avconv.c:1479: error: Null Dereference
  pointer `desc` last assigned on line 1476 could be null and is dereferenced at line 1479, column 15.

avconv.c:1469:1: start of procedure get_format()
1467. }
1468. 
1469. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1470. {
1471.     InputStream *ist = s->opaque;

avconv.c:1471:5: 
1469. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1470. {
1471.     InputStream *ist = s->opaque;
          ^
1472.     const enum AVPixelFormat *p;
1473.     int ret;

avconv.c:1475:10: 
1473.     int ret;
1474. 
1475.     for (p = pix_fmts; *p != -1; p++) {
               ^
1476.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1477.         const HWAccel *hwaccel;

avconv.c:1475:24: Loop condition is true. Entering loop body
1473.     int ret;
1474. 
1475.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1476.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1477.         const HWAccel *hwaccel;

avconv.c:1476:9: 
1474. 
1475.     for (p = pix_fmts; *p != -1; p++) {
1476.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1477.         const HWAccel *hwaccel;
1478. 

libavutil/pixdesc.c:1682:1: start of procedure av_pix_fmt_desc_get()
  1680. }
  1681. 
  1682. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1683. {
  1684.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1684:9: Taking false branch
  1682. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1683. {
  1684.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1685.         return NULL;
  1686.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1684:24: Taking true branch
  1682. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1683. {
  1684.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1685.         return NULL;
  1686.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1685:9: 
  1683. {
  1684.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1685.         return NULL;
                ^
  1686.     return &av_pix_fmt_descriptors[pix_fmt];
  1687. }

libavutil/pixdesc.c:1687:1: return from a call to av_pix_fmt_desc_get
  1685.         return NULL;
  1686.     return &av_pix_fmt_descriptors[pix_fmt];
  1687. }
        ^
  1688. 
  1689. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1479:15: 
1477.         const HWAccel *hwaccel;
1478. 
1479.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1480.             break;
1481. 
