From 095356b67e76a1f080f80b9a300ea56c1db73a4f Mon Sep 17 00:00:00 2001
From: Edward Hervey <edward@centricular.com>
Date: Mon, 20 Mar 2023 16:16:34 +0100
Subject: [PATCH] parsebin: Improve elementary stream handling

The goal of parsebin is to figure out which elements to link together in order
to provide elementary streams given any random input.

The problem is that deciding whether a given stream should still have more
elements plugged in or not was dependent on ... the presence of compatible
decoders (sic).

Instead of that, if we can't plug anymore elements on a given stream *and* it is
detected as being an elementary stream, expose it.

Fixes #2118

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4231>
---
 .../gst/playback/gstparsebin.c                | 21 +++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/subprojects/gst-plugins-base/gst/playback/gstparsebin.c b/subprojects/gst-plugins-base/gst/playback/gstparsebin.c
index e384f9dc9c..56f42ae6d3 100644
--- a/subprojects/gst-plugins-base/gst/playback/gstparsebin.c
+++ b/subprojects/gst-plugins-base/gst/playback/gstparsebin.c
@@ -1272,7 +1272,7 @@ analyze_new_pad (GstParseBin * parsebin, GstElement * src, GstPad * pad,
 {
   gboolean apcontinue = TRUE;
   GValueArray *factories = NULL, *result = NULL;
-  GstParsePad *parsepad;
+  GstParsePad *parsepad = NULL;
   GstElementFactory *factory;
   const gchar *classification;
   gboolean is_parser_converter = FALSE;
@@ -1418,7 +1418,6 @@ analyze_new_pad (GstParseBin * parsebin, GstElement * src, GstPad * pad,
       goto expose_pad;
     }
     /* Else we will bail out */
-    gst_object_unref (parsepad);
     goto unknown_type;
   }
 
@@ -1513,12 +1512,24 @@ analyze_new_pad (GstParseBin * parsebin, GstElement * src, GstPad * pad,
   if (is_parser_converter)
     gst_object_unref (pad);
 
-  gst_object_unref (parsepad);
   g_value_array_free (factories);
 
-  if (!res)
+  if (!res) {
+    if (deadend_details == NULL) {
+      /* connect_pad() only failed because no element was compatible
+       * (i.e. deadend_details is NULL). If this stream is an elementary stream,
+       * we can expose it since this is non-fatal */
+      GstPbUtilsCapsDescriptionFlags caps_flags =
+          gst_pb_utils_get_caps_description_flags (caps);
+      if (caps_flags
+          && !(caps_flags & GST_PBUTILS_CAPS_DESCRIPTION_FLAG_CONTAINER)) {
+        goto expose_pad;
+      }
+    }
     goto unknown_type;
+  }
 
+  gst_object_unref (parsepad);
   gst_caps_unref (caps);
 
   return;
@@ -1535,6 +1546,8 @@ expose_pad:
 unknown_type:
   {
     GST_LOG_OBJECT (pad, "Unknown type, posting message and firing signal");
+    if (parsepad)
+      gst_object_unref (parsepad);
 
     chain->deadend_details = deadend_details;
     chain->deadend = TRUE;