libswscale/utils.c:785: error: Null Dereference
  pointer `desc` last assigned on line 784 could be null and is dereferenced at line 785, column 10.

libswscale/utils.c:782:1: start of procedure getSubSampleFactors()
780. #endif /* HAVE_MMXEXT_INLINE */
781. 
782. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
783. {
784.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:784:5: 
782. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
783. {
784.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
785.     *h = desc->log2_chroma_w;
786.     *v = desc->log2_chroma_h;

libavutil/pixdesc.c:1559:1: start of procedure av_pix_fmt_desc_get()
  1557. }
  1558. 
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1561:9: Taking false branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1561:24: Taking true branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1562:9: 
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1562.         return NULL;
                ^
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }

libavutil/pixdesc.c:1564:1: return from a call to av_pix_fmt_desc_get
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }
        ^
  1565. 
  1566. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/utils.c:785:5: 
783. {
784.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
785.     *h = desc->log2_chroma_w;
         ^
786.     *v = desc->log2_chroma_h;
787. }
