[mythtv-users] New user impressions: Mythtv+Matrox RRG

[Mark J. Small]

Hi all,

I've recently installed mythtv on a spare parts box and really like what I 
see.  

My box: P2 333 on a junky PC Chips M761 BX board
                192MB RAM
                1 GB HD for linux
                40 GB HD for mythtv storage
                Matrox G400 dual head
                Matrox Rainbow runner G-series
                Debian Sarge
                Linux kernel 2.4.25
I previously used an Ati TV Wonder with a Rage Pro 128.

Here are some of my experiences, mostly to do with the matrox cards:

(1) The marvel drivers don't seem to be ready for the 2.6 kernel. I found a 
patch that would make the CVS fb drivers compile and work, but the card would 
lose its interrupt after about 20-25 minutes using xawtv.  It made me miss 
the conclusion of Astroboy on Saturday.  Things work much better with the 2.4 
kernel.

(2) When I record using the Rainbow Runner, the horizontal resolution seems to 
be off.  On playback, I get a gray bar along the right side of the screen.  
If I set the horizontal overscan to 5%, everything looks OK.  I think that 
this fellow's problems are related:

http://mythtv.org/pipermail/mythtv-users/2003-July/010523.html

(3)Changing the resolutions doesn't seem to change the file size!!!  If I 
record 2.5 minutes at 320x240 using Q=50, HD=2, VD=2, I get a 98 MB file.  If 
I record 2.5 minutes at 400X288 with the same other stuff, I still get a 98 
MB file.  Is it being forced to another resolution?  The manual for this card 
only lists the following resolutions for recording NTSC:
704x480, 352x480, 352x240, and 176x120.

(4) I don't really understand what the different parameters for mjpeg mean.  I 
know that the default decimations of 4 look REALLY bad, and 2 looks okay.  I 
tried 1, but playing it eats all of my CPU.  The quality setting makes a huge 
difference in CPU usage.

Does the decimation actually set my resolution?  Is the actual resolution 
704x480 divided by decimation?  This is conjecture, but I haven't seen it 
explained anywhere.  If this is true, perhaps it would be better to only show 
the available resolutions, or only give decimation options.

In general, it would be nice if the help for each recording setting would tell 
how each setting affects file size, CPU usage, and quality.  

(5) Recording takes little (10-30%) CPU power.  However, playing the MJPEGs 
does seem to take a fair bit.  Playing the above videos takes about 60% CPU.  
If I transcode to a mpeg4, it takes more like 30%.  I thought these cards 
were supposed to have hardware decoders as well.  Perhaps the linux drivers 
don't do that part yet.  I find it funny that little mpeg4's take less cpu 
than big mjpegs.  Hurry for automatic transcoding!

(6) I didn't see anything in the FAQ about mixer settings, but it was really 
important to set the line in volume to zero, otherwise I could hear the 
television as it was being recorded.  Rather distracting, especially while 
watching Live tv.  I'd hear both the recording and playback audio streams.  
Talk about Echo-land.  This may be a useful thing to put in to the install 
FAQ.

Sorry for such a long post.  I really like what I've see so far with Mythtv.  

Mark