gst/mpegvideoparse/: Fix some silly bugs with calculating the guard sizes.

Original commit message from CVS:
* gst/mpegvideoparse/mpegpacketiser.c:
(mpeg_util_parse_extension_packet), (mpeg_util_parse_sequence_hdr),
(mpeg_util_parse_picture_hdr):
* gst/mpegvideoparse/mpegvideoparse.c:
(mpegvideoparse_handle_sequence), (mpegvideoparse_drain_avail):
Fix some silly bugs with calculating the guard sizes.
Properly compare the old sequence header structure with the new one.
Don't error out on an invalid sequence - just ignore it.

ChangeLog

@@ -1,3 +1,14 @@
+2007-06-06  Jan Schmidt  <thaytan@mad.scientist.com>
+
+	* gst/mpegvideoparse/mpegpacketiser.c:
+	(mpeg_util_parse_extension_packet), (mpeg_util_parse_sequence_hdr),
+	(mpeg_util_parse_picture_hdr):
+	* gst/mpegvideoparse/mpegvideoparse.c:
+	(mpegvideoparse_handle_sequence), (mpegvideoparse_drain_avail):
+	Fix some silly bugs with calculating the guard sizes.
+	Properly compare the old sequence header structure with the new one.
+	Don't error out on an invalid sequence - just ignore it.
+
 2007-06-06  Tim-Philipp Müller  <tim at centricular dot net>
 
 	* gst/real/gstrealvideodec.c: (gst_real_video_dec_decode):

gst/mpegvideoparse/mpegpacketiser.c

@@ -487,7 +487,7 @@ mpeg_util_parse_extension_packet (MPEGSeqHdr * hdr, guint8 * data, guint8 * end)
 {
   guint8 ext_code;
 
-  if (G_UNLIKELY ((end - data - 1) < 1))
+  if (G_UNLIKELY (data >= end))
     return FALSE;               /* short extension packet */
 
   ext_code = data[0] >> 4;
@@ -499,7 +499,7 @@ mpeg_util_parse_extension_packet (MPEGSeqHdr * hdr, guint8 * data, guint8 * end)
       guint8 horiz_size_ext, vert_size_ext;
       guint8 fps_n_ext, fps_d_ext;
 
-      if ((end - data - 1) < 6)
+      if (G_UNLIKELY ((end - data) < 6))
         /* need at least 10 bytes, minus 4 for the start code 000001b5 */
         return FALSE;
 
@@ -531,7 +531,7 @@ mpeg_util_parse_sequence_hdr (MPEGSeqHdr * hdr, guint8 * data, guint8 * end)
   gboolean load_intra_flag;
   gboolean load_non_intra_flag;
 
-  if (G_UNLIKELY ((end - data - 1) < 12))
+  if (G_UNLIKELY ((end - data) < 12))
     return FALSE;               /* Too small to be a sequence header */
 
   code = GST_READ_UINT32_BE (data);
@@ -556,14 +556,14 @@ mpeg_util_parse_sequence_hdr (MPEGSeqHdr * hdr, guint8 * data, guint8 * end)
   constrained_flag = (data[7] >> 2) & 0x01;
   load_intra_flag = (data[7] >> 1) & 0x01;
   if (load_intra_flag) {
-    if (G_UNLIKELY ((end - data - 1) < 64))
+    if (G_UNLIKELY ((end - data) < 64))
       return FALSE;
     data += 64;
   }
 
   load_non_intra_flag = data[7] & 0x01;
   if (load_non_intra_flag) {
-    if (G_UNLIKELY ((end - data - 1) < 64))
+    if (G_UNLIKELY ((end - data) < 64))
       return FALSE;
     data += 64;
   }
@@ -574,7 +574,7 @@ mpeg_util_parse_sequence_hdr (MPEGSeqHdr * hdr, guint8 * data, guint8 * end)
   /* Read MPEG-2 sequence extensions */
   data = mpeg_util_find_start_code (&sync_word, data, end);
   while (data != NULL) {
-    if (G_UNLIKELY ((end - data - 1) < 1))
+    if (G_UNLIKELY (data >= end))
       return FALSE;
 
     /* data points at the last byte of the start code */
@@ -595,7 +595,7 @@ mpeg_util_parse_picture_hdr (MPEGPictureHdr * hdr, guint8 * data, guint8 * end)
 {
   guint32 code;
 
-  if (G_UNLIKELY ((end - data - 1) < 6))
+  if (G_UNLIKELY ((end - data) < 6))
     return FALSE;               /* Packet too small */
 
   code = GST_READ_UINT32_BE (data);

gst/mpegvideoparse/mpegvideoparse.c

@@ -206,7 +206,7 @@ mpegvideoparse_handle_sequence (MpegVideoParse * mpegvideoparse,
   if (G_UNLIKELY (!mpeg_util_parse_sequence_hdr (&new_hdr, cur, end)))
     return FALSE;
 
-  if (memcmp (&mpegvideoparse, &new_hdr, sizeof (MPEGSeqHdr)) != 0) {
+  if (memcmp (&mpegvideoparse->seq_hdr, &new_hdr, sizeof (MPEGSeqHdr)) != 0) {
     GstCaps *caps;
     GstBuffer *seq_buf;
 
@@ -216,9 +216,6 @@ mpegvideoparse_handle_sequence (MpegVideoParse * mpegvideoparse,
     gst_buffer_replace (&mpegvideoparse->seq_hdr_buf, seq_buf);
     gst_buffer_unref (seq_buf);
 
-    /* And update the new_hdr into our stored version */
-    mpegvideoparse->seq_hdr = new_hdr;
-
     caps = gst_caps_new_simple ("video/mpeg",
         "systemstream", G_TYPE_BOOLEAN, FALSE,
         "parsed", G_TYPE_BOOLEAN, TRUE,
@@ -232,6 +229,9 @@ mpegvideoparse_handle_sequence (MpegVideoParse * mpegvideoparse,
     GST_DEBUG ("New mpegvideoparse caps: %" GST_PTR_FORMAT, caps);
     if (!gst_pad_set_caps (mpegvideoparse->srcpad, caps))
       return FALSE;
+
+    /* And update the new_hdr into our stored version */
+    mpegvideoparse->seq_hdr = new_hdr;
   }
 
   return TRUE;
@@ -312,8 +312,12 @@ mpegvideoparse_drain_avail (MpegVideoParse * mpegvideoparse)
     if (mpegvideoparse->seq_hdr.mpeg_version == 0) {
       if (cur->flags & MPEG_BLOCK_FLAG_SEQUENCE) {
         /* Found a sequence header */
-        if (!mpegvideoparse_handle_sequence (mpegvideoparse, buf))
+        if (!mpegvideoparse_handle_sequence (mpegvideoparse, buf)) {
-          goto error;
+          GST_DEBUG_OBJECT (mpegvideoparse,
+              "Invalid sequence header. Dropping buffer.");
+          gst_buffer_unref (buf);
+          buf = NULL;
+        }
       } else {
         if (buf) {
           GST_DEBUG_OBJECT (mpegvideoparse,
@@ -364,10 +368,6 @@ mpegvideoparse_drain_avail (MpegVideoParse * mpegvideoparse)
   };
 
   return res;
-error:
-  if (buf != NULL)
-    gst_buffer_unref (buf);
-  return GST_FLOW_ERROR;
 }
 
 static GstFlowReturn