libavcodec/h264.c:89: error: Null Dereference
  pointer `desc` last assigned on line 88 could be null and is dereferenced at line 89, column 18.

libavcodec/h264.c:83:1: start of procedure ff_h264_draw_horiz_band()
81. }
82. 
83. void ff_h264_draw_horiz_band(const H264Context *h, H264SliceContext *sl,
    ^
84.                              int y, int height)
85. {

libavcodec/h264.c:86:5: 
84.                              int y, int height)
85. {
86.     AVCodecContext *avctx = h->avctx;
        ^
87.     const AVFrame   *src  = h->cur_pic.f;
88.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);

libavcodec/h264.c:87:5: 
85. {
86.     AVCodecContext *avctx = h->avctx;
87.     const AVFrame   *src  = h->cur_pic.f;
        ^
88.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
89.     int vshift = desc->log2_chroma_h;

libavcodec/h264.c:88:5: 
86.     AVCodecContext *avctx = h->avctx;
87.     const AVFrame   *src  = h->cur_pic.f;
88.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
        ^
89.     int vshift = desc->log2_chroma_h;
90.     const int field_pic = h->picture_structure != PICT_FRAME;

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/h264.c:89:5: 
87.     const AVFrame   *src  = h->cur_pic.f;
88.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
89.     int vshift = desc->log2_chroma_h;
        ^
90.     const int field_pic = h->picture_structure != PICT_FRAME;
91.     if (field_pic) {
