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February 12, 2004

The Pains and Joys of PVRs

'Leedvermaak' is this Dutch word for which there seem to be no direct translation, but which means 'having fun with someone's suffering'. The subject of my leedvermaak is Sam Ruby and his experiences with the installing the Hauppauge WinTV PVR-350 board under Linux. In essence this board is a TV tuner enhanced with some mpeg encoders. I have one of those boards and use it as a PVR to fuel the AV380. Sam got himself one of these boards with the goal to run MythTV, a very nice looking PVR application under Linux. Sam thought he was being smart by installing the Linux version the main MythTV developer uses, but his journey is a typical one of searching for packaging, puzzled debugging and a apparently a final victory, although Sam doesn't really report on how well it runs.

Where does the 'leedvermaak' comes in? Because my TV350 installation under XP was a very different experience, my luxury headache was which of the 6 PVR applications to use that all seem to work fine with the TV350. And what format to store the video captures in to allow easy manipulation. My limited pain was that I realized that I don't know enough about media processing to make sensible decisions about the 50 different options some of the encoders present you with (DivX comes with 4 resize filters, why would I ever choose anything but the default?). But after a few weeks of experimenting with applications both free and commercial, I have found an set of tools that works for me.

Please keep in mind that my main goal is to encode for the AV380, which runs best at a 320x240 resolution. But occasionally I do want to encode for watching on  the high resolution laptop/desktop.

  • I currently use WinTvCap for basic recording. It does its job as a basic background recoding task. In the GUI section the scheduler/recorder that comes with the board does a reasonable job, but I don't like the GUI as much as I like the ones from GBPvr (free) or Beyond TV from SnapStream. ($60). There are other commercial PVRs worth looking at. I would also give XP Media Center a try if AV380 would be able to display WMV videos.
  • I record 720x480 MPEG2 at 6 Mbits/sec VBR and audio at 192 Kbits/sec. A one hour show results in about 3 GB data.
  • After recording I use Womble mpeg-vcr to edit out the commercials. This program rocks and is worth every penny. I have tried a whole collection of mpeg editors, but for this task mpeg-vcr beats all the fancy big expensive editors hands down. Removing commercials from a 1 hour show takes about 3-4 minutes. And you are left with about 40 minutes of effective video.
  • I then use Dr.Divx to encode it to DivX. Free tools such as Xmpeg  are also good, also to encode to other formats such as XviD, but as I wanted to buy the professional DivX encoder I decided to get Dr.DivX for a few bucks more. The extra feature I use a lot is the 'batch encoding' where it just takes a whole set of the recording and converts it to the DivX. What still frustrates me to no end is that non of the tools are capable of exploiting multiprocessors.
  • For the AV380 I re-encode to 320x240 at about 900 Kbits/sec and sample the sound down to 96 Kbits/sec @ 32 KHz. I have had some strange sync problems on the AV with other audio encodings which I am still investigating. The resulting files are about 300 MB
  • For laptop I recode to 640x480 but with better audio (128Kbits/sec) as I have seen any sync problems there.

The only real problem I have is that I have no time to watch all these videos that this process is pumping out. But I now do have a nice collection of BBC reruns I would normally would miss...

Posted by Werner Vogels at February 12, 2004 11:35 AM
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Comments

The german word is schadenfreude :)
I pull shows off a ReplayTV, and use Vidomi to trim ads and compress to xvid @10MB/minute bitrate.. it's a freebie. The UI is pretty streamlined (haven't used Womble, though I've heard good things). I set up a few jobs - my favorite is Good Eats - and save to VBR XVID.
Working with a single program is nice.. also, it supports jobs so you can set up a big job queue. It supports distributed compression across multiple machines; I haven't used it.
I reduce image to 75% to smooth things out, and shoot for a bitrate about 10MB/minute.

Posted by: Jeff Winkler on February 25, 2004 12:57 PM