Looping a timeline group in Qlab 4?

[Greg Leeper]

The goal was to have a sequence of video clips, all different lengths, with crossfades between them, that repeats endlessly.

A timeline group was a quick way to get the fade cues all in the right places, which would be harder and more time consuming using the 2nd sample group workflow below it, which is in  'enter group and start first child' mode.

I've simplified my workspace, to make it easier to see what is going on- removing the fades, and swapping the movies for stills - it looks like the last cue in the group never gets 'stopped' & I can't figure out why...?

I had even more strange behavior when the fades were in there  - the timeline would play once, then repeat all but the last cue on the timeline, and then stop.  I think it's related to the 4th cue never stopping when the group is restarted in the simplified no fade version.

In comparison the second group works fine.. it would just take a long time to adjust the timing of every fade uniquely.

Can anyone explain what is going on here?

Workspace attached

[micpool]

When using stills to simulate videos in demo workspaces, give the stills a duration.

In the timeline group you can put the start cue in the timeline group itself.

If the timeline group loop fails, it's because the start cue is still technically running when the group restarts. To fix this put a 0.01s pre wait on the group (or set the group to 'on second trigger hard stop and restart in the triggers tab.

If you are using a Start first child group, then for this case you would want to use the 'and go to next cue 'variant, as presumably the next time you hit the go you would want something else to happen.

If your stills have duration, to simulate video  files, then you can use auto continues  with negative post waits to overlap them to allow for your fades

In this instance you don't need fade cues; you can just set all video cues to bottom layer, and select fade and stop peers in x seconds in the triggers tab.

In this screenshot:

Basics Tab: 

Stills set to duration of 3 secs (to simulate videos of 3 secs duration.)

Video cues set to auto continue with a prewait of -1 sec, i.e the next cue will start 1 second before the end of the cue, this is precalculated which is why the inspector shows a post wait of -1s and the cue list shows a post wait of 2s (3s-1s)

Triggers tab

Video Cues set to fade and stop peers in 1 second.

Geometry tab:

Video Cues set to bottom layer.

Screen recording attached of final result.

Does this do what you want?

Mic

[micpool]

Just realised you may have been wanting to crossfade the images in quadrants as in your workspace.

Here is the timeline group solution to do that with fades. Note the 0.01s pre wait on the group.
All videos are set to top layer. Nothing is set in trigger tabs. Still durations set to 2 secs to simulate a video file duration.


Screen recording attached

On Monday, September 11, 2023 at 3:14:39 AM UTC+1 gr...@opticusvideo.com wrote:

[Ethan Eldred]

In QLab 5, you can do this with a Playlist group with crossfade enabled, unless I’m missing something. 

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Ethan Eldred
Sound and Media Artist
MFA Student in Sound Design, Class of '24
UCSD Department of Theatre and Dance
bardsound.com
c. 814.215.3423

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[micpool]

On Monday, September 11, 2023 at 6:10:49 PM UTC+1 eel...@ucsd.edu wrote:

In QLab 5, you can do this with a Playlist group with crossfade enabled, unless I’m missing something. 

I think all you are missing is the subject of the post. Looping a timeline group in Qlab 4?

Mic

[Greg Leeper]

Thanks Mic & Ethan!

Apologies for slow replies while determining one can't reply to this on an iPhone unless you force load the desktop site for Google Groups - which then renders so small you can't read it!

Yes, Mic, everything you said makes sense - thanks so much!

I didn't realize you had to wait for the group to complete before firing a start cue, I thought those things would time out by default, since they were being triggered in sequence.

I divided it into quads just to be able to better see how things were triggering, and yes, originally these were all video clips of various lengths - stills were just meant to simplify & debug.

Ethan, good to know Qlab 5 handles this better.