libavcodec/mpegvideo_enc.c:1356: error: Null Dereference
  pointer `desc` last assigned on line 1355 could be null and is dereferenced at line 1356, column 22.

libavcodec/mpegvideo_enc.c:1348:1: start of procedure frame_end()
1346. }
1347. 
1348. static void frame_end(MpegEncContext *s)
      ^
1349. {
1350.     int i;

libavcodec/mpegvideo_enc.c:1352:9: Taking true branch
1350.     int i;
1351. 
1352.     if (s->unrestricted_mv &&
              ^
1353.         s->current_picture.reference &&
1354.         !s->intra_only) {

libavcodec/mpegvideo_enc.c:1353:9: Taking true branch
1351. 
1352.     if (s->unrestricted_mv &&
1353.         s->current_picture.reference &&
              ^
1354.         !s->intra_only) {
1355.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);

libavcodec/mpegvideo_enc.c:1354:10: Taking true branch
1352.     if (s->unrestricted_mv &&
1353.         s->current_picture.reference &&
1354.         !s->intra_only) {
               ^
1355.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1356.         int hshift = desc->log2_chroma_w;

libavcodec/mpegvideo_enc.c:1355:9: 
1353.         s->current_picture.reference &&
1354.         !s->intra_only) {
1355.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
              ^
1356.         int hshift = desc->log2_chroma_w;
1357.         int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1559:1: start of procedure av_pix_fmt_desc_get()
  1557. }
  1558. 
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1561:9: Taking false branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1561:24: Taking true branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1562:9: 
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1562.         return NULL;
                ^
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }

libavutil/pixdesc.c:1564:1: return from a call to av_pix_fmt_desc_get
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }
        ^
  1565. 
  1566. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo_enc.c:1356:9: 
1354.         !s->intra_only) {
1355.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1356.         int hshift = desc->log2_chroma_w;
              ^
1357.         int vshift = desc->log2_chroma_h;
1358.         s->dsp.draw_edges(s->current_picture.f.data[0], s->linesize,
