Video and audio are transcoded separately -- the audio will be passed through if it's compatible. Also, pyTivo will transcode to 5.1, although some people have reported issues with this. Consider also trying a pull with "ts=on" in the Server section of pyTivo.conf. This will pull the H.264 video without transcoding -- only a remux to transport stream format -- on a Series 4 or 5. But note that it's pickier than transcoding, and both pyTivo and the TiVo have issues with full-rate Blu-Ray video.