weird VIDDLL sound behaviour /bug?

stefano's icon

Hi dear Maxers!
I am preparing some lectures, I wanted to show to my students how to trigger videos and I noticed a weird behaviour while using the VIDDLL engine:
I had 3 videos loaded in 3 movies and I randomly triggered them via (frame 0,start) message, after I while I noticed a weird volume balance and I recognised that some videos went up with their volume. After some testing I heard sometimes some double triggering of the audio content and I had the feeling the jit.movie was randomly stacking up / loading more the one audio track per video (but this is just a feeling)
I also recognised that if loading the same video in the same moment in 3 jit.movies the sound problem happens (at least on my computer -16inch MacBook latest macOS [10.15.2], latest MAX [8.1.3])
patch:

Max Patch
Copy patch and select New From Clipboard in Max.


Rob Ramirez's icon

sounds to me like it's simply the audio tracks adding together which makes it sound louder. if you want more control over the audio, use jit.movie~

stefano's icon

thanks for the answer Rob,
Yes surely they are sounding louder when played all together after load, but I am not referring to that.
If you turn ON the metro on top of the patch the movies play one at the time, there I can clearly hear that the first movie sounds normal, the second louder and the third way louder.

stefano's icon

I am routing back the output of my computer and checking the amplitude of each single video, as u can see the second and the third are getting louder

Rob Ramirez's icon

weird, i can hear it now. i'll take a look.

stefano's icon

Thanks a lot Rob!!!

stefano's icon

I started using the jit.movie~ as I need to interactively and continuously change the rate of the video
and it seems jit.movie~ behaves the best in this situation. I noticed an other curious behaviour thou, maybe this is related to the previous problem and can help? check out the attached video

viddllProblem-Small.mov
video/quicktime 4.29 MB

Rob Ramirez's icon

thanks for the video but the best way to get this addressed is to send along the patch and movie file you used. can send to me privately if preferred.

stefano's icon

glissLoop.mov
video/quicktime 1.21 MB


stefano's icon

Max Patch
Copy patch and select New From Clipboard in Max.



Rob Ramirez's icon

hey Stefano, just wanted to follow up that I managed to track down and solve the original issue with jit.movie audio getting louder with multiple clips. thanks for persisting with that!

for the other issue, I have to recommend for this kind of audio manipulation that you separate the audio file and use buffer~ based objects to achieve your effect. the jit.movie can easily be synced to the playback from groove~ using the position attribute, and probably best to have playback in the jit.movie disabled.

stefano's icon

Hi Rob! Nice you spotted the problem! Thanks for looking in to that!
About the rate change and the little artefacts: yes using groove~ is clearly a more elegant way, I was working on some examples for my students and so I was trying to be as minimal as possible, also I was surprised the issue happened only after loading a second video in an other jit.movie, so I thought maybe it's related to the first volume problem!
Thanks again!
Cheers!
S