libavcodec/mpegvideo_enc.c:1454: error: Null Dereference
  pointer `desc` last assigned on line 1453 could be null and is dereferenced at line 1454, column 22.

libavcodec/mpegvideo_enc.c:1446:1: start of procedure frame_end()
1444. }
1445. 
1446. static void frame_end(MpegEncContext *s)
      ^
1447. {
1448.     int i;

libavcodec/mpegvideo_enc.c:1450:9: Taking true branch
1448.     int i;
1449. 
1450.     if (s->unrestricted_mv &&
              ^
1451.         s->current_picture.reference &&
1452.         !s->intra_only) {

libavcodec/mpegvideo_enc.c:1451:9: Taking true branch
1449. 
1450.     if (s->unrestricted_mv &&
1451.         s->current_picture.reference &&
              ^
1452.         !s->intra_only) {
1453.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);

libavcodec/mpegvideo_enc.c:1452:10: Taking true branch
1450.     if (s->unrestricted_mv &&
1451.         s->current_picture.reference &&
1452.         !s->intra_only) {
               ^
1453.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1454.         int hshift = desc->log2_chroma_w;

libavcodec/mpegvideo_enc.c:1453:9: 
1451.         s->current_picture.reference &&
1452.         !s->intra_only) {
1453.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
              ^
1454.         int hshift = desc->log2_chroma_w;
1455.         int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1686:1: start of procedure av_pix_fmt_desc_get()
  1684. }
  1685. 
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1688:9: Taking false branch
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1688:24: Taking true branch
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1689:9: 
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1689.         return NULL;
                ^
  1690.     return &av_pix_fmt_descriptors[pix_fmt];
  1691. }

libavutil/pixdesc.c:1691:1: return from a call to av_pix_fmt_desc_get
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];
  1691. }
        ^
  1692. 
  1693. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo_enc.c:1454:9: 
1452.         !s->intra_only) {
1453.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1454.         int hshift = desc->log2_chroma_w;
              ^
1455.         int vshift = desc->log2_chroma_h;
1456.         s->mpvencdsp.draw_edges(s->current_picture.f->data[0], s->linesize,
