matroska-mux: Refuse caps changes after starting to write headers

Matroska does not support changing the stream type and stream properties
after the headers were started to be written, and for example H264
codec_data changes can't be supported.

https://bugzilla.gnome.org/show_bug.cgi?id=782949

1 files changed, 44 insertions, 0 deletions

diff --git a/gst/matroska/matroska-mux.c b/gst/matroska/matroska-mux.c
index fd09e2ef0..0a05ba2d6 100644
--- a/gst/matroska/matroska-mux.c
+++ b/gst/matroska/matroska-mux.c
@@ -975,9 +975,21 @@ gst_matroska_mux_video_pad_setcaps (GstPad * pad, GstCaps * caps)
   gint width, height, pixel_width, pixel_height;
   gint fps_d, fps_n;
   guint multiview_flags;
+  GstCaps *old_caps;
 
   mux = GST_MATROSKA_MUX (GST_PAD_PARENT (pad));
 
+  if ((old_caps = gst_pad_get_current_caps (pad))) {
+    if (mux->state >= GST_MATROSKA_MUX_STATE_HEADER
+        && !gst_caps_is_equal (caps, old_caps)) {
+      GST_ELEMENT_ERROR (mux, STREAM, MUX, (NULL),
+          ("Caps changed are not supported by Matroska"));
+      gst_caps_unref (old_caps);
+      goto refuse_caps;
+    }
+    gst_caps_unref (old_caps);
+  }
+
   /* find context */
   collect_pad = (GstMatroskaPad *) gst_pad_get_element_private (pad);
   g_assert (collect_pad);
@@ -1787,9 +1799,21 @@ gst_matroska_mux_audio_pad_setcaps (GstPad * pad, GstCaps * caps)
   const GValue *codec_data = NULL;
   GstBuffer *buf = NULL;
   const gchar *stream_format = NULL;
+  GstCaps *old_caps;
 
   mux = GST_MATROSKA_MUX (GST_PAD_PARENT (pad));
 
+  if ((old_caps = gst_pad_get_current_caps (pad))) {
+    if (mux->state >= GST_MATROSKA_MUX_STATE_HEADER
+        && !gst_caps_is_equal (caps, old_caps)) {
+      GST_ELEMENT_ERROR (mux, STREAM, MUX, (NULL),
+          ("Caps changed are not supported by Matroska"));
+      gst_caps_unref (old_caps);
+      goto refuse_caps;
+    }
+    gst_caps_unref (old_caps);
+  }
+
   /* find context */
   collect_pad = (GstMatroskaPad *) gst_pad_get_element_private (pad);
   g_assert (collect_pad);
@@ -2211,9 +2235,21 @@ gst_matroska_mux_subtitle_pad_setcaps (GstPad * pad, GstCaps * caps)
   const GValue *value = NULL;
   GstBuffer *buf = NULL;
   gboolean ret = TRUE;
+  GstCaps *old_caps;
 
   mux = GST_MATROSKA_MUX (GST_PAD_PARENT (pad));
 
+  if ((old_caps = gst_pad_get_current_caps (pad))) {
+    if (mux->state >= GST_MATROSKA_MUX_STATE_HEADER
+        && !gst_caps_is_equal (caps, old_caps)) {
+      GST_ELEMENT_ERROR (mux, STREAM, MUX, (NULL),
+          ("Caps changed are not supported by Matroska"));
+      gst_caps_unref (old_caps);
+      goto refuse_caps;
+    }
+    gst_caps_unref (old_caps);
+  }
+
   /* find context */
   collect_pad = (GstMatroskaPad *) gst_pad_get_element_private (pad);
   g_assert (collect_pad);
@@ -2295,6 +2331,14 @@ gst_matroska_mux_subtitle_pad_setcaps (GstPad * pad, GstCaps * caps)
 exit:
 
   return ret;
+
+  /* ERRORS */
+refuse_caps:
+  {
+    GST_WARNING_OBJECT (mux, "pad %s refused caps %" GST_PTR_FORMAT,
+        GST_PAD_NAME (pad), caps);
+    return FALSE;
+  }
 }