The specifications explicitly state to use roundf() which also rounds half-integer values away from zero. This does fix a few IS artifacts.
Showing the changes to libavcodec/aaccoder.c (1 of 1 file). Show all
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| @@ -332,11 +332,11 @@ static void set_special_band_scalefactors(AACEncContext *s, SingleChannelElement · 331 unmodified lines | ||
| 332 | 332 | start = 0; |
| 333 | 333 | for (g = 0; g < sce->ics.num_swb; g++) { |
| 334 | 334 | if (sce->band_type[w*16+g] == INTENSITY_BT || sce->band_type[w*16+g] == INTENSITY_BT2) { |
| 335 | − sce->sf_idx[w*16+g] = av_clip(ceilf(log2f(sce->is_ener[w*16+g])*2), -155, 100); | |
| 335 | + sce->sf_idx[w*16+g] = av_clip(roundf(log2f(sce->is_ener[w*16+g])*2), -155, 100); | |
| 336 | 336 | minscaler_i = FFMIN(minscaler_i, sce->sf_idx[w*16+g]); |
| 337 | 337 | bands++; |
| 338 | 338 | } else if (sce->band_type[w*16+g] == NOISE_BT) { |
| 339 | − sce->sf_idx[w*16+g] = av_clip(4+log2f(sce->pns_ener[w*16+g])*2, -100, 155); | |
| 339 | + sce->sf_idx[w*16+g] = av_clip(roundf(log2f(sce->pns_ener[w*16+g])*2), -100, 155); | |
| 340 | 340 | minscaler_n = FFMIN(minscaler_n, sce->sf_idx[w*16+g]); |
| 341 | 341 | bands++; |
| 342 | 342 | } |