https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/4091

This needs more work. With this patch the error code returned changes from 1 to 26.

--- gst-plugins-good-1.28.0/gst/flv/gstflvmux.c.orig	2026-01-27 18:02:33.000000000 +0100
+++ gst-plugins-good-1.28.0/gst/flv/gstflvmux.c	2026-02-27 16:47:52.186053941 +0100
@@ -2753,16 +2753,12 @@
           break;
         }
 
-        t = gst_flv_mux_segment_to_running_time (&apad->segment,
-            GST_BUFFER_DTS_OR_PTS (buffer));
+        if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS_OR_PTS (buffer))) {
+          t = gst_flv_mux_segment_to_running_time (&apad->segment,
+              GST_BUFFER_DTS_OR_PTS (buffer));
+        }
 
-        if (!GST_CLOCK_TIME_IS_VALID (t)) {
-          GST_WARNING_OBJECT (apad, "Buffer has no timestamp: %" GST_PTR_FORMAT,
-              buffer);
-          gst_object_replace ((GstObject **) & best, GST_OBJECT (apad));
-          best_ts = GST_CLOCK_TIME_NONE;
-          done = TRUE;
-        } else if (!GST_CLOCK_TIME_IS_VALID (best_ts) ||
+        if (!GST_CLOCK_TIME_IS_VALID (best_ts) ||
             (GST_CLOCK_TIME_IS_VALID (t) && t < best_ts)) {
           gst_object_replace ((GstObject **) & best, GST_OBJECT (apad));
           best_ts = t;
@@ -2986,8 +2982,8 @@
 gst_flv_mux_get_next_time (GstAggregator * aggregator)
 {
   GstFlvMux *mux = GST_FLV_MUX (aggregator);
-  GstFlvMuxPad *best = NULL;
-  GstClockTime best_time = GST_CLOCK_TIME_NONE;
+  GstAggregatorPad *agg_audio_pad = GST_AGGREGATOR_PAD_CAST (mux->audio_pads);
+  GstAggregatorPad *agg_video_pad = GST_AGGREGATOR_PAD_CAST (mux->video_pads);
 
   GST_OBJECT_LOCK (aggregator);
   if (mux->state == GST_FLV_MUX_STATE_HEADER &&
@@ -2995,12 +2991,11 @@
           || (mux->video_pads
               && !gst_flv_mux_pads_codec_valid (mux->video_pads))))
     goto wait_for_data;
+  if (!((agg_audio_pad && gst_aggregator_pad_has_buffer (agg_audio_pad)) ||
+              (agg_video_pad && gst_aggregator_pad_has_buffer (agg_video_pad))))
+      goto wait_for_data;
   GST_OBJECT_UNLOCK (aggregator);
-
-  best = gst_flv_mux_find_best_pad (aggregator, &best_time, TRUE);
-  gst_clear_object (&best);
-
-  return best_time;
+  return gst_aggregator_simple_get_next_time (aggregator);
 
 wait_for_data:
   GST_OBJECT_UNLOCK (aggregator);