Implement shared parsing of INFO tag in Canopus family

Add some bounds checking to CLLC; reduce HQX variable scoping,
add an error message.

1 files changed, 63 insertions, 0 deletions

diff --git a/libavcodec/canopus.c b/libavcodec/canopus.c
new file mode 100644
index 0000000000..729e7ef876
--- /dev/null
+++ b/libavcodec/canopus.c
@@ -0,0 +1,63 @@
+/*
+ * Canopus common routines
+ * Copyright (c) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdint.h>
+
+#include "libavutil/rational.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "canopus.h"
+
+int ff_canopus_parse_info_tag(AVCodecContext *avctx,
+                              const uint8_t *src, size_t size)
+{
+    GetByteContext gbc;
+    int par_x, par_y, field_order;
+
+    bytestream2_init(&gbc, src, size);
+
+    /* Parse aspect ratio. */
+    bytestream2_skip(&gbc, 8); // unknown, 16 bits 1
+    par_x = bytestream2_get_le32(&gbc);
+    par_y = bytestream2_get_le32(&gbc);
+    if (par_x && par_y)
+        av_reduce(&avctx->sample_aspect_ratio.num,
+                  &avctx->sample_aspect_ratio.den,
+                  par_x, par_y, 255);
+
+    /* Short INFO tag (used in CLLC) has only AR data. */
+    if (size == 0x18)
+        return 0;
+
+    bytestream2_skip(&gbc, 16); // unknown RDRT tag
+
+    /* Parse FIEL tag. */
+    bytestream2_skip(&gbc, 8); // 'FIEL' and 4 bytes 0
+    field_order = bytestream2_get_le32(&gbc);
+    switch (field_order) {
+    case 0: avctx->field_order = AV_FIELD_TT; break;
+    case 1: avctx->field_order = AV_FIELD_BB; break;
+    case 2: avctx->field_order = AV_FIELD_PROGRESSIVE; break;
+    }
+
+    return 0;
+}