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Code Issues Releases Activity

avutil: Add av_q2intfloat()

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This function allows writing AVRationals as IEEE floats without the need
of platform dependant float operations

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2015-05-24 14:19:57 +02:00
parent 894d8cf418
commit 1fb9b2a283
4 changed files with 59 additions and 1 deletions
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3
doc/APIchanges
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@ -15,6 +15,9 @@ libavutil: 2014-08-09
API changes, most recent first:
2015-05-26 - xxxxxxx - lavu 54.25.100 - rational.h
Add av_q2intfloat().
2015-05-13 - xxxxxxx - lavc 56.39.100 / 56.23.0
Add av_vda_default_init2.

48
libavutil/rational.c
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@ -148,6 +148,40 @@ int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
return nearest_q_idx;
}
uint32_t av_q2intfloat(AVRational q) {
int64_t n;
int shift;
int sign = 0;
if (q.den < 0) {
q.den *= -1;
q.num *= -1;
}
if (q.num < 0) {
q.num *= -1;
sign = 1;
}
if (!q.num && !q.den) return 0xFFC00000;
if (!q.num) return 0;
if (!q.den) return 0x7F800000 | (q.num & 0x80000000);
shift = 23 + av_log2(q.den) - av_log2(q.num);
if (shift >= 0) n = av_rescale(q.num, 1LL<<shift, q.den);
else n = av_rescale(q.num, 1, ((int64_t)q.den) << -shift);
shift -= n >= (1<<24);
shift += n < (1<<23);
if (shift >= 0) n = av_rescale(q.num, 1LL<<shift, q.den);
else n = av_rescale(q.num, 1, ((int64_t)q.den) << -shift);
av_assert1(n < (1<<24));
av_assert1(n >= (1<<23));
return sign<<31 | (150-shift)<<23 | (n - (1<<23));
}
#ifdef TEST
int main(void)
{
@ -202,6 +236,20 @@ int main(void)
}
}
}
for (a.den = 1; a.den < 0x100000000U/3; a.den*=3) {
for (a.num = -1; a.num < (1<<27); a.num += 1 + a.num/100) {
float f = av_int2float(av_q2intfloat(a));
float f2 = av_q2d(a);
if (fabs(f - f2) > fabs(f)/5000000) {
av_log(NULL, AV_LOG_ERROR, "%d/%d %f %f\n", a.num,
a.den, f, f2);
return 1;
}
}
}
return 0;
}
#endif

7
libavutil/rational.h
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@ -159,6 +159,13 @@ int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
*/
int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
/**
* Converts a AVRational to a IEEE 32bit float.
*
* The float is returned in a uint32_t and its value is platform indepenant.
*/
uint32_t av_q2intfloat(AVRational q);
/**
* @}
*/

2
libavutil/version.h
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@ -56,7 +56,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 54
#define LIBAVUTIL_VERSION_MINOR 24
#define LIBAVUTIL_VERSION_MINOR 25
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \