libavfilter/vf_showinfo.c:78: error: Null Dereference
  pointer `desc` last assigned on line 76 could be null and is dereferenced at line 78, column 26.

libavfilter/vf_showinfo.c:72:1: start of procedure filter_frame()
70. }
71. 
72. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
    ^
73. {
74.     AVFilterContext *ctx = inlink->dst;

libavfilter/vf_showinfo.c:74:5: 
72. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
73. {
74.     AVFilterContext *ctx = inlink->dst;
        ^
75.     ShowInfoContext *showinfo = ctx->priv;
76.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_showinfo.c:75:5: 
73. {
74.     AVFilterContext *ctx = inlink->dst;
75.     ShowInfoContext *showinfo = ctx->priv;
        ^
76.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
77.     uint32_t plane_checksum[4] = {0}, checksum = 0;

libavfilter/vf_showinfo.c:76:5: 
74.     AVFilterContext *ctx = inlink->dst;
75.     ShowInfoContext *showinfo = ctx->priv;
76.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
        ^
77.     uint32_t plane_checksum[4] = {0}, checksum = 0;
78.     int i, plane, vsub = desc->log2_chroma_h;

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)

libavfilter/vf_showinfo.c:77:5: 
75.     ShowInfoContext *showinfo = ctx->priv;
76.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
77.     uint32_t plane_checksum[4] = {0}, checksum = 0;
        ^
78.     int i, plane, vsub = desc->log2_chroma_h;
79. 

libavfilter/vf_showinfo.c:78:5: 
76.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
77.     uint32_t plane_checksum[4] = {0}, checksum = 0;
78.     int i, plane, vsub = desc->log2_chroma_h;
        ^
79. 
80.     for (plane = 0; frame->data[plane] && plane < 4; plane++) {
