libavcodec/h264.c:85: error: Null Dereference
  pointer `desc` last assigned on line 84 could be null and is dereferenced at line 85, column 18.

libavcodec/h264.c:79:1: start of procedure ff_h264_draw_horiz_band()
77. }
78. 
79. void ff_h264_draw_horiz_band(H264Context *h, int y, int height)
    ^
80. {
81.     AVCodecContext *avctx = h->avctx;

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

libavcodec/h264.c:82:5: 
80. {
81.     AVCodecContext *avctx = h->avctx;
82.     AVFrame *cur  = &h->cur_pic.f;
        ^
83.     AVFrame *last = h->ref_list[0][0].f.data[0] ? &h->ref_list[0][0].f : NULL;
84.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(avctx->pix_fmt);

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

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

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

libavutil/pixdesc.c:1559:1: start of procedure av_pix_fmt_desc_get()
  1557. }
  1558. 
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1561:9: Taking false branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1561:24: Taking true branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1562:9: 
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1562.         return NULL;
                ^
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }

libavutil/pixdesc.c:1564:1: return from a call to av_pix_fmt_desc_get
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }
        ^
  1565. 
  1566. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

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