From 54329ade6a5032cf04975229b835cf0973dd1585 Mon Sep 17 00:00:00 2001
From: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
Date: Thu, 24 Jan 2013 11:21:28 +0100
Subject: [PATCH] typefind: detect VC-1 elementary streams.

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
---
 gst/typefind/gsttypefindfunctions.c |  120 +++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c
index 19ee389..0a2de49 100644
--- a/gst/typefind/gsttypefindfunctions.c
+++ b/gst/typefind/gsttypefindfunctions.c
@@ -2470,6 +2470,123 @@ h264_video_type_find (GstTypeFind * tf, gpointer unused)
   }
 }
 
+/*** video/x-wmv VC-1 elementary video stream ***/
+
+static GstStaticCaps vc1_video_caps =
+GST_STATIC_CAPS ("video/x-wmv,wmvversion=3,stream-format=bdu");
+
+#define VC1_VIDEO_CAPS gst_static_caps_get(&vc1_video_caps)
+
+#define VC1_MAX_PROBE_LENGTH (128 * 1024)
+
+static void
+vc1_video_type_find (GstTypeFind * tf, gpointer unused)
+{
+  DataScanCtx c = { 0, NULL, 0 };
+
+  /* BDUs consist of the Start Code Prefix (SCP = 00 00 01) followed
+   * by the Start Code Suffix (SCS), which represents the BDU type */
+  guint8 scs;
+  guint8 profile = 0;
+  guint eos_hdrs = 0;
+  guint seq_hdrs = 0;
+  guint pic_hdrs = 0;
+  guint etp_hdrs = 0;
+  guint bad = 0;
+
+  while (c.offset < VC1_MAX_PROBE_LENGTH) {
+    if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 4)))
+      break;
+
+    if (!IS_MPEG_HEADER (c.data)) {
+      data_scan_ctx_advance (tf, &c, 1);
+      continue;
+    }
+
+    /* Collect statistics about the BDU types */
+    scs = c.data[3];
+    switch (scs) {
+      case 0x0a:
+        /* End-of-Sequence */
+        eos_hdrs++;
+        break;
+      case 0x0f:
+        /* Sequence Header */
+        seq_hdrs++;
+        if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 5)))
+          break;
+        profile = (c.data[4] >> 6) & 3;
+        if (profile != 3)
+          bad++;
+        if (((c.data[4] >> 3) & 7) > 4) /* level */
+          bad++;
+        if (((c.data[4] >> 1) & 3) != 1)        /* color difference format */
+          bad++;
+        break;
+      case 0x0b:
+        /* Slice */
+      case 0x0c:
+        /* Field */
+      case 0x0d:
+        /* Frame */
+        pic_hdrs++;
+        break;
+      case 0x0e:
+        /* Entry-point header */
+        etp_hdrs++;
+        if (profile != 3)
+          bad++;
+        break;
+      default:
+        /* User data */
+        if (scs >= 0x1b && scs <= 0x1f)
+          break;
+
+        /* Forbidden */
+        if (scs >= 0x80 && scs <= 0xff)
+          bad++;
+
+        /* SMPTE Reserved */
+        else
+          bad++;
+        break;
+    }
+
+    if (seq_hdrs + etp_hdrs + pic_hdrs >= 10 && bad < 4)
+      break;
+
+    data_scan_ctx_advance (tf, &c, 4);
+  }
+
+  GST_LOG ("bad:%u, seq:%u, pic:%u, etp:%u", bad, seq_hdrs, pic_hdrs, etp_hdrs);
+
+  if (pic_hdrs > 0) {
+    GstTypeFindProbability probability = 0;
+    GstCaps *caps;
+
+    if (seq_hdrs > 0 && pic_hdrs >= GST_MPEGVID_TYPEFIND_TRY_PICTURES &&
+        etp_hdrs > 0 && eos_hdrs <= seq_hdrs && bad == 0)
+      probability = GST_TYPE_FIND_NEARLY_CERTAIN - 9;
+    else if (pic_hdrs >= GST_MPEGVID_TYPEFIND_TRY_PICTURES && bad == 0)
+      probability = GST_TYPE_FIND_LIKELY + 5;
+    else if (pic_hdrs >= 3 && bad == 0)
+      probability = GST_TYPE_FIND_LIKELY;
+    else if (pic_hdrs > 0 && bad == 0)
+      probability = GST_TYPE_FIND_POSSIBLE;
+    else if (pic_hdrs > 0 && bad < 4)
+      probability = GST_TYPE_FIND_POSSIBLE - 5;
+    else
+      probability = GST_TYPE_FIND_POSSIBLE - 10;
+
+    caps = gst_caps_copy (VC1_VIDEO_CAPS);
+    if (seq_hdrs > 0 && profile == 3)
+      gst_caps_set_simple (caps, "format", GST_TYPE_FOURCC,
+          GST_MAKE_FOURCC ('W', 'V', 'C', '1'), NULL);
+    gst_type_find_suggest (tf, probability, caps);
+    gst_caps_unref (caps);
+  }
+}
+
 /*** video/mpeg video stream ***/
 
 static GstStaticCaps mpeg_video_caps = GST_STATIC_CAPS ("video/mpeg, "
@@ -4540,6 +4657,7 @@ plugin_init (GstPlugin * plugin)
   static const gchar *dsstore_exts[] = { "DS_Store", NULL };
   static const gchar *psd_exts[] = { "psd", NULL };
   static const gchar *y4m_exts[] = { "y4m", NULL };
+  static const gchar *vc1_exts[] = { "vc1", NULL };
 
   GST_DEBUG_CATEGORY_INIT (type_find_debug, "typefindfunctions",
       GST_DEBUG_FG_GREEN | GST_DEBUG_BG_RED, "generic type find functions");
@@ -4611,6 +4729,8 @@ plugin_init (GstPlugin * plugin)
       h264_video_type_find, h264_exts, H264_VIDEO_CAPS, NULL, NULL);
   TYPE_FIND_REGISTER (plugin, "video/x-nuv", GST_RANK_SECONDARY, nuv_type_find,
       nuv_exts, NUV_CAPS, NULL, NULL);
+  TYPE_FIND_REGISTER (plugin, "video/x-wmv", GST_RANK_PRIMARY,
+      vc1_video_type_find, vc1_exts, VC1_VIDEO_CAPS, NULL, NULL);
 
   /* ISO formats */
   TYPE_FIND_REGISTER (plugin, "audio/x-m4a", GST_RANK_PRIMARY, m4a_type_find,
-- 
1.7.9.5