libavcodec/h264.c:87: error: Null Dereference
  pointer `desc` last assigned on line 86 could be null and is dereferenced at line 87, column 18.

libavcodec/h264.c:81:1: start of procedure ff_h264_draw_horiz_band()
79. }
80. 
81. void ff_h264_draw_horiz_band(const H264Context *h, H264SliceContext *sl,
    ^
82.                              int y, int height)
83. {

libavcodec/h264.c:84:5: 
82.                              int y, int height)
83. {
84.     AVCodecContext *avctx = h->avctx;
        ^
85.     const AVFrame   *src  = &h->cur_pic.f;
86.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);

libavcodec/h264.c:85:5: 
83. {
84.     AVCodecContext *avctx = h->avctx;
85.     const AVFrame   *src  = &h->cur_pic.f;
        ^
86.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
87.     int vshift = desc->log2_chroma_h;

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

libavutil/pixdesc.c:1676:1: start of procedure av_pix_fmt_desc_get()
  1674. }
  1675. 
  1676. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1677. {
  1678.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1678:9: Taking false branch
  1676. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1677. {
  1678.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1679.         return NULL;
  1680.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1678:24: Taking true branch
  1676. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1677. {
  1678.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1679.         return NULL;
  1680.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1679:9: 
  1677. {
  1678.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1679.         return NULL;
                ^
  1680.     return &av_pix_fmt_descriptors[pix_fmt];
  1681. }

libavutil/pixdesc.c:1681:1: return from a call to av_pix_fmt_desc_get
  1679.         return NULL;
  1680.     return &av_pix_fmt_descriptors[pix_fmt];
  1681. }
        ^
  1682. 
  1683. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

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