libavcodec/mpegvideo_enc.c:1432: error: Null Dereference
  pointer `desc` last assigned on line 1431 could be null and is dereferenced at line 1432, column 22.

libavcodec/mpegvideo_enc.c:1424:1: start of procedure frame_end()
1422. }
1423. 
1424. static void frame_end(MpegEncContext *s)
      ^
1425. {
1426.     int i;

libavcodec/mpegvideo_enc.c:1428:9: Taking true branch
1426.     int i;
1427. 
1428.     if (s->unrestricted_mv &&
              ^
1429.         s->current_picture.reference &&
1430.         !s->intra_only) {

libavcodec/mpegvideo_enc.c:1429:9: Taking true branch
1427. 
1428.     if (s->unrestricted_mv &&
1429.         s->current_picture.reference &&
              ^
1430.         !s->intra_only) {
1431.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);

libavcodec/mpegvideo_enc.c:1430:10: Taking true branch
1428.     if (s->unrestricted_mv &&
1429.         s->current_picture.reference &&
1430.         !s->intra_only) {
               ^
1431.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1432.         int hshift = desc->log2_chroma_w;

libavcodec/mpegvideo_enc.c:1431:9: 
1429.         s->current_picture.reference &&
1430.         !s->intra_only) {
1431.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
              ^
1432.         int hshift = desc->log2_chroma_w;
1433.         int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1669:1: start of procedure av_pix_fmt_desc_get()
  1667. }
  1668. 
  1669. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1670. {
  1671.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1671:9: Taking false branch
  1669. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1670. {
  1671.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1672.         return NULL;
  1673.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1671:24: Taking true branch
  1669. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1670. {
  1671.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1672.         return NULL;
  1673.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1672:9: 
  1670. {
  1671.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1672.         return NULL;
                ^
  1673.     return &av_pix_fmt_descriptors[pix_fmt];
  1674. }

libavutil/pixdesc.c:1674:1: return from a call to av_pix_fmt_desc_get
  1672.         return NULL;
  1673.     return &av_pix_fmt_descriptors[pix_fmt];
  1674. }
        ^
  1675. 
  1676. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo_enc.c:1432:9: 
1430.         !s->intra_only) {
1431.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1432.         int hshift = desc->log2_chroma_w;
              ^
1433.         int vshift = desc->log2_chroma_h;
1434.         s->mpvencdsp.draw_edges(s->current_picture.f->data[0], s->linesize,
