auto-load with cues set to follow

[Richard Williamson]

Hello

I think this is probably a feature request. We have a piece with 12 x 1 hour videos playing back to back, these total about 180GB of video in MP4 (we would prefer to run in 422 but our HDD just isn’t big enough for a few reasons)

Each video is set to auto follow, however when one video finishes and the next starts there is a slight blip.

We tried turning on auto-load to fix this, but it seems that when cues are auto following then all cues in the sequence load at the same time, which made the machine unhappy (it’s a slightly old trash can)

We have fixed this by manually loading the next video each time one starts, but my request would be to slightly change the way that auto load behaviour starts. My suggestion would be that a cue only autoloads when the previous cue has started - by which I mean when that cue’s Pre-wait or action has begun. This would mean that a chain of auto-continues would all load at the same time, but a chain of auto-follows would only load when the cue before has started.

Thanks!

Richard

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Richard Williamson
www.richard-williamson.com
ric...@richard-williamson.com
07957 457 362

[Simon VB]

When dealing with large videos or large group cues (eg. with multitrack audio), I tend to program a load cue after each cue, in auto-continue but with a pre-wait of a couple of seconds.

That way, you never need to load multiple cues at the same time, slowing down your computer. When the previous cue is playing nicely, the load cue fires, and the next cue loads.

[micpool]

I think the current implementation makes sense. Autoload as standard for the 99% of straightforward use cases where this is the best option, with the option of disabling this per cue and, using load cues, to precisely determine what is loaded and when, for more advanced use, and to interrupt  autoloading of long chains of linked cues to prevent memory pressure, or interruption of currently playing material. 

Unpicking the rest of your post, 

Loading the first few frames of 12 videos should not really overtax any QLab system. The memory pressure should remain relatively unchanged and reasonably low, although it might take  a few seconds, which shouldn't be a problem at the start of a 12 hour playback sequence

MP4 is a container. I assume you are using it with h264 codec. Because of the number of settable parameters in h264 it is possible to produce files that have excellent playback performance, but the main problem is that it is far more likely to produce files that don't play nicely , particularly if using keyframes with long GOP intervals. I don't really understand why the 50 quid it would cost for a 1TB HD to allow you to use ProRes files isn't a better option.

Having said all that, I just tried this  in QLab 5 and it appears there might be some playback anomalies with sequences of very long files  (which I have reported to Figure 53). Are you using QLab 4 or 5 for this?

Best

Mic