From 063efae0bea571112a152a7e23e09579900ce74c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Tue, 14 May 2024 14:44:45 +0300
Subject: [PATCH] mpegtsmux: Allow pads to have no caps until they receive
 their first buffer

If the muxer times out because of the latency deadline it can happen
that some pads have no caps yet. In that case skip creation of streams
for these pads and create updated section tables once the first buffer
arrives later.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6859>
---
 .../gst/mpegtsmux/gstbasetsmux.c              | 39 +++++++++++++------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/subprojects/gst-plugins-bad/gst/mpegtsmux/gstbasetsmux.c b/subprojects/gst-plugins-bad/gst/mpegtsmux/gstbasetsmux.c
index 2c166ffe7a..7e0b981cee 100644
--- a/subprojects/gst-plugins-bad/gst/mpegtsmux/gstbasetsmux.c
+++ b/subprojects/gst-plugins-bad/gst/mpegtsmux/gstbasetsmux.c
@@ -856,18 +856,12 @@ is_valid_pmt_pid (guint16 pmt_pid)
 
 /* Must be called with mux->lock held */
 static GstFlowReturn
-gst_base_ts_mux_create_stream (GstBaseTsMux * mux, GstBaseTsMuxPad * ts_pad)
+gst_base_ts_mux_create_stream (GstBaseTsMux * mux, GstBaseTsMuxPad * ts_pad,
+    GstCaps * caps)
 {
-  GstCaps *caps = gst_pad_get_current_caps (GST_PAD (ts_pad));
   GstFlowReturn ret;
 
-  if (caps == NULL) {
-    GST_DEBUG_OBJECT (ts_pad, "Sink pad caps were not set before pushing");
-    return GST_FLOW_NOT_NEGOTIATED;
-  }
-
   ret = gst_base_ts_mux_create_or_update_stream (mux, ts_pad, caps);
-  gst_caps_unref (caps);
 
   if (ret == GST_FLOW_OK) {
     tsmux_program_add_stream (ts_pad->prog, ts_pad->stream);
@@ -904,12 +898,22 @@ get_pmt_pcr_sink (GstBaseTsMux * mux, const gchar * prop_name)
 
 /* Must be called with mux->lock held */
 static GstFlowReturn
-gst_base_ts_mux_create_pad_stream (GstBaseTsMux * mux, GstPad * pad)
+gst_base_ts_mux_create_pad_stream (GstBaseTsMux * mux, GstPad * pad,
+    gboolean allow_no_caps)
 {
   GstBaseTsMuxPad *ts_pad = GST_BASE_TS_MUX_PAD (pad);
   gchar *name = NULL;
   gchar *prop_name;
   GstFlowReturn ret = GST_FLOW_OK;
+  GstCaps *caps = gst_pad_get_current_caps (pad);
+
+  if (caps == NULL) {
+    GST_DEBUG_OBJECT (ts_pad, "Sink pad caps were not set yet");
+    /* Try again later once the first buffer is pushed */
+    if (allow_no_caps)
+      return GST_FLOW_OK;
+    return GST_FLOW_NOT_NEGOTIATED;
+  }
 
   if (ts_pad->prog_id == -1) {
     name = GST_PAD_NAME (pad);
@@ -967,7 +971,7 @@ gst_base_ts_mux_create_pad_stream (GstBaseTsMux * mux, GstPad * pad)
   }
 
   if (ts_pad->stream == NULL) {
-    ret = gst_base_ts_mux_create_stream (mux, ts_pad);
+    ret = gst_base_ts_mux_create_stream (mux, ts_pad, caps);
     if (ret != GST_FLOW_OK)
       goto no_stream;
   }
@@ -991,6 +995,7 @@ gst_base_ts_mux_create_pad_stream (GstBaseTsMux * mux, GstPad * pad)
     tsmux_program_set_pcr_pid (ts_pad->prog, pcr_pid);
     goto have_pcr_pid;
   }
+
   gchar *pcr_sink_name = get_pmt_pcr_sink (mux, prop_name);
   if (!g_strcmp0 (GST_PAD_NAME (pad), pcr_sink_name)) {
     GST_DEBUG_OBJECT (mux, "User specified stream (pid=%d) as PCR for "
@@ -1001,6 +1006,7 @@ gst_base_ts_mux_create_pad_stream (GstBaseTsMux * mux, GstPad * pad)
 
 have_pcr_pid:
   g_clear_pointer (&prop_name, g_free);
+  gst_clear_caps (&caps);
 
   return ret;
 
@@ -1009,12 +1015,14 @@ no_program:
   {
     GST_ELEMENT_ERROR (mux, STREAM, MUX,
         ("Could not create new program"), (NULL));
+    gst_clear_caps (&caps);
     return GST_FLOW_ERROR;
   }
 no_stream:
   {
     GST_ELEMENT_ERROR (mux, STREAM, MUX,
         ("Could not create handler for stream"), (NULL));
+    gst_clear_caps (&caps);
     return ret;
   }
 }
@@ -1026,7 +1034,8 @@ gst_base_ts_mux_create_pad_stream_func (GstElement * element, GstPad * pad,
 {
   GstFlowReturn *ret = user_data;
 
-  *ret = gst_base_ts_mux_create_pad_stream (GST_BASE_TS_MUX (element), pad);
+  *ret =
+      gst_base_ts_mux_create_pad_stream (GST_BASE_TS_MUX (element), pad, TRUE);
 
   return *ret == GST_FLOW_OK;
 }
@@ -1371,7 +1380,13 @@ gst_base_ts_mux_aggregate_buffer (GstBaseTsMux * mux,
   if (prog == NULL) {
     GList *cur;
 
-    gst_base_ts_mux_create_pad_stream (mux, GST_PAD (best));
+    ret = gst_base_ts_mux_create_pad_stream (mux, GST_PAD (best), FALSE);
+    if (G_UNLIKELY (ret != GST_FLOW_OK)) {
+      if (buf)
+        gst_buffer_unref (buf);
+      g_mutex_unlock (&mux->lock);
+      return ret;
+    }
     tsmux_resend_pat (mux->tsmux);
     tsmux_resend_si (mux->tsmux);
     prog = best->prog;