v4l2loopback - Why Cheese of Gnome can't find my virtual v4l2 video device?

Question

I created a virtual v4l2 video device with V4L2LOOPBACK driver,and recode the part of VIDIOC_ENUM_FRAMESIZES ioctl because orginal code has no support of multi-format.FORMAT INFORMATION is sended through "write" function recoded by me.And,when I run Cheese program,I got an error as:

cheese-Message: 17:14:11.543: mylog: priv->num 0

cheese-Message: 17:14:11.548: monitor_coldplug (nil)

Message: 17:14:11.548: cheese-application.vala:222: Error during camera setup: No device found

(cheese:6475): cheese-CRITICAL **: 17:14:11.578: cheese_camera_device_get_name: assertion 'CHEESE_IS_CAMERA_DEVICE (device)' failed

(cheese:6475): GLib-CRITICAL **: 17:14:11.578: g_variant_new_string: assertion 'string != NULL' failed

(cheese:6475): GLib-CRITICAL **: 17:14:11.578: g_variant_ref_sink: assertion 'value != NULL' failed

(cheese:6475): GLib-GIO-CRITICAL **: 17:14:11.578: g_settings_schema_key_type_check: assertion 'value != NULL' failed

(cheese:6475): GLib-CRITICAL **: 17:14:11.578: g_variant_get_type_string: assertion 'value != NULL' failed

(cheese:6475): GLib-GIO-CRITICAL **: 17:14:11.578: g_settings_set_value: key 'camera' in 'org.gnome.Cheese' expects type 's', but a GVariant of type '(null)' was given

(cheese:6475): GLib-CRITICAL **: 17:14:11.578: g_variant_unref: assertion 'value != NULL' failed

** (cheese:6475): CRITICAL **: 17:14:11.578: cheese_preferences_dialog_setup_resolutions_for_device: assertion 'device != NULL' failed

question from:https://stackoverflow.com/questions/65934465/why-cheese-of-gnome-cant-find-my-virtual-v4l2-video-device

Answer 1

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