private void open_video()
 {
     this.width  = (int)this.ti.frame_width;
     this.height = (int)this.ti.frame_height;
     Xiph.th_stripe_callback stripe_callback;
     stripe_callback.ctx            = null;
     stripe_callback.stripe_decoded = new Xiph.th_stripe_decoded_func(this.stripe_decoded);
     Xiph.th_decode_ctl_opts th_decode_ctl_opts = new Xiph.th_decode_ctl_opts();
     th_decode_ctl_opts.stripe_callback = stripe_callback;
     Xiph.th_decode_ctl(this.td, 7, th_decode_ctl_opts);
 }