Sorry. But actually they way you fixed it accomplishes the same thing. (Putting the entire "mp4a / 0xblahblah" in the compatible audio codecs). My post was just changing the regular expression to accomplish the same thing. I haven't looked into exactly how pyTivo tivo determines when to transcode, but what jumps out now that I am taking a closer look at both your ffmpeg -i output and the pyTivo log from above is: vFps=59.94 Which may be causing pyTivo to force transcoding. (As it should if the frame rate is really 59.94 fps, because TiVo won't like that) Your mediainfo dump shows 29.97 as the fps, so it looks like ffmpeg is somehow getting an incorrect frame rate from that file.