LIVE Video input latency - Best hardware options?



  • HI All, I am starting this thread to get all your feedback on best options for reducing video latency with live input feeds.
    There is info across many threads but it would be great to get your results and recommendations in one place.
    (There is already a separate thread for wireless video, so lets not include that here)

    I am especially curious about peoples recent results with BM products versus USB3 cameras, and other hardware solutions?



  • Another related thread here: http://troikatronix.com/troikatronixforum/discussion/comment/12539/#Comment_12539
    about Blackmagic mini recorders.



  • I have the black magic thunderbolt intensity. Works fine for what I use it for but never done any testing to work out frame rates, etc.

    I know that Alexander (@Feinsinn) has the USB3 version which works on his mac too.


  • I have used the BM Thunderbolt intensity and a MacPro with a Dual AMD FirePro D500.  My use has been on live interactions with orchestras and there is still a visible delay when seeing a live conductor and a video projection (approximately 3-5 FPS).


  • Tech Staff

    As Graham mentioned the BM USB3 Intensity shuttle works great with my Macbook Pro. Latency is very good, but cant tell frames. Could be something like kdobbe mentioned...



  • As i said here i measured 5-6 Frames end-to-end.

    How and at what point of the signal chain do you guys measure?


  • I measure input latency, I get 2 frames to the screen of my laptop with SDI cameras and bkackmagic thunderbolt. Output latency is anotger topic. Large projectors video walls and other proces sors an extenders will all induce more delay. These all change setup to setup. You can with some devices reduced delay by running a ref signal if the gear can take it and Eliminating the sync cycle.



  • 2 to 3 frames of input lag, and between 8 and 11 frames of output lag with nothing between MacBook and projector. This is with BM intensity shuttle USB3 and Canon HFG25 over HDMI at 1080i50, into the MBPro in my sig. Measured by separately videoing performance with live subject, Izzy and projection screen all in view and counting frame by frame in Adobe Premiere. Experiments with analog (Svhs) input at 720x486(29.9fps NTSC - Sony EVI D30) via the BM show this dropping to a more solid 2 frames at input and 9 frames at output.



  • In terms of measuring latency, @Michel has an excellent technique:

    1. Setup Isadora to have two stages.
    2. Play video with burned in timecode to Stage 1.
    3. Setup video capture with your camera. Point the capture camera at Stage 1 and start the live video input.
    4. Use a Video In Watcher to render the captured video to Stage 2.
    5. Point second camera (could be a phone or whatever) so it sees Stage 1 and Stage 2. Record.
    6. Examine the resulting video recording. You will be able to precisely (and easily) see how many frames apart Stage 1 and Stage 2 are, thus telling you the exact latency.
    Best Wishes,
    Mark

  • Tech Staff

    yep thats the way I do it :-).



  • 5. you can also make a screen capture of your screens



  • Dear @ioio,

    That's true, but screen capturing like that might affect the frame rate and thus the latency. Seems better to capture it with an external camera.
    Best Wishes,
    Mark

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