[mythtv] New Mythtv user with Matrox Marvel G200TV

Seth Wonder mythtv-dev@snowman.net
Sat, 26 Oct 2002 20:42:31 -0400

There is indeed external command functionality in the existing code - it's
just undocumented/unspoken. ;) The code currently only acts as a 'global'
command (eg, it applies to all cards if you have more than 1). I have seen
quite a demand for this in the past week or two, so I think there will end
up being some code contributions to it ....  Anyway, last quote from Isaac
regarding the externalcommand functionality is:

>It should be.  If you add a line like the following to your settings.txt
>str ExternalChannelCommand=changechannel
>With 'changechannel' being the program to run on channel change, it'll
>that program like 'changechannel 57' if you tune to channel 57 on a
>input of the capture card.  I don't know if anyone's tested it or anything,
>so YMMV.

Apparently someone has discovered some issues regarding tuning high channel
numbers with it, however (>125?)... and has throw together a little blurb
about the options to 'fix' it. You may want to hop on
irc.openprojects.net/#mythtv and watch the convo in there, as this is
generally often discussed. =) hopefully your G200TV issues will manifest
into something positive, because it sounds like it could prove to be a nice
myth solution... I too intend to use mythtv w/ my dtv receivers (controlled
via serial port as well).. perhaps we can collaborate on this if you are

Seth (skitzo)

----- Original Message -----
From: "Ray" <maillists@sonictech.net>
To: <mythtv-dev@snowman.net>
Sent: Saturday, October 26, 2002 8:31 PM
Subject: [mythtv] New Mythtv user with Matrox Marvel G200TV

> First and formost I want to say thanks to Isaac and everyone else who has
> contributed to this project.  I'm really impressed with Mythtv.  My system
> is as follows:
> Dual Celerons @ 500
> 256MB Ram
> 2 - 60GB 7200RPM Hard drives, 1 on a ATA33 controller and 1 on ATA66
> Matrox Marvel G200TV for video capture and display
> Trident 4d Wave PCI sound card using Alsa.
> DirecTV Satellite as my primary input/tuner
> Some issues I've run into so far:
> 1.  The Marvel captures best used with it's hardware mjpeg compression
> isn't supported in Mythtv (but IS well supported under Linux via the mjpeg
> tools).  Using raw uncompressed capture the card is limited to around
> 352x240 with the current Linux drivers.
> 2.  TV Out.  this card has 2 methods of outputting video to a TV.  The
> method is used by the mjpeg tools and Xawtv.  This method is easy to setup
> and produces excellent output.  The second method requires using the
> matrox framebuffer driver and basically involves mirroring your
> desktop/console to the TV.  It works but it's a pain to get set up just
> right and never really looks as good as the first method.  Unfortunately
> this is the only one supported by Mythtv.
> 3.  For some reason when I watch TV with the record method set to mpeg4 I
> see random odd artifacts on the screen.  Normally they are a few small
> blocks of color.  I'm not sure these are real compression artifacts though
> since they don't appear if I just record and playback later.  Also
> resolution and quality settings seem to have no affect.  I saw some
> of this in the archives but it was apparently fixed by a newer avifile
> was included in cvs last month and I'm using the current release version.
> 4.  Timed recording isn't real useable since Mythtv doesn't support
> tuners.  I know this is in the FAQ but I really didn't understand the
> reasoning in the answer.  I have a script to change channels on my dss
> receiver via serial port so I really just need to get the desired channel
> out to said script.  I'll probably ask about this in more detail after
> looked more carefully at the code.  I'm not a real programmer so it may
> a while.
> Basically, it looks great and sort of works with my particular hardware
> it would work far better if it could make use of external tools for bits
> that actually interface with the hardware.   With all of the cheap mjpeg
> cards out there and the growing popularity of DV capture and digital cable
> can only see this becoming an issue for more people in the future.
> --
> Ray
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