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bytereader: Accelerate MPEG/H264 start code scanning

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Accelerate MPEG/H264 start code scanning using Boyer-Moor bad character
heuristic.

https://bugzilla.gnome.org/show_bug.cgi?id=702357
This commit is contained in:
Nicolas Dufresne 2013-08-08 12:08:31 +02:00 committed by Nicolas Dufresne
parent d97aa274c2
commit de75bca9b3
1 changed files with 29 additions and 0 deletions
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29
libs/gst/base/gstbytereader.c
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@ -771,6 +771,31 @@ gst_byte_reader_dup_data (GstByteReader * reader, guint size, guint8 ** val)
return _gst_byte_reader_dup_data_inline (reader, size, val);
}
/* Special optimized scan for mask 0xffffff00 and pattern 0x00000100 */
static inline gint
_scan_for_start_code (const guint8 * data, guint offset, guint size)
{
guint i = 0;
while (i <= (size - 4)) {
if (data[i + 2] > 1) {
i += 3;
} else if (data[i + 1]) {
i += 2;
} else if (data[i] || data[i + 2] != 1) {
i++;
} else {
break;
}
}
if (i <= (size - 4))
return i + offset;
/* nothing found */
return -1;
}
/**
* gst_byte_reader_masked_scan_uint32:
* @reader: a #GstByteReader
@ -831,6 +856,10 @@ gst_byte_reader_masked_scan_uint32 (const GstByteReader * reader, guint32 mask,
data = reader->data + reader->byte + offset;
/* Handle special case found in MPEG and H264 */
if ((pattern == 0x00000100) && (mask == 0xffffff00))
return _scan_for_start_code (data, offset, size);
/* set the state to something that does not match */
state = ~pattern;