libavfilter/vf_showinfo.c:77: error: Null Dereference
  pointer `desc` last assigned on line 75 could be null and is dereferenced at line 77, column 26.

libavfilter/vf_showinfo.c:71:1: start of procedure filter_frame()
69. }
70. 
71. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
    ^
72. {
73.     AVFilterContext *ctx = inlink->dst;

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

libavfilter/vf_showinfo.c:74:5: 
72. {
73.     AVFilterContext *ctx = inlink->dst;
74.     ShowInfoContext *showinfo = ctx->priv;
        ^
75.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
76.     uint32_t plane_checksum[4] = {0}, checksum = 0;

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

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)

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

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