libswscale/swscale_unscaled.c:1167: error: Null Dereference
  pointer `desc` last assigned on line 1163 could be null and is dereferenced at line 1167, column 21.

libswscale/swscale_unscaled.c:1160:1: start of procedure check_image_pointers()
1158. }
1159. 
1160. static int check_image_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt,
      ^
1161.                                 const int linesizes[4])
1162. {

libswscale/swscale_unscaled.c:1163:5: 
1161.                                 const int linesizes[4])
1162. {
1163.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
          ^
1164.     int i;
1165. 

libavutil/pixdesc.c:1626:1: start of procedure av_pix_fmt_desc_get()
  1624. }
  1625. 
  1626. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1627. {
  1628.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1628:9: Taking false branch
  1626. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1627. {
  1628.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1629.         return NULL;
  1630.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1628:24: Taking true branch
  1626. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1627. {
  1628.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1629.         return NULL;
  1630.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1629:9: 
  1627. {
  1628.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1629.         return NULL;
                ^
  1630.     return &av_pix_fmt_descriptors[pix_fmt];
  1631. }

libavutil/pixdesc.c:1631:1: return from a call to av_pix_fmt_desc_get
  1629.         return NULL;
  1630.     return &av_pix_fmt_descriptors[pix_fmt];
  1631. }
        ^
  1632. 
  1633. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/swscale_unscaled.c:1166:10: 
1164.     int i;
1165. 
1166.     for (i = 0; i < 4; i++) {
               ^
1167.         int plane = desc->comp[i].plane;
1168.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1166:17: Loop condition is true. Entering loop body
1164.     int i;
1165. 
1166.     for (i = 0; i < 4; i++) {
                      ^
1167.         int plane = desc->comp[i].plane;
1168.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1167:9: 
1165. 
1166.     for (i = 0; i < 4; i++) {
1167.         int plane = desc->comp[i].plane;
              ^
1168.         if (!data[plane] || !linesizes[plane])
1169.             return 0;
