Latency is a topic very important to me. Interactive, audio reactive, and optical feedback applications are negatively impacted by latency.
Every digital device in a signal chain is going to introduce at least one field or frame of delay. That includes digital video monitors.
TBC2 and Chromagnon are going to delay any incoming signal by one frame. Not sure if greater frame delays have been implemented in TBC2 firmware, I’m waiting on the second run of TBC2 production.
Note that an analog decoder, e.g. VU003, does not introduce a frame delay at all, so that’s the best way to push video through the modular system to minimize latency.
It may be possible for LZX to implement a low latency mode in their time base corrector firmware, which would reduce the delay to the range of lines or pixels, rather than entire frames.
All analog devices are also going to introduce some latency, but it will be in the range of nanoseconds. In a modular system, this results in the picture shifting to the right. We see that evil horizontal blank bar on the left side of the image. Even worse, the picture data on the right side of the image is destructively cropped.
Traditionally, pro analog video devices (TBCs, VTRs etc) have a horizontal phase adjustment allowing the picture to be offset relative to sync. End result is that we can properly center the picture, we don’t get ultra wide horizontal blanking, and we don’t crop the image on the right.
It may also be possible for LZX to update the time base corrector firmware to implement an h-phase functionality. This would be done by delaying the output by slightly less than one frame, a so-called “negative delay”. Don’t know if it would be technically possible to combine low latency with negative delay.
Within the modular analog signal path, sending different signals through different modules will introduce different amounts of delay, resulting in an unintended horizontal differential between those different signals. They won’t line up unless they go through identical chains of modules. This issue can be addressed with a delay line analog module. @creatorlars has indicated that this is a likely future product, but there are design and functionality questions to be addressed.
If we had a TBC low latency mode we could minimize the frame delay introduced by the modular system.
If we had TBC negative delay, we could prevent the horizontal shift and loss of image data, at least for simpler patches that don’t have branching structures where different signals are delayed differently.
If we had a delay line module, we could correct horizontal misalignments in those complex, branching patches.
I think these are all very important for different reasons. Right now I’m much more concerned about the destructive data loss caused by the h-phase issue. That’s just really, really bad. Every frame of footage I record needs to be re-scaled and cropped to eliminate that evil black bar on the left, which means at the end of the post process I have lost up to ~10% of the original image. (Welcome back to the bad old days of excessive, unpredictable, and device/site-specific cropping from overscan CRTs and projections cropped by black curtains.)
But eventually I’ll be resuming a real-time performative practice, and at that point the frame delay introduced by all of these digital devices will become a major creative barrier.
