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Questions tagged [v4l]

v4l ("Video For Linux") is a video capture infrastructure provided by the linux kernel. the historic "v4l" has been obsoleted by the "v4l2" ("Video for Linux 2") infastructure and has been removed from the linux-kernel starting with 2.6.38.

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OpenCV Capture from Camera Results in Noisy-like Image

I am using OpenCV on an embedded target board (FriendlyARM mini6410, processor arm 1176 running linux kernel 2.6.38). I compiled OpenCV 2.4.4 library using toolchain provided for the board, found in the ftp (pls see the website of FriendlyARM). I…
bonchenko
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Android Support4Demos build failure

I tried to get the SupportDemos run, but when I import the demo I get several failures in the Project. I don't understand why there are so many failures and how I could solve them, I am not advanced enough to get them out. I will give you some…
user1052984
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Slow webcam read in OpenCV vs ffmpeg (both using V4L)

As per the title, I'm getting very different framerates. I have a simple C++ OpenCV app that just reads a frame from the camera and then encodes it in JPG. About 50% of the runs, the reading takes 20ms and the encoding 19ms. In the other 50% of the…
Alex
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Display Camera Input in / onto QT application HOWTO / Way to go

I am working on the implementation of a QT application on an Embedded Linux Display with CAN Bus Interface and PAl Camera Interface. The overall aim is to visualize then Sensor Data of the machine (driving speed km/h etc.) with modern looking Gauges…
SpeedyV
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I am using Tinker Board with PiCamera v2.1. How do I set the Color format for the captured image and also how to set exposure params?

I am able to capture NV12 format pictures using Tinker Board with PiCam. I am using gstreamer pipeline with v4l2src plugin to capture images as follows: gst-launch-1.0 v4l2src ! video/x-raw,format=NV12,width=1640,height=1232, framerate=20/1 !…
AK_30
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Tricking libdc1394

I have a third party vision library that would only work with a firewire camera, is it possible to somehow trick libdc1394 into thinking that there is a firewire camera connected but pass frames from a usb webcam via v4l?
Hamza Yerlikaya
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How to configure v4l2src for GStream?

I am trying stream a webcam stream to .flv format using GStreamer. Something similar to below command. gst-launch-1.0 v4l2src ! videoconvert ! x264enc ! flvmux ! filesink location=xyz.flv I am getting below error - erroneous pipeline: no element…
ajayramesh
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How to get the video from webcam using v4l2 linux interface?

I am trying to run the sample code from v4l2 API. When I tried to run the sample code, I am facing problem while compiling the program itself. Please check the error, is there something I need to install or flag to pass during the compilation…
ajayramesh
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Read from linux web camera using OpenCV

I'm trying to read raw video from web camera connected to my linux machine. I'm using OpenCV and l4v2 library (gstreamer). Here are some details on my camera: root@blah:~$ v4l2-ctl -d /dev/video0 --list-formats ioctl: VIDIOC_ENUM_FMT Index …
Pavel Podlipensky
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How to query the available data size in Linux DVB kernel demux buffers?

I am using a Linux-DVB frontend/demux driver pair to get a program stream remuxed from live broadcast TS into user land. I am using the poll/read combination, however, to keep the context switching and kernel to user space copying penalties at…
abdus_salam
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50% faulty pictures from webcam using VideoCapture

I want to take single frames from a Logitech C300 webcam using openCV. When I use the code below. Images are saved but, in about 50% of the cases they contain errors (see image). I now have been searching for hours, but as I don't know what is…
the_summer
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Capturing webcam stream under linux

I'm trying to get images from a minoru3d webcam, which is actually two Vimicro webcams plus a USB hub in a single package. The problem is, opencv always takes streams in maximum resolution, making simultaneous capture from two webcams impossible(due…
Atilla Filiz
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How to get proper saturated frame from see3cam cu135M using OpenCV

I was trying to get 8 single shot frames from 5 x CU135M E-con cameras using OpenCV(4.5.5-dev). Each ~20 seconds every camera take single shot (one cam by one so stream should not be overloaded). I use powered USB-hub so all of them are connected…
Tom Sevet
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Cameras randomly disconnect or don't run

I am making a surveillance system and it requires at least 6 cameras. Currently I have connected 4 to my PC by USB. I am using supplementary power for each camera since the USB output of my PC is sometimes not capable of delivering enough…
KCC
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Is it possible to use cv2.Videocapture to access video devices greater than 7 index on Ubuntu 18.04?

Currently trying to simultaneously capturing 10 images with 10 usb cameras connected to a Raspberry Pi 4 (through board USB ports and usb hub) with Ubuntu 18.04 installed. I am using a multithreading approach to create multiple camera objects which…
Asherk03
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