libavfilter/vf_showinfo.c:51: error: Null Dereference
  pointer `desc` last assigned on line 49 could be null and is dereferenced at line 51, column 26.

libavfilter/vf_showinfo.c:44:1: start of procedure end_frame()
42. }
43. 
44. static int end_frame(AVFilterLink *inlink)
    ^
45. {
46.     AVFilterContext *ctx = inlink->dst;

libavfilter/vf_showinfo.c:46:5: 
44. static int end_frame(AVFilterLink *inlink)
45. {
46.     AVFilterContext *ctx = inlink->dst;
        ^
47.     ShowInfoContext *showinfo = ctx->priv;
48.     AVFilterBufferRef *picref = inlink->cur_buf;

libavfilter/vf_showinfo.c:47:5: 
45. {
46.     AVFilterContext *ctx = inlink->dst;
47.     ShowInfoContext *showinfo = ctx->priv;
        ^
48.     AVFilterBufferRef *picref = inlink->cur_buf;
49.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_showinfo.c:48:5: 
46.     AVFilterContext *ctx = inlink->dst;
47.     ShowInfoContext *showinfo = ctx->priv;
48.     AVFilterBufferRef *picref = inlink->cur_buf;
        ^
49.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
50.     uint32_t plane_checksum[4] = {0}, checksum = 0;

libavfilter/vf_showinfo.c:49:5: 
47.     ShowInfoContext *showinfo = ctx->priv;
48.     AVFilterBufferRef *picref = inlink->cur_buf;
49.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
        ^
50.     uint32_t plane_checksum[4] = {0}, checksum = 0;
51.     int i, plane, vsub = desc->log2_chroma_h;

libavutil/pixdesc.c:1199:1: start of procedure av_pix_fmt_desc_get()
  1197. }
  1198. 
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1201:9: Taking false branch
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1201:24: Taking true branch
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1202:9: 
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1202.         return NULL;
                ^
  1203.     return &av_pix_fmt_descriptors[pix_fmt];
  1204. }

libavutil/pixdesc.c:1204:1: return from a call to av_pix_fmt_desc_get
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];
  1204. }
        ^
  1205. 
  1206. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_showinfo.c:50:5: 
48.     AVFilterBufferRef *picref = inlink->cur_buf;
49.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
50.     uint32_t plane_checksum[4] = {0}, checksum = 0;
        ^
51.     int i, plane, vsub = desc->log2_chroma_h;
52. 

libavfilter/vf_showinfo.c:51:5: 
49.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
50.     uint32_t plane_checksum[4] = {0}, checksum = 0;
51.     int i, plane, vsub = desc->log2_chroma_h;
        ^
52. 
53.     for (plane = 0; picref->data[plane] && plane < 4; plane++) {
