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typefind: ADTS/AAC, find more aac sync to select correctly

Browse source 
https://bugzilla.gnome.org/show_bug.cgi?id=691462
This commit is contained in:
Jie Yang 2013-08-15 16:12:45 +08:00 committed by Sebastian Dröge
parent 61c1d15ce7
commit 5640ba17c8
1 changed files with 32 additions and 3 deletions
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35
gst/typefind/gsttypefindfunctions.c
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@ -1006,7 +1006,7 @@ aac_type_find (GstTypeFind * tf, gpointer unused)
guint best_count = 0;
while (c.offset < AAC_AMOUNT) {
guint snc, len;
guint snc, len, offset, i;
/* detect adts header or adif header.
* The ADIF header is 4 bytes, that should be OK. The ADTS header, on
@ -1033,8 +1033,9 @@ aac_type_find (GstTypeFind * tf, gpointer unused)
goto next;
}
offset = len;
/* check if there's a second ADTS frame */
snc = GST_READ_UINT16_BE (c.data + len);
snc = GST_READ_UINT16_BE (c.data + offset);
if ((snc & 0xfff6) == 0xfff0) {
GstCaps *caps;
guint mpegversion, sample_freq_idx, channel_config, profile_idx, rate;
@ -1083,7 +1084,35 @@ aac_type_find (GstTypeFind * tf, gpointer unused)
channels_map[channel_config], "rate", G_TYPE_INT, rate, NULL);
}
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, caps);
/* length of the second ADTS frame */
len = ((c.data[offset + 3] & 0x03) << 11) |
(c.data[offset + 4] << 3) | ((c.data[offset + 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);
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, caps);
} else {
offset += len;
/* find more aac sync to select correctly */
/* check if there's a third/fourth/fifth/sixth ADTS frame, if there is a sixth frame, set probability to maximum:100% */
for (i = 3; i <= 6; i++) {
len = ((c.data[offset + 3] & 0x03) << 11) |
(c.data[offset + 4] << 3) | ((c.data[offset + 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);
break;
}
snc = GST_READ_UINT16_BE (c.data + offset);
if ((snc & 0xfff6) == 0xfff0) {
GST_DEBUG ("Find %und Sync..probability is %u ", i, GST_TYPE_FIND_LIKELY + 5 * (i - 2));
offset += len;
} else {
break;
}
}
gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY + 5 * (i - 3), caps);
}
gst_caps_unref (caps);
break;
}