From fabc5c969be34e496662a810ba1b3f0b2721163d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian.droege@collabora.co.uk>
Date: Thu, 24 Nov 2011 09:48:33 +0100
Subject: [PATCH] ac3parse: Implement ::get_sink_caps vfunc to propagate
 downstream caps constraints upstream

---
 gst/audioparsers/gstac3parse.c | 38 +++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/gst/audioparsers/gstac3parse.c b/gst/audioparsers/gstac3parse.c
index f907249076..d7354eb1df 100644
--- a/gst/audioparsers/gstac3parse.c
+++ b/gst/audioparsers/gstac3parse.c
@@ -165,6 +165,7 @@ static GstFlowReturn gst_ac3_parse_parse_frame (GstBaseParse * parse,
     GstBaseParseFrame * frame);
 static gboolean gst_ac3_parse_src_event (GstBaseParse * parse,
     GstEvent * event);
+static GstCaps *gst_ac3_parse_get_sink_caps (GstBaseParse * parse);
 
 GST_BOILERPLATE (GstAc3Parse, gst_ac3_parse, GstBaseParse, GST_TYPE_BASE_PARSE);
 
@@ -199,8 +200,8 @@ gst_ac3_parse_class_init (GstAc3ParseClass * klass)
   parse_class->check_valid_frame =
       GST_DEBUG_FUNCPTR (gst_ac3_parse_check_valid_frame);
   parse_class->parse_frame = GST_DEBUG_FUNCPTR (gst_ac3_parse_parse_frame);
-
   parse_class->src_event = GST_DEBUG_FUNCPTR (gst_ac3_parse_src_event);
+  parse_class->get_sink_caps = GST_DEBUG_FUNCPTR (gst_ac3_parse_get_sink_caps);
 }
 
 static void
@@ -662,3 +663,38 @@ gst_ac3_parse_src_event (GstBaseParse * parse, GstEvent * event)
 
   return GST_BASE_PARSE_CLASS (parent_class)->src_event (parse, event);
 }
+
+static GstCaps *
+gst_ac3_parse_get_sink_caps (GstBaseParse * parse)
+{
+  GstCaps *peercaps;
+  GstCaps *res;
+
+  peercaps = gst_pad_get_allowed_caps (GST_BASE_PARSE_SRC_PAD (parse));
+  if (peercaps) {
+    guint i, n;
+
+    /* Remove the framed and alignment field. We can convert
+     * between different alignments. */
+    peercaps = gst_caps_make_writable (peercaps);
+    n = gst_caps_get_size (peercaps);
+    for (i = 0; i < n; i++) {
+      GstStructure *s = gst_caps_get_structure (peercaps, i);
+
+      gst_structure_remove_field (s, "framed");
+      gst_structure_remove_field (s, "alignment");
+    }
+
+    res =
+        gst_caps_intersect_full (peercaps,
+        gst_pad_get_pad_template_caps (GST_BASE_PARSE_SRC_PAD (parse)),
+        GST_CAPS_INTERSECT_FIRST);
+    gst_caps_unref (peercaps);
+  } else {
+    res =
+        gst_caps_copy (gst_pad_get_pad_template_caps (GST_BASE_PARSE_SRC_PAD
+            (parse)));
+  }
+
+  return res;
+}