libswscale/swscale_unscaled.c:1117: error: Null Dereference
  pointer `desc` last assigned on line 1113 could be null and is dereferenced at line 1117, column 21.

libswscale/swscale_unscaled.c:1110:1: start of procedure check_image_pointers()
1108. }
1109. 
1110. static int check_image_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt,
      ^
1111.                                 const int linesizes[4])
1112. {

libswscale/swscale_unscaled.c:1113:5: 
1111.                                 const int linesizes[4])
1112. {
1113.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
          ^
1114.     int i;
1115. 

libavutil/pixdesc.c:1440:1: start of procedure av_pix_fmt_desc_get()
  1438. }
  1439. 
  1440. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1441. {
  1442.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1442:9: Taking false branch
  1440. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1441. {
  1442.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1443.         return NULL;
  1444.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1442:24: Taking true branch
  1440. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1441. {
  1442.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1443.         return NULL;
  1444.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1443:9: 
  1441. {
  1442.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1443.         return NULL;
                ^
  1444.     return &av_pix_fmt_descriptors[pix_fmt];
  1445. }

libavutil/pixdesc.c:1445:1: return from a call to av_pix_fmt_desc_get
  1443.         return NULL;
  1444.     return &av_pix_fmt_descriptors[pix_fmt];
  1445. }
        ^
  1446. 
  1447. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/swscale_unscaled.c:1116:10: 
1114.     int i;
1115. 
1116.     for (i = 0; i < 4; i++) {
               ^
1117.         int plane = desc->comp[i].plane;
1118.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1116:17: Loop condition is true. Entering loop body
1114.     int i;
1115. 
1116.     for (i = 0; i < 4; i++) {
                      ^
1117.         int plane = desc->comp[i].plane;
1118.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1117:9: 
1115. 
1116.     for (i = 0; i < 4; i++) {
1117.         int plane = desc->comp[i].plane;
              ^
1118.         if (!data[plane] || !linesizes[plane])
1119.             return 0;
