Control: tags 1101728 patch
Dear maintainer,
The attached patch fixes this issue. I will send an NMU with
5 days of delay soon.
Cheers,
Eriberto
Description: linux-v4l2: Fix virtual camera start failure
Add function that tries to reset v4l2loopback output for module versions
from 0.12.5 to 0.12.7. If successful, then set flag that STREAMON and
STREAMOFF are necessary each time the device is opened/closed.
Author: stephematician <steph.fn.cont...@proton.me>
Origin: https://github.com/obsproject/obs-studio/commit/12c6feb
Bug: https://github.com/obsproject/obs-studio/issues/11891
Bug-Debian: https://bugs.debian.org/1101728
Bug-Debian: https://bugs.debian.org/1101351
Reviewed-By: Joao Eriberto Mota Filho <eribe...@debian.org>
Last-Update: 2025-04-25
--- obs-studio-30.2.3+dfsg.orig/plugins/linux-v4l2/v4l2-output.c
+++ obs-studio-30.2.3+dfsg/plugins/linux-v4l2/v4l2-output.c
@@ -15,6 +15,7 @@ struct virtualcam_data {
obs_output_t *output;
int device;
uint32_t frame_size;
+ bool use_caps_workaround;
};
static const char *virtualcam_name(void *unused)
@@ -111,11 +112,54 @@ static void *virtualcam_create(obs_data_
return vcam;
}
+bool try_reset_output_caps(const char *device)
+{
+ struct v4l2_capability capability;
+ struct v4l2_format format;
+ int fd;
+
+ blog(LOG_INFO, "Attempting to reset output capability of '%s'", device);
+
+ fd = open(device, O_RDWR);
+ if (fd < 0)
+ return false;
+
+ format.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+ if (ioctl(fd, VIDIOC_G_FMT, &format) < 0)
+ goto fail_close_reset_caps_fd;
+
+ if (ioctl(fd, VIDIOC_S_FMT, &format) < 0)
+ goto fail_close_reset_caps_fd;
+
+ if (ioctl(fd, VIDIOC_STREAMON, &format.type) < 0)
+ goto fail_close_reset_caps_fd;
+
+ if (ioctl(fd, VIDIOC_STREAMOFF, &format.type) < 0)
+ goto fail_close_reset_caps_fd;
+
+ close(fd);
+
+ fd = open(device, O_RDWR);
+ if (fd < 0)
+ return false;
+
+ if (ioctl(fd, VIDIOC_QUERYCAP, &capability) < 0)
+ goto fail_close_reset_caps_fd;
+
+ close(fd);
+ return (capability.device_caps & V4L2_CAP_VIDEO_OUTPUT) != 0;
+
+fail_close_reset_caps_fd:
+ close(fd);
+ return false;
+}
+
static bool try_connect(void *data, const char *device)
{
+ static bool use_caps_workaround = false;
struct virtualcam_data *vcam = (struct virtualcam_data *)data;
- struct v4l2_format format;
struct v4l2_capability capability;
+ struct v4l2_format format;
struct v4l2_streamparm parm;
uint32_t width = obs_output_get_width(vcam->output);
@@ -131,6 +175,14 @@ static bool try_connect(void *data, cons
if (ioctl(vcam->device, VIDIOC_QUERYCAP, &capability) < 0)
goto fail_close_device;
+ if (!use_caps_workaround && !(capability.device_caps & V4L2_CAP_VIDEO_OUTPUT)) {
+ if (!try_reset_output_caps(device))
+ goto fail_close_device;
+
+ use_caps_workaround = true;
+ }
+ vcam->use_caps_workaround = use_caps_workaround;
+
format.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
if (ioctl(vcam->device, VIDIOC_G_FMT, &format) < 0)
@@ -166,7 +218,7 @@ static bool try_connect(void *data, cons
memset(&parm, 0, sizeof(parm));
parm.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
- if (ioctl(vcam->device, VIDIOC_STREAMON, &parm) < 0) {
+ if (vcam->use_caps_workaround && ioctl(vcam->device, VIDIOC_STREAMON, &format.type) < 0) {
blog(LOG_ERROR, "Failed to start streaming on '%s' (%s)",
device, strerror(errno));
goto fail_close_device;
@@ -241,10 +293,9 @@ static void virtualcam_stop(void *data,
struct virtualcam_data *vcam = (struct virtualcam_data *)data;
obs_output_end_data_capture(vcam->output);
- struct v4l2_streamparm parm = {0};
- parm.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+ uint32_t buf_type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
- if (ioctl(vcam->device, VIDIOC_STREAMOFF, &parm) < 0) {
+ if (vcam->use_caps_workaround && ioctl(vcam->device, VIDIOC_STREAMOFF, buf_type) < 0) {
blog(LOG_WARNING,
"Failed to stop streaming on video device %d (%s)",
vcam->device, strerror(errno));
