QU 16 input delay

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This topic contains 10 replies, has 5 voices, and was last updated by Profile photo of airickess airickess 1 year, 12 months ago.

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  • #85531
    Profile photo of Chan
    Chan
    Participant

    Hey all. I’m going to be running sound at a large conference. There will be at least 6 other countries participating via satellite link. They have told me To be prepared to have delay setup for each separate input to deal with any sync issues with the video playback. I’m new to this board. And don’t have a lot of time to research. Can anyone help me out with the setup?

    Thanks so much!

    #85533
    Profile photo of volounteer
    volounteer
    Participant

    Depends what delay they are talking about.

    AFAIK the video and sound are synced. And Qu16 does not do video only audio.

    The only problem I see at home is when my device buffers. Then the audio tends to lag the picture.
    I have to restart that channel to resync. Else I would be changing the video delay constantly to match.
    If the signal is good and no buffering problems then they stay in sync for me.
    That sort of problem is for the video guy to fix.

    There may be other delays on the satellite links so that the 6 countries are not in sync.
    But that should also be up the guy with the video equipment not something for the Qu16.

    If they mean delay from the video sound out of the loudspeakers til it reaches the audience then you may need to delay the sound through the Qu16 so it appears in sync with the picture. Depends where the pictures are and where the sound finally comes from that the audience hears. Rule of thumb about 1ms per foot difference, between the location of the picture and the sound, so as to figure the needed delay. Temperature and humidity affect the actual value which is likely a little bit different from that estimate. Use your ear to tweak. People up front and in the back will need different delays as light goes faster than sound. Do you have zone speakers? Adjust them separately for their delay. Else use an average for the center of the audience.

    #85536
    Profile photo of garyh
    garyh
    Participant

    For the house speakers, there should be no reason to add any delay unless you have speakers situated at different distances throughout the auditorium. Your live speakers will just need to adapt their interaction with the delayed satellite feeds. If you’re also sending out a feed for audio only recording and/or streaming, you might want to add a bit of delay to the live speakers to that output to remove those awkward pauses a bit. If your groups are free, send the satellite feeds to group 1-2 and the live audio to group 3-4. Assign both of those to a matrix and use it’s output to feed the recording/stream. Adjust the delay for group 3-4 so the pauses aren’t as noticeable.

    #85537
    Profile photo of Chan
    Chan
    Participant

    @garyh Last time we did it, I was on an analog mixer and there was around 1 second delay between sound and video playback. The video/ broadcast guys are saying they have no fix for it and it’s my responsibility to deal with. Will sending to different groups and matrix allow me to control this? If so, how do I set it up? Many, many thanks

    #85540
    Profile photo of garyh
    garyh
    Participant

    So to be clear, you are getting satellite feeds that have the audio arriving slightly ahead of the video? If yes, then you can delay the satellite feed channels directly on the channel’s preamp screen.

    #85541
    Profile photo of garyh
    garyh
    Participant

    To continue, one problem is the channels have a maximum delay of 85ms. Send these to a group for another 170ms. Assign the group to a matrix and delay this for an additional 170ms. Total of 425ms. Now feed the matrix output to a free input channel and delay for an additional 85ms. Total, 510ms (half a second).

    #85543
    Profile photo of Chan
    Chan
    Participant

    Wow. Tnx for the tips… Got my work cut out for me.

    #85549
    Profile photo of Roy
    Roy
    Participant

    Just to point out there are no groups or matrices on the QU 16.

    #85560
    Profile photo of garyh
    garyh
    Participant

    Oops. I should probably read post titles. On the Qu-16 you’ll need to use only mixes.

    Another option you might try is to use the delay effect. Turn all the parameters to 0 so you only get one echo. Tap the delay duration. Assign the satellite feed channel to the effect but not to the main LR out. Assign the effect return to the LR out.

    #85563
    Profile photo of volounteer
    volounteer
    Participant

    @chan

    Tell them you have limited delay ability and they need to sync the video/audio when it is received from the satellite.
    The delay in the Qu16 is meant to sync up locally when source loudspeakers and audience are far apart.

    What did you do that last time when it was a second?

    At home I can get off a lot if there is too much buffering due to comms problems like rain but I just restart the show and the sound is in sync with video again.

    #85591
    Profile photo of airickess
    airickess
    Participant

    Telling the truck to sync the audio for you is pointless. After the satellite feed has hit the truck the delay between picture and sound can be due to a number of factors, including how many D/A conversions they go through. At some point the audio and video will be split from each other so that the audio can be split between the broadcast audio mixer and the live audio mixer, and the video can be sent through all of the digital video switching gear for the presentation. That usually causes some kind of sync issues in live feeds.
    Since the Qu-16 has delays on each input you should definitely rely on each channel input delay first, especially since you are going to have 6 separate feeds. Then, instead of sending each of those channels to L/R, UNASSIGN them from L/R and only assign them, post-fader, to one of your FX sends. On that FX send, put the native Qu16 delay plugin on that. As GaryH suggested, make sure you set the delay times fully “wet” (no feedback) to get only one “echo”. Then set each side of the delay to the exact same delay time to avoid any ping-pong delay.
    Use your Delay FX plug-in as the main delay and then use each individual channel delay to fine-tune the delays for each feed. Send the FX Return channel of your Delay FX to L/R (or whatever outputs you’ve chosen to drive your house speakers).

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