libavcodec/h264.c:90: error: Null Dereference
  pointer `desc` last assigned on line 89 could be null and is dereferenced at line 90, column 18.

libavcodec/h264.c:84:1: start of procedure ff_h264_draw_horiz_band()
82. }
83. 
84. void ff_h264_draw_horiz_band(const H264Context *h, H264SliceContext *sl,
    ^
85.                              int y, int height)
86. {

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

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

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

libavutil/pixdesc.c:1703:1: start of procedure av_pix_fmt_desc_get()
  1701. }
  1702. 
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1705:9: Taking false branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1705:24: Taking true branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1706:9: 
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1706.         return NULL;
                ^
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }

libavutil/pixdesc.c:1708:1: return from a call to av_pix_fmt_desc_get
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }
        ^
  1709. 
  1710. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

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