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author | Michael Niedermayer <michael@niedermayer.cc> | 2023-05-23 00:03:31 +0200 |
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committer | Michael Niedermayer <michael@niedermayer.cc> | 2023-05-29 00:55:52 +0200 |
commit | 0c7a0514e3d2b30ba081968d2829ca751a835967 (patch) | |
tree | 0c042e8f3300095e9ac6ab7e54f49127feb041e2 | |
parent | 1e9c337e0f1f179b6fded7cbe62395ed5053ef5f (diff) | |
download | ffmpeg-0c7a0514e3d2b30ba081968d2829ca751a835967.tar.gz |
avfilter/window_func: Use av_bessel_i0()
Old code needed about 6 times as long as new with defaults in afftfilt
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
-rw-r--r-- | libavfilter/window_func.h | 19 |
1 files changed, 4 insertions, 15 deletions
diff --git a/libavfilter/window_func.h b/libavfilter/window_func.h index 02b5def9dd..d0de63b5a8 100644 --- a/libavfilter/window_func.h +++ b/libavfilter/window_func.h @@ -59,19 +59,6 @@ enum WindowFunc { WFUNC_RECT, WFUNC_HANNING, WFUNC_HAMMING, WFUNC_BLACKMAN, { "bohman", "Bohman", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN}, 0, 0, flag, "win_func" }, \ { "kaiser", "Kaiser", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_KAISER}, 0, 0, flag, "win_func" } -static inline double get_i0(double x) -{ - double y = 1.0, prev = 1.0, i = 1.0; - - while (fabs(prev) > 1e-20) { - double summand = prev * x * x / (4 * i * i); - y += summand; - prev = summand; - i++; - } - - return y; -} static inline void generate_window_func(float *lut, int N, int win_func, float *overlap) @@ -232,13 +219,15 @@ static inline void generate_window_func(float *lut, int N, int win_func, *overlap = 0.75; break; case WFUNC_KAISER: + { + double scale = 1.0 / av_bessel_i0(12.); for (n = 0; n < N; n++) { double x = 2.0 / (double)(N - 1); - - lut[n] = get_i0(12. * sqrt(1. - SQR(n * x - 1.))) / get_i0(12.); + lut[n] = av_bessel_i0(12. * sqrt(1. - SQR(n * x - 1.))) * scale; } *overlap = 0.75; break; + } default: av_assert0(0); } |