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lavf/matroska*: add support for signed integers

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Jan Gerber 2013-11-15 19:00:37 +01:00 committed by Michael Niedermayer
parent 5592d1b741
commit d03eea36b2
2 changed files with 51 additions and 0 deletions
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30
libavformat/matroskadec.c
View File

@ -62,6 +62,7 @@ typedef enum {
EBML_NEST,
EBML_PASS,
EBML_STOP,
EBML_SINT,
EBML_TYPE_COUNT
} EbmlType;
@ -758,6 +759,34 @@ static int ebml_read_uint(AVIOContext *pb, int size, uint64_t *num)
return 0;
}
/*
* Read the next element as a signed int.
* 0 is success, < 0 is failure.
*/
static int ebml_read_sint(AVIOContext *pb, int size, int64_t *num)
{
int n = 1;
if (size > 8)
return AVERROR_INVALIDDATA;
if (size == 0) {
*num = 0;
} else {
*num = avio_r8(pb);
/* negative value */
if (*num & 0x80) {
*num = (-1 << 8) | *num;
}
/* big-endian ordering; build up number */
while (n++ < size)
*num = (*num << 8) | avio_r8(pb);
}
return 0;
}
/*
* Read the next element as a float.
* 0 is success, < 0 is failure.
@ -985,6 +1014,7 @@ static int ebml_parse_elem(MatroskaDemuxContext *matroska,
switch (syntax->type) {
case EBML_UINT: res = ebml_read_uint (pb, length, data); break;
case EBML_SINT: res = ebml_read_sint (pb, length, data); break;
case EBML_FLOAT: res = ebml_read_float (pb, length, data); break;
case EBML_STR:
case EBML_UTF8: res = ebml_read_ascii (pb, length, data); break;

21
libavformat/matroskaenc.c
View File

@ -202,6 +202,27 @@ static void put_ebml_uint(AVIOContext *pb, unsigned int elementid, uint64_t val)
avio_w8(pb, (uint8_t)(val >> i*8));
}
static void put_ebml_sint(AVIOContext *pb, unsigned int elementid, int64_t val)
{
int i, bytes = 1;
uint64_t uval = (val < 0 ? (-val - 1) << 1 : val << 1);
while (uval>>=8) bytes++;
/* make unsigned */
if (val >= 0) {
uval = val;
} else {
uval = 0x80 << (bytes - 1);
uval += val;
uval |= 0x80 << (bytes - 1);
}
put_ebml_id(pb, elementid);
put_ebml_num(pb, bytes, 0);
for (i = bytes - 1; i >= 0; i--)
avio_w8(pb, (uint8_t)(uval >> i*8));
}
static void put_ebml_float(AVIOContext *pb, unsigned int elementid, double val)
{
put_ebml_id(pb, elementid);