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Questions tagged [video4linux]

Video4Linux or V4L is a video capture application programming interface (API) for Linux, supporting many USB webcams, TV tuners, and other devices. Video4Linux is closely integrated with the Linux kernel.

Video4Linux or V4L is a video capture application programming interface (API) for Linux, supporting many USB webcams, TV tuners, and other devices. Video4Linux is closely integrated with the Linux kernel.

References

  1. Video4Linux - Wikipedia
41 questions
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Cross-Platform webcam access

I'm looking for a cross-platform video capture library, for webcam access. One that wraps V4L/V4L2 on Linux, DirectShow on Windows, and QuickTime on the Mac. C or C++ is preferred, but I can work in Java or Python if those have better options for…
Branan
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mjpeg to raw rgb24 with video4linux

I'm writing a c++ webcam viewer using video4linux. I need a RGB24 output (interleaved R8B8G8) for displaying. I'm able to get video input for almost all low-resolution webcam, using YUYV, GREY8 or RGB24. But I need to get input also from…
Alessandro Pezzato
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UV4L on RPI WebRTC with Janus Gateway ICE error

I need to stream from the RPI Camera to a Janus room with webrtc. I installed UV4L on my PI, and try the demo with the gateway url https://janus.conf.meetecho.com : it's work. I installed janus-gateway on a server (demos here :…
cylwin
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Why can I stream h264 encoded video from webcam to BOTH display and file, but NOT raw video?

I want to stream raw video from a Logitech C920 webcam and while both displaying and saving the video to file using GStreamer 1.0. This works if I stream h264 encoded video from the camera (the camera provides hardware encoded h264), but it fails…
kalleknast
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Getting BeagleBone to capture a still frame using OpenCV

I've a BeagleBone running Ångström Linux 3.2.28, and I'm trying to capture a frame from my camera. So I plug in my USB webcam, and check /dev to ensure it shows up. It does, as video0 (bottom right). I know this is correct, because it disappears…
Chris
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Video4Linux ioctl error (#25) when attempting to read device information from /dev/video0

I am currently attempting to retrieve device information for a built in web-cam using the following code: #include #include #include #include #include #include #include…
tiredone
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How to read h264 stream as a file from the USB webcam directly in c/c++ without using opencv?

I am able to read a video file of h264 format and doing some machine learning inference on top of it. The code works absolutely fine for input from a file. Below code is a sample code from Deepstream SDK FileDataProvider(const char *szFilePath,…
ajayramesh
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setting/getting camera jpeg compression quality in v4l2 with JPEG pixel format via C/C++

Can you please show how to get and set the JPEG compression quality (with JPEG pixel format) in V4L2 via C++? I can detect the various pixel formats supported by the camera and the corresponding resolutions and frame-rates. I can also select them…
mcioni
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GStreamer timestamps (PTS) are not monotonically increasing for captured frames

I wrote some code to capture frames from a webcam using GStreamer 1.0 (PyGST). It is important for me to know the exact time of capture. For this, I set the v4l2src property do-timestamp, and I use appsink to write the buffer PTS to a text…
kalleknast
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How to detect the camera disconnection in linux?

How will you detect the camera signal disconnection (not the module disconnection or hardware disconnection) without the support of V4l2-ctl command? Because my Camera Driver is not supporting v4l2-ctl command.
Kernel
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Error (893) can't open camera by index, python and jupyter notebook

The code: import cv2 cap= cv2.VideoCapture(1) if not cap.isOpened(): raise IOError("Cannot open webcam") cntr =0 while True: ret,frame = cap.read() cntr= cntr+1; if ((cntr%30)==0): …
Ron Bergen
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gspca compilation errors / raspberry pi raspbian

I have webcam Veo Stingray Ox545:8333 (vendor and product ID) I have Raspberry Pi model A uname -r = Linux raspberrypi 4.1.15+ #830 Tue Dec 15 16:58:28 GMT 2015 armv6l GNU/Linux gspca drivers from http://mxhaard.free.fr/spca5xx.html list this…
Salvador Gv
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How to get memory address of the FileDescriptor of mmap() function in Linux, for Video4Linux

Good afternoon, I am trying to determine the physical memory location of the buffer allocated by video for linux's IO_METHOD_MMAP Looking through the mmap function, mmap(NULL /* start anywhere */, buf.length, …
Mich
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How to get list of supported frame size and frame interval of webcam device using video4linux api?

I'm trying to use V4L2 api to enumertate supported frame size and frame rate of webcam device. I try to do it with the following code without success. The ioctl function always returns -1. #include #include #include…
Meti
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Missing gstreamer plugin

I've never used gstreamer before but I'm trying to use it and video4linuxloopback to turn my IPad into a jury-rigged webcam. I have an app that outputs the video from the camera to an IP on the local network but no matter what I did I kept getting…
Admiralthrawnbar
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