I have the MythTV and love it. Tivo is sitting on the floor unplugged. Luckly I never upgraded to a series 2 Tivo. Tivo is dying anyways. With myth I can watch my shows 2 times (2x) the speed (time stretch) and it edits out the commericals.I can finish a 1 hr show in 15mins. It can also convert shows to almost any video format so you can watch it on any computer or you can burn them to DVD. My last favorite feature is the web interface. You can schedule shows, see recorded shows, browse and search listings, and stream video. It destroys Tivo and best of all it's free software.
I wanted an easy way of taking a screen grab with MythTV but could not find any easy way that anyone had come up with. MythTV runs on linux so I have all the software on the machine at my disposal. I figured I'd use the same player MythTV uses to play DVD's to take the screen shots. The recordings are done in an MPEG 2 format called NuppelVideo. Mplayer can play this format. Mplayer also has a video output driver for JPEG, PNG, gif89a, and TGA. So here's the command that gets you the screen grabs.
mplayer /video/videoname.nuv -vo jpeg:quality=90,optimize=100 -ss 6 -frames 90
The above command uses mplayer to play the video file and uses mplayer's video output driver for JPEG. It starts on the 6th second of the video and grabs 90 frames (3 seconds of video). Just adjust the seconds (-ss) for where you want to start the capture and for frames multiply 30 x # of seconds of video you want from that start point. Adjust the quality and optimization to your liking. See the mplayer man page for options of the other formats PNG, gif89a, and TGA. Actually, you can do screen grabs of any file mplayer can play so this works regardless of MythTV files.
Also, when streaming video to mplayer from MythTV over the internet I like to save the video and start it ahead of time so I can skip commercials while it's going. Also it gives me the ability to pause it if I feel the need. Here is the command I use to play and dump the stream from MythTV to disk.
mplayer http://mythtvmachine.net:8001 -dumpstream -dumpfile /tmp/filename.mpg
Once you start the dump just wait as long as you want and just play the file like you would any other mpg.
The settings I like to use over a 384Kbps upload connection for MythStream are the following:
Video Codec: div3 Video Speed: 256 Audio Speed: 48 Video Size: 50% Video FPS: 25 Stream Protocol: http