Merge branch 'sklug/upstream/fix-stream-synchronization-v1' into 'master'

RFC: Improve/fix timestamping issues with gstpipewiresrc

See merge request pipewire/pipewire!2786

src/gst/gstpipewireclock.c

@@ -34,16 +34,17 @@ gst_pipewire_clock_get_internal_time (GstClock * clock)
   GstClockTime result;
   uint64_t now;
 
-  if (G_UNLIKELY (!s))
-    return pclock->last_time;
-
   now = pw_stream_get_nsec(s->pwstream);
+
+  if (G_UNLIKELY (!s))
+    return pclock->last_time ? pclock->last_time : now;
+
 #if 1
   struct pw_time t;
   if (s->pwstream == NULL ||
       pw_stream_get_time_n (s->pwstream, &t, sizeof(t)) < 0 ||
       t.rate.denom == 0)
-    return pclock->last_time;
+    return pclock->last_time ? pclock->last_time : now;
 
   result = gst_util_uint64_scale (t.ticks, GST_SECOND * t.rate.num, t.rate.denom);
   result += now - t.now;

src/gst/gstpipewiresrc.c

@@ -116,8 +116,6 @@ static gboolean gst_pipewire_src_start (GstBaseSrc * basesrc);
 static gboolean gst_pipewire_src_stop (GstBaseSrc * basesrc);
 static gboolean gst_pipewire_src_event (GstBaseSrc * src, GstEvent * event);
 static gboolean gst_pipewire_src_query (GstBaseSrc * src, GstQuery * query);
-static void gst_pipewire_src_get_times (GstBaseSrc * basesrc, GstBuffer * buffer,
-    GstClockTime * start, GstClockTime * end);
 
 static void
 gst_pipewire_src_set_property (GObject * object, guint prop_id,
@@ -501,7 +499,6 @@ gst_pipewire_src_class_init (GstPipeWireSrcClass * klass)
   gstbasesrc_class->stop = gst_pipewire_src_stop;
   gstbasesrc_class->event = gst_pipewire_src_event;
   gstbasesrc_class->query = gst_pipewire_src_query;
-  gstbasesrc_class->get_times = gst_pipewire_src_get_times;
   gstpushsrc_class->create = gst_pipewire_src_create;
 
   GST_DEBUG_CATEGORY_INIT (pipewire_src_debug, "pipewiresrc", 0,
@@ -531,7 +528,6 @@ gst_pipewire_src_init (GstPipeWireSrc * src)
   src->autoconnect = DEFAULT_AUTOCONNECT;
   src->min_latency = 0;
   src->max_latency = GST_CLOCK_TIME_NONE;
-  src->last_buffer_clock_time = GST_CLOCK_TIME_NONE;
   src->n_buffers = 0;
   src->flushing_on_remove_buffer = FALSE;
   src->on_disconnect = DEFAULT_ON_DISCONNECT;
@@ -1523,40 +1519,13 @@ gst_pipewire_src_query (GstBaseSrc * src, GstQuery * query)
   return res;
 }
 
-static void
-gst_pipewire_src_get_times (GstBaseSrc * basesrc, GstBuffer * buffer,
-    GstClockTime * start, GstClockTime * end)
-{
-  GstPipeWireSrc *pwsrc = GST_PIPEWIRE_SRC (basesrc);
-
-  /* for live sources, sync on the timestamp of the buffer */
-  if (gst_base_src_is_live (basesrc)) {
-    GstClockTime timestamp = GST_BUFFER_PTS (buffer);
-
-    if (GST_CLOCK_TIME_IS_VALID (timestamp)) {
-      /* get duration to calculate end time */
-      GstClockTime duration = GST_BUFFER_DURATION (buffer);
-
-      if (GST_CLOCK_TIME_IS_VALID (duration)) {
-        *end = timestamp + duration;
-      }
-      *start = timestamp;
-    }
-  } else {
-    *start = GST_CLOCK_TIME_NONE;
-    *end = GST_CLOCK_TIME_NONE;
-  }
-
-  GST_LOG_OBJECT (pwsrc, "start %" GST_TIME_FORMAT " (%" G_GUINT64_FORMAT
-      "), end %" GST_TIME_FORMAT " (%" G_GUINT64_FORMAT ")",
-      GST_TIME_ARGS (*start), *start, GST_TIME_ARGS (*end), *end);
-}
-
 static GstFlowReturn
 gst_pipewire_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
 {
   GstPipeWireSrc *pwsrc;
+  GstClockTime pts, dts, base_time;
   const char *error = NULL;
+  GstClock *clock;
   GstBuffer *buf;
   gboolean update_time = FALSE, timeout = FALSE;
   GstCaps *caps = NULL;
@@ -1615,21 +1584,12 @@ gst_pipewire_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
       GST_LOG_OBJECT (pwsrc, "popped buffer %p", buf);
       if (buf != NULL) {
         if (pwsrc->resend_last || pwsrc->keepalive_time > 0) {
-          GstClock *clock;
           GstBuffer *old;
 
           old = pwsrc->last_buffer;
           pwsrc->last_buffer = gst_buffer_copy (buf);
           gst_buffer_unref (old);
           gst_buffer_add_parent_buffer_meta (pwsrc->last_buffer, buf);
-
-          clock = gst_element_get_clock (GST_ELEMENT_CAST (pwsrc));
-          if (clock != NULL) {
-            pwsrc->last_buffer_clock_time = gst_clock_get_time (clock);
-            gst_object_unref (clock);
-          } else {
-            pwsrc->last_buffer_clock_time = GST_CLOCK_TIME_NONE;
-          }
         }
         break;
       }
@@ -1652,38 +1612,52 @@ gst_pipewire_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
   pw_thread_loop_unlock (pwsrc->stream->core->loop);
 
   *buffer = buf;
+  clock = gst_element_get_clock (GST_ELEMENT_CAST (pwsrc));
 
   if (update_time) {
-    GstClock *clock;
-    GstClockTime current_clock_time;
-
-    clock = gst_element_get_clock (GST_ELEMENT_CAST (pwsrc));
     if (clock != NULL) {
-      current_clock_time = gst_clock_get_time (clock);
+      pts = dts = gst_clock_get_time (clock);
       gst_object_unref (clock);
     } else {
-      current_clock_time = GST_CLOCK_TIME_NONE;
+      pts = dts = GST_CLOCK_TIME_NONE;
     }
 
-    if (GST_CLOCK_TIME_IS_VALID (current_clock_time) &&
+    GST_LOG_OBJECT (pwsrc, "Sending keepalive buffer");
-        GST_CLOCK_TIME_IS_VALID (pwsrc->last_buffer_clock_time) &&
+  } else {
-        GST_CLOCK_TIME_IS_VALID (GST_BUFFER_PTS (*buffer)) &&
+    pts = GST_BUFFER_PTS (*buffer);
-        GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS (*buffer))) {
+    dts = GST_BUFFER_DTS (*buffer);
-      GstClockTime diff;
-
-      diff = current_clock_time - pwsrc->last_buffer_clock_time;
-
-      GST_BUFFER_PTS (*buffer) += diff;
-      GST_BUFFER_DTS (*buffer) += diff;
-    } else {
-      GST_BUFFER_PTS (*buffer) = GST_BUFFER_DTS (*buffer) = current_clock_time;
-    }
-
-    GST_LOG_OBJECT (pwsrc, "Sending keepalive buffer pts/dts: %" GST_TIME_FORMAT
-      " (%" G_GUINT64_FORMAT ")", GST_TIME_ARGS (current_clock_time),
-      current_clock_time);
   }
 
+  /*
+   * We need to map the pipwire time to gstreamer time. If the gstreamer clock
+   * is provided by us, we can safely use the base_time of the element.
+   * Otherwise we can not assume that the gstreamer clock is CLOCK_MONOTONIC and
+   * must therefore fall back to our own base_time. This might introduce a bit
+   * of jitter.
+   */
+  base_time = 0;
+  if (pwsrc->is_live) {
+    if (clock == pwsrc->stream->clock) {
+      base_time = gst_element_get_base_time (GST_ELEMENT_CAST (pwsrc));
+    } else {
+      base_time = pwsrc->pw_base_time;
+    }
+  }
+
+  if (GST_CLOCK_TIME_IS_VALID (pts))
+    pts = (pts >= base_time ? pts - base_time : 0);
+  if (GST_CLOCK_TIME_IS_VALID (dts))
+    dts = (dts >= base_time ? dts - base_time : 0);
+
+  GST_LOG_OBJECT (pwsrc,
+      "pts %" G_GUINT64_FORMAT ", dts %" G_GUINT64_FORMAT
+      ", base-time %" GST_TIME_FORMAT " -> %" GST_TIME_FORMAT ", %" GST_TIME_FORMAT,
+      GST_BUFFER_PTS (*buffer), GST_BUFFER_DTS (*buffer), GST_TIME_ARGS (base_time),
+      GST_TIME_ARGS (pts), GST_TIME_ARGS (dts));
+
+  GST_BUFFER_PTS (*buffer) = pts;
+  GST_BUFFER_DTS (*buffer) = dts;
+
   return GST_FLOW_OK;
 
 not_negotiated:
@@ -1781,6 +1755,7 @@ gst_pipewire_src_change_state (GstElement * element, GstStateChange transition)
       GST_DEBUG_OBJECT (this, "activating stream");
 
       pw_thread_loop_lock (this->stream->core->loop);
+      this->pw_base_time = pw_stream_get_nsec (this->stream->pwstream);
       pw_stream_set_active (this->stream->pwstream, true);
       /* if state have been paused for longer time, the underlying node might
        * be moved from idle to suspended, which would mean format cleared via

src/gst/gstpipewiresrc.h

@@ -79,11 +79,11 @@ struct _GstPipeWireSrc {
 
   gboolean is_live;
   int64_t delay;
+  uint64_t pw_base_time;
   GstClockTime min_latency;
   GstClockTime max_latency;
 
   GstBuffer *last_buffer;
-  GstClockTime last_buffer_clock_time;
 
   enum spa_meta_videotransform_value transform_value;