In very large scale shows, where the crowd extends to hundreds of meters from the main stage, sound obviously takes a long and noticeable time to reach the crowd, and it becomes a lot delayed relative to the video in large video walls in the stage itself, nothing to do about it in that situation.
But, in even larger scale concerts where additional video walls must be put far from main stage, you could, and perhaps should (in my opinion at least) delay the video in these additional video walls to be in sync with the sound reaching that point of the crowd.
Perhaps this is a rare problem, as usually you don't have such massive crowds where they can't even see the main stage, but this is a reality here in Copacabana, where the crowd extends to 1 kilometer from the main stage, and you need several delay towers plus several video walls so the crowd can see the show.
(picture from the Lady Gaga concert in May 3, other concerts here use a similar structure)
The "delay towers" here are themselves a pair of large line arrays with subs (both hanging as a line array behind the mid and treble array and in the ground), and all are, of course, delayed to be in sync with the main stage and with the previous towers.
But, the video and lights in all of those 8 pairs of screens (which are 100 meters from each other) is in sync instead of being delayed to match the sound.
I was in the last screen, sound took over 2 seconds from the main stage, and the video was thus 2 seconds advanced, I only heard what I saw in the video way after.
I think the video should be delayed by the same amount as the audio, so we could feel the video in the closest screen is in sync, or at least almost in sync (as sound itself takes 0.3 s to propagate from one pair of delay towers to the next, so it can't be in sync for everyone anyway, but at least it won't be as gruesome as 2+ seconds).
So, my question is: Is adding a delay in the video on video walls a easy task using the standard equipment used to control them? Like a buffer to store frames and display with a delay?
Sure, if they are to be delayed, so should be the lights over the towers, so the MIDI system should add a delay as well, but this may be not ideal, as it breaks the visual sync in their blinking and changing we can see from far away. But at least would be in sync with the sound.
But, in even larger scale concerts where additional video walls must be put far from main stage, you could, and perhaps should (in my opinion at least) delay the video in these additional video walls to be in sync with the sound reaching that point of the crowd.
Perhaps this is a rare problem, as usually you don't have such massive crowds where they can't even see the main stage, but this is a reality here in Copacabana, where the crowd extends to 1 kilometer from the main stage, and you need several delay towers plus several video walls so the crowd can see the show.
(picture from the Lady Gaga concert in May 3, other concerts here use a similar structure)
The "delay towers" here are themselves a pair of large line arrays with subs (both hanging as a line array behind the mid and treble array and in the ground), and all are, of course, delayed to be in sync with the main stage and with the previous towers.
But, the video and lights in all of those 8 pairs of screens (which are 100 meters from each other) is in sync instead of being delayed to match the sound.
I was in the last screen, sound took over 2 seconds from the main stage, and the video was thus 2 seconds advanced, I only heard what I saw in the video way after.
I think the video should be delayed by the same amount as the audio, so we could feel the video in the closest screen is in sync, or at least almost in sync (as sound itself takes 0.3 s to propagate from one pair of delay towers to the next, so it can't be in sync for everyone anyway, but at least it won't be as gruesome as 2+ seconds).
So, my question is: Is adding a delay in the video on video walls a easy task using the standard equipment used to control them? Like a buffer to store frames and display with a delay?
Sure, if they are to be delayed, so should be the lights over the towers, so the MIDI system should add a delay as well, but this may be not ideal, as it breaks the visual sync in their blinking and changing we can see from far away. But at least would be in sync with the sound.
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I think the typical scenario is that video processing has higher latency, so there's not normally as much video delay flexibility in consumer equipment.
In most cases the video bitrate is much higher also, so buffering a significant number of seconds of that isn't easy.
In prosound/studio gear there are options though.
https://www.bhphotovideo.com/c/product/1034516-REG/gra_vue_mvio_delay_hd_sd_sdi_signal.html
"MVIO Delay HD/SD-SDI Signal Delay Device from Gra-Vue enables delaying an HD-SDI signal up to 20 seconds."
In most cases the video bitrate is much higher also, so buffering a significant number of seconds of that isn't easy.
In prosound/studio gear there are options though.
https://www.bhphotovideo.com/c/product/1034516-REG/gra_vue_mvio_delay_hd_sd_sdi_signal.html
"MVIO Delay HD/SD-SDI Signal Delay Device from Gra-Vue enables delaying an HD-SDI signal up to 20 seconds."