libavfilter/vf_showinfo.c:50: error: Null Dereference
  pointer `desc` last assigned on line 48 could be null and is dereferenced at line 50, column 26.

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

libavfilter/vf_showinfo.c:46:5: 
44. static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *frame)
45. {
46.     AVFilterContext *ctx = inlink->dst;
        ^
47.     ShowInfoContext *showinfo = ctx->priv;
48.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_showinfo.c:47:5: 
45. {
46.     AVFilterContext *ctx = inlink->dst;
47.     ShowInfoContext *showinfo = ctx->priv;
        ^
48.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
49.     uint32_t plane_checksum[4] = {0}, checksum = 0;

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

libavutil/pixdesc.c:1434:1: start of procedure av_pix_fmt_desc_get()
  1432. }
  1433. 
  1434. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1435. {
  1436.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1436:9: Taking false branch
  1434. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1435. {
  1436.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1437.         return NULL;
  1438.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1436:24: Taking true branch
  1434. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1435. {
  1436.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1437.         return NULL;
  1438.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1437:9: 
  1435. {
  1436.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1437.         return NULL;
                ^
  1438.     return &av_pix_fmt_descriptors[pix_fmt];
  1439. }

libavutil/pixdesc.c:1439:1: return from a call to av_pix_fmt_desc_get
  1437.         return NULL;
  1438.     return &av_pix_fmt_descriptors[pix_fmt];
  1439. }
        ^
  1440. 
  1441. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

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

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