From 98b7dc7c0c57c7f7c0d11fd00e470dbdd0895527 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wtaymans@redhat.com>
Date: Thu, 6 Aug 2020 13:03:40 +0200
Subject: gst: don't do set_caps from the pipewire callback

Don't do any GStreamer data transport from the PipeWire callback
because it might block in preroll and block our communication with
PipeWire. Instead, take the caps and wake up the caller to continue
with negotiation.
---
 src/gst/gstpipewiresrc.c | 39 +++++++++++++++++++++++----------------
 src/gst/gstpipewiresrc.h |  2 ++
 2 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/src/gst/gstpipewiresrc.c b/src/gst/gstpipewiresrc.c
index 302bd9ad..9502b3b2 100644
--- a/src/gst/gstpipewiresrc.c
+++ b/src/gst/gstpipewiresrc.c
@@ -60,7 +60,7 @@ GST_DEBUG_CATEGORY_STATIC (pipewire_src_debug);
 #define GST_CAT_DEFAULT pipewire_src_debug
 
 #define DEFAULT_ALWAYS_COPY     false
-#define DEFAULT_MIN_BUFFERS     1
+#define DEFAULT_MIN_BUFFERS     8
 #define DEFAULT_MAX_BUFFERS     INT32_MAX
 #define DEFAULT_RESEND_LAST     false
 #define DEFAULT_KEEPALIVE_TIME  0
@@ -561,6 +561,7 @@ static gboolean
 gst_pipewire_src_stream_start (GstPipeWireSrc *pwsrc)
 {
   const char *error = NULL;
+
   pw_thread_loop_lock (pwsrc->core->loop);
   GST_DEBUG_OBJECT (pwsrc, "doing stream start");
   while (TRUE) {
@@ -593,7 +594,7 @@ start_error:
 }
 
 static enum pw_stream_state
-wait_negotiated (GstPipeWireSrc *this)
+wait_started (GstPipeWireSrc *this)
 {
   enum pw_stream_state state;
   const char *error = NULL;
@@ -693,9 +694,8 @@ gst_pipewire_src_negotiate (GstBaseSrc * basesrc)
   while (TRUE) {
     enum pw_stream_state state = pw_stream_get_state (pwsrc->stream, &error);
 
-    GST_DEBUG_OBJECT (basesrc, "waiting for PAUSED, now %s", pw_stream_state_as_string (state));
-    if (state == PW_STREAM_STATE_PAUSED ||
-        state == PW_STREAM_STATE_STREAMING)
+    GST_DEBUG_OBJECT (basesrc, "waiting for NEGOTIATED, now %s", pw_stream_state_as_string (state));
+    if (pwsrc->negotiated)
       break;
 
     if (state == PW_STREAM_STATE_ERROR)
@@ -703,11 +703,19 @@ gst_pipewire_src_negotiate (GstBaseSrc * basesrc)
 
     pw_thread_loop_wait (pwsrc->core->loop);
   }
+  caps = pwsrc->caps;
+  pwsrc->caps = NULL;
   pw_thread_loop_unlock (pwsrc->core->loop);
 
+  gst_pipewire_clock_reset (GST_PIPEWIRE_CLOCK (pwsrc->clock), 0);
+
+  GST_DEBUG_OBJECT (pwsrc, "set format %" GST_PTR_FORMAT, caps);
+  result = gst_base_src_set_caps (GST_BASE_SRC (pwsrc), caps);
+  gst_caps_unref (caps);
+
   result = gst_pipewire_src_stream_start (pwsrc);
 
-  pwsrc->negotiated = result;
+  pwsrc->started = result;
 
   return result;
 
@@ -748,22 +756,19 @@ on_param_changed (void *data, uint32_t id,
                    const struct spa_pod *param)
 {
   GstPipeWireSrc *pwsrc = data;
-  GstCaps *caps;
-  gboolean res;
 
   if (param == NULL || id != SPA_PARAM_Format) {
     GST_DEBUG_OBJECT (pwsrc, "clear format");
     return;
   }
+  if (pwsrc->caps)
+	  gst_caps_unref(pwsrc->caps);
+  pwsrc->caps = gst_caps_from_format (param);
+  GST_DEBUG_OBJECT (pwsrc, "we got format %" GST_PTR_FORMAT, pwsrc->caps);
 
-  gst_pipewire_clock_reset (GST_PIPEWIRE_CLOCK (pwsrc->clock), 0);
-
-  caps = gst_caps_from_format (param);
-  GST_DEBUG_OBJECT (pwsrc, "we got format %" GST_PTR_FORMAT, caps);
-  res = gst_base_src_set_caps (GST_BASE_SRC (pwsrc), caps);
-  gst_caps_unref (caps);
+  pwsrc->negotiated = pwsrc->caps != NULL;
 
-  if (res) {
+  if (pwsrc->negotiated) {
     const struct spa_pod *params[3];
     struct spa_pod_builder b = { NULL };
     uint8_t buffer[512];
@@ -795,6 +800,7 @@ on_param_changed (void *data, uint32_t id,
     GST_WARNING_OBJECT (pwsrc, "finish format with error");
     pw_stream_set_error (pwsrc->stream, -EINVAL, "unhandled format");
   }
+  pw_thread_loop_signal (pwsrc->core->loop, FALSE);
 }
 
 static gboolean
@@ -1021,6 +1027,7 @@ gst_pipewire_src_stop (GstBaseSrc * basesrc)
   pw_thread_loop_lock (pwsrc->core->loop);
   pwsrc->eos = false;
   gst_buffer_replace (&pwsrc->last_buffer, NULL);
+  gst_caps_replace(&pwsrc->caps, NULL);
   pw_thread_loop_unlock (pwsrc->core->loop);
 
   return TRUE;
@@ -1179,7 +1186,7 @@ gst_pipewire_src_change_state (GstElement * element, GstStateChange transition)
 
   switch (transition) {
     case GST_STATE_CHANGE_READY_TO_PAUSED:
-      if (wait_negotiated (this) == PW_STREAM_STATE_ERROR)
+      if (wait_started (this) == PW_STREAM_STATE_ERROR)
         goto open_failed;
 
       if (gst_base_src_is_live (GST_BASE_SRC (element)))
diff --git a/src/gst/gstpipewiresrc.h b/src/gst/gstpipewiresrc.h
index b36a3542..6b5094b5 100644
--- a/src/gst/gstpipewiresrc.h
+++ b/src/gst/gstpipewiresrc.h
@@ -68,6 +68,8 @@ struct _GstPipeWireSrc {
   gboolean resend_last;
   gint keepalive_time;
 
+  GstCaps *caps;
+
   gboolean negotiated;
   gboolean flushing;
   gboolean started;
-- 
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