libavcodec/mpegvideo.c:2212: error: Null Dereference
  pointer `desc` last assigned on line 2211 could be null and is dereferenced at line 2212, column 18.

libavcodec/mpegvideo.c:2206:1: start of procedure ff_draw_horiz_band()
2204.  * @param h is the normal height, this will be reduced automatically if needed for the last row
2205.  */
2206. void ff_draw_horiz_band(AVCodecContext *avctx, DSPContext *dsp, Picture *cur,
      ^
2207.                         Picture *last, int y, int h, int picture_structure,
2208.                         int first_field, int draw_edges, int low_delay,

libavcodec/mpegvideo.c:2211:5: 
2209.                         int v_edge_pos, int h_edge_pos)
2210. {
2211.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
          ^
2212.     int hshift = desc->log2_chroma_w;
2213.     int vshift = desc->log2_chroma_h;

libavutil/pixdesc.c:1464:1: start of procedure av_pix_fmt_desc_get()
  1462. }
  1463. 
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1466:9: Taking false branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1466:24: Taking true branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1467:9: 
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1467.         return NULL;
                ^
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }

libavutil/pixdesc.c:1469:1: return from a call to av_pix_fmt_desc_get
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }
        ^
  1470. 
  1471. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/mpegvideo.c:2212:5: 
2210. {
2211.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
2212.     int hshift = desc->log2_chroma_w;
          ^
2213.     int vshift = desc->log2_chroma_h;
2214.     const int field_pic = picture_structure != PICT_FRAME;
