avconv.c:1519: error: Null Dereference
  pointer `desc` last assigned on line 1516 could be null and is dereferenced at line 1519, column 15.

avconv.c:1509:1: start of procedure get_format()
1507. }
1508. 
1509. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
      ^
1510. {
1511.     InputStream *ist = s->opaque;

avconv.c:1511:5: 
1509. static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
1510. {
1511.     InputStream *ist = s->opaque;
          ^
1512.     const enum AVPixelFormat *p;
1513.     int ret;

avconv.c:1515:10: 
1513.     int ret;
1514. 
1515.     for (p = pix_fmts; *p != -1; p++) {
               ^
1516.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1517.         const HWAccel *hwaccel;

avconv.c:1515:24: Loop condition is true. Entering loop body
1513.     int ret;
1514. 
1515.     for (p = pix_fmts; *p != -1; p++) {
                             ^
1516.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
1517.         const HWAccel *hwaccel;

avconv.c:1516:9: 
1514. 
1515.     for (p = pix_fmts; *p != -1; p++) {
1516.         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
              ^
1517.         const HWAccel *hwaccel;
1518. 

libavutil/pixdesc.c:1703:1: start of procedure av_pix_fmt_desc_get()
  1701. }
  1702. 
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1705:9: Taking false branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1705:24: Taking true branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1706:9: 
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1706.         return NULL;
                ^
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }

libavutil/pixdesc.c:1708:1: return from a call to av_pix_fmt_desc_get
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }
        ^
  1709. 
  1710. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

avconv.c:1519:15: 
1517.         const HWAccel *hwaccel;
1518. 
1519.         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
                    ^
1520.             break;
1521. 

static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)
{
    InputStream *ist = s->opaque;
    const enum AVPixelFormat *p;
    int ret;
    for (p = pix_fmts; *p != -1; p++) {
        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);
        const HWAccel *hwaccel;
        if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
            break;
        hwaccel = get_hwaccel(*p);
        if (!hwaccel ||
            (ist->active_hwaccel_id && ist->active_hwaccel_id != hwaccel->id) ||
            (ist->hwaccel_id != HWACCEL_AUTO && ist->hwaccel_id != hwaccel->id))
            continue;
        ret = hwaccel->init(s);
        if (ret < 0) {
            if (ist->hwaccel_id == hwaccel->id) {
                av_log(NULL, AV_LOG_FATAL,
                       "%s hwaccel requested for input stream #%d:%d, "
                       "but cannot be initialized.\n", hwaccel->name,
                       ist->file_index, ist->st->index);
                return AV_PIX_FMT_NONE;
            }
            continue;
        }
        ist->active_hwaccel_id = hwaccel->id;
        ist->hwaccel_pix_fmt   = *p;
        break;
    }
    return *p;
}
['static enum AVPixelFormat get_format(AVCodecContext *s, const enum AVPixelFormat *pix_fmts)\n{\n    InputStream *ist = s->opaque;\n    const enum AVPixelFormat *p;\n    int ret;\n    for (p = pix_fmts; *p != -1; p++) {\n        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(*p);\n        const HWAccel *hwaccel;\n        if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))\n            break;\n        hwaccel = get_hwaccel(*p);\n        if (!hwaccel ||\n            (ist->active_hwaccel_id && ist->active_hwaccel_id != hwaccel->id) ||\n            (ist->hwaccel_id != HWACCEL_AUTO && ist->hwaccel_id != hwaccel->id))\n            continue;\n        ret = hwaccel->init(s);\n        if (ret < 0) {\n            if (ist->hwaccel_id == hwaccel->id) {\n                av_log(NULL, AV_LOG_FATAL,\n                       "%s hwaccel requested for input stream #%d:%d, "\n                       "but cannot be initialized.\\n", hwaccel->name,\n                       ist->file_index, ist->st->index);\n                return AV_PIX_FMT_NONE;\n            }\n            continue;\n        }\n        ist->active_hwaccel_id = hwaccel->id;\n        ist->hwaccel_pix_fmt   = *p;\n        break;\n    }\n    return *p;\n}', 'const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)\n{\n    if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)\n        return NULL;\n    return &av_pix_fmt_descriptors[pix_fmt];\n}']