libswscale/utils.c:796: error: Null Dereference
  pointer `desc` last assigned on line 795 could be null and is dereferenced at line 796, column 10.

libswscale/utils.c:793:1: start of procedure getSubSampleFactors()
791. #endif /* HAVE_MMXEXT_INLINE */
792. 
793. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
794. {
795.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:795:5: 
793. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
794. {
795.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
796.     *h = desc->log2_chroma_w;
797.     *v = desc->log2_chroma_h;

libavutil/pixdesc.c:1892:1: start of procedure av_pix_fmt_desc_get()
  1890. }
  1891. 
  1892. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1893. {
  1894.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1894:9: Taking false branch
  1892. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1893. {
  1894.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1895.         return NULL;
  1896.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1894:24: Taking true branch
  1892. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1893. {
  1894.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1895.         return NULL;
  1896.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1895:9: 
  1893. {
  1894.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1895.         return NULL;
                ^
  1896.     return &av_pix_fmt_descriptors[pix_fmt];
  1897. }

libavutil/pixdesc.c:1897:1: return from a call to av_pix_fmt_desc_get
  1895.         return NULL;
  1896.     return &av_pix_fmt_descriptors[pix_fmt];
  1897. }
        ^
  1898. 
  1899. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/utils.c:796:5: 
794. {
795.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
796.     *h = desc->log2_chroma_w;
         ^
797.     *v = desc->log2_chroma_h;
798. }
