libswscale/utils.c:782: error: Null Dereference
  pointer `desc` last assigned on line 781 could be null and is dereferenced at line 782, column 10.

libswscale/utils.c:779:1: start of procedure getSubSampleFactors()
777. #endif /* HAVE_MMXEXT_INLINE */
778. 
779. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
780. {
781.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:781:5: 
779. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
780. {
781.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
782.     *h = desc->log2_chroma_w;
783.     *v = desc->log2_chroma_h;

libavutil/pixdesc.c:1464:1: start of procedure av_pix_fmt_desc_get()
  1462. }
  1463. 
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1466:9: Taking false branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1466:24: Taking true branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1467:9: 
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1467.         return NULL;
                ^
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }

libavutil/pixdesc.c:1469:1: return from a call to av_pix_fmt_desc_get
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }
        ^
  1470. 
  1471. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/utils.c:782:5: 
780. {
781.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
782.     *h = desc->log2_chroma_w;
         ^
783.     *v = desc->log2_chroma_h;
784. }
