This is a very interesting topic and one that raises some doubts for me. I would like to pose some questions here open for debate, if you don´t mind:
What goes actually under the hood of the Video Sync Offset process?
I also work with another DAW that allows a delay in ms to be applied on the audio monitoring path only.Very useful as it only delays the audio monitoring path and not the final busses audio, leaving ADC intact as well of course. You can also choose on which busses to insert the delay.
But in PT, the process is applied as a video sync offset, which in my mind and considering the name, works as a method of offsetting the video playback in relation to the audio playback but without moving the video or audio positions in the timeline. Nudging when in stop not affected. Not sure about scrubbing.
If this is true and considering that due to picture display processing and audio monitoring having diferent paths, audio usually leads video, PT must have a process of playing back video earlier by the offset inserted by the user. True? If so how is that possible? Meaning how can it play video before you hit play? I guess that what it does it to delay audio playback in the background by the same value as inserted in the Video Sync Offset.
But what happens if you want the video to lead the audio? Not very common but as apparently the video sync offset allows for minus values to be inserted as well, I wonder how it works then. It plays the audio first and only then the video in the timeline to match?
So if you insert lets say, -4 (minus) quarter frames of delay are you offsetting video after the audio? As opposed to inserting only 4 quarter frames which is supposed to "play video ahead"?
If the process is what I´ve described, people using the same busses on final mixes as on the listening path could get in trouble if still laying back live to tape.
Does the process affect bouncing to QT as well? Meaning if you have an offsett and bouncing to QT, does it wrap the video file with offsetted audio?Both in real time and offline (PT 11)?
Also some video cards introduce a lag when transcoding outputs. Let alone some lag that may be introduced in the PCIe bus if applicable. For instance some BM cards introduce a one frame delay, it´s stated in the manual. Add your own display or projector lag and things start to get really out of sync. But when you switch to the computer display using the Video Window, now the video card does not play a part anymore. What to do, go into Video Sync Offset and change the value everytime you switch viewing devices?
What if the main display in your room as a diferent lag from the display in your booth when you are ADR´ing? Both are taking a feed from the same video card, so that may become a problem as well if you are not able to insert diferent offsets in diferent video paths.
If anybody would care to explain the in-depths of the Video Sync Offset or it´s approaches to this subject I would appreciate. Thanks.
Another curiosity I have is about human perception of sync issues. You can use a device like Syncheck and measure the lag in your setup, then insert the measured value in PT. All fine and the way to go in my view.
But if using your own eyes only, how far can you go in terms of spotting lag?
I see people worrying about quarter frames, 16ths of a frame, but can you actually see it in reality? Meaning after a few hours of work? I can hear a milisecond but can´t see it to be honest. Diferent shots, diferent words being spoken, diferent lips and face movements all contribute to be easily fooled by small amounts, so sometimes I wonder how deep should we go in terms of technical perfectionism. Let alone all the lags introduced after a file leaves the studio, is really out of control in my opinion.
What goes actually under the hood of the Video Sync Offset process?
I also work with another DAW that allows a delay in ms to be applied on the audio monitoring path only.Very useful as it only delays the audio monitoring path and not the final busses audio, leaving ADC intact as well of course. You can also choose on which busses to insert the delay.
But in PT, the process is applied as a video sync offset, which in my mind and considering the name, works as a method of offsetting the video playback in relation to the audio playback but without moving the video or audio positions in the timeline. Nudging when in stop not affected. Not sure about scrubbing.
If this is true and considering that due to picture display processing and audio monitoring having diferent paths, audio usually leads video, PT must have a process of playing back video earlier by the offset inserted by the user. True? If so how is that possible? Meaning how can it play video before you hit play? I guess that what it does it to delay audio playback in the background by the same value as inserted in the Video Sync Offset.
But what happens if you want the video to lead the audio? Not very common but as apparently the video sync offset allows for minus values to be inserted as well, I wonder how it works then. It plays the audio first and only then the video in the timeline to match?
So if you insert lets say, -4 (minus) quarter frames of delay are you offsetting video after the audio? As opposed to inserting only 4 quarter frames which is supposed to "play video ahead"?
If the process is what I´ve described, people using the same busses on final mixes as on the listening path could get in trouble if still laying back live to tape.
Does the process affect bouncing to QT as well? Meaning if you have an offsett and bouncing to QT, does it wrap the video file with offsetted audio?Both in real time and offline (PT 11)?
Also some video cards introduce a lag when transcoding outputs. Let alone some lag that may be introduced in the PCIe bus if applicable. For instance some BM cards introduce a one frame delay, it´s stated in the manual. Add your own display or projector lag and things start to get really out of sync. But when you switch to the computer display using the Video Window, now the video card does not play a part anymore. What to do, go into Video Sync Offset and change the value everytime you switch viewing devices?
What if the main display in your room as a diferent lag from the display in your booth when you are ADR´ing? Both are taking a feed from the same video card, so that may become a problem as well if you are not able to insert diferent offsets in diferent video paths.
If anybody would care to explain the in-depths of the Video Sync Offset or it´s approaches to this subject I would appreciate. Thanks.
Another curiosity I have is about human perception of sync issues. You can use a device like Syncheck and measure the lag in your setup, then insert the measured value in PT. All fine and the way to go in my view.
But if using your own eyes only, how far can you go in terms of spotting lag?
I see people worrying about quarter frames, 16ths of a frame, but can you actually see it in reality? Meaning after a few hours of work? I can hear a milisecond but can´t see it to be honest. Diferent shots, diferent words being spoken, diferent lips and face movements all contribute to be easily fooled by small amounts, so sometimes I wonder how deep should we go in terms of technical perfectionism. Let alone all the lags introduced after a file leaves the studio, is really out of control in my opinion.
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