[mythtv-users] XvMC on NVidia with Myth .20 (Anyonegetting goodHD off a P4 3

R. G. Newbury newbury at mandamus.org
Mon Jan 8 17:51:43 UTC 2007

Drew Bernat wrote:
> On Jan 8, 2007, at 11:13 AM, R. G. Newbury wrote:
>> If you are using S-video for output to a CRT, I doubt that you are
>> actually getting an 'HD' level signal. You are likely dealing with a
>> digital SD level signal (which is quite a different thing). Good that
>> you can get digital output. Weird that you are getting problems with a
>> PVR doing analog SD signals.
> Right. This is HD-input or SD-input. I've got much higher recording 
> quality than playback.

You appear to have missed the point here, and it is amazingly easy to 
get confused about what is being discused.

There are two types of signal delivery.
There are (for our purposes) two levels of signal definition.

One type of delivery can do both levels of definition.
The other type of delivery can do only the lower level of definition.

Digital delivery can be SD or HD level definition.
Analog delivery can only do SD delivery.

On top of that, S-video output from your system is limited to SD level 

So if you have a digital source with HD level definition, but feed it 
out by S-Video, you will get an SD level resolution picture... but it 
will likely be clearer etc. than an analog version of the same program.

> Hrm... I can get a digital-in SD program. I should record one and 
> compare that to the cable-in PVR recording. They should just be MPEG-2, 
> but hey...

These *should* be the same, but realistically the digital will be a 
better picture. The one is sent as MPEG and streamed to your hard drive. 
The other is sent as analog, and converted by your PVR's onboard 
encoder, and streamed to your harddrive.

> Also interesting that the S-video out ignores modelines. I know you can 
> futz with resolutions, but I thought you could also do refresh rates. I 
> guess not.

Well, technically, I guess it has a hard wired modeline based on NTSC or 
PAL standards... which include the refresh rate.

>> Have you tried setting your output to an NTSC (or PAL) standard output?
>> The buffer pauses may be the result of the system trying to change
>> resolution on the output signal, and not succeeding gracefully.

Clean down your xorg.conf to either 800x600 or 720x480 and see what 
happems. Since you are using the S-video for output, remember to set the 
output to 'CRT,TV' to get both.


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