Random tidbits Bdale thinks are worth documenting.
Bdale Garbee
bdale@gag.com
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Thu, 22 Jan 2004
Adventures with DVI
Our new display device, a Panasonic
PT-50LC13
LCD rear-projection HDTV set,
arrived and got turned on only a couple of hours before I left for
LCA 2004
in Adelaide. Ever since returning home, I've been working on how to get the
MythTV
frontend driving it optimally.
I'm pretty happy with the results so far.
After trying lots of combinations, I've ended up with an AGP video card using the nVIDIA FX 5200, driving the TV through the DVI cable that came with the set, at 1280x720 pixels resolution to match the display's native resolution (this is 720P in HDTV terminology). The only trick was figuring out a reasonable Modeline for the X config file:
Modeline "720p" 74.25 1280 1312 1592 1648 720 735 742 757
With that, the display is rock-solid and crisp. As a digitally-oriented kind
of guy, I find the whole concept of "overscan" in televisions mildy offensive,
but the industry is accustomed to not having viewers see to the edge of the
transmitted image... and that's just life. What this means in practical terms
with this display is that only the middle 1210x680 of the total 1280x720 pixels
are actually visible. I'm told that's a completely typical overscan percentage
by the folks who hang out on the MythTV IRC channel.
Two consequences of the overscan that I'll have to figure out eventually are that text in the Linux console framebuffer is clipped off on the left and sort of hard to read (only an issue when something breaks), and the MythTV on-screen display could stand to be shrunk slightly to fit into the visible pixel area better. That's probably tweakable in the setup, but I haven't looked yet.
Now I guess I have to decide whether to play with the HD-2000 card I bought from pchdtv.com first, or start tweaking the video capture and display parameters to optimize picture quality. Since it appears that we might actually be able to watch the Super Bowl in HDTV if I get all of that together in time, I'm pretty sure I know what my wife's vote would be... ;-)
Sat, 03 Jan 2004
KnoppMyth R4
Been a while since I reported on progress with my PVR setup. That's mostly
because I've been beating my head against the wall instead of making any
real progress. In summary, ivtv cvs-latest and latest mythtv cvs just aren't
happy here... there are persistent problems with choppy audio and video and
lots of prebuffering pauses no matter what hardware combinations I try. So,
I decided it was time to put all the complex plans aside and put a simple
config together for the family room.
So, I downloaded a KnoppMyth r4 CD and used it to get a reasonably simple single-box MythTV setup running. The only real problems I had making this work were the need to update to a fresher xmltv package, and the fact that I somehow got some program guide info loaded with the wrong timezone the first time.
Extras I loaded include the latest SiS driver and sisctrl from Thomas Winischhofer, and a Perl script that handles channel changing duties on the Sony DirecTV receiver with a simple RS-232 cable from ttyS0.
The hardware is my Micro ATX system, with the following bits and pieces:
- Athenatech Micro ATX Case w/200W Supply, A100BB.
- Asus A7N266-VM motherboard.
- AMD Athlon XP 2400+
- 512Mb PC-2100 DDR266 RAM
- 80Gb Maxtor
- Hauppauge PVR-250
- ECS AG315P/TV video card
It feels good having something the family can start using. KnoppMyth definitely gets a "stuff that works" rating here. Try it if you want to see what MythTV is all about with minimal pain... ;-)
Wed, 10 Dec 2003
New Receiver Ordered
I've been kind of stuck for a while, because the receiver in the living room
A/V stack is completely out of inputs (no place to plug in the Myth box
without unhooking something else the family cares about), plus the power
switch got damaged a while back. So, I've been thinking about replacing it,
and today I finally ordered a new
Sony STR-DE895
from J&R.
Should be here next week.
I'll move the current receiver to the basement so that I have something to test 5.1 audio with. Taking it out of routine use also means I can take it apart and see about replacing the power switch, without having the whole family standing on first one foot and then the other waiting for me to finish...
Sat, 06 Sep 2003
Working NTSC Output
It's easy when you have the right hardware. I struggled more than I
want to admit without any real success to make my ATI Radeon 7500 All-in-Wonder
card do NTSC video out from
MythTV.
I was frustrated enough that I was pricing
nVidia cards on the web, knowing that their driver would "just work" despite
being hideously non-free. To the rescue came a co-worker, who pointed me to
Thomas Winischhofer's
Linux and SiS
site, which suggested that I could have a fully open source solution for NTSC
video output for cheap.
And it works!
I bought an ECS AG315P/TV card from newegg.com, which is fast becoming my favorite place to buy stuff like this. For the princely sum of $29, I got an AGP video card using the SiS 315 controller and an SiS 301 video bridge... that auto-detects the presence of a load on the RCA composite output at boot time, and gives me full BIOS video support on the TV output!
I didn't even need to load up Thomas' drivers for X, the stock Debian 4.3.0-0pre1v1 from experimental "just worked" with the following device selection. The option tells the card to assign the one available set of overlay support registers (which MythTV needs for video playback) to the TV output instead of the default VGA output. That's it!
Section "Device"
Identifier "SiS315PRO"
Driver "sis"
Option "XvOnCRT2" "true"
EndSection
Wish I'd known about this before I went do the ATI path... and by the way, I decided I really don't like the feel of the ATI UHF remote control, so I bought some IR modules from Radio Shack and am building up lirc receivers... but more about that another day...
Fri, 29 Aug 2003
NTSC Composite and S/PDIF from Nehemiah
I've mostly been playing with the Asus
A7N266-VM
board since it arrived, but a
conversation with a co-worker got me wondering this morning about the RCA
jack on the back of the
Nehemiah board I have.
There's a jumper on the board that selects whether you get composite video
or S/PDIF audio output. I've been annoyed by this since I really want both...
A quick check with my trusty multimeter confirms that the jumper is merely selecting which trace gets routed to the center pin of the RCA socket! So, to use both, all we need to do is fashion a cable to pick up the other signal and a ground from somewhere and route it to another RCA socket. Cool. Could even wire in an optical interface for the S/PDIF like the one provided with the Asus board, I suppose...
With the ongoing work to enable the mpeg2 decoder in the CLE266, that board may end up being a pretty cool standalone frontend for mythtv someday...
Mon, 25 Aug 2003
Ordered Another System
I'm really quite happy with MythTV at this point, except that the ITX system
just isn't quite cutting it as the machine to go into the family room media
center. Mostly because it only has one PCI slot. If the ivtv driver could
support both input and output on the PVR-350 at the same time, it'd be nearly
right... but...
I have an unused ATI Radeon 7500 All-In-Wonder card. The video input and tuner sound like a lost cause for MythTV, but with the GATOS ati.2 driver the card reportedly works fine for output including NTSC. The card also came with a UHF remote control that would adequately replace our "dependency" on the Sony DirecTV UHF remote we are using today. So, this feels like a good output and remote control support card for the media center frontend. Thus, we need an AGP slot.
I have a Hauppauge Bt878 capture card in the ham shack machine that is unused since it doesn't seem to work well in the dual Celeron motherboard. With an available PCI slot, MythTV should be able to use it just fine if there's enough CPU to compress in software.
I also have a 4dwave NX audio card with optical S/PDIF output if I have a PCI slot and inadequate sound output support on the motherboard.
So, I ordered parts for a new machine from newegg.com. My first order from them, but others seem to think they're OK. The components I ordered will make a fairly fast Micro ATX system. As long as it's not too loud, it should work out fine.
- Asus A7N266-VM motherboard. This board is cheap, has what I need, and apparently works well under Linux.
- Athenatech Micro ATX Case w/200W Supply, A100BB.
- AMD Athlon XP 2400+, the fastest 266 FSB boxed Athlon in stock.
- 512Mb PC-2100 DDR266 RAM