libswscale/utils.c:752: error: Null Dereference
  pointer `desc` last assigned on line 751 could be null and is dereferenced at line 752, column 10.

libswscale/utils.c:749:1: start of procedure getSubSampleFactors()
747. #endif /* HAVE_MMXEXT_INLINE */
748. 
749. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
750. {
751.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:751:5: 
749. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
750. {
751.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
752.     *h = desc->log2_chroma_w;
753.     *v = 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)

libswscale/utils.c:752:5: 
750. {
751.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
752.     *h = desc->log2_chroma_w;
         ^
753.     *v = desc->log2_chroma_h;
754. }
