No Logitech c920 Webcam Input
Hi All,
I'm a new member, a new Max user, AND this is my first post! I am having an issue viewing my webcam in Max. I am using Max 8 on Windows 10 with a Logitech c920 webcam. The webcam works fine in every other program except when I am trying to view the input in Max. I am using a very basic patch with the jit.qt.grab object. I have tried unplugging the camera, deleting and reinstalling the driver, rebooting, etc. Any thoughts?
Thank you!
David
I opened a ticket and received an email from support with a number of suggestions. I highly recommend using support if you have an issue. They were great! I had to create the following object:
[jit.grab @vdevice 0 @format 72]
I hope this is helpful to someone having a similar issue.
Hi, Davevad! I have exactly the same problem with the same camera. And your example did not help. Did you do anything else special? Can you put here all the solutions they gave you?
Thank you so much!
Good Morning YGREQ!
This feels like a lifetime ago. I also recently switched to macOS so I unfortunately can't recreate the issue. I don't have the patch that I think solved the issue but I have a jpeg of the patch (why, I don't know). Try that. I also installed the Logitech camera software but I don't believe that it helped. Good luck!
DavevaD
Do you remember why format 72 (and not, I don't know. 70?). :)
Same with vdevice 0.
The help files don't say much about what these attributes mean.
That's a great question but it was so long ago that I don't remember. I must have purged the emails from support because I don't have those either. I did find an explanation of those fields in the reference but they are brief descriptions at best. Sorry I can't be more helpful. Despite the values, were you able to get it working?
https://docs.cycling74.com/max8/refpages/jit.grab#vdevice
Yeap. The documentation pretty much sucks. I do not understand what they say there in relation to the 2 attributes
Oh, well! Thank you for taking your time to reply.
Have a great day!
it's a difficult thing to document because there is different behavior on mac and win, and every device is going to behave differently. when a jit.grab instantiates, the OS sends it a list of attached video input devices. the names of these devices are accessed via getvdevlist. to choose a device send the desired device index to the vdevice attribute (usually accomplished with a umenu as in the help file).
each device then has a list of formats that it supports. these formats are accessed similarly to vdevice, via getformatlist, and the index of the desired format is sent to the format attribute.
we've had reports that certain logitech cameras behave somewhat unpredictably when the format is not specified, but for the most part should work as expected once you set a format.
format 72 means the 72nd format in the format list. However sometime back the jit.grab object on windows was fixed to remove a bunch of bogus items in the formatlist. In any case you can't rely on any format index being the same for different devices on different operating systems.
hope that clears things up, but if not please file an issue with support (if you haven't already).
Thank you, Rob! Your info helps. May I ask what does format mean in jit.grab's case? Btw, if I press getdevlist, I get the list of available devices. But if I press getformatlist I get nothing.
Thank you so much!!
Hey, Rob!
With the knowledge I got from your reply, I mingled a bit and it seems it works with format 0 and 1 and 2 and so forth. All these formats differ in the quality of the image.
So my deduction is that for sure this type of camera we have does not work with @format -1 which I saw stands for "enable automatic format detection" and is the default.
But please let me know what does format mean in this case with one or 2 examples.
Thank you so much for your help!
for jit.grab format typically refers to a pixel format and image dimensions, but may mean different things to different devices.
automatic format detection only works with blackmagic native devices (it should only be mentioned in the blackamagic tab of the help file, please let me know if that's not the case). Otherwise it simply means use the "default" format, which will mean different things on different OSes and different devices (noticing a trend here?)
on windows, I believe you must first select the vdevice and open it before sending the getformatlist message to get the supported formats. Please let me know if that's not the case.
This is how it is mentioned Indeed automatic format detection in the help file. But considering that when I do not input anything as format for the C920 webcam, I don't get any input, perhaps there is some format it is choosing by itself that is not ok. But once I input format 0 or format 1, it works.
This is link I got from support http://www.optojump.com/Support/Knowledge-Base/Webcams-and-video-formats-en.aspx. Maybe it will help someone else. I did not test yet, but my guess is that the first in this list is format 0
Format Resolution Frame rate
MJPG1920 x 1080 30/60 fps
MJPG1280 x 720 30/60/90 fps
MJPG800 x 600 30 fps
MJPG640 x 480 30/60/90 fps
ASF640 x 480 30 fps
ASF320 x 240 30 fps
Hello, I have to buy a webcam for a project with Max 8 and Windows 10.
Are the problems with the Logitech C920 solved ?
Otherwise have you a model of webcam to advise ?
Thanks
I tested it and it works. Keep in mind the settings mentioned above.
Thanks !