[mythtv-users] numerous newbie questions

Michael T. Dean mtdean at thirdcontact.com
Fri May 27 18:40:33 UTC 2005


Peter T. Abplanalp wrote:

>* On Fri, May 27, 2005 at 02:55:08AM -0400, Michael T. Dean wrote:
>  
>
>>Peter T. Abplanalp wrote:
>>    
>>
>>>keep up.  is that true?  does anyone know if the ati
>>>wonder pro does onboard encoding and if so, how do i get
>>>that working?
>>>      
>>>
>>No.  It's a frame grabber.  Requires software encoding, so
>>your P2/450 is a bit underpowered.
>>    
>>
>that's exactly what i was afraid of; however, i did ask the
>sales person whether the card did onboard mpeg2 encoding
>before i bought it at worst buy and the sales person said
>yes it did.  oh well, i guess i can always use it as another
>recording source.  i assume that if i get a faster cpu, the
>video recorded from this card will be acceptable.  is that
>true?
>  
>
Yeah.  However, you could always try taking it back.  When you tell the 
store manager that the salesman told you it did hardware encoding and 
you found it uses the CPU, I'm sure you can convince him to let you 
return it (especially if you mention a P2/450).

>>If you get a PVR-350, you don't need a video card with TV
>>out.  (Also, if you don't upgrade your CPU, you'll
>>probably want to go with the PVR-350,
>>    
>>
>ok but if i have a video card and the pvr-350, how does
>linux know where to pipe what?  or is linux out of the loop
>and the tv out of the 350 is strictly tv tuner output?
>
If you tell MythTV to output via the PVR-350 ("Use the PVR-350's TV out 
/ MPEG decoder"), it will.  Otherwise, it won't (it will use the video 
card).  ;)

>or does all video out go to both outputs?
>
No.

>say i want to use
>the 350 to hardware decode a recording, how does that work?
>  
>
Tell Myth, as above, then the PVR-350 decodes and will *only* output the 
video on its own TV out--not your video card's.

>>but as a PVR-350 owner who's not using PVR-350 TV out
>>because of its shortcomings
>>    
>>
>what short comings are those?
>  
>
Primarily the lack of hardware acceleration.  It does hardware decoding, 
but on a relatively modern CPU, decoding an NTSC-size MPEG stream takes 
very little effort if you have XVideo (Xv) support in your video card 
driver.  The hard part of graphics today is real-time rendering of 3-D 
scenes, so I prefer to have OpenGL support.  OpenGL can be used with 
games in MythGame, for the Goom visualization in MythMusic, for 
transitions in MythGallery, and much more.

Also, the PVR-350 only does 720x480 output.  I didn't like the GUI at 
this size (so I use 800x600 and have my video card scale it).  And, if 
you use anything besides an NTSC/PAL TV, the PVR-350 won't work.  So, 
when you get that pcHDTV 3000 and start recording high-definition, 
you'll have to change everything up--get a video card and reconfigure 
your Myth box (hardware and software).  Or, if you buy a new digital TV 
with DVI input or a projector with VGA/DVI input, you'll get much better 
quality using that than using the NTSC input.

Thanks to John Harvey, the PVR-350 just got Xv support (within the last 
couple of months).  Without it, it was nearly unusable for anything 
except MPEG-2 recordings (i.e. DVD playback, MPEG-4 playback, and just 
about everything else was severely crippled).  At the point when I set 
mine up, there was no Xv and I considered adding support for it, but as 
I got to know the PVR-350 better I decided that even with Xv, I would 
prefer to use a video card for output.

You should make your own decision, but using a PVR-350 as a PVR-{1,2}50 
(the way I'm using it) is a waste of at least $100.  Now if Hauppauge 
made a hardware-based HDTV decoder...

>>>actually, can someone please explain how the video and
>>>audio is handled?  specifically, how do things need to be
>>>wired to and from the computer.
>>>
>>Depends on what you're hooking up--analog cable, digital
>>cable with serial control, digital cable with IR control,
>>digital cable with firewire, satellite with serial
>>control, satellite with IR control, ...
>>
>i will be hooking up digital cable.  i think i will be
>buying a second tuner card so what i would like is to hook
>one cable directly to one tuner card and get a subset of
>channels there (specifically, 2-63 in my case) and hook the
>output of the stb to the second card; however, i have a
>crappy stb with no rs232 or other data port so i think i
>will have to set up an ir blaster.  true?
>
Yes.

>in my stb
>scenario, i think that the stb will handle the actual
>channel changing and that the card in this case will be set
>to some fixed channel (usually 3 or 4 like a vcr.)  is this
>also true?
>
Yes.  Or, better yet, use the STB's Composite or S-Video output.  RF 
modulated output will be a lower-quality signal.

>is there some good documentation on remotes in
>general somewhere?
>
http://www.lirc.org/

>  speaking of the crappy stb, i am using
>comcast's service, does anyone have any experience asking
>comcast for a better stb with a data port?
>
>>>finally, the video is pretty awful when viewed on the
>>>screen.  why might that be?
>>>      
>>>
>>P2/450 and a frame grabber instead of a hardware encoder.
>>Might also be a bad choice of resolution/bitrate, but you
>>should probably focus on the encoding problem first (i.e.
>>either get a hardware encoder, a better CPU/motherboard,
>>or--better yet--both).
>>
>that's what i thought, thanks for the confirmation.  on the
>resolution/bitrate issue, is there some good documentation
>somewhere i could read up on with respect to this?  i don't
>think i understand computer/tv resolution, dpi v 720x680
>stuff, scan rates, hdtv, etc.
>  
>
Lots of good stuff on the list.  Check the archives.  
http://www.gossamer-threads.com/lists/mythtv/

Mike


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