avcodec/mpegvideo_enc: fix frame skipping with intra only codecs

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

libavcodec/mpegvideo.c

@@ -2655,7 +2655,9 @@ FF_ENABLE_DEPRECATION_WARNINGS
     else if (!is_mpeg12 && (s->h263_pred || s->h263_aic))
         s->mbintra_table[mb_xy]=1;
 
-    if ((s->flags&CODEC_FLAG_PSNR) || !(s->encoding && (s->intra_only || s->pict_type==AV_PICTURE_TYPE_B) && s->avctx->mb_decision != FF_MB_DECISION_RD)) { //FIXME precalc
+    if (   (s->flags&CODEC_FLAG_PSNR)
+        || s->avctx->frame_skip_threshold || s->avctx->frame_skip_factor
+        || !(s->encoding && (s->intra_only || s->pict_type==AV_PICTURE_TYPE_B) && s->avctx->mb_decision != FF_MB_DECISION_RD)) { //FIXME precalc
         uint8_t *dest_y, *dest_cb, *dest_cr;
         int dct_linesize, dct_offset;
         op_pixels_func (*op_pix)[4];

libavcodec/mpegvideo_enc.c

@@ -1300,17 +1300,9 @@ static int select_input_picture(MpegEncContext *s)
 
     /* set next picture type & ordering */
     if (s->reordered_input_picture[0] == NULL && s->input_picture[0]) {
-        if (/*s->picture_in_gop_number >= s->gop_size ||*/
-            s->next_picture_ptr == NULL || s->intra_only) {
-            s->reordered_input_picture[0] = s->input_picture[0];
-            s->reordered_input_picture[0]->f.pict_type = AV_PICTURE_TYPE_I;
-            s->reordered_input_picture[0]->f.coded_picture_number =
-                s->coded_picture_number++;
-        } else {
-            int b_frames;
-
         if (s->avctx->frame_skip_threshold || s->avctx->frame_skip_factor) {
             if (s->picture_in_gop_number < s->gop_size &&
+                s->next_picture_ptr &&
                 skip_check(s, s->input_picture[0], s->next_picture_ptr)) {
                 // FIXME check that te gop check above is +-1 correct
                 av_frame_unref(&s->input_picture[0]->f);
@@ -1322,6 +1314,15 @@ static int select_input_picture(MpegEncContext *s)
             }
         }
 
+        if (/*s->picture_in_gop_number >= s->gop_size ||*/
+            s->next_picture_ptr == NULL || s->intra_only) {
+            s->reordered_input_picture[0] = s->input_picture[0];
+            s->reordered_input_picture[0]->f.pict_type = AV_PICTURE_TYPE_I;
+            s->reordered_input_picture[0]->f.coded_picture_number =
+                s->coded_picture_number++;
+        } else {
+            int b_frames;
+
             if (s->flags & CODEC_FLAG_PASS2) {
                 for (i = 0; i < s->max_b_frames + 1; i++) {
                     int pict_num = s->input_picture[0]->f.display_picture_number + i;