OK, I'm able to record hi-def very nicely with R5A16 using firewire and a motorola 6200 box. Seems reliable so far. Now on to smooth playback.

My current system is a 2.4GHZ P4 with 512MB of RDRAM and an ATI 9200SE card. My TV is a Samsung DLP 50" with VGA & HDMI input (as well as s-video, composite and component.) Here are my questions:

1. CPU is fully utilized during playback. Is there any reason to believe that I will ever get things to work with an ATI card, or should I go buy an FX5200?

2. Has anyone out there succeeded in achieving smooth HDTV playback on a P4-2.4GHZ? If so, what video card did you use?

Thanks!

marc

to get smooth playback on a 2.4 you'll probably need to use xvmc, and as far as I know ATI does not support xvmc.

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Xsecrets

X, thanks for the info. I've read some postings that suggest that mythtv and xvmc don't do well together. Is this still an issue, or does xvmc work well with Myth?

Thanks!

Marc

I don't normally use XvMC... But in testing, it works a lot better than it use to.

_________________
cesman

When the source is open, the possibilities are endless!

I have to use XvMC to play back my HD recordings on my Athlon XP 2400. I can get through watching a recorded program with no problems.

However, 30-second skip glitches the picture for a second or two, there's still the gray OSD issue, I never try using LiveTV, and the frontend sometimes crashes when watching SD MPEG2 recordings. (The SD recordings also show a periodic glitch when XvMC and Bob deinterlacing are both on).

I usually turn XvMC on to watch some HDTV recordings, then turn it back off for other stuff.

as you can see from the other postings here xvmc still has some issues, but it is greatly improved and nearly usable these days. Unfortunately from most reports the bare minumum cpu to not have to use xvmc and get smooth hd playback is 2.8G PIV

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Xsecrets

OK, I've done some more playing based on the feedback here and reading some more threads. This was done connected to my 17" dell LCD monitor at 1024x768, playing ER recorded from the hidef channel.

1. Turning off "deinterlacing" results in smooth playback and 45% CPU utilization.
2. Enabeling "libmpeg2" decoding & turning deinterlace back on results in 40% CPU utilization.

I am tempted to connect the myth machine to my Samsung TV's VGA connector, but I've read various warnings that, with improper settings, one can damage their TV set. Here are my questions:

1. Can anyone advise me if this is a serious risk factor for this experiment? Has anyone else tried to connect to a samsung DLP TV with the default modlines?

2. I realize that displaying at 1024x768 is not full hidef, but I'm guessing it will look better than an svideo connection playing standard def mpeg2 material. My assumption is that when I eventually figure out how to re-configure to 1080i output, the CPU utilization won't get any worse because the source material and output resolution will match. Is this a reasonable assumption?

3. If anyone has already worked up the correct settings for a Samsung 50" DLP TV, I would certainly appreciate any pointers you can provide on how to do this "right" the first time.


Thanks!

Marc

Do you still have your TV's manual? Samsung is usually pretty good about listing what resolutions are possible and the corresponding horizontal and vertical frequencies. Then with the online modeline builders (search the wiki or Google it) you should be able to get a working modeline. My guess is that if it's got a VGA connector, it'll work with the default 1024x768 modeline.

You can also search avsforum or the PowerStrip forums for your TV and see if someone's posted a modeline for your specific set.

biggest thing you usually have to worry about is the vert refresh, make sure that is at 60 in your XF86Config-4 file unless you know your tv can do a higher rate.

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Xsecrets

I go straight VGA to my Pioneer Elite RPTV. It too came with all the warnings saying not to do this. Xsecrets is right that you really want to make sure 60 is your refresh, and don't do anything 'dumb'. Stick to normal parameters. I find most warnings are related to burn in. The TV folk think that TVs will stay on the same screen for longer compared to TV and thus burn the screen. I think this is an issue with myth/pvrs in general, and not a VGA. For instance when I listen to mythstream I often just turn of the tv cause only bits and pieces of the screen ever change. You also need to make sure the menus don't stay on overnight and things like that. Again, not VGA specific.

Does anyone know if blanking the screen (like 6 or something does in mythmusic) stops burn in? Has anyone shortcutted a button do blank the screen at any point in time? I have seen some threads about getting the screen saver to do this at various levels of success. If anyone is confident of a safe solution, please post.

well actually the warnings are because older tv's could be severely damaged by sending refresh rates that were out of spec, though most tv's today will just blank out the screen and refuse to work if they get the wrong refresh rates we still shout the warnings as a cya.

Well I'm not sure what I've done or not done to my setup, I've looked at several things people asked me to and haven't figured out why, but my screen blanks if it sits on the menu's for a bit, but never blanks while watching tv or video. It also blanks if the video is paused for an extended period of time. I suppose it could be something in my tv, but I'm not sure.

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Xsecrets

Thanks for all the feedback. Two final questions before I do the connection.

1. I am under the impression that the " XF86Config-4" file is generated automatically. Does this happen at boot time, or is it done during intital system installation. I'm trying to confirm that any edits I make will "stick" and not be blown away by some sort of automatic regeneration process.

2. I am under the impression that the system somehow probes the monitor to understand what it will support. Will a modern TV like a samsung respond to this type of problem and provide appropraite responses?

Thanks!

Marc

Maybe initially during setup but the mechanism is extremely simplistic. There are utilities that are supposed to gnerate them but the results tend to be spotty.

If the TV acts like a monitor and supports DDC probing it will provide certain timing and resolution information but many HDTVs seem to under report their capabilities. Search the HDTV topic for "DDC" and you should find more information.

1) after initial install the only thing that will change the XF86Config-4 file is an upgrade of the video drivers, so you should be safe.

2) unfortunately like tjc said most hdtv either don't report thier specs or report them incorrectly.

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Xsecrets

X, thanks for the info. The outcome is good-new, bad news.

The good news: I tweaked the modeline in accordence to the specs that came with the TV set -- h-freq=60.02; v-freq=75.00; negative v-sync. All went well -- no damage to the TV set and I could watch the video.

The bad news: I now realize that the episode of ER, through recorded on the HD channel, was transmitted in SD. The give away, which I should have noticed before, was the 3GB file size for 1 hour. Not nearly big enough. I now have a partial recording of an HD transmission, and it won't play smoothly at 1024x768 output, as was the expected outcome with a 9200SE card and a 2.4ghz system.

Tomorrow I will try to re-configure to 1080i output. I am hoping that if the source material resolution and the output resolution match, the CPU load will be lower. If that doesn't work, I will pick up an FX5200 card as I've seen others say good things about that.

Marc