avcodec/ppc/idctdsp: Only select non bitexact IDCTs by default when bitexact is not set

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/ppc/idctdsp.c

@@ -249,7 +249,7 @@ av_cold void ff_idctdsp_init_ppc(IDCTDSPContext *c, AVCodecContext *avctx,
 #if HAVE_ALTIVEC
     if (PPC_ALTIVEC(av_get_cpu_flags())) {
         if (!high_bit_depth && avctx->lowres == 0) {
-            if ((avctx->idct_algo == FF_IDCT_AUTO) ||
+            if ((avctx->idct_algo == FF_IDCT_AUTO && !(avctx->flags & CODEC_FLAG_BITEXACT)) ||
                 (avctx->idct_algo == FF_IDCT_ALTIVEC)) {
                 c->idct      = idct_altivec;
                 c->idct_add  = idct_add_altivec;