libavcodec/hevcdec: implement skip_frame

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/hevcdec.c

@@ -2905,6 +2905,13 @@ static int decode_nal_unit(HEVCContext *s, const H2645NAL *nal)
         if (ret < 0)
             return ret;
 
+        if (
+            (s->avctx->skip_frame >= AVDISCARD_BIDIR && s->sh.slice_type == HEVC_SLICE_B) ||
+            (s->avctx->skip_frame >= AVDISCARD_NONINTRA && s->sh.slice_type != HEVC_SLICE_I) ||
+            (s->avctx->skip_frame >= AVDISCARD_NONKEY && !IS_IDR(s))) {
+            break;
+        }
+
         if (s->sh.first_slice_in_pic_flag) {
             if (s->max_ra == INT_MAX) {
                 if (s->nal_unit_type == HEVC_NAL_CRA_NUT || IS_BLA(s)) {
@@ -3028,7 +3035,14 @@ static int decode_nal_units(HEVCContext *s, const uint8_t *buf, int length)
 
     /* decode the NAL units */
     for (i = 0; i < s->pkt.nb_nals; i++) {
-        ret = decode_nal_unit(s, &s->pkt.nals[i]);
+        H2645NAL *nal = &s->pkt.nals[i];
+
+        if (s->avctx->skip_frame >= AVDISCARD_ALL ||
+            (s->avctx->skip_frame >= AVDISCARD_NONREF
+            && ff_hevc_nal_is_nonref(nal->type)))
+            continue;
+
+        ret = decode_nal_unit(s, nal);
         if (ret < 0) {
             av_log(s->avctx, AV_LOG_WARNING,
                    "Error parsing NAL unit #%d.\n", i);