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lavu: add av_rescale_delta()

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-10-26 21:23:19 +02:00
parent 03e44bcb3f
commit 8766ad9eb1
2 changed files with 28 additions and 0 deletions
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23
libavutil/mathematics.c
View file

@ -142,3 +142,26 @@ int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod){
c-= mod;
return c;
}
int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb){
int64_t a, b, this;
av_assert0(in_ts != AV_NOPTS_VALUE);
av_assert0(duration >= 0);
if (*last == AV_NOPTS_VALUE || !duration || in_tb.num*(int64_t)out_tb.den <= out_tb.num*(int64_t)in_tb.den) {
simple_round:
*last = av_rescale_q(in_ts, in_tb, fs_tb) + duration;
return av_rescale_q(in_ts, in_tb, out_tb);
}
a = av_rescale_q_rnd(2*in_ts-1, in_tb, fs_tb, AV_ROUND_DOWN) >>1;
b = (av_rescale_q_rnd(2*in_ts+1, in_tb, fs_tb, AV_ROUND_UP )+1)>>1;
if (*last < 2*a - b || *last > 2*b - a)
goto simple_round;
this = av_clip64(*last, a, b);
*last = this + duration;
return av_rescale_q(this, fs_tb, out_tb);
}

5
libavutil/mathematics.h
View file

@ -122,6 +122,11 @@ int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
*/
int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
/**
* Rescale a timestamp while preserving known durations.
*/
int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb);
/**
* @}
*/