proc av_rc4_alloc(): ptr AVRC4 {.importc, cdecl, ...raises: [], tags: [],
                                 forbids: [].}

proc av_rc4_crypt(d: ptr AVRC4; dst, src: ptr uint8; count: cint; iv: ptr uint8;
                  decrypt: cint) {.importc, cdecl, ...raises: [], tags: [],
                                   forbids: [].}

proc av_rc4_init(d: ptr AVRC4; key: ptr uint8; key_bits, decrypt: cint): cint {.
    importc, cdecl, ...raises: [], tags: [], forbids: [].}