I have a multiple camera setup and an OpenCV application that has been working using two cameras. One camera is a Logitech C310, and the other has been my built-in camera on my MacBook Pro. On initialization I call cvCaptureFromCAM(), once for each camera. However, hooking up a second Logitech C310 (total of 3 cameras) causes the call to cvCaptureFromCAM() to hang for my MacBook pro camera.
Both Logitech cameras work together just fine. Once I call cvQueryFrame() for my MacBook camera it hangs, but eventually after maybe 2-3 minutes it returns what appears to be a valid pointer (i.e. not NULL), but that camera is not initialized. I receive no frames from that camera, and the light that is typically green when the camera is in use is not lit.
Here is a snippet of my code:
for( size_t i = 0; i < NUM_CAMERAS; i++ ) // Works fine when NUM_CAMERAS is 2, but hangs when it is 3
{
capture[i] = cvCaptureFromCAM( i );
if( capture[i] != NULL )
{
// Start a thread for each camera
}
}
// Threads manage calling cvQueryFrame() for each camera.
I am certain this is not an issue with multiple threads, because cvQueryFrame() always hangs, even if I do not start any new threads.
Thanks for any help - I'm having trouble finding anyone else with a similar issue.
OpenCV 2.4.5
OSX 10.8.4
gcc 4.2
Qt 5.0.2
Boost version 105300
2.4GHz Intel Core i7, retina Mac, 8BG RAM
2 x Logitech C310, 1 x MacBook Pro Camera
1 x Frustrated Dude
Turns out this is a limitation with my MacBook Pro. Running 2 USB cameras as well as the built-in iSight (which I believe is also USB internally), initialization of the 3rd device hangs. I can't provide a technical reason, but it seems it is a USB bandwidth issue.
I resolved this by using a Thunderbolt dock (http://www.belkin.com/us/p/P-F4U055) which has additional USB ports. Now my application works fine and initializes all cameras as it should. Also verified an Apple Thunderbolt display (which has a built in USB hub) also works.
Cheers!
Related
I'm working on a project requiring real-time access to the webcam, and have problems with getting a suitable camera stream under Windows 10 for processing the frames with OpenCV.
I'm able to access the camera just fine under Windows 8.1. using either
OpenCV 2.4.9 with Evgeny Pereguda's VideoInput
library(http://www.codeproject.com/Articles/776058/Capturing-Live-video-from-Web-camera-on-Windows-an)
for accessing the camera through Windows Media Foundation, or
OpenCV 3.0 without any additional libraries
These allow for capturing the webcam stream with high frame rate (~30fps), and setting the webcam resolution with e.g.
cvCapture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
cvCapture.set(CV_CAP_PROP_FRAME_HEIGHT, 480);
Under Windows 10, however, both solutions above result in problems:
the solution using OpenCV 2.4.9, and the VideoInput library allow
setting the resolution to 640x480, but the frame rate is around 1FPS
(or worse?!), and the picture is very dark
the solution using OpenCV 3.0 gives me a nice 1920x1080 image on a good frame rate, but I'm unable to set the resolution for the stream
I even tried opening the camera stream with:
cv::VideoCapture cvCapture( CV_CAP_DSHOW + camnum );
cv::VideoCapture cvCapture ( CV_CAP_MSMF + camnum );
The first one works (as far as opening the stream, but with the same problems as above), the MSMF (Microsoft Media Foundation) results in cvCapture.isOpened() returning false;
Handling the FullHD stream real-time isn't feasible for the image processing algorithms, nor is resizing down the resulting frame with OpenCV.
The Windows 8.1 version is running on a Surface Pro 3 (Core i7), and the Windows 10 version on a Surface Pro 4 (Core i7). Could this be a hardware / camera driver problem? I tried finding updated drivers for the Surface 4, but to no avail.
Has anyone had similar problems? Is there an obvious solution I'm overlooking?
I think that your problem with videoInput on Windows 10 is related with selecting of the correct mediaType of web cameras. The fact is that OpenCV uses DirectShow by default and videoInput on Media Foundation is only optional.
I advise you correct check variables:
float MF_MT_FRAME_RATE_RANGE_MAX;
float MF_MT_FRAME_RATE;
float MF_MT_FRAME_RATE_RANGE_MIN;
in
// Structure of info MediaType
struct MediaType
Also I can advise to visit on site Capture Manager Topology Editor - this a free software for working with web cameras via Media Foundation. It allows verify accessible features of Media Foundation on your Surface Pro 4 (Core i7).
With best regards,
Evgeny Pereguda
For several days now, I encounter a problem regarding depth frame acquisition with my Asus Xtion Pro Live, Openni 2 and Qt. My application works fine when the camera is connected to a USB 2.0 port, but when I try to connect the camera to a USB 3.0 port, I cannot display images from the depth stream.
I wrote a very basic console application in order to solve the problem, that just acquire color and depth frames and for each frame, write the timestamp and the index in a file. It appears that the number of depth frames received become very small compared to color frames (1784 color frames against 464 depth frames, for an acquisition of 1 mn). Connecting the camera to USB 2.0 port, I get well 1784 color frames and 1784 depth frames.
I noticed that using QApplication instead of a QCoreApplication, the number of depth frame images decrease in number (44 depth frames for an acquisition of 1 mn).
Do you think that the problem come from Qt or from the camera and its drivers ? I red on Asus support that there were some problems with Asus Xtion Pro live and USB 3.0. I downloaded a patch from http://reconstructme.net/2012/10/13/asus-xtion-usb-3-0-hotfix-2/ but it doesn't correct my problem.
Thanks !
Last week, i decided to take my courage in both hands and tried to solve my problem regarding my Asus Xtion Pro Live and Qt. I am sorry to resurrect this topic, but i have recently come across a website that solves my problem http://www.qimaging.com/support/chipset.php. As they say, the problem comes from the USB controller :
"Intel released a new version of their mother board chipsets (Series 7/C216, Series 8/C220 and later) with a native Intel based USB 3.0 host controller (USB3 extensible host controller, xHCI in the Device Manager). On these newer PCs, the Intel USB 3.0 host controller does not communicate properly with some traditional USB 2.0 chipsets to the extent where data is not properly delivered"
I followed their advice and bought a StarTech 2 Port PCI Express Card Adapter and now i can acquire depth stream and color stream from camera without any problem.
I am using the QCamera class to show the camera output to QcameraViewFinder.
There is two camera : one is HD and other is normal.
Switching to normal camera is fast, but switching to HD cam takes some seconds and the machine is getting hanged for a while.
I am using Ubuntu 14.04 OS.
I am trying to get video stream from analog camera connected to usb easycap - in OpenCV C++.
using MATLAB, I can get stream the same approach like for laptop webcam (with changing the index from 1 to 2).
with OpenCV, I can get stream from laptop webcam with index 0.
but when I am trying to get with the camera connected to the easycap (using index 1) , the laptop crashes and get blue screen.
Anyone have done this before?
Thanks
I work on the same device and I also have some BSOD with it.
Do you plug it with the USB extension provided ? If yes, try don't use it.
If your problem is still hapening, it's probably because like me, you use a low quality chinese fake EasyCap. I bought a real one and I haven't problems anymore
If you want to keep your device, you can use it with VideoCapture in python, it works very well and there is no more BSOD
Try using Linux. I tested my code with a fake EasyCAP in windows and I got many BSOD then I built and executed the same code in Linux and it worked.
Linux is driver friendly.
I can get an image from web-cam (Microsot HD-3000) with OpenCV and everything works fine, when Xtion isn't plug in USB of computer, but if I just plug it in I get only a gray image from web-cam. Skype can't get image too. Xtion works well with OpenNI 2. I use Windows 7 x86 on my Computer and OpenCV 2.4.0.
The problem you are likely facing is the limitation of the USB bus. Especially Microsoft lifecams are sensitive to this problem as they tend to grab the maximum bus speed they can. If they can't do this they stop working. The solution to this can be either very simple or a little more complicated.
1: Switch around USB plugs. Some mainboards have different USB buses on different ports. By swapping around you might be able to find a configuration that does work for you.
2: Expand your system with another USB bracket. If the solution in 1 doesn't work you're going to have to expand your computer with more USB ports to get around the bus limitation.
3: Use as less USB devices as possible, don't use the ASUS Xtion, or buy a different webcam