Blackmagic SDI video capture cards tests and delay results

philamand

Hi everybody,

I made some processing delay testings using Millumin 2 and several Blackmagic SDI capture cards. 

Setup for testings was:

MacbookPro 15 inch, 2016 2.7 GHz Intel Core i7 - MacOS Sierra 10.12.6

Decklink Duo inside a Sonnet Echo Express SE I Thunderbolt 3 version

Blackmagic UltraStudio Mini Recorder

Blackmagic UltraStudio 3D with a Thunderbolt 1 to Thunderbolt 3 apple adapter

Blackmagic Cinema Camera 2.5k connected through SDI 1080p 30 FPS

At the top of images, FPS are displayed using an iPad with ANIMTIME FPS app to use same FPS as camera, and at the bottom the results through Millumin 2.

(For testings using the camera connected through thunderbolt, I was not able to use 30 FPS, so I changed it to 29.97 FPS)

Please see attached file for results.

RESULTS (PDF File)

All the best,

Philippe A.

Millumin

Hello @philamand,

Thank you for sharing your results. So from what I understand the delay is quite the same for all configuration : around 85ms.

Also, you have to keep in mind that to project such a video, at least one frame of delay would be added : so the total latency would be around 100ms (because projectors usually work at 60fps, not 30fps).

We didn't test yet, but the results with the NDI/Spark could be better. I guess this is an interesting road to diminish latency.

Best. Philippe

philamand

Hello Philippe,

Thank you for the info on Spark. After reading about that new product, I've decided to buy an NDI HX - PTZOPTICS Camera. As soon as I get it, I will post new tests using NDI directly from the camera. It looks promising.

Best. Philippe A.

philamand

Hello,

I've run some tests with the PTZOptics-NDI HX 30x camera.

Compared to SDI using a Blackmagic Mini Recorder, NDI is 1.1 frame faster at 30FPS (37ms)

But.... The latency of the PTZoptics camera itself is bigger than the latency of the Blackmagic Camera.

Using NDI the PTZOptics camera has aprox 5.4 frames of delay (180 ms).

I have to run some tests connecting both cameras on my ATEM using SDI to compare the exact latency of both cameras.

The good news is that NDI is a bit faster than using SDI and a BM Mini Recorder.

Best. Philippe A.

Millumin

Hello @philamand,

Thank you for the tests and infos !

The latency on your PTZoptics seems very high, for such a live camera. Maybe you should check the format of the video, and in lower resolution : for example, 720p60.

Best. Philippe

philamand

Hello,

I've been working on more accurate testings using a Blackmagic ATEM 1 M/E Production Studio, a Decklink Duo, a Blackmagic Cinema Camera and the PTZOptics. I also made some tests using a converter to see how much latency is added. Converter adds 90ms every time. The best results for the PTZoptics are 150ms using 720p50 SDI on the ATEM compared to 90ms for the Blackmagic Cinema at 1080p25 and 1080p29.97. Please see attached file for better understanding.

Best,

Philippe A.

Millumin

Hello @philamand,

Thank you for all these detailled tests.

Sad that the latency of the camera itself is high.

Best. Philippe

mjehnichen

Thank you too for the work - i just got my first ptzoptics 20x NDI Camera and was wondering about the big latency of 233ms i experienced in 1080i50 in to my ATEM via SDI. (latency compared to audio XLR in) But now i know, it seems because of the cameras internal processing.

I tried to import the ndi Stream in to my ATEM by using a MacBookAirs HDMI out, which worke fine but delay is even worse: 900ms..

All this wouldnt be terrible because i can add sound delay in OBS but my other cameras are much faster (Legria HF200 with BMD Converter hdmi>sdi (40ms).

I will probably return the PTZoptics camera, looking for another, faster PTZ camera.

Unless you have an idea or workaround to get sound and images in sync.. ?