diff options
| -rw-r--r-- | libavutil/mathematics.c | 23 | ||||
| -rw-r--r-- | libavutil/mathematics.h | 5 |
2 files changed, 28 insertions, 0 deletions
diff --git a/libavutil/mathematics.c b/libavutil/mathematics.c index c334aa12b8..6c2f6c04de 100644 --- a/libavutil/mathematics.c +++ b/libavutil/mathematics.c @@ -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); +} diff --git a/libavutil/mathematics.h b/libavutil/mathematics.h index 113286cd8d..81b14fd29e 100644 --- a/libavutil/mathematics.h +++ b/libavutil/mathematics.h @@ -123,6 +123,11 @@ 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); + +/** * @} */ |