Author Topic: Possible to watch HD channels on a SD capable media director?  (Read 943 times)

jeangot

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Hello,

I am building some very low end media directors for secondary bedrooms. On a celeron 1.8 Ghz with a PCI Nvidia NVS 200 card (very very old) I am able to view SD TV channels in Mythtv, but HD channels are choppy, which is probably normal given the hardware.
I use the 96xx series nvidia drivers (which was a challenge in itself because the latest version simply would not work).

Since these computers are not even connected to HD capable TVs (but to computer monitors), I'm wondering if there is a way to tell MythTV to scale down the 1080p channels (which I get through HD Homerun) and send them to the MD as a 480p stream?

If that's not possible, is there a way to specify different channel listings per MD (by fumbling in some config file?), basically hide different channels on each MD. Then I could simply have the HD channels available on my high end MDs (in the living room) and on the low end MDs I could show the 480p version of the same channel (which exists for each channel), then it would just work.

Jean

PS: I gave up on using the HP T5700 thin clients to watch TV. Even after adding an Nvidia card through the PCI extension slot, video playback and low def TV was choppy. I guess the computer itself is just too slow (1 Ghz). But other than that they make a fine low cost low ($50 on ebay) power use MD for places where I need only music and external applications (web browsing, remote desktop). The Mythtv wiki says that T5720 are suitable, but I haven't gottent my hand on those yet. They are only slightly more powerfull than the T5700 too...

tschak909

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Re: Possible to watch HD channels on a SD capable media director?
« Reply #1 on: June 18, 2008, 06:18:15 pm »
the graphic card will scale down video appropriately. There is no problem.

-Thom

skeptic

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Re: Possible to watch HD channels on a SD capable media director?
« Reply #2 on: June 18, 2008, 07:26:12 pm »
I don't think MythTV can scale the video before sending it to the MD unless you transcode after recording and play previously recorded shows.  I haven't followed the discussions on having multiple streams on the same channel, ie channel 501 has HBO in HD and HBO in SD on my DirecTV, I forget what that's called.  However, there was some talk about adding support for it in MythTV, but it's likely dependent on tuner card support as well.  In my case, my only option for recording is via the s-video output which will always be the SD version of whatever the component output is.  I'm not a MythTV guru, but it may be possible to set it up so the remote MDs get their feed from the s-video port (if you have one wherever the HD signal is coming from) and HD output for the HDTV.

Have you tried just running a lower resolution on the MDs?  The issue may not be in streaming OR scaling on the MD, but the video card itself.

jeangot

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Re: Possible to watch HD channels on a SD capable media director?
« Reply #3 on: June 18, 2008, 10:45:52 pm »
Hi guys,

thanks, I didn't think about trying a lowe resolution. These MDs run 1280x1024, the main reason being that I also use them for remote desktop working, and there a lowe resolution is unusable.
But I will try lowering the resolution to 640x480 tonight and see if that makes the TV smooth. Will report the results. It still won't solve my problem since I can't use that low resolution permanently, but it's an interesting exercice.

Skeptic: to answer your question, I get my channels through an HD Homerun. What that does I think is that it takes the MPEG 2 stream and simply resends it to the core and then to the MD. That would be a fairly big amount of data for HD channels.

No ideas about how to have different channel lists in Myth on different MDs? I do know how to get a channel 123 for ABC HD and a channel 124 for ABC SD for example, the goal would be that certain MDs only show 123 and others only 124...

Jean

jeangot

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Re: Possible to watch HD channels on a SD capable media director?
« Reply #4 on: June 19, 2008, 05:12:37 am »
So I tried decreasing the resolution on my MD to 640x480 (which means in theory that no more than 480 lines can be displayed, which matches SD 480p resolution), and the HD channels are still as choppy (it cuts every second when the cpu maxes out, then starts again).
So the video resolution is apparently not helping to reduce the amount of data that MythTV Player has to process for those HDTV channels.

For now I will just enable in mythtv setup both the HD and SD version of each channel. It would be even nicer to be able to hide certain channels on certain MDs, but this may be a question that I should ask in a MythTV forum.

Jean