h263parse: fix custom picture format (CPFMT) parsing

In the H263 spec, CPFMT is present only if the use of a custom
picture format is signalled in PLUSEPTYPE and UFEP is "001",
so we need to check params->format and only if the value is
6 (custom source format) the CPFMT should be read, otherwise
it's not present and wrong data will be parsed.

When reading the CPFMT, the width and height were not
calculated correctly (wrong bitmask).

https://bugzilla.gnome.org//show_bug.cgi?id=749253

1 files changed, 37 insertions, 20 deletions

diff --git a/gst/videoparsers/h263parse.c b/gst/videoparsers/h263parse.c
index d794f7aed..98a30e797 100644
--- a/gst/videoparsers/h263parse.c
+++ b/gst/videoparsers/h263parse.c
@@ -271,29 +271,46 @@ gst_h263_parse_get_params (H263Params * params, GstBuffer * buffer,
     }
 
     if (ufep == 1) {
-      guint32 cpfmt = 0;
+      if (params->format == 6) {
+        /* A fixed length codeword of 23 bits that is present only if the use of
+         * a custom picture format is signalled in PLUSPTYPE and UFEP is 001 */
+        guint32 cpfmt = 0;
 
-      /* 5.1.5 CPFMT : Custom Picture Format (23 bits) */
-      if (!gst_bit_reader_get_bits_uint32 (&br, &cpfmt, 23))
-        goto more;
-      if (!(cpfmt & 0x200)) {
-        GST_WARNING ("Corrupted CPFMT (0x%x)", cpfmt);
-        goto beach;
-      }
-      temp8 = cpfmt >> 19;
-      params->width = (((cpfmt >> 10) & 0x1f) + 1) * 4;
-      params->height = ((cpfmt & 0x1f) + 1) * 4;
-
-      if (temp8 == 0xf) {
-        guint32 epar = 0;
-        /* 5.1.6 EPAR : Extended Pixel Aspect Ratio (16bits) */
-        if (!gst_bit_reader_get_bits_uint32 (&br, &epar, 16))
+        /* 5.1.5 CPFMT : Custom Picture Format (23 bits) */
+        if (!gst_bit_reader_get_bits_uint32 (&br, &cpfmt, 23))
           goto more;
-        params->parnum = epar >> 8;
-        params->pardenom = epar & 0xf;
+        if (!(cpfmt & 0x200)) {
+          GST_WARNING ("Corrupted CPFMT (0x%x)", cpfmt);
+          goto beach;
+        }
+        temp8 = cpfmt >> 19;
+        /* Bits 5-13: Picture Width Indication: Range [0, ... , 511];
+         * Number of pixels per line = (PWI + 1) * 4 */
+        params->width = (((cpfmt >> 10) & 0x1ff) + 1) * 4;
+        /* Bits 15-23  Picture Height Indication: Range [1, ... , 288];
+         * Number of lines = PHI * 4 */
+        params->height = (cpfmt & 0x1ff) * 4;
+
+        if (temp8 == 0xf) {
+          guint32 epar = 0;
+          /* 5.1.6 EPAR : Extended Pixel Aspect Ratio (16bits) */
+          if (!gst_bit_reader_get_bits_uint32 (&br, &epar, 16))
+            goto more;
+          params->parnum = epar >> 8;
+          params->pardenom = epar & 0xf;
+        } else {
+          params->parnum = partable[temp8][0];
+          params->pardenom = partable[temp8][1];
+        }
       } else {
-        params->parnum = partable[temp8][0];
-        params->pardenom = partable[temp8][1];
+        /* Fill in width/height based on format */
+        params->width = sizetable[params->format][0];
+        params->height = sizetable[params->format][1];
+        GST_DEBUG (" Picture width x height: %d x %d",
+            params->width, params->height);
+        /* Fill in default Pixel aspect ratios */
+        params->parnum = 12;
+        params->pardenom = 11;
       }
 
       if (params->custompcfpresent) {