From cf40739da9b31b1c61d39a85ea1b606eb7542d3a Mon Sep 17 00:00:00 2001
From: Mathieu Duponchelle <mathieu@centricular.com>
Date: Tue, 7 Jan 2025 18:12:39 +0100
Subject: [PATCH] transcriberbin: forward sticky events on unsynced source pads

This way an application can tell the language code right away at
pad-added time.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/2029>
---
 video/closedcaption/src/transcriberbin/imp.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/video/closedcaption/src/transcriberbin/imp.rs b/video/closedcaption/src/transcriberbin/imp.rs
index c6c2e8406..50d35129b 100644
--- a/video/closedcaption/src/transcriberbin/imp.rs
+++ b/video/closedcaption/src/transcriberbin/imp.rs
@@ -2645,6 +2645,23 @@ impl TranscriberSinkPadState {
             state.internal_bin.add_pad(&srcpad)?;
 
             let srcpad = gst::GhostPad::with_target(&srcpad).unwrap();
+
+            srcpad.set_active(true).unwrap();
+
+            unsynced_pad.sticky_events_foreach(|event| {
+                if event.type_() == gst::EventType::Tag
+                    || event.type_() == gst::EventType::StreamStart
+                {
+                    gst::debug!(
+                        CAT,
+                        obj = srcpad,
+                        "Storing {event:?} on unsynced source pad"
+                    );
+                    let _ = srcpad.store_sticky_event(event);
+                }
+                std::ops::ControlFlow::Continue(gst::EventForeachAction::Keep)
+            });
+
             topbin.add_pad(&srcpad)?;
         }