vp9: fix overflow in 8x8 topleft 32x32 idct ssse3 version.

Also disable the mmx/iwht optimization when the bitexact flag is set.
With synthetically coded coefficients (i.e. these that lead to a
residual well outside the [-255,255] range), our optimizations will
overflow. It doesn't make sense to fix the overflows, since they can
only occur on synthetic input, not on real fwht-generated input. Thus,
add a bitexact flag that disables this optimization.

1 files changed, 1 insertions, 1 deletions

diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
index 98fd8a3046..fcdd6e128e 100644
--- a/libavcodec/vp9.c
+++ b/libavcodec/vp9.c
@@ -360,7 +360,7 @@ static int update_size(AVCodecContext *ctx, int w, int h, enum AVPixelFormat fmt
     av_freep(&s->block_base);
 
     if (s->bpp != s->last_bpp) {
-        ff_vp9dsp_init(&s->dsp, s->bpp);
+        ff_vp9dsp_init(&s->dsp, s->bpp, ctx->flags & AV_CODEC_FLAG_BITEXACT);
         ff_videodsp_init(&s->vdsp, s->bpp);
         s->last_bpp = s->bpp;
     }