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gst/typefind/gsttypefindfunctions.c: Use data scan helper in aac typefinder and stop scanning for headers when we've ...

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Original commit message from CVS:
* gst/typefind/gsttypefindfunctions.c: (aac_type_find):
Use data scan helper in aac typefinder and stop scanning
for headers when we've found a type. Also fix potential invalid
memory access when calculating the frame length.
This commit is contained in:
Tim-Philipp Müller 2008-05-19 15:59:40 +00:00
parent cfc8f3c0d7
commit 7cb1276dac
2 changed files with 55 additions and 51 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
2008-05-19 Tim-Philipp Müller <tim.muller at collabora co uk>
* gst/typefind/gsttypefindfunctions.c: (aac_type_find):
Use data scan helper in aac typefinder and stop scanning
for headers when we've found a type. Also fix potential invalid
memory access when calculating the frame length.
2008-05-19 Tim-Philipp Müller <tim.muller at collabora co uk>
* gst/typefind/gsttypefindfunctions.c: (data_scan_ctx_ensure_data),

99
gst/typefind/gsttypefindfunctions.c
View file

@ -547,68 +547,65 @@ static GstStaticCaps aac_caps = GST_STATIC_CAPS ("audio/mpeg, "
static void
aac_type_find (GstTypeFind * tf, gpointer unused)
{
guint8 *data = gst_type_find_peek (tf, 0, AAC_AMOUNT);
gint snc;
DataScanCtx c = { 0, NULL, 0 };
/* detect adts header or adif header.
* The ADIF header is 4 bytes, that should be OK. The ADTS header, on
* the other hand, is 14 bits only, so we require one valid frame with
* again a valid syncpoint on the next one (28 bits) for certainty. We
* require 4 kB, which is quite a lot, since frames are generally 200-400
* bytes.
*/
if (data) {
gint n;
while (c.offset < AAC_AMOUNT) {
guint snc, len;
for (n = 0; n < AAC_AMOUNT - 3; n++) {
snc = GST_READ_UINT16_BE (&data[n]);
/* detect adts header or adif header.
* The ADIF header is 4 bytes, that should be OK. The ADTS header, on
* the other hand, is 14 bits only, so we require one valid frame with
* again a valid syncpoint on the next one (28 bits) for certainty. We
* require 4 kB, which is quite a lot, since frames are generally 200-400
* bytes.
*/
if (G_UNLIKELY (!data_scan_ctx_ensure_data (tf, &c, 6)))
break;
snc = GST_READ_UINT16_BE (c.data);
if (G_UNLIKELY ((snc & 0xfff6) == 0xfff0)) {
/* ADTS header - find frame length */
GST_DEBUG ("Found one ADTS syncpoint at offset 0x%x, tracing next...",
c.offset);
len = ((c.data[3] & 0x03) << 11) |
(c.data[4] << 3) | ((c.data[5] & 0xe0) >> 5);
if (len == 0 || !data_scan_ctx_ensure_data (tf, &c, len + 2)) {
GST_DEBUG ("Wrong sync or next frame not within reach, len=%u", len);
goto next;
}
snc = GST_READ_UINT16_BE (c.data + len);
if ((snc & 0xfff6) == 0xfff0) {
/* ADTS header - find frame length */
gint len;
GST_DEBUG ("Found one ADTS syncpoint at offset 0x%x, tracing next...",
n);
if (AAC_AMOUNT - n < 5) {
GST_DEBUG ("Not enough data to parse ADTS header");
break;
}
len = ((data[n + 3] & 0x03) << 11) |
(data[n + 4] << 3) | ((data[n + 5] & 0xe0) >> 5);
if (n + len + 2 >= AAC_AMOUNT) {
GST_DEBUG ("Next frame is not within reach");
break;
} else if (len == 0) {
continue;
}
snc = GST_READ_UINT16_BE (&data[n + len]);
if ((snc & 0xfff6) == 0xfff0) {
gint mpegversion = (data[n + 1] & 0x08) ? 2 : 4;
GstCaps *caps = gst_caps_new_simple ("audio/mpeg",
"framed", G_TYPE_BOOLEAN, FALSE,
"mpegversion", G_TYPE_INT, mpegversion,
NULL);
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, caps);
gst_caps_unref (caps);
GST_DEBUG ("Found ADTS-%d syncpoint at offset 0x%x (framelen %u)",
mpegversion, n, len);
break;
}
GST_DEBUG ("No next frame found... (should be at 0x%x)", n + len);
} else if (!memcmp (&data[n], "ADIF", 4)) {
/* ADIF header */
gint mpegversion = (c.data[1] & 0x08) ? 2 : 4;
GstCaps *caps = gst_caps_new_simple ("audio/mpeg",
"framed", G_TYPE_BOOLEAN, FALSE,
"mpegversion", G_TYPE_INT, 4,
"mpegversion", G_TYPE_INT, mpegversion,
NULL);
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, caps);
gst_caps_unref (caps);
GST_DEBUG ("Found second ADTS-%d syncpoint at offset 0x%x, framelen %u",
mpegversion, c.offset, len);
break;
}
GST_DEBUG ("No next frame found... (should have been at 0x%x)", len);
} else if (!memcmp (c.data, "ADIF", 4)) {
/* ADIF header */
GstCaps *caps = gst_caps_new_simple ("audio/mpeg",
"framed", G_TYPE_BOOLEAN, FALSE,
"mpegversion", G_TYPE_INT, 4,
NULL);
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, caps);
gst_caps_unref (caps);
break;
}
next:
data_scan_ctx_advance (tf, &c, 1);
}
}