From c9a196d54dd41b68473e5a15d17cc37713735147 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Aur=C3=A9lien=20Zanelli?= <aurelien.zanelli@parrot.com>
Date: Thu, 18 Sep 2014 11:49:13 +0200
Subject: [PATCH] vc1parser: take care of endianness when parsing
 sequence-layer

sequence-layer is serialized in little-endian byte order except for
STRUCT_C which is serialized in big-endian byte order.

But since STRUCT_A and STRUCT_B fields are defined as unsigned int msb
first, we have to pass them as big-endian to their parsing function. So
we basically use temporary buffers to convert them in big-endian.

See SMPTE 421M Annex J and L.

https://bugzilla.gnome.org/show_bug.cgi?id=736871
---
 gst-libs/gst/codecparsers/gstvc1parser.c | 59 +++++++++++++++++++++---
 1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/gst-libs/gst/codecparsers/gstvc1parser.c b/gst-libs/gst/codecparsers/gstvc1parser.c
index 84817bbf8d..081e813264 100644
--- a/gst-libs/gst/codecparsers/gstvc1parser.c
+++ b/gst-libs/gst/codecparsers/gstvc1parser.c
@@ -35,6 +35,7 @@
 #include "gstvc1parser.h"
 #include "parserutils.h"
 #include <gst/base/gstbytereader.h>
+#include <gst/base/gstbytewriter.h>
 #include <gst/base/gstbitreader.h>
 #include <string.h>
 
@@ -1728,32 +1729,78 @@ gst_vc1_parse_sequence_layer (const guint8 * data, gsize size,
     GstVC1SeqLayer * seqlayer)
 {
   guint32 tmp;
-  GstBitReader br = GST_BIT_READER_INIT (data, size);
+  guint8 tmp8;
+  guint8 structA[8] = { 0, };
+  guint8 structB[12] = { 0, };
+  GstBitReader br;
+  GstByteReader byter = GST_BYTE_READER_INIT (data, size);
+  GstByteWriter bytew;
 
   g_return_val_if_fail (seqlayer != NULL, GST_VC1_PARSER_ERROR);
 
-  READ_UINT32 (&br, tmp, 8);
-  if (tmp != 0xC5)
+  /* Thanks to the specification, structA and structB fields are defined
+   * as unisgned integer msb first.
+   * But in sequence-layer there are serialized in little-endian byte order,
+   * so we must take care of their endianness before using bit reader */
+
+  if (!gst_byte_reader_get_uint24_le (&byter, &seqlayer->numframes))
     goto failed;
 
-  READ_UINT32 (&br, seqlayer->numframes, 24);
+  if (!gst_byte_reader_get_uint8 (&byter, &tmp8))
+    goto failed;
+
+  if (tmp8 != 0xC5)
+    goto failed;
+
+  /* 0x00000004 */
+  if (!gst_byte_reader_get_uint32_le (&byter, &tmp))
+    goto failed;
 
-  READ_UINT32 (&br, tmp, 32);
   if (tmp != 0x04)
     goto failed;
 
+  /* As an exception, structC is serialized in big-endian byte order so
+   * no endianness issue here but we should at least have 4 bytes */
+  if (gst_byte_reader_get_remaining (&byter) < 4)
+    goto failed;
+
+  gst_bit_reader_init (&br, data + gst_byte_reader_get_pos (&byter), 4);
   if (parse_sequence_header_struct_c (&br, &seqlayer->struct_c) ==
       GST_VC1_PARSER_ERROR)
     goto failed;
 
+  gst_byte_reader_skip (&byter, 4);
+
+  /* structA */
+  gst_byte_writer_init_with_data (&bytew, structA, 8, TRUE);
+  gst_byte_reader_get_uint32_le (&byter, &tmp);
+  gst_byte_writer_put_uint32_be (&bytew, tmp);
+  gst_byte_reader_get_uint32_le (&byter, &tmp);
+  gst_byte_writer_put_uint32_be (&bytew, tmp);
+
+  gst_bit_reader_init (&br, structA, 8);
   if (parse_sequence_header_struct_a (&br, &seqlayer->struct_a) ==
       GST_VC1_PARSER_ERROR)
     goto failed;
 
-  READ_UINT32 (&br, tmp, 32);
+  /* 0x0000000C */
+  if (!gst_byte_reader_get_uint32_le (&byter, &tmp))
+    goto failed;
+
   if (tmp != 0x0C)
     goto failed;
 
+  /* structB */
+  gst_byte_writer_reset (&bytew);
+  gst_byte_writer_init_with_data (&bytew, structB, 12, TRUE);
+  gst_byte_reader_get_uint32_le (&byter, &tmp);
+  gst_byte_writer_put_uint32_be (&bytew, tmp);
+  gst_byte_reader_get_uint32_le (&byter, &tmp);
+  gst_byte_writer_put_uint32_be (&bytew, tmp);
+  gst_byte_reader_get_uint32_le (&byter, &tmp);
+  gst_byte_writer_put_uint32_be (&bytew, tmp);
+
+  gst_bit_reader_init (&br, structB, 12);
   if (parse_sequence_header_struct_b (&br, &seqlayer->struct_b) ==
       GST_VC1_PARSER_ERROR)
     goto failed;