libswscale/utils.c:793: error: Null Dereference
  pointer `desc` last assigned on line 792 could be null and is dereferenced at line 793, column 10.

libswscale/utils.c:790:1: start of procedure getSubSampleFactors()
788. #endif /* HAVE_MMXEXT_INLINE */
789. 
790. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
791. {
792.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:792:5: 
790. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
791. {
792.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
793.     *h = desc->log2_chroma_w;
794.     *v = desc->log2_chroma_h;

libavutil/pixdesc.c:1768:1: start of procedure av_pix_fmt_desc_get()
  1766. }
  1767. 
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1770:9: Taking false branch
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1770:24: Taking true branch
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1771:9: 
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1771.         return NULL;
                ^
  1772.     return &av_pix_fmt_descriptors[pix_fmt];
  1773. }

libavutil/pixdesc.c:1773:1: return from a call to av_pix_fmt_desc_get
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];
  1773. }
        ^
  1774. 
  1775. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/utils.c:793:5: 
791. {
792.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
793.     *h = desc->log2_chroma_w;
         ^
794.     *v = desc->log2_chroma_h;
795. }

static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
    *h = desc->log2_chroma_w;
    *v = desc->log2_chroma_h;
}
['static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)\n{\n    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);\n    *h = desc->log2_chroma_w;\n    *v = desc->log2_chroma_h;\n}', 'const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)\n{\n    if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)\n        return NULL;\n    return &av_pix_fmt_descriptors[pix_fmt];\n}']