From 8455e8c7c0ad183e8904e583def669ba4b7b4c90 Mon Sep 17 00:00:00 2001 From: Gregory Maxwell Date: Fri, 12 Nov 2010 04:33:26 +0000 Subject: [PATCH] vorbisdec: Fix floor1 decoding An intermediate value in the floor 1 linear interpolation was overflowing resulting in obvious artifacts on some files. e.g. http://upload.wikimedia.org/wikipedia/commons/7/79/Big_Buck_Bunny_small.ogv Prior to this fix 87 out of 128 64kbit/s mono files decoded with ffmpeg have lower PEAQ ODG values than the same files decoded with libvorbis. With this fix none of that set have significantly worse ODG values than libvorbis. Fixes issue 2352 Patch by Gregory Maxwell Originally committed as revision 25724 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/vorbis_dec.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/libavcodec/vorbis_dec.c b/libavcodec/vorbis_dec.c index c209912cd1..284b8dfaca 100644 --- a/libavcodec/vorbis_dec.c +++ b/libavcodec/vorbis_dec.c @@ -1146,8 +1146,8 @@ static int vorbis_floor1_decode(vorbis_context *vc, int_fast16_t book; uint_fast16_t offset; uint_fast16_t i,j; - /*u*/int_fast16_t adx, ady, off, predicted; // WTF ? dy/adx = (unsigned)dy/adx ? - int_fast16_t dy, err; + int_fast16_t adx, ady, dx, off, predicted; + int_fast32_t err; if (!get_bits1(gb)) // silence @@ -1210,7 +1210,7 @@ static int vorbis_floor1_decode(vorbis_context *vc, adx = vf->list[high_neigh_offs].x - vf->list[low_neigh_offs].x; ady = FFABS(dy); err = ady * (vf->list[i].x - vf->list[low_neigh_offs].x); - off = (int16_t)err / (int16_t)adx; + off = err / adx; if (dy < 0) { predicted = floor1_Y_final[low_neigh_offs] - off; } else {