libavcodec/h264.c:86: error: Null Dereference
  pointer `desc` last assigned on line 85 could be null and is dereferenced at line 86, column 18.

libavcodec/h264.c:80:1: start of procedure ff_h264_draw_horiz_band()
78. }
79. 
80. void ff_h264_draw_horiz_band(H264Context *h, int y, int height)
    ^
81. {
82.     AVCodecContext *avctx = h->avctx;

libavcodec/h264.c:82:5: 
80. void ff_h264_draw_horiz_band(H264Context *h, int y, int height)
81. {
82.     AVCodecContext *avctx = h->avctx;
        ^
83.     AVFrame *cur  = &h->cur_pic.f;
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;

libavcodec/h264.c:83:5: 
81. {
82.     AVCodecContext *avctx = h->avctx;
83.     AVFrame *cur  = &h->cur_pic.f;
        ^
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
85.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);

libavcodec/h264.c:84:21: Condition is true
82.     AVCodecContext *avctx = h->avctx;
83.     AVFrame *cur  = &h->cur_pic.f;
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
                        ^
85.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
86.     int vshift = desc->log2_chroma_h;

libavcodec/h264.c:84:5: 
82.     AVCodecContext *avctx = h->avctx;
83.     AVFrame *cur  = &h->cur_pic.f;
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
        ^
85.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
86.     int vshift = desc->log2_chroma_h;

libavcodec/h264.c:85:5: 
83.     AVFrame *cur  = &h->cur_pic.f;
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
85.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
        ^
86.     int vshift = desc->log2_chroma_h;
87.     const int field_pic = h->picture_structure != PICT_FRAME;

libavutil/pixdesc.c:1574:1: start of procedure av_pix_fmt_desc_get()
  1572. }
  1573. 
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1576:9: Taking false branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1576:24: Taking true branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1577:9: 
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1577.         return NULL;
                ^
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }

libavutil/pixdesc.c:1579:1: return from a call to av_pix_fmt_desc_get
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }
        ^
  1580. 
  1581. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavcodec/h264.c:86:5: 
84.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
85.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);
86.     int vshift = desc->log2_chroma_h;
        ^
87.     const int field_pic = h->picture_structure != PICT_FRAME;
88.     if (field_pic) {
