avconv.c:1391: error: Null Dereference
  pointer `desc` last assigned on line 1388 could be null and is dereferenced at line 1391, column 15.

avconv.c:1381:1: start of procedure get_format()
1379. }
1380. 
1381. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1382. {
1383.     InputStream *ist = s->opaque;

avconv.c:1383:5: 
1381. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1382. {
1383.     InputStream *ist = s->opaque;
          ^
1384.     const enum AVPixelFormat *p;
1385.     int ret;

avconv.c:1387:10: 
1385.     int ret;
1386. 
1387.     for (p = pix_fmts; *p != -1; p++) {
               ^
1388.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1389.         const HWAccel *hwaccel;

avconv.c:1387:24: Loop condition is true. Entering loop body
1385.     int ret;
1386. 
1387.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1388.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1389.         const HWAccel *hwaccel;

avconv.c:1388:9: 
1386. 
1387.     for (p = pix_fmts; *p != -1; p++) {
1388.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1389.         const HWAccel *hwaccel;
1390. 

libavutil/pixdesc.c:1507:1: start of procedure av_pix_fmt_desc_get()
  1505. }
  1506. 
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1509:9: Taking false branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1509:24: Taking true branch
  1507. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1510:9: 
  1508. {
  1509.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1510.         return NULL;
                ^
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }

libavutil/pixdesc.c:1512:1: return from a call to av_pix_fmt_desc_get
  1510.         return NULL;
  1511.     return &av_pix_fmt_descriptors[pix_fmt];
  1512. }
        ^
  1513. 
  1514. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1391:15: 
1389.         const HWAccel *hwaccel;
1390. 
1391.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1392.             break;
1393. 
