libavcodec/mpegvideo_enc.c:1353: error: Null Dereference
  pointer `desc` last assigned on line 1352 could be null and is dereferenced at line 1353, column 22.

libavcodec/mpegvideo_enc.c:1345:1: start of procedure frame_end()
1343. }
1344. 
1345. static void frame_end(MpegEncContext *s)
      ^
1346. {
1347.     int i;

libavcodec/mpegvideo_enc.c:1349:9: Taking true branch
1347.     int i;
1348. 
1349.     if (s->unrestricted_mv &&
              ^
1350.         s->current_picture.reference &&
1351.         !s->intra_only) {

libavcodec/mpegvideo_enc.c:1350:9: Taking true branch
1348. 
1349.     if (s->unrestricted_mv &&
1350.         s->current_picture.reference &&
              ^
1351.         !s->intra_only) {
1352.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);

libavcodec/mpegvideo_enc.c:1351:10: Taking true branch
1349.     if (s->unrestricted_mv &&
1350.         s->current_picture.reference &&
1351.         !s->intra_only) {
               ^
1352.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1353.         int hshift = desc->log2_chroma_w;

libavcodec/mpegvideo_enc.c:1352:9: 
1350.         s->current_picture.reference &&
1351.         !s->intra_only) {
1352.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
              ^
1353.         int hshift = desc->log2_chroma_w;
1354.         int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1507:1: start of procedure av_pix_fmt_desc_get()
  1505. }
  1506. 
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1509:9: Taking false branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1509:24: Taking true branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1510:9: 
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1510.         return NULL;
                ^
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }

libavutil/pixdesc.c:1512:1: return from a call to av_pix_fmt_desc_get
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }
        ^
  1513. 
  1514. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo_enc.c:1353:9: 
1351.         !s->intra_only) {
1352.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(s->avctx->pix_fmt);
1353.         int hshift = desc->log2_chroma_w;
              ^
1354.         int vshift = desc->log2_chroma_h;
1355.         s->dsp.draw_edges(s->current_picture.f.data[0], s->linesize,
