From 3cbda26f0757ca32d3a3004986529bb26ac9d80c Mon Sep 17 00:00:00 2001
From: Robert Rosengren <robertr@axis.com>
Date: Mon, 17 Jun 2024 11:03:41 +0200
Subject: [PATCH] gst: src: disable active state when only going to PAUSED

The pipewiresrc starts the stream in active state but should be inactive
if only going to PAUSED state. This patch sets the stream to inactive
when wait_started has returned in the GStreamer state tranistions.

Also resets internal started state when going PAUSED -> READY.

Fixes #4049
---
 src/gst/gstpipewiresrc.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/gst/gstpipewiresrc.c b/src/gst/gstpipewiresrc.c
index 270567302..6e0c67e04 100644
--- a/src/gst/gstpipewiresrc.c
+++ b/src/gst/gstpipewiresrc.c
@@ -768,6 +768,7 @@ gst_pipewire_src_stream_start (GstPipeWireSrc *pwsrc)
 start_error:
   {
     GST_DEBUG_OBJECT (pwsrc, "error starting stream: %s", error);
+    pwsrc->started = FALSE;
     pw_thread_loop_signal (pwsrc->stream->core->loop, FALSE);
     pw_thread_loop_unlock (pwsrc->stream->core->loop);
     return FALSE;
@@ -780,12 +781,21 @@ wait_started (GstPipeWireSrc *this)
   enum pw_stream_state state, prev_state = PW_STREAM_STATE_UNCONNECTED;
   const char *error = NULL;
   struct timespec abstime;
+  gboolean restart = FALSE;
 
   pw_thread_loop_lock (this->stream->core->loop);
 
   pw_thread_loop_get_time (this->stream->core->loop, &abstime,
                   GST_PIPEWIRE_DEFAULT_TIMEOUT * SPA_NSEC_PER_SEC);
 
+  /* when started already is true then expects a re-start, so allow prev_state
+   * degrade until turned around. */
+  if (this->started) {
+    GST_DEBUG_OBJECT (this, "restart in progress");
+    restart = TRUE;
+    this->started = FALSE;
+  }
+
   while (TRUE) {
     state = pw_stream_get_state (this->stream->pwstream, &error);
 
@@ -793,7 +803,7 @@ wait_started (GstPipeWireSrc *this)
         pw_stream_state_as_string (state));
 
     if (state == PW_STREAM_STATE_ERROR ||
-        (state == PW_STREAM_STATE_UNCONNECTED && prev_state > PW_STREAM_STATE_UNCONNECTED) ||
+        (state == PW_STREAM_STATE_UNCONNECTED && prev_state > PW_STREAM_STATE_UNCONNECTED && !restart) ||
         this->flushing) {
       state = PW_STREAM_STATE_ERROR;
       break;
@@ -811,6 +821,8 @@ wait_started (GstPipeWireSrc *this)
       pw_thread_loop_wait (this->stream->core->loop);
     }
 
+    if (restart)
+      restart = state != PW_STREAM_STATE_UNCONNECTED;
     prev_state = state;
   }
   GST_DEBUG_OBJECT (this, "got started signal: %s",
@@ -973,11 +985,11 @@ gst_pipewire_src_negotiate (GstBaseSrc * basesrc)
 
   GST_DEBUG_OBJECT (pwsrc, "set format %" GST_PTR_FORMAT, negotiated_caps);
   result = gst_base_src_set_caps (GST_BASE_SRC (pwsrc), negotiated_caps);
+  if (!result)
+    goto no_caps;
 
   result = gst_pipewire_src_stream_start (pwsrc);
 
-  pwsrc->started = result;
-
   return result;
 
 no_nego_needed:
@@ -1431,13 +1443,13 @@ gst_pipewire_src_change_state (GstElement * element, GstStateChange transition)
     case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
       /* uncork and start recording */
       pw_thread_loop_lock (this->stream->core->loop);
-      pw_stream_set_active(this->stream->pwstream, true);
+      pw_stream_set_active (this->stream->pwstream, true);
       pw_thread_loop_unlock (this->stream->core->loop);
       break;
     case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
       /* stop recording ASAP by corking */
       pw_thread_loop_lock (this->stream->core->loop);
-      pw_stream_set_active(this->stream->pwstream, false);
+      pw_stream_set_active (this->stream->pwstream, false);
       pw_thread_loop_unlock (this->stream->core->loop);
       break;
     default:
@@ -1451,6 +1463,16 @@ gst_pipewire_src_change_state (GstElement * element, GstStateChange transition)
       if (wait_started (this) == PW_STREAM_STATE_ERROR)
         goto open_failed;
 
+      pw_thread_loop_lock (this->stream->core->loop);
+      /* the initial stream state is active, which is needed for linking and
+       * negotiation to happen and the bufferpool to be set up. We don't know
+       * if we'll go to playing, so we deactivate the stream until that
+       * transition happens. This is janky, but because of how bins propagate
+       * state changes one transition at a time, there may not be a better way
+       * to do this. */
+      pw_stream_set_active (this->stream->pwstream, false);
+      pw_thread_loop_unlock (this->stream->core->loop);
+
       if (gst_base_src_is_live (GST_BASE_SRC (element)))
         ret = GST_STATE_CHANGE_NO_PREROLL;
       break;