libavformat/movenc.c:3729: error: Uninitialized Value
  The value read from first[_] was never initialized.

libavformat/movenc.c:3729:13: 
3727.             continue;
3728. 
3729.         if (first[st->codecpar->codec_type] < 0)
                  ^
3730.             first[st->codecpar->codec_type] = i;
3731.         if (st->disposition & AV_DISPOSITION_DEFAULT) {
