Setting up MythTv (knoppmyth) with a pchdtv hd-3000 card
copyright Randy Melton 2006

Overview

I'm writting this to document the process ans setup I used to get a MythTV system working. I encountered several obstacles in the process, where the documentation on other web sites was obsolte, or misleading.

I attended a calug meeting where they did a presentation on building a pcHDTV system. I concluded that te key was to buy a digital boradcast tuner card before the dreaded broadcast flag made such devices unavaliable. The group put together a group order for the pcHDTV HD-3000 cards (around $170 if I remember correctly.) After asking around I bought a used nvidia graphics card (5200?) for $20. I choose this card because it was cheap, had a DVI connector and was supposed to support hardware decoding of mpeg video.

I didn't want to spend a lot on a system especially without knowing if any of it would work, or if the whole thing was worth the trouble. So the 2 cards sat around for over a year. I recently found time to build a test system.

Tuner CardpcHDTV HD-3000
Video Cardnvidia 5200
PC an old discarded office PC (1.60GHz Pentium-4)
with CDROM, and 40GB Hard Disk
Software knoppmyth R5C7 - (KnoppMythR5C7.iso)

Installation

  1. Install the 2 cards... (no details given)
  2. Burn the iso image from knoppmyth to a CDROM (I used k3b on another linux xystem)
  3. Boot the "myth" PC from the CDROM.
  4. When The CD boots choose automatic install
    (When I tried manaul install I always got stuck trying to partition the hard disk. It kept saying /dev/hda open read only.)
  5. ...

Post Install Setup

Once the PC reboots it will come up in "mythtv-setup". This is where you configure the system to use your tuner card.
  1. Enable XvMC to offload some of the video rendering to the nvidia card.
    X-Video Motion Compensation, or XvMC, is a part of The X Window System which allows video programs to offload motion compensation and iDCT (Inverse Discrete Cosine Transform) portions of MPEG2 decoding to the GPU hardware.
    1. Navigate through these frontend menus:
      Setup -> TV Settings -> Playback
    2. Change the "Preferred MPEG2 Decoder" to "Standard XvMC"
    3. Make sure "Extra audio buffering" is checked.
    4. full details at http://www.mythtv.org/wiki/index.php/XvMC
    Note that this makes my playback less "jumpy", but it also makes the osd displays black and white.

Quick Recipes

I Want To...Recipe
stop the backend /etc/init.d/mythtv-backend stop
start the backend sudo /etc/init.d/mythtv-backend start
start the frontendmythfrontend
Calibrate Antenna
  1. (download/compile a new version of dtvsignal/dbv-atsc-tools dvb-atsc-tools-1.0.3.tar.gz)
  2. dtvsignal -dvb 0 22 (22 is a local channel from antennaweb)
Scan for Channels
  1. exit out of the frontend (hit the 'esc' key a few times)
  2. create an xterm window
  3. stop the backend
  4. mythtv-setup
  5. select channels, followed by scan
  6. quit mythtv-setup (hit the 'esc' key a few times)
  7. start the backend
  8. mythfilldatabase
  9. restart the frontend

Background Information

dvb vs Video4Linux I was confused by the fact that there are 2 linux standards for capturing/decoding the signal from the tuner card. I kept trying to run "signalscan" to test the signal strength, but the knoppmyth system uses the dvb system. Moral, ignore /dev/dtv and use /dev/dvb along with the dvb* tools.
ATSC The US standard for Digital Television (in summary NTSC is to analog what ATSC is to digital)

Problems Encountered

myth quit responding to keyboard My first attempt was using a slightly older knoppmyth R5B7. I found that sometimes the keyboard would quit responding. I This thread is what tipped me off to the problem.
Signal strength too low Tried these antenna's:
  • "2 wires"
  • radioshack 150-2186 ($49, better, but I returned that one after reading hdtvprimer)
  • I plan to order a db2 from antennasdirect. (I recmmended it to a friend and he tried it and it works great.)

References

Randy's Projects / Sawbee Home page
email any comments to:

Last modified: Thu Sep 13 20:44:46 MDT 2007
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