codecparsers: vc1: add API to parse slice headers.

Add gst_vc1_parse_slice_header() function to parse slice headers as
described in 7.1.2. Slice layers are optional and allowed in advanced
profile mode only. Picture header, if available (PIC_HEADER_FLAG),
is parsed but not recorded because it shall be the same as that was
previously parsed with gst_vc1_parse_frame_header().

This fixes SA00049.vc1 conformance test.

https://bugzilla.gnome.org/show_bug.cgi?id=692388

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>

gst-libs/gst/codecparsers/gstvc1parser.c

@@ -2052,6 +2052,50 @@ gst_vc1_parse_field_header (const guint8 * data, gsize size,
   return result;
 }
 
+/**
+ * gst_vc1_parse_slice_header:
+ * @data: The data to parse
+ * @size: The size of @data
+ * @slicehdr: The #GstVC1SliceHdr to fill
+ * @seqhdr: The #GstVC1SeqHdr that was previously parsed
+ *
+ * Parses @data, and fills @slicehdr fields.
+ *
+ * Returns: a #GstVC1ParserResult
+ *
+ * Since: 1.2
+ */
+GstVC1ParserResult
+gst_vc1_parse_slice_header (const guint8 * data, gsize size,
+    GstVC1SliceHdr * slicehdr, GstVC1SeqHdr * seqhdr)
+{
+  GstBitReader br;
+  GstVC1FrameHdr framehdr;
+  GstVC1ParserResult result;
+  guint8 pic_header_flag;
+
+  GST_DEBUG ("Parsing slice header");
+
+  if (seqhdr->profile != GST_VC1_PROFILE_ADVANCED)
+    return GST_VC1_PARSER_BROKEN_DATA;
+
+  gst_bit_reader_init (&br, data, size);
+
+  READ_UINT16 (&br, slicehdr->slice_addr, 9);
+  READ_UINT8 (&br, pic_header_flag, 1);
+  if (pic_header_flag)
+    result = parse_frame_header_advanced (&br, &framehdr, seqhdr, NULL, FALSE);
+  else
+    result = GST_VC1_PARSER_OK;
+
+  slicehdr->header_size = gst_bit_reader_get_pos (&br);
+  return result;
+
+failed:
+  GST_WARNING ("Failed to parse slice header");
+  return GST_VC1_PARSER_ERROR;
+}
+
 /**
  * gst_vc1_bitplanes_new:
  * @seqhdr: The #GstVC1SeqHdr from which to set @bitplanes

gst-libs/gst/codecparsers/gstvc1parser.h

@@ -154,6 +154,7 @@ typedef struct _GstVC1FrameHdr          GstVC1FrameHdr;
 typedef struct _GstVC1PicAdvanced       GstVC1PicAdvanced;
 typedef struct _GstVC1PicSimpleMain     GstVC1PicSimpleMain;
 typedef struct _GstVC1Picture           GstVC1Picture;
+typedef struct _GstVC1SliceHdr          GstVC1SliceHdr;
 
 typedef struct _GstVC1VopDquant         GstVC1VopDquant;
 
@@ -547,6 +548,19 @@ struct _GstVC1FrameHdr
   guint header_size;
 };
 
+/**
+ * GstVC1SliceHdr:
+ *
+ * Structure that represents slice layer in advanced profile.
+ */
+struct _GstVC1SliceHdr
+{
+  guint16 slice_addr;
+
+  /* Size of the slice layer in bits */
+  guint header_size;
+};
+
 /**
  * GstVC1BDU:
  *
@@ -609,6 +623,11 @@ GstVC1ParserResult gst_vc1_parse_field_header          (const guint8 *data,
                                                         GstVC1SeqHdr *seqhdr,
                                                         GstVC1BitPlanes *bitplanes);
 
+GstVC1ParserResult gst_vc1_parse_slice_header           (const guint8 *data,
+                                                         gsize size,
+                                                         GstVC1SliceHdr *slicehdr, 
+                                                         GstVC1SeqHdr *seqhdr);
+
 GstVC1BitPlanes *  gst_vc1_bitplanes_new               (void);
 
 void               gst_vc1_bitplanes_free              (GstVC1BitPlanes *bitplanes);