mxfvanc: Handle empty VANC packets

Some XDCAM recorders store empty packets for VANC, and don't even include the
2byte length.

Handle them in the same way as VANC packets with 0 packets.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2122>

diff --git a/subprojects/gst-plugins-bad/gst/mxf/mxfvanc.c b/subprojects/gst-plugins-bad/gst/mxf/mxfvanc.c
index d2530e0..69279c3 100644 (file)
--- a/subprojects/gst-plugins-bad/gst/mxf/mxfvanc.c
+++ b/subprojects/gst-plugins-bad/gst/mxf/mxfvanc.c
@@ -116,7 +116,9 @@ mxf_vanc_handle_essence_element (const MXFUL * key, GstBuffer * buffer,
     return GST_FLOW_ERROR;
   }
 
-  if (gst_buffer_get_size (buffer) < 2) {
+  /* Either there is no data or there is at least room for the 16bit length,
+   * therefore the only invalid packet length is 1 */
+  if (gst_buffer_get_size (buffer) == 1) {
     GST_ERROR ("Invalid VANC essence element size");
     gst_buffer_unref (buffer);
     return GST_FLOW_ERROR;
@@ -125,6 +127,11 @@ mxf_vanc_handle_essence_element (const MXFUL * key, GstBuffer * buffer,
   gst_buffer_map (buffer, &map, GST_MAP_READ);
   gst_byte_reader_init (&reader, map.data, map.size);
 
+  /* Some XDCAM recorders store empty vanc packets (without even the
+   * length). Treat them as gaps */
+  if (map.size == 0)
+    goto no_data;
+
   num_packets = gst_byte_reader_get_uint16_be_unchecked (&reader);
   if (num_packets == 0) {
     /* SMPTE 436-1:2013 5.5 The Number of VI Lines or ANC Packets Property