bytedeco/javacv

OpenCVFrameGrabber default search path

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#2,061 opened on Jul 13, 2023

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Description

Hello,

I'm working with a decklink capture card and when running: OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0) this works great on Windows.

But when running the same thing: OpenCVFrameGrabber grabber = new OpenCVFrameGrabber(0) it fails on Ubuntu.

The error I get is [ WARN:0@0.196] global /__w/javacpp-presets/javacpp-presets/opencv/cppbuild/linux-x86_64/opencv-4.6.0/modules/videoio/src/cap_v4l.cpp (902) open VIDEOIO(V4L2:/dev/video0): can't open camera by index and this makes sense as the decklink capture devices are not stored there. They are stored in dev/blackmagic/io0 so I'm wondering if there is a way to pick where the OpenCVFrameGrabber searches for the video input?

Please let me know if there is anything I can do.

Thanks, Nick

Contributor guide

Research direction
Investigate how OpenCVFrameGrabber selects the video device. Look for constructors or configuration options to specify a custom device path (e.g., /dev/blackmagic/io0). Check the OpenCV videoio backend documentation and the javacpp presets build configuration for decklink support.
Tech stack
java
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaOpenCV
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70