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Questions tagged [v4l2]

v4l2 (video for Linux 2) is a video capture interface for a variety of video capture devices tested to be fully compatible with Linux. v4l2 is commonly used by programs and frameworks such as Ekiga, gstreamer, Mplayer, Skype, and VLC media player.

A good place to start understanding the V4L2 framework is the following series of articles on lwn.net.

Part 1: The Video4Linux2 API
Part 2: registration and open()
Part 3: Basic ioctl() handling
Part 4: Inputs and Outputs
Part 5a: Colors and formats
Part 5b: Format negotiation
Part 6a: Basic frame I/O
Part 6b: Streaming I/O
Part 7: Controls

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Raspberry Pi Camera Module undetectable by common applications

I bought a 5 mp camera module available at Amazon for my raspberry pi 4 2 gb model. Then I configured it for use and tested it with raspistill and raspivid, it is working as expected. But since it is a module connected to the CSI port and not a USB…
Popcorn Movies
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Unknown format error on running examples on coral board along with coral camera

I was running examples from google coral. They worked fine on my coral board. Then i modified the examples after following this post to increase fps output of camera. The details of platform : mendel@coral2:~$ uname -a Linux coral2 4.14.98-imx #1…
Deepanshu Yadav
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How can you get a B&W or Grayscale image by adjusting webcam controls?

I have a cheap webcam connected (soldered don't ask why) to an Intel Edison. The problem is I am doing experiments with video capture and wanted a B&W or grayscale image from the camera (saves overheads/delays/bandwidth involved in programmatically…
Flood Gravemind
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Video4Linux is crashing when start capturing

i try to capture images from a webcam with video4linux and mmap method. My device is an Aptina MT9M114 camera on a Gentoo Linux (Kernel version 2.6.33.20). The code is based on this sample program:…
user1911083
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liverserver.so cannot open. uv4l mjpegstream

I'm having issues making a virtual camera with uv4l mjpegstream. This mjpegstream is not a camera but rather a graphic that I created. pi@iot:~ $uv4l --driver mjpegstream --auto-video_nr --verbosity=8 -f --uri "http://10.1.7.191/api/gfx/stream.jpg"…
halo test
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Does changing v4l2 default settings improves usb camera performance?

I have USB ELP camera. I'm using the v4l2 driver to capture images from that USB camera. I've found that we can change v4l2 default parameters like brightness, contrast, gamma, exposure, resolution. Can we able to increase the speed of camera access…
Chakri
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VGA capture card for linux

I am looking for a "VGA capture card for linux", that captures VGA input from remote computer in such a way that I may be able to use V4L2 to capture the feed. Kindly suggest some.
vsk
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V4l2 MJPEG Chroma Subsumpling

My cam gives me jpeg with chroma sub-sampling 4:2:2, but I need 4:2:0. Can I change MJPEG default chroma sub-sampling with v4l2?
Grotrek
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How to decode an MJPEG to raw RGB (or YUV) data

I am using Video4Linux2 to open a connection to the camera connected to my machine. I have the ability to either request YUV or MJPEG data from my camera device. Since increasing the requested resolution from the camera, while also requesting YUV,…
Gabe Rundlett
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