Constant stainless_ffmpeg_sys::AVERROR_UNKNOWN

pub const AVERROR_UNKNOWN: c_int = -(b'U' as isize | (b'N' as isize) << 8 | (b'K' as isize) << 16 |
      (b'N' as isize) << 24) as c_int; // -1_313_558_101i32