From 355d1ac8481728d78faa005aa260ba450bb65d43 Mon Sep 17 00:00:00 2001
From: capitalistspz <[EMAIL REDACTED]>
Date: Wed, 5 Aug 2026 14:32:57 +0000
Subject: [PATCH] camera: Detect `exclusive_caps` v4l2loopback devices (#16116)
---
src/core/linux/SDL_udev.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/src/core/linux/SDL_udev.c b/src/core/linux/SDL_udev.c
index 35db562cdd6e7..941c93b73ac38 100644
--- a/src/core/linux/SDL_udev.c
+++ b/src/core/linux/SDL_udev.c
@@ -485,6 +485,7 @@ static int device_class(struct udev_device *dev)
{
const char *subsystem;
const char *val = NULL;
+ const char *attr = NULL;
int devclass = 0;
subsystem = _this->syms.udev_device_get_subsystem(dev);
@@ -496,8 +497,18 @@ static int device_class(struct udev_device *dev)
devclass = SDL_UDEV_DEVICE_SOUND;
} else if (SDL_strcmp(subsystem, "video4linux") == 0) {
val = _this->syms.udev_device_get_property_value(dev, "ID_V4L_CAPABILITIES");
- if (val && SDL_strcasestr(val, "capture")) {
- devclass = SDL_UDEV_DEVICE_VIDEO_CAPTURE;
+ if (val) {
+ if (SDL_strcasestr(val, "capture")) {
+ devclass = SDL_UDEV_DEVICE_VIDEO_CAPTURE;
+ }
+ // v4l2loopback may report output caps before reporting capture caps
+ // and ID_V4L_CAPABILITIES is never updated
+ else if (SDL_strcasestr(val, "video_output")) {
+ attr = _this->syms.udev_device_get_sysattr_value(dev, "state");
+ if (attr && SDL_strcmp(attr, "capture") == 0) {
+ devclass = SDL_UDEV_DEVICE_VIDEO_CAPTURE;
+ }
+ }
}
} else if (SDL_strcmp(subsystem, "input") == 0) {
// udev rules reference: http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-input_id.c