avcodec/ffv1dec: Fix copying planes of paletted formats

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 3a4d387195)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/ffv1dec.c

@@ -883,7 +883,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
             const uint8_t *src[4];
             uint8_t *dst[4];
             ff_thread_await_progress(&f->last_picture, INT_MAX, 0);
-            for (j = 0; j < 4; j++) {
+            for (j = 0; j < desc->nb_components; j++) {
                 int pixshift = desc->comp[j].depth > 8;
                 int sh = (j == 1 || j == 2) ? f->chroma_h_shift : 0;
                 int sv = (j == 1 || j == 2) ? f->chroma_v_shift : 0;
@@ -891,6 +891,12 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
                          (fs->slice_y >> sv) + ((fs->slice_x >> sh) << pixshift);
                 src[j] = f->last_picture.f->data[j] + f->last_picture.f->linesize[j] *
                          (fs->slice_y >> sv) + ((fs->slice_x >> sh) << pixshift);
+
+            }
+            if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
+                desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+                dst[1] = p->data[1];
+                src[1] = f->last_picture.f->data[1];
             }
             av_image_copy(dst, p->linesize, src,
                           f->last_picture.f->linesize,