TwinLights

So I'm getting the following error when I try to open an input device using jit.grab and the qt engine:

A bit of snooping on the forum and found the following thread:

https://cycling74.com/forums/jit-qt-grab-cant-open-device/

None of the suggestions here have worked except changing the overall engine to avf. This is an issue because in the patch Im creating I need to use jit.qt.broadcast - which will only work with the qt engine. Anyone have any suggestions about how I could get around this issue?

could not create video channel -9405
error opening device for grab

A bit of snooping on the forum  and found the following thread:

Specs:
Max 7 in 32Bit mode
MacBook Pro Retina running 10.10.2

jit-grab-wont-work-in-qt-engine-but-i-need-to-broadcast-in-qt-engine

hi twinlights. you should be able to use the default jit.grab with AVF engine in conjunction with jit.qt.broadcast. you could also try jit.broadcast. the Video Engine only affects the backend of jit.grab, jit.movie, and jit.record.

Thanks for the reply. When I look at the help file for jit.qt.broadcast I see the following message:

"The Quicktime engine (qt) must be selected in the Max Preferences window in order for this object to function"

This suggests to me that I cannot use jit.grab and jit.qt.broadcast at the same time with the avf engine selected?

Unfortunately, jit.broadcast lacks the extra functionality that I need such as .sdp creation.

that information is incorrect, and i'll get it removed. jit.qt.broadcast does not require the qt engine selected.

regardless, any of the video engine objects (movie, grab, record) can override the Video Engine preference, by setting the @engine attribute in the max box when instantiating. e.g. jit.grab @engine avf

ahh, thanks for pointing that out.
that information is incorrect, and i'll get it removed. jit.qt.broadcast does not require the qt engine selected.

regardless, any of the video engine objects (movie, grab, record) can override the Video Engine preference, by setting the @engine attribute in the max box when instantiating. e.g. jit.grab @engine avf


I did not realise you could override the engine in the call, as I also need to use jt.qt.movie with an .sdp file in the same patch, this is actually the perfect piece of knowledge!!

Much obliged for the information Rob. Cheers!

I did not realise you could override the engine in the call, as I also need to use jt.qt.movie with an .sdp file in the same patch, this is actually the perfect piece of knowledge!! 

Much obliged for the information Rob. Cheers!


jit.grab wont work in qt engine, but I need to broadcast in qt engine...