transcriberbin: fix initial transcription bin setup

When passthrough=false at construction and the transcription bin
is linked after receiving video caps (and not on state change),
there could be a race where transcription-bin was linked with
tee but state change of the transcription-bin was not finished.

If upstream pushed a buffer at that point, it got a flushing flow
return and stopped streaming.

This is the same issue and the same fix as 558656deb5037a85d6213f2f9a857f4902c9502f
for the initial passthrough=false case.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1142>

1 files changed, 4 insertions, 4 deletions

diff --git a/video/closedcaption/src/transcriberbin/imp.rs b/video/closedcaption/src/transcriberbin/imp.rs
index 338eca6b..997c9451 100644
--- a/video/closedcaption/src/transcriberbin/imp.rs
+++ b/video/closedcaption/src/transcriberbin/imp.rs
@@ -261,10 +261,6 @@ impl TranscriberBin {
         state.transcriber.set_property("latency", latency_ms);
 
         if !settings.passthrough {
-            let audio_tee_pad = state.audio_tee.request_pad_simple("src_%u").unwrap();
-            let transcription_sink_pad = state.transcription_bin.static_pad("sink").unwrap();
-            audio_tee_pad.link(&transcription_sink_pad).unwrap();
-
             state
                 .transcription_bin
                 .link_pads(Some("src"), &state.cccombiner, Some("caption"))
@@ -272,6 +268,10 @@ impl TranscriberBin {
 
             state.transcription_bin.set_locked_state(false);
             state.transcription_bin.sync_state_with_parent().unwrap();
+
+            let audio_tee_pad = state.audio_tee.request_pad_simple("src_%u").unwrap();
+            let transcription_sink_pad = state.transcription_bin.static_pad("sink").unwrap();
+            audio_tee_pad.link(&transcription_sink_pad).unwrap();
         }
 
         drop(settings);