static int tight_init_stream(VncState *vs, int stream_id,
                             int level, int strategy)
{
    z_streamp zstream = &vs->tight->stream[stream_id];

    if (zstream->opaque == NULL) {
        int err;

        VNC_DEBUG("VNC: TIGHT: initializing zlib stream %d\n", stream_id);
        VNC_DEBUG("VNC: TIGHT: opaque = %p | vs = %p\n", zstream->opaque, vs);
        zstream->zalloc = vnc_zlib_zalloc;
        zstream->zfree = vnc_zlib_zfree;

        err = deflateInit2(zstream, level, Z_DEFLATED, MAX_WBITS,
                           MAX_MEM_LEVEL, strategy);

        if (err != Z_OK) {
            fprintf(stderr, "VNC: error initializing zlib\n");
            return -1;
        }

        vs->tight->levels[stream_id] = level;
        zstream->opaque = vs;
    }

    if (vs->tight->levels[stream_id] != level) {
        if (deflateParams(zstream, level, strategy) != Z_OK) {
            return -1;
        }
        vs->tight->levels[stream_id] = level;
    }
    return 0;
}