[mythtv-users] New user setup questions?

[Andrew Dodd]

Quoting Alex Van Deusen <alex_van_deusen at hotmail.com>:

> I am ready to begin building a mythtv environment.  I have a few questions 
> before I get started.
> 
> I currently have the following
> Toshiba H8016x9 TV,  It has component inputs only  ( I intend to purchase a
> 
> transcoder for vga to component video and use powerstrip)  Zenith DTV 1080 
> HD Direct TV Receiver with SPDIF.
> 27" RCA TV with Svideo,  Sony BT55 DirectTV
> 19" Samsung Flat Panel DVI monitor/Analog
> 12" Sony with only cable RF
> 
> I have purchased (1)  PVR-250, (1) Wincast TV (848 chipset)
> I am also going to purchase a PCHDTV, and other cards depending on answers 
> from you!
> 
> My questions are as follows.
> 
> 1. I love the HD TV that is delivered from the Zenith HD DirectTV box. ( I 
> live directly across from NYC so I get all the HDTV channels available)  I 
> could never ever go back to standard TV watching if I don't have to.   The 
> guide  integrates the ATSC with Satellite channels and is great for 
> previewing TV while I watch other channels.
> a.  I know that I will not be able to capture HDTV from the HD DirectTV,  so
> 
> I will need to purchase the PCHDTV.  Will the guide be integrated within 
> Myth.  Will it remap channels (sub channels) ie CBS is 56-1 to 2-1 etc..... 
Not sure about channel remapping.  I intentionally don't remap on my MyHD -
leads to too much confusion.  :)

BTW, it is *theoretically* possible to capture HD from a DirecTV box if you have
a receiver modified by 169time for Firewire output, although currently Myth
doesn't support Firewire tuners.  It might happen if tuner manufacturers get off
their asses...  169time-modified DTV receivers seem to be the only ones that
will feed Firewire HD recorders such as the JVC HM-DH30000U or a Linux box with
the right software.  (There is software in existence to act as a recording
device in such setups, I forget the exact name, look around on avsforum...

> Can I choose to exclude channels that have no signal?
Yes.

> b.  The quality for the main TV is paramount.  I know that DirecTV is highly
> 
> compressed so will I be able to capture that in at least 720x480. ( I am 
> sure the answer is yes). Can I scale that with FFDshow or Dscaler.
Yes, you can capture that at 720x480, although that would be pointless since
DirecTV's SD broadcasts are only 480x480.  Not sure what the box downconverts HD
channels to.

> c. For the HD broadcast will I be able to capture full 1080i for 2,4,11 and
> 
> 720p and 480p for ABC and Fox.
With a pcHDTV
2:  Yes
4:  ??? - WNBC hadn't gotten their act together last I heard.  I know I can't
get any signal from them out here in Martinsville, NJ.  I get 44 (FOX 480p plus
UPN's 480i subchannel), 45 (ABC 720p, new as of the past 3 months or so), and 56
(CBS).  I believe WPIX is still only broadcasting extremely low power, but that
may have changed.

> d. How does the sound work.  The Zenith has optical out and analog out.  I 
> have purchased a Mad Dog card with the Envy chipset and it has optical in 
> and out.  Do I need to even bother with the optical in to get DD 5.1 for HD
> 
> broadcast or Direct TV.  Will the capture card(s) just send the data over 
> the PCI bus?  Or would I need to plug the optical in from the HD DirectTV 
> into the soundcard in and route optical out from my soundcard to my 
> receiver?
If you use a pcHDTV, it captures the transport stream, after which the MPEG is
decoded by your CPU.  Thus the sound becomes available at your soundcard, and
what the setup supports is dependent on what your soundcard supports.

Same with video - Whatever your VGA card's output can do, the pcHDTV setup can do.

Note one caveat though:  You need a wicked fast CPU in the frontend to even
think about 1080i decoding.

> e. I intend to build separate backends and front ends.  Therefore what is 
> the best configuration for this system.  I concerned that the PCI bus won't
> 
> be able to handle all this from a central mammoth server.  So I have 
> different scenarios which would make more sense?
Decoding is done on the frontend.  Streaming of HDTV MPEG transport streams over
a 100 Mbit network is no problem at all.  It's only 19.2 Mbits/sec, not anywhere
close to saturating your PCI bus.  :)

> Again image quality on the main RPTV is paramount.
>         i. build low end front end pII 333mhz  with a (new purchase) PVR-350
> 
> that has Mpeg2 Hardware Encoder/Decoder and a PCHDTV for HDTV.  I       
> would use a Radeon 9600xt or Geforce Ti200 for graphics card.  I would use 
> the Envy card for audio.  Lirc with a low speed data serial connection.
>         ii. or I would need much more powerful front end 2.6 ghz machine at
> 
> least for HDTV.  Then I could run just a PVR 250 in a backend.
>         iii dont need to run anything on frontend except graphics card, so i
> 
> could go lowend with a nic card and pull everything from the backend of (2) 
> 
>       PVR-250s connected to (2)DirectTV's and a PCHDTV
>         iv.  does the slave backend need a graphics card?  Or could I load 
> up an old box that has scsi and ata 133 with multiple drives and just the   
> 
>        capture cards.
>         v.  can I even use the Wincast TV card.   It has composite video out
> 
> and analog out.  Coud I use this without a graphics card?  Will that be good
> 
> enough on the 27" TV.
>         vi.  If intend to build a frontend only for the 27" TV and the 
> bedroom small TV do I need anything except for graphics card and sound cards
> 
> in those machines with minimal drives (9 gigs).  What is the minimum configs
> 
> for front ends like this if I have a big backend with (2)PVR 250 and
> PCHDTV?
>         vii I like to channel surf and don't intend to completely Timeshift
> 
> all material.  So if I wanted to watch Direct TV in one room while my wife 
> records something on another TV and watches Live TV is this possible. Or 
> would I need to have three PVR-250 connected to three DirectTV.    Same 
> question for PCHDTV.  Would I need to have two PCHDTV to watch LiveTV and 
> record.  Would that crush the PCI bus? Does the box need to be superpowerful
> 
> for dual PCHDTVs
Trying to answer these all at once:

Backend may or may not need a graphics card.  Depends on the motherboard.  Most
machines prefer to at least have some VGA card for setup/booting.  But you don't
need anything more than the basic, crappiest card available for the backend.

Backend doesn't need any CPU either if you're using PVR-x50s and pcHDTVs.  A 500
MHz machine should work without breaking a sweat, although you may want a faster
machine just for support for more modern (faster) ATA interfaces, because you
WILL need fast hard drives.  As I mentioned earlier, the compressed MPEG is
child's play for the PCI bus.  The hard drives are a different story.  2 streams
at once should be no problem with any modern hard drive.  2 HD and 2 SD streams
will probably push things a little as far as seeking...  Seeking between 4
different spots on a disk will send transfer rates down the tubes.

As far as frontends for the 27" TV - You'll still need insane amounts of CPU to
decode HD, even though it'll be eventually be downconverted to 720x480
interlaced.  If you are only interested in viewing your SD recordings on the
non-HD TV, then it's actually possible to use an Xbox which supposedly is
dropping to $100 in May.

Oh, one last comment:  The PVR-350's hardware MPEG decoder has no support for
MPEG-2 MP at HL, onl MP at ML.  In short, it won't decode any HD content and
downconvert it to 480i.  The highest-res MPEG it will decode is 720x480.  MP at HL
capable decoders are rare and $$$ (that's why the HD cards with hardware
decoding are usually $130-150 more than software ones, as compared to the
PVR-350 only being $30 more than the 250).  And no MP at HL capable decoders are
supported under Linux.