libswscale/utils.c:801: error: Null Dereference
  pointer `desc` last assigned on line 800 could be null and is dereferenced at line 801, column 10.

libswscale/utils.c:798:1: start of procedure getSubSampleFactors()
796. #endif /* HAVE_MMXEXT_INLINE */
797. 
798. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
799. {
800.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:800:5: 
798. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
799. {
800.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
801.     *h = desc->log2_chroma_w;
802.     *v = desc->log2_chroma_h;

libavutil/pixdesc.c:1898:1: start of procedure av_pix_fmt_desc_get()
  1896. }
  1897. 
  1898. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1899. {
  1900.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1900:9: Taking false branch
  1898. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1899. {
  1900.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1901.         return NULL;
  1902.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1900:24: Taking true branch
  1898. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1899. {
  1900.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1901.         return NULL;
  1902.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1901:9: 
  1899. {
  1900.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1901.         return NULL;
                ^
  1902.     return &av_pix_fmt_descriptors[pix_fmt];
  1903. }

libavutil/pixdesc.c:1903:1: return from a call to av_pix_fmt_desc_get
  1901.         return NULL;
  1902.     return &av_pix_fmt_descriptors[pix_fmt];
  1903. }
        ^
  1904. 
  1905. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/utils.c:801:5: 
799. {
800.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
801.     *h = desc->log2_chroma_w;
         ^
802.     *v = desc->log2_chroma_h;
803. }
