may be the lowest latency option for Isadora at this time.

Elgato 4k capture likely runs some form of compression on the video (I have a 4k USB dongle version) and seems to have more than 1 frame of delay although I haven't tested with timecode overlays to get an exact count.

Any additional video adjustment/processing done by the camera or capture device will likely add additional frames of delay. So if your camera is natively 1080p but you are capturing at 4k, something in the chain is scaling the video, and possibly adding more delay.

keftaparty

Hi,

Keep in mind that latency in this case is "frame based". It means that if you run at 50fps, your latency in ms will be divided by 2, as each frame lasts half of the time.

Also, I can confirm that the GH5 is quite "slow". There is a latency of around 5 frames I think on the HDMI output.

Mehdi