libswscale/utils.c:772: error: Null Dereference
  pointer `desc` last assigned on line 771 could be null and is dereferenced at line 772, column 10.

libswscale/utils.c:769:1: start of procedure getSubSampleFactors()
767. #endif /* HAVE_MMXEXT_INLINE */
768. 
769. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
     ^
770. {
771.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);

libswscale/utils.c:771:5: 
769. static void getSubSampleFactors(int *h, int *v, enum AVPixelFormat format)
770. {
771.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
         ^
772.     *h = desc->log2_chroma_w;
773.     *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:772:5: 
770. {
771.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
772.     *h = desc->log2_chroma_w;
         ^
773.     *v = desc->log2_chroma_h;
774. }

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}']