avconv.c:1510: error: Null Dereference
  pointer `desc` last assigned on line 1507 could be null and is dereferenced at line 1510, column 15.

avconv.c:1500:1: start of procedure get_format()
1498. }
1499. 
1500. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1501. {
1502.     InputStream *ist = s->opaque;

avconv.c:1502:5: 
1500. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1501. {
1502.     InputStream *ist = s->opaque;
          ^
1503.     const enum AVPixelFormat *p;
1504.     int ret;

avconv.c:1506:10: 
1504.     int ret;
1505. 
1506.     for (p = pix_fmts; *p != -1; p++) {
               ^
1507.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1508.         const HWAccel *hwaccel;

avconv.c:1506:24: Loop condition is true. Entering loop body
1504.     int ret;
1505. 
1506.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1507.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1508.         const HWAccel *hwaccel;

avconv.c:1507:9: 
1505. 
1506.     for (p = pix_fmts; *p != -1; p++) {
1507.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1508.         const HWAccel *hwaccel;
1509. 

libavutil/pixdesc.c:1574:1: start of procedure av_pix_fmt_desc_get()
  1572. }
  1573. 
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1576:9: Taking false branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1576:24: Taking true branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1577:9: 
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1577.         return NULL;
                ^
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }

libavutil/pixdesc.c:1579:1: return from a call to av_pix_fmt_desc_get
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }
        ^
  1580. 
  1581. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1510:15: 
1508.         const HWAccel *hwaccel;
1509. 
1510.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1511.             break;
1512. 
