Monday, February 23, 2004
Viewer Mail #1 - Digital Cable and PVR
As promised, viewer mail. In this first installment, reader Britain W. asks the following questions:
Middle caveat: Your cable box may be made to work with a MythTV system. See Section 11.4 of the MythTv.org documentation.
Long answer: BBC America, home to a favorite (favourite) show of ours, Monarch of the Glen. Of course, it would be easier for us to watch this show if we actually had digital cable ourselves - we tended to watch the show on PBS whenever they happen to show it. In 2001, when I had a a sweetheart of a deal from Charter Cable in Madison, WI for betraying my loyalty to SkyCableTV of Madison, WI, I had BBC America and didn't even know the treasure I had. Pity. In those days, I had a 25" Color TV by Zenith with a faulty ON/OFF switch donated to me by some good friends. The SkyCableTV and Charter packages both yielded me a converter box to turn their scrambled analog/digital signals into Channel 4 output for the old TV and actually provided a 120 VAC connection to turn the old TV on and off with the remote. These digital video cards don't work miracles, they just replicate the ability your TV has to see signals. If you need a box for descrambling analog signals or converting digital signals, your PVR will need a box as well.
Physics answer: For background information on television's and cable's inner technologies, look here.
I am wondering what TV tuner card you used, whether you have basic or digital cable, and -- if you have digital, like we do -- how many channels can you tune in? A couple of the channels we would be interested in, like BBC America and G4, are up in the 100s.Short answer: Digital cable outputs analog signals to televisions. If your TV can't see a signal without a box, the computer can't see it without a box either. From MythTV, "There are no known capture cards for digital cable. You must use the set-top box provided by your digital cable provider and capture the analog video output using either composite or S-Video."
Middle caveat: Your cable box may be made to work with a MythTV system. See Section 11.4 of the MythTv.org documentation.
Long answer: BBC America, home to a favorite (favourite) show of ours, Monarch of the Glen. Of course, it would be easier for us to watch this show if we actually had digital cable ourselves - we tended to watch the show on PBS whenever they happen to show it. In 2001, when I had a a sweetheart of a deal from Charter Cable in Madison, WI for betraying my loyalty to SkyCableTV of Madison, WI, I had BBC America and didn't even know the treasure I had. Pity. In those days, I had a 25" Color TV by Zenith with a faulty ON/OFF switch donated to me by some good friends. The SkyCableTV and Charter packages both yielded me a converter box to turn their scrambled analog/digital signals into Channel 4 output for the old TV and actually provided a 120 VAC connection to turn the old TV on and off with the remote. These digital video cards don't work miracles, they just replicate the ability your TV has to see signals. If you need a box for descrambling analog signals or converting digital signals, your PVR will need a box as well.
Physics answer: For background information on television's and cable's inner technologies, look here.
Saturday, February 21, 2004
Blue lines using a GeForceFX 5200 card with TV-out
While staving off yet more thesis work, I was looking around for a solution to an ever-present problem. There are blue lines bordering the top and left of my TV programs. You get used to them after a while, but you are always left knowing that you have watched a facsimile of a TV program, not the real thing. This occurs only for the playing of TV programs, and NOT in the normal operation of KDE.
Adjusting parameters in mythtv didn't help. Adjusting overscan parameters within XF86Config-4, to stretch the boundaries of my display window on the TV, didn't work either.
Apparently, this problem was noted just yesterday by someone at the nVidia corporate site. It may be specific to the TV-out of the GeForceFX 5200 card. From the nV News Forums, someone noted the very same problem and after his efforts, he reported that the solution is to roll back to the the nVidia-Linux-1.0-4496 driver from the current version, 1.0-5336.
My attempts to do so, brief as they were, were thwarted by my inability to clear up some files related to lirc_dev for my non-working remote control. More as it develops, and a promise of my first viewer mail.
Adjusting parameters in mythtv didn't help. Adjusting overscan parameters within XF86Config-4, to stretch the boundaries of my display window on the TV, didn't work either.
Apparently, this problem was noted just yesterday by someone at the nVidia corporate site. It may be specific to the TV-out of the GeForceFX 5200 card. From the nV News Forums, someone noted the very same problem and after his efforts, he reported that the solution is to roll back to the the nVidia-Linux-1.0-4496 driver from the current version, 1.0-5336.
My attempts to do so, brief as they were, were thwarted by my inability to clear up some files related to lirc_dev for my non-working remote control. More as it develops, and a promise of my first viewer mail.
Tuesday, February 10, 2004
Complaining about uptime
OK, below I decided to write about how efficiently my Linux PVR box was running while watching and recording programming.
Here on February 10, 2004, here is my current Linux box uptime:
14:24:29 up 30 days, 27 min, 2 users, load average: 2.43, 2.38, 2.30
Of all the wonders of Linux, one of the most mysterious parts is getting an honest answer from the computer just how much it is doing at a given time. One way to start investigating how hard the PVR is working is to run an uptime query. The one-line enrty shows the current time, and the uptime for the box, now over 30 days. I have 2 user logins running right now, and then we come to the 1-minute, 5-minute, and 15-minute load averages on the box right now.
At least on a Windows box, you get an idea in % how much a particular program is eating CPU cycles. To approximate how much Law and Order: SVU and Match Game PM below used the box, consider that I was quoting, inaccurately, the 1-minute load averages.
Is "2.43" 100% then. I have seen higher. But, consider that I am now running at 2.43-2.38-2.30 because I signed up with distributed.net to use the lost cycles on the machine when it isn't transcoding the shows. Statistics from my participation also include the P4 2.4GHz Windows machine on my desk, so it isn't all from the Linux PVR. So, approximate 2.43 as "100%". This would imply that watching Match Game PM below took only 4% of my CPU and that adding the recording of Law and Order: SVU shot it to 11%. Not much at all.
So then, was 933 MHz overkill? No, transcoding occurs shortly after recording and it gets done rather well.
After one month of use, our Disk Usage:
And will all apologies to Ice-T, who is an excellent actor, we stopped watching Law and Order: SVU. As we watch TV during supper often, it just wasn't condusive to winding down while eating. The refinement of our TV schedule, this box gives television freedom AND helps solve mathematical problems (through distributed.net).
Here on February 10, 2004, here is my current Linux box uptime:
14:24:29 up 30 days, 27 min, 2 users, load average: 2.43, 2.38, 2.30
Of all the wonders of Linux, one of the most mysterious parts is getting an honest answer from the computer just how much it is doing at a given time. One way to start investigating how hard the PVR is working is to run an uptime query. The one-line enrty shows the current time, and the uptime for the box, now over 30 days. I have 2 user logins running right now, and then we come to the 1-minute, 5-minute, and 15-minute load averages on the box right now.
At least on a Windows box, you get an idea in % how much a particular program is eating CPU cycles. To approximate how much Law and Order: SVU and Match Game PM below used the box, consider that I was quoting, inaccurately, the 1-minute load averages.
Is "2.43" 100% then. I have seen higher. But, consider that I am now running at 2.43-2.38-2.30 because I signed up with distributed.net to use the lost cycles on the machine when it isn't transcoding the shows. Statistics from my participation also include the P4 2.4GHz Windows machine on my desk, so it isn't all from the Linux PVR. So, approximate 2.43 as "100%". This would imply that watching Match Game PM below took only 4% of my CPU and that adding the recording of Law and Order: SVU shot it to 11%. Not much at all.
So then, was 933 MHz overkill? No, transcoding occurs shortly after recording and it gets done rather well.
After one month of use, our Disk Usage:
- Total Space: 130,938 MB
- Space Used: 85,120 MB
- Space Free: 45,818 MB
And will all apologies to Ice-T, who is an excellent actor, we stopped watching Law and Order: SVU. As we watch TV during supper often, it just wasn't condusive to winding down while eating. The refinement of our TV schedule, this box gives television freedom AND helps solve mathematical problems (through distributed.net).
