typefind: add typefinder for Apple/iTunes itc artwork files

Avoids audio/mpeg false-positive described at:

https://bugzilla.gnome.org/show_bug.cgi?id=773172

diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c
index 353525a..7cac6bd 100644 (file)
--- a/gst/typefind/gsttypefindfunctions.c
+++ b/gst/typefind/gsttypefindfunctions.c
@@ -422,6 +422,67 @@ uri_type_find (GstTypeFind * tf, gpointer unused)
   }
 }
 
+/*** application/itc ***/
+static GstStaticCaps itc_caps = GST_STATIC_CAPS ("application/itc");
+#define ITC_CAPS (gst_static_caps_get(&itc_caps))
+
+static void
+itc_type_find (GstTypeFind * tf, gpointer unused)
+{
+  DataScanCtx c = { 0, NULL, 0 };
+  guint8 magic[8] = { 0x00, 0x00, 0x01, 0x1C, 0x69, 0x74, 0x63, 0x68 };
+  guint8 preamble[4] = { 0x00, 0x00, 0x00, 0x02 };
+  guint8 artwork_marker[8] = { 0x00, 0x00, 0x00, 0x00, 0x61, 0x72, 0x74, 0x77 };
+  GstTypeFindProbability itc_prob = GST_TYPE_FIND_NONE;
+  int i;
+
+  if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 8)))
+    return;
+
+  if (memcmp (c.data, magic, 8))
+    return;
+
+  /* At least we found the right magic */
+  itc_prob = GST_TYPE_FIND_MINIMUM;
+  data_scan_ctx_advance (tf, &c, 8);
+
+  if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 12)))
+    goto done;
+
+  /* Check preamble 3 consecutive times */
+  for (i = 0; i < 3; i++) {
+    if (memcmp (c.data, preamble, 4))
+      goto done;
+    data_scan_ctx_advance (tf, &c, 4);
+  }
+
+  itc_prob = GST_TYPE_FIND_POSSIBLE;
+
+  if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 8)))
+    goto done;
+
+  /* Look for "artw" marker */
+  if (memcmp (c.data, artwork_marker, 8))
+    goto done;
+
+  itc_prob = GST_TYPE_FIND_LIKELY;
+  data_scan_ctx_advance (tf, &c, 8);
+
+  if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 256)))
+    goto done;
+
+  /* ...and 256 0x00 padding bytes on what looks like the header's end */
+  for (i = 0; i < 256; i++) {
+    if (c.data[i])
+      goto done;
+  }
+
+  itc_prob = GST_TYPE_FIND_NEARLY_CERTAIN;
+
+done:
+  gst_type_find_suggest (tf, itc_prob, ITC_CAPS);
+}
+
 /*** application/x-hls ***/
 
 static GstStaticCaps hls_caps = GST_STATIC_CAPS ("application/x-hls");
@@ -5683,6 +5744,8 @@ plugin_init (GstPlugin * plugin)
       "txt", UTF32_CAPS, NULL, NULL);
   TYPE_FIND_REGISTER (plugin, "text/uri-list", GST_RANK_MARGINAL, uri_type_find,
       "ram", URI_CAPS, NULL, NULL);
+  TYPE_FIND_REGISTER (plugin, "application/itc", GST_RANK_SECONDARY,
+      itc_type_find, "itc", ITC_CAPS, NULL, NULL);
   TYPE_FIND_REGISTER (plugin, "application/x-hls", GST_RANK_MARGINAL,
       hls_type_find, "m3u8", HLS_CAPS, NULL, NULL);
   TYPE_FIND_REGISTER (plugin, "application/sdp", GST_RANK_SECONDARY,