diff options
| author | Michael Niedermayer <michaelni@gmx.at> | 2014-01-03 17:30:50 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2014-01-04 15:10:09 +0100 |
| commit | b317f9459f4c8f96b01bf20ce33a7f243d33a02c (patch) | |
| tree | aa3e9a013f26401df286356058bd3ed858214c0f | |
| parent | de5b6c736bcba27357b98782afdc642128cf1f89 (diff) | |
| download | ffmpeg-b317f9459f4c8f96b01bf20ce33a7f243d33a02c.tar.gz | |
avutil/mathematics: add av_add_stable()
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
| -rw-r--r-- | doc/APIchanges | 3 | ||||
| -rw-r--r-- | libavutil/mathematics.c | 14 | ||||
| -rw-r--r-- | libavutil/mathematics.h | 14 | ||||
| -rw-r--r-- | libavutil/version.h | 2 |
4 files changed, 32 insertions, 1 deletions
diff --git a/doc/APIchanges b/doc/APIchanges index 21a8c4c0c4..fe6ddce49d 100644 --- a/doc/APIchanges +++ b/doc/APIchanges @@ -15,6 +15,9 @@ libavutil: 2012-10-22 API changes, most recent first: +2014-01-04 - xxxxxxx - lavu 52.60.100 - mathematics.h + Add av_add_stable() function. + 2013-12-22 - xxxxxxx - lavu 52.59.100 - avstring.h Add av_strnlen() function. diff --git a/libavutil/mathematics.c b/libavutil/mathematics.c index 2e0cf0cbd4..30963aa07b 100644 --- a/libavutil/mathematics.c +++ b/libavutil/mathematics.c @@ -174,3 +174,17 @@ simple_round: return av_rescale_q(this, fs_tb, out_tb); } + +int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc) +{ + AVRational step = av_mul_q(inc_tb, (AVRational) {inc, 1}); + + if (av_cmp_q(step, ts_tb) < 0) { + //increase step is too small for even 1 step to be representable + return ts; + } else { + int64_t old = av_rescale_q(ts, ts_tb, step); + int64_t old_ts = av_rescale_q(old, step, ts_tb); + return av_rescale_q(old + 1, step, ts_tb) + (ts - old_ts); + } +} diff --git a/libavutil/mathematics.h b/libavutil/mathematics.h index bfb5414312..a8b1d8eb31 100644 --- a/libavutil/mathematics.h +++ b/libavutil/mathematics.h @@ -141,6 +141,20 @@ int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb); /** + * Add a value to a timestamp. + * + * This function gurantees that when the same value is repeatly added that + * no accumulation of rounding errors occurs. + * + * @param ts Input timestamp + * @param ts_tb Input timestamp timebase + * @param inc value to add to ts + * @param inc_tb inc timebase + */ +int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc); + + + /** * @} */ diff --git a/libavutil/version.h b/libavutil/version.h index adbe230c85..833d4ee42c 100644 --- a/libavutil/version.h +++ b/libavutil/version.h @@ -56,7 +56,7 @@ */ #define LIBAVUTIL_VERSION_MAJOR 52 -#define LIBAVUTIL_VERSION_MINOR 59 +#define LIBAVUTIL_VERSION_MINOR 60 #define LIBAVUTIL_VERSION_MICRO 100 #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \ |