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Boston Linux Meeting Wed, July 15, 2009 Another Look at MythTV and MythDora

On Thu, Jul 09, 2009 at 01:20:12AM -0400, Bill Ricker wrote:
> * how can I use mythTV eg MythBuntu and eg Haupage parts to build a DTV DVR?

MythTV  has two major components: the backend, which gets
scheduling information, puts it in a MySQL database, does the
recording, optionally processes recordings, and offers them for 
playback; and the frontend, which handles user interfaces for 
all these functions.

You need at least one backend and at least one frontend, though
they can be on the same machine.

> * is there a choice besides Haupage?

The backend needs at least one recorder. Ignoring the old
standard-definition-only interfaces, these range from $10
FireWire cards (if you have a suitable FireWire-equipped video
source, like a cable or FIOS set-top box) through $30-$100 USB
and PCI tuners that attach to either antennae (ATSC / 8VSB) or
unencrypted cable (ATSC / Clear QAM), to the HDHomeRun, which is
a pair of tuners and an infrared receiver connected to ethernet,
to the Hauppauge HDPVR, which is a USB-attached tuner that
connects to a component HDTV source like a satellite or cable

> * What's the limit on how many DTV tuners and analog capture cards can
> be installed? active recording? playing?

Installed: no real limit.

Actively recording: depends on bandwidth available to disk. With
a single  disk, I wouldn't try more than 2 recordings or 1
recording plus 1 playback. With the database and OS on one disk,
and storage on another, you could reasonably expect up to 3
recordings + playback. I have five disks including one USB
external on my backend, and I can record from three HD sources
plus playback in three locations simultaneously.

> * will they work with off-air, ComCast, or DiSH SD, HD, remnant analog?

Different tuners, yes. There are no direct recorders of
encrypted cable channels, and no practical direct recorders of
satellite channels. Both can be tuned via set-top-boxes and then
recorded either as SD or HD via analog outputs.

Tuners for over-the-air (ATSC / 8VSB) and unencrypted cable
(ATSC / Clear QAM) are pretty cheap.

> * how does IR blaster work?

You plug in a supported device, point it at the IR receiver on a
set-top-box, figure out the encoding scheme, test it, and tell
the backend about how to access it via a program and what tuner
it's associated with.

> * is there a system76 style integrator that will preinstall and
> preconfigure so it's not a six weekend google-and-irc HELP project?

Not currently. In theory, there's, but I don't think
they're currently selling anything except parts.

> * can it do the pause live show then fast forward?

Superbly well. It can also do a reasonable job of processing a
recording to locate commercials, then skip over them during
playback. And you can automatically transcode down to a format
that your pocket device will understand, or record to a DVD,
or play in faster or slower than realtime with automatic pitch

> * better help - is there an uptodate book? or wiki/web?

The wiki at is pretty useful, though it needs to be
reorganized. The user's mailing list is extremely helpful. The
most recent book that I'm aware of is out of date, but has a
good overview of what's going on. _Hacking MythTV_ is the title,
and some guy named Jarod Wilson is a coauthor...

> * what disk arch is good for this?

As many spindles as you can get. Assuming that you feel that
video information is essentially low-value, a bunch of large disks
mostly hooked up via SATA or PATA is the way to go. Keeping the
database away from the storage areas is essential to good
performance. MythTV has a concept of storage groups, which is to
say a list of paths which are all considered usable in parallel.


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