avconv.c:1459: error: Null Dereference
  pointer `desc` last assigned on line 1456 could be null and is dereferenced at line 1459, column 15.

avconv.c:1449:1: start of procedure get_format()
1447. }
1448. 
1449. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1450. {
1451.     InputStream *ist = s->opaque;

avconv.c:1451:5: 
1449. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1450. {
1451.     InputStream *ist = s->opaque;
          ^
1452.     const enum AVPixelFormat *p;
1453.     int ret;

avconv.c:1455:10: 
1453.     int ret;
1454. 
1455.     for (p = pix_fmts; *p != -1; p++) {
               ^
1456.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1457.         const HWAccel *hwaccel;

avconv.c:1455:24: Loop condition is true. Entering loop body
1453.     int ret;
1454. 
1455.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1456.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1457.         const HWAccel *hwaccel;

avconv.c:1456:9: 
1454. 
1455.     for (p = pix_fmts; *p != -1; p++) {
1456.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1457.         const HWAccel *hwaccel;
1458. 

libavutil/pixdesc.c:1686:1: start of procedure av_pix_fmt_desc_get()
  1684. }
  1685. 
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1688:9: Taking false branch
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1688:24: Taking true branch
  1686. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1689:9: 
  1687. {
  1688.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1689.         return NULL;
                ^
  1690.     return &av_pix_fmt_descriptors[pix_fmt];
  1691. }

libavutil/pixdesc.c:1691:1: return from a call to av_pix_fmt_desc_get
  1689.         return NULL;
  1690.     return &av_pix_fmt_descriptors[pix_fmt];
  1691. }
        ^
  1692. 
  1693. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1459:15: 
1457.         const HWAccel *hwaccel;
1458. 
1459.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1460.             break;
1461. 
