avconv.c:1492: error: Null Dereference
  pointer `desc` last assigned on line 1489 could be null and is dereferenced at line 1492, column 15.

avconv.c:1482:1: start of procedure get_format()
1480. }
1481. 
1482. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1483. {
1484.     InputStream *ist = s->opaque;

avconv.c:1484:5: 
1482. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1483. {
1484.     InputStream *ist = s->opaque;
          ^
1485.     const enum AVPixelFormat *p;
1486.     int ret;

avconv.c:1488:10: 
1486.     int ret;
1487. 
1488.     for (p = pix_fmts; *p != -1; p++) {
               ^
1489.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1490.         const HWAccel *hwaccel;

avconv.c:1488:24: Loop condition is true. Entering loop body
1486.     int ret;
1487. 
1488.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1489.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1490.         const HWAccel *hwaccel;

avconv.c:1489:9: 
1487. 
1488.     for (p = pix_fmts; *p != -1; p++) {
1489.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1490.         const HWAccel *hwaccel;
1491. 

libavutil/pixdesc.c:1559:1: start of procedure av_pix_fmt_desc_get()
  1557. }
  1558. 
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1561:9: Taking false branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1561:24: Taking true branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1562:9: 
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1562.         return NULL;
                ^
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }

libavutil/pixdesc.c:1564:1: return from a call to av_pix_fmt_desc_get
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }
        ^
  1565. 
  1566. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1492:15: 
1490.         const HWAccel *hwaccel;
1491. 
1492.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1493.             break;
1494. 
