Gaggery Tsai
5644881bcb
When the last camera reader disconnects, cycle the output pipeline (v4l2sink) through READY → PLAYING to reset v4l2loopback's format state. Without this, switching between camera apps that use different PipeWire paths (e.g. Chromium → GNOME Snapshot) fails with "no more input formats" because v4l2loopback retains stale format state from the previous session. The reset is guarded by an input_was_active flag so it only triggers after an actual streaming session, not during PipeWire's brief device probes on startup. Tested on Dell XPS 16 (Panther Lake) with PipeWire 1.6.2: - Snapshot → Zoom → Snapshot: working - Suspend → resume → Snapshot: working - Boot → first Snapshot: 30fps
38 lines
1.4 KiB
Diff
38 lines
1.4 KiB
Diff
--- src/v4l2-relayd.c.orig 2026-03-30 09:59:14.804751921 -0700
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+++ src/v4l2-relayd.c 2026-03-30 09:59:14.827617699 -0700
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@@ -58,6 +58,7 @@
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static GstElement *input_pipeline = NULL;
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static GstElement *output_pipeline = NULL;
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static GstElement *splash_pipeline = NULL;
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+static GTimer *input_timer = NULL;
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static gboolean backend_pipeline_bus_call (GstBus *bus,
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GstMessage *msg,
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@@ -278,6 +279,10 @@
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{
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gst_element_set_state (splash_pipeline_get (), GST_STATE_NULL);
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gst_element_set_state (input_pipeline_get (), GST_STATE_PLAYING);
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+ if (input_timer == NULL)
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+ input_timer = g_timer_new ();
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+ else
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+ g_timer_start (input_timer);
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}
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static void
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@@ -285,6 +290,15 @@
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{
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if (input_pipeline != NULL)
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gst_element_set_state (input_pipeline, GST_STATE_NULL);
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+ /* After a real streaming session (>3s), reset the output pipeline
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+ * to clear stale v4l2loopback state that causes format negotiation
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+ * failures when switching between camera apps. Brief probes from
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+ * PipeWire/WirePlumber (<1s) are skipped. */
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+ if (input_timer != NULL && g_timer_elapsed (input_timer, NULL) > 3.0
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+ && output_pipeline != NULL) {
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+ gst_element_set_state (output_pipeline, GST_STATE_READY);
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+ gst_element_set_state (output_pipeline, GST_STATE_PLAYING);
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+ }
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if (input_pipeline != NULL)
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gst_element_set_state (splash_pipeline, GST_STATE_PLAYING);
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}
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