avconv.c:1501: error: Null Dereference
  pointer `desc` last assigned on line 1498 could be null and is dereferenced at line 1501, column 15.

avconv.c:1491:1: start of procedure get_format()
1489. }
1490. 
1491. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1492. {
1493.     InputStream *ist = s->opaque;

avconv.c:1493:5: 
1491. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1492. {
1493.     InputStream *ist = s->opaque;
          ^
1494.     const enum AVPixelFormat *p;
1495.     int ret;

avconv.c:1497:10: 
1495.     int ret;
1496. 
1497.     for (p = pix_fmts; *p != -1; p++) {
               ^
1498.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1499.         const HWAccel *hwaccel;

avconv.c:1497:24: Loop condition is true. Entering loop body
1495.     int ret;
1496. 
1497.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1498.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1499.         const HWAccel *hwaccel;

avconv.c:1498:9: 
1496. 
1497.     for (p = pix_fmts; *p != -1; p++) {
1498.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1499.         const HWAccel *hwaccel;
1500. 

libavutil/pixdesc.c:1570:1: start of procedure av_pix_fmt_desc_get()
  1568. }
  1569. 
  1570. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1571. {
  1572.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1572:9: Taking false branch
  1570. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1571. {
  1572.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1573.         return NULL;
  1574.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1572:24: Taking true branch
  1570. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1571. {
  1572.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1573.         return NULL;
  1574.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1573:9: 
  1571. {
  1572.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1573.         return NULL;
                ^
  1574.     return &av_pix_fmt_descriptors[pix_fmt];
  1575. }

libavutil/pixdesc.c:1575:1: return from a call to av_pix_fmt_desc_get
  1573.         return NULL;
  1574.     return &av_pix_fmt_descriptors[pix_fmt];
  1575. }
        ^
  1576. 
  1577. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1501:15: 
1499.         const HWAccel *hwaccel;
1500. 
1501.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1502.             break;
1503. 
