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Thread: NDI lip sync problem

  1. #1
    Registered User DStoneburner's Avatar
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    NDI lip sync problem

    I just used my new HN-130 cameras, NDI to my TC8000. We have audio coming in wireless mic to mixer to TC audio input. I was so busy testing video that I didn't think about lip sync before the event started. I've never had that problem. It looks out of sync to me. Take a look : https://www.youtube.com/watch?v=oT0R...ature=youtu.be
    Any ideas to fix this? Thanks

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    'the write stuff' SBowie's Avatar
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    Quote Originally Posted by DStoneburner View Post
    I just used my new HN-130 cameras, NDI to my TC8000. We have audio coming in wireless mic to mixer to TC audio input. I was so busy testing video that I didn't think about lip sync before the event started. I've never had that problem. It looks out of sync to me. Take a look : https://www.youtube.com/watch?v=oT0R...ature=youtu.be
    Any ideas to fix this? Thanks
    I wouldn't be surprised if audio arriving one way and video another were not in perfect sync. This often occurs, for example, with cameras with HDMI or SDI output and analog audio connections. This is why TriCaster (many versions, at least) have audio delay options per input.
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    Registered User DStoneburner's Avatar
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    Steve, I understand that, I've used TC since the old pro system and have it used a 460 in Arena to do Imag with the audio coming from an analog source and cameras SDI and didn't have this obvious of the lip sync off. I'm putting the video in Premiere today to see how much it is off, but I'm perplexed that it happened the way it did running everything in the same room with short runs. I know I can delay the audio for my stream, but I'm wondering if there are some settings I can improve on the cameras or maybe the switch. One of my big problems is that I do Imag for commencements 3 times a year and I won't be able to use these cameras in NDI mode if I can't make them sync better.

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    The AV delay options in TriCaster should allow you to compensate for this issue.
    Zane Condren
    Senior Integrated Production Specialist

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    I have ALWAYS had to add at least 30-40ms Audio Delay in TriCaster when audio is analog and cameras are HDMI or SDI. Jim Davis did an experiment to compare SDI and NDI inputs on TriCaster and did not find any additional latency when using NDI versus SDI sources - https://youtu.be/X_y6wLJl1BY

    I had duplicated this myself, connecting a single Newtek PTZ1 camera to two inputs on my TriCaster, as SDI and NDI. Then I set up a split screen in an M/E to compare the two sources, moving my hand up and down, back and forth across the split screen and most of the time both sides matched perfectly, or perhaps 1 frame off at times, but never more than that.

    So really, I don't believe the issue is the NDI, but more likely is the PTZ camera itself. All digital cameras add a small amount of latency as they process the signal before it comes out as HDMI or SDI - no different with NDI. Just that the PTZ cam might be taking a few frames more to output the video than you are used to. If possible, try the split-screen SDI/NDI experiment yourself and see if there is a timing difference between the two. You might find that the issue is just the camera itself, with the same delay over SDI. Had you tried the camera with SDI before using NDI? It's a new camera so maybe not?

    Keep in mind that using 60p can reduce latency since each frame is half the duration of 60i or 30p frames. So either 720p60 or if you have the TC1 then 1080p60 will help. Of course MATCH the video output format on camera to TriCaster Session to avoid additional frame-sync delays.

    Thanks

    Jeff
    Jeff Pulera
    Streaming Broadcast Solutions - Newtek Elite

    TriCasters: Mini with AE, TC1
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    Registered User DStoneburner's Avatar
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    Ok, so I was able to get the video in Premiere for testing. The project is 1080 in the TC. I have the cameras set to NDIHX at 59.94i. There is no 29.97 option except for 29.97p. I have the cameras NDI in inputs 1,2,3 and I have the analog audio coming into 4 set to black. Here is the strange thing that I found. The audio is actually behind the video. In Premiere, I had to move the audio forward 4 frames for it to be in sync with the video. That is strange and I'm a little baffled. Thoughts?

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    Registered User DStoneburner's Avatar
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    Quote Originally Posted by JPulera View Post
    I have ALWAYS had to add at least 30-40ms Audio Delay in TriCaster when audio is analog and cameras are HDMI or SDI. Jim Davis did an experiment to compare SDI and NDI inputs on TriCaster and did not find any additional latency when using NDI versus SDI sources - https://youtu.be/X_y6wLJl1BY

    I had duplicated this myself, connecting a single Newtek PTZ1 camera to two inputs on my TriCaster, as SDI and NDI. Then I set up a split screen in an M/E to compare the two sources, moving my hand up and down, back and forth across the split screen and most of the time both sides matched perfectly, or perhaps 1 frame off at times, but never more than that.

    So really, I don't believe the issue is the NDI, but more likely is the PTZ camera itself. All digital cameras add a small amount of latency as they process the signal before it comes out as HDMI or SDI - no different with NDI. Just that the PTZ cam might be taking a few frames more to output the video than you are used to. If possible, try the split-screen SDI/NDI experiment yourself and see if there is a timing difference between the two. You might find that the issue is just the camera itself, with the same delay over SDI. Had you tried the camera with SDI before using NDI? It's a new camera so maybe not?

    Keep in mind that using 60p can reduce latency since each frame is half the duration of 60i or 30p frames. So either 720p60 or if you have the TC1 then 1080p60 will help. Of course MATCH the video output format on camera to TriCaster Session to avoid additional frame-sync delays.

    Thanks

    Jeff
    Thanks for the info. I expect a little delay but have used SDI in an arena set up going through to a video board with enough minimal delay that it wasn't noticeable to most people. I couldn't delay the audio going into the arena. I have a TC8000 so I can't do 60p. 1080 is what is being asked for to stream, so I'm using the 1080i project. In my other post you'll see that for some reason the video is in front of the audio by 4 frames. I haven't used the SDI yet, other than to test it working, because I don't have the length needed for my events. That is something I'm working on.

  8. #8
    Registered User DStoneburner's Avatar
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    I've been racking my brain with this one. This is the first time that I have used NDI cameras. I'm used to SDI and don't remember running into this type of delay issues. I appreciate all the help, I'm just a little stressed because I'm trying to figure this out in the middle of supporting events with the cameras. So this is what I have found so far and have tried to look up. First of all at 29.97 fps, 1 frame is equal to 33.3 ms. Is that about right? So the event I did yesterday I delayed the audio by 133 ms, which should be equal to about 4 frames. It looks pretty spot on. With the project at 1080i on TC8000 and the cameras set to 59.94i and adjusted to the default NDI-hx settings. Is 4 frames of delay to be expected? Again, approximately. I don't think I should turn frame sync off for the NDI inputs. I've never seen that mentioned and they aren't gen-locked. Thank you in advance for any help. I'm reaching out to the Panasonic sales tech to see if he can put me in contact with someone that can help me optimize all the settings on the cameras.

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    Quote Originally Posted by JPulera View Post
    So really, I don't believe the issue is the NDI, but more likely is the PTZ camera itself. All digital cameras add a small amount of latency as they process the signal before it comes out as HDMI or SDI - no different with NDI. Just that the PTZ cam might be taking a few frames more to output the video than you are used to. If possible, try the split-screen SDI/NDI experiment yourself and see if there is a timing difference between the two. You might find that the issue is just the camera itself, with the same delay over SDI. Had you tried the camera with SDI before using NDI? It's a new camera so maybe not?
    This has been my experience. When I tested the PTZs from Newtek and others the delay in the camera was longer than my usual Canon XF305. As such I would have to adjust the delay more than normal too line up audio. Other option I have been fairly happy with was to pass my audio into one my cameras. In that situation the camera merged audio and video and accounted for its own delays and things are all set there.

  10. #10
    Registered User DStoneburner's Avatar
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    Thanks. Good points. I don't mind adjusting the audio for streamed or recorded events, but I do about 4 Imag events a year so I'm going to have to do some rewiring and add SDI. I did some testing today with an A/V sync video at 29.97 I found on YouTube. My test came out at about a 7 frame delay but when I did my event the audio only needed to be delayed by 133 ms or approx. 4 frames.

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