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typefind: add typefinder for DEGAS images

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This fixes at least one DEGAS image from being misdetected as DTS audio.

https://bugzilla.gnome.org/show_bug.cgi?id=625129
This commit is contained in:
Vincent Penquerc'h 2011-01-25 13:39:25 +00:00 committed by Tim-Philipp Müller
parent d144f7a3a5
commit 2acdbdabaa
1 changed files with 51 additions and 0 deletions
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51
gst/typefind/gsttypefindfunctions.c
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@ -3911,6 +3911,54 @@ windows_icon_typefind (GstTypeFind * find, gpointer user_data)
"image/vnd.microsoft.icon", NULL);
}
/*** DEGAS Atari images (also to avoid false positives, see #625129) ***/
static void
degas_type_find (GstTypeFind * tf, gpointer private)
{
/* No magic, but it should have a fixed size and a few invalid values */
/* http://www.fileformat.info/format/atari/spec/6ecf9f6eb5be494284a47feb8a214687/view.htm */
gint64 len;
const guint8 *data;
guint16 resolution;
int n;
len = gst_type_find_get_length (tf);
if (len < 34) /* smallest header of the lot */
return;
data = gst_type_find_peek (tf, 0, 4);
resolution = GST_READ_UINT16_BE (data);
if (len == 32034) {
/* could be DEGAS */
if (resolution <= 2)
gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
"image/x-degas", NULL);
} else if (len == 32066) {
/* could be DEGAS Elite */
if (resolution <= 2) {
data = gst_type_find_peek (tf, len - 16, 8);
for (n = 0; n < 4; n++) {
if (GST_READ_UINT16_BE (data + n * 2) > 2)
return;
}
gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
"image/x-degas", NULL);
}
} else if (len >= 66 && len < 32066) {
/* could be compressed DEGAS Elite, but it's compressed and so we can't rely on size,
it does have 4 16 bytes values near the end that are 0-2 though. */
if ((resolution & 0x8000) && (resolution & 0x7fff) <= 2) {
data = gst_type_find_peek (tf, len - 16, 8);
for (n = 0; n < 4; n++) {
if (GST_READ_UINT16_BE (data + n * 2) > 2)
return;
}
gst_type_find_suggest_simple (tf, GST_TYPE_FIND_POSSIBLE + 5,
"image/x-degas", NULL);
}
}
}
/*** generic typefind for streams that have some data at a specific position***/
typedef struct
{
@ -4382,6 +4430,9 @@ plugin_init (GstPlugin * plugin)
xdgmime_typefind, NULL, NULL, NULL, NULL);
#endif
TYPE_FIND_REGISTER (plugin, "image/x-degas", GST_RANK_MARGINAL,
degas_type_find, NULL, NULL, NULL, NULL);
return TRUE;
}