avconv.c:1609: error: Null Dereference
  pointer `desc` last assigned on line 1606 could be null and is dereferenced at line 1609, column 15.

avconv.c:1599:1: start of procedure get_format()
1597. }
1598. 
1599. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1600. {
1601.     InputStream *ist = s->opaque;

avconv.c:1601:5: 
1599. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1600. {
1601.     InputStream *ist = s->opaque;
          ^
1602.     const enum AVPixelFormat *p;
1603.     int ret;

avconv.c:1605:10: 
1603.     int ret;
1604. 
1605.     for (p = pix_fmts; *p != -1; p++) {
               ^
1606.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1607.         const HWAccel *hwaccel;

avconv.c:1605:24: Loop condition is true. Entering loop body
1603.     int ret;
1604. 
1605.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1606.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1607.         const HWAccel *hwaccel;

avconv.c:1606:9: 
1604. 
1605.     for (p = pix_fmts; *p != -1; p++) {
1606.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1607.         const HWAccel *hwaccel;
1608. 

libavutil/pixdesc.c:1744:1: start of procedure av_pix_fmt_desc_get()
  1742. }
  1743. 
  1744. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1745. {
  1746.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1746:9: Taking false branch
  1744. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1745. {
  1746.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1747.         return NULL;
  1748.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1746:24: Taking true branch
  1744. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1745. {
  1746.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1747.         return NULL;
  1748.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1747:9: 
  1745. {
  1746.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1747.         return NULL;
                ^
  1748.     return &av_pix_fmt_descriptors[pix_fmt];
  1749. }

libavutil/pixdesc.c:1749:1: return from a call to av_pix_fmt_desc_get
  1747.         return NULL;
  1748.     return &av_pix_fmt_descriptors[pix_fmt];
  1749. }
        ^
  1750. 
  1751. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1609:15: 
1607.         const HWAccel *hwaccel;
1608. 
1609.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1610.             break;
1611. 
