diff options
Diffstat (limited to 'libswresample/resample.c')
| -rw-r--r-- | libswresample/resample.c | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/libswresample/resample.c b/libswresample/resample.c index 072e0d6a78..d0a406e5e4 100644 --- a/libswresample/resample.c +++ b/libswresample/resample.c @@ -144,24 +144,34 @@ static double bessel(double x) { static int build_filter(ResampleContext *c, void *filter, double factor, int tap_count, int alloc, int phase_count, int scale, int filter_type, double kaiser_beta){ int ph, i; - double x, y, w, t; + double x, y, w, t, s; double *tab = av_malloc_array(tap_count+1, sizeof(*tab)); + double *sin_lut = av_malloc_array(phase_count / 2 + 1, sizeof(*sin_lut)); const int center= (tap_count-1)/2; - if (!tab) - return AVERROR(ENOMEM); + if (!tab || !sin_lut) + goto fail; /* if upsampling, only need to interpolate, no filter */ if (factor > 1.0) factor = 1.0; av_assert0(phase_count == 1 || phase_count % 2 == 0); + + if (factor == 1.0) { + for (ph = 0; ph <= phase_count / 2; ph++) + sin_lut[ph] = sin(M_PI * ph / phase_count); + } for(ph = 0; ph <= phase_count / 2; ph++) { double norm = 0; + s = sin_lut[ph]; for(i=0;i<=tap_count;i++) { x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor; if (x == 0) y = 1.0; - else y = sin(x) / x; + else if (factor == 1.0) + y = s / x; + else + y = sin(x) / x; switch(filter_type){ case SWR_FILTER_TYPE_CUBIC:{ const float d= -0.5; //first order derivative = -0.5 @@ -183,6 +193,7 @@ static int build_filter(ResampleContext *c, void *filter, double factor, int tap } tab[i] = y; + s = -s; if (i < tap_count) norm += y; } @@ -278,7 +289,9 @@ static int build_filter(ResampleContext *c, void *filter, double factor, int tap } #endif +fail: av_free(tab); + av_free(sin_lut); return 0; } |