Show visuals and sync problems.

[Val]

Hi there, I'm new to the world of Qlab, and although I love what I've been able to do so far, I did encounter a fatal flaw that is preventing me to use live reliably. I'm pretty sure I'm doing something wrong, but I'll give you some context:

I'm the drummer, producer and director of my band, we are launching a Soda Stereo tribute band, and have our first show in a couple of weeks. I created some visuals to go with each song, to be triggered from my SPD-SX PRO, the SPD is taking care of our backing tracks, click tracks, vocal cues, 4 audio channels out in total, and Qlab is only outputting video to one screen wall from my MacBook Pro M1.

I structured the show adding each song to a group, each croup has a fade-in cue, the main song visual, and an animated logo at the end. The SPD is triggering each group/song individually via MIDI, each song has different trigger MIDI note assigned, so each SPD kit/patch will trigger a specific song, so we can change the setlist at any time. I also added a stop cue triggered by a SPD midi note on each group/song as a "panic" solution.

Everything is working as it should, triggering everything correctly. The big problem is that most of the time, when I hit the SPD to trigger a video, is a lottery, it can sync perfectly, next song will be a little bit off (video is a little behind) and sometimes is crazy out-of-sync. I tried every combination of cue settings when I feel is working, I hit the next song and is bad again. I reduced buffer on my settings without luck, tried different computers, nothing, fast SSD, nothing.

I'm not sure how to resolve this issue, it is so close of being perfect, but the out-of-sync issue is killing me!

Thank you and sorry for the long message, English is not my first language and I have problems summarizing my thoughts!

Cheers,

Val

[Paul]

You must have the Fade cue AFTER the Video cue (on version 5) 

(I'm not sure that has anything to do with sync but you can look at the Window menu - Workspace Status - Logs tab to view the MIDI input which might help solve that)

[Tommy]

MP4 often causes such synchronization issues.
This is unrelated to whether it plays fine in VLC or QuickTime.

Please try re-encoding to ProRes or HAP, which are the officially recommended formats.
https://qlab.app/docs/v5/video/video-cues/

[Val]

Thank you all for your suggestions, I really appreciate them!

unfortunately none of the suggestions had any positive effect on the random delay/lag between the trigger and the video start, re-encoded everything with the recommended settings (.mov/Prores422Proxy) Changed the fades from the beginning of the group to after the cue, I even removed the fade cues and use the option under the trigger tab to fade and stop all to have less cues in the list, and nothing, there is still a slight delay that since I have video edits time with the song parts changing, it is very annoying.

We rehearsed last night and even though the delay wasn't that bad, I noticed it, especially during fast and quickly edited passages.

Is there anyway to sync the MIDI clock/time between the SPD-SX PRO and Qlab, will that improve the situation? I'm a MIDI noob, sorry.

Any other ideas?

Thanks again!

Val

[Sam Kusnetz]

If you want perfect sync, you’ll need to play both video and audio from QLab. QLab is only able to guarantee perfect sync between video and audio when:

1. Video and Audio cues are started together with a single GO, as in a Timeline Group or connected with auto-continue and without pre-waits
2. The Video cue has an audio track (even a silent one will do) and is assigned to the same audio output patch as the audio cue.
3. In the IO tab of the inspector, the Video cue is set to follow the audio clock.

Since your audio is playing from a different device, none of those three are relevant and so sync is not guaranteed.

Best

Sam

—

Sam Kusnetz (he/him) | Figure 53

s...@figure53.com

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[sftechguy]

Are you, by any chance, applying any QLab video effects to your video cues?  While I've not seen doing so cause random delays, I have had cases where, depending on the effect being applied, there was a consistent delay.

Just throwing that out there...

-s

[Simon VB]

Also, pre-loading the videos (or groups) may have them play more 'immediately' when triggered. This could be a solution if you experience a delay when starting the video. Is this the case?
If what you experience is that your video starts in sync but drifts out of sync during the song, then Sam's answer is definitely the one you need.

[Kinetic Screen]

Try pre-loading the video before you hit the start cue and see if that makes it more reliable - you might need to create a pre-load cue that you hit before each video.

[Kinetic Screen]

Haha apologies to Simon who