Re: [mythtv-users] Various questions

[Brian Steele]

On 9/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Another gentleman by the name of Brian Steele responded to my post, also.  He noted:
You
are correct, they are hardware tuners and they don't perform any
hardware encoding.  The reason they don't need to do this is
that ATSC video is already encoded and compressed into MPEG2 before it
is broadcast.  The video recorded by the HD-3000 and Air2PC
cards is just streamed over the bus directly to the hard disk with very
little CPU involvement.  I have two HD-3000 cards and can
record with both at the same time while using less than 5% of a 3Ghz
Pentium4 CPU.  Playback on the other hand, requires quite a
bit of CPU time.  I average about 85-90% CPU usage when
playing back 1080i HDTV.That said, why would
anyone need a hardware encoder if the stream is passed through the PCI
bus and dumped directly to the hard disk as an MPEG2 formatted
file?  And where does ATSC come in to play?  I
thought the signals we receive in the US are NTSC.  Please
forgive my ignorance.

Analog signals in the US are broadcast in NTSC format.  Digital
signals (SDTV and HDTV) are broadcast in ATSC format.  In my area,
the major broadcast networks are broadcasting in both formats
simultaneously using two different channels.  ATSC is already
MPEG2 compressed.  NTSC is not compressed.  You would use a
hardware encoder if you are recording analog signals either from cable
or over the air.  Basically, digital broadcasts are just written
to disk because they are already encoded, analog broadcasts have to be
encoded before they are written to disk, either using a hardware
encoder or doing it in software.

Hope that helps.

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Re: [mythtv-users] Various questions

[Brian Steele]

On 9/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Thanks
for the info, Brian.  So I assume you're not using an nVidia
card with a hardware MPEG2 decoder?  Or, are you using an
nVidia card, and its' MPEG2 decoder just doesn't cut it?
I'm using an nVidia card but I chose not to use XvMC for playback
because I've heard it has stability problems in Myth 0.18.1 and because
I have enough CPU power to playback without it.
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Re: [mythtv-users] Various questions

[kteague]

> Just wanted to add a few things to earlier posts.
>
>
> On 9/22/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> > 2. I would like to record HD stuff, however, it appears that the only way 
> > to do this is
> >via encoding with CPU overhead (no hardware encoders), as there are
> no video capture >cards (supported under Linux) that can perform
> hardware HD encoding.  I did some
> >reasearch on chipsets used on the Hauppauge PVR-500, and it appears
> the maximum
> >encoding resolution they support is SD.  Now this is where it becomes
> very confusing.
> > The chipset used on the card is a Conexant CX23416.  The product brief
> >(http://www.conexant.com/servlets/DownloadServlet/102074B.pdf?FileId=996)
> states
> >that it supports hardware encoding of 720x480, yet, just below that,
> it says it also
> >supports "HDTV MPEG Capture".  So, does this card also perform
> hardware encoding
> >of 1280x720, or even 1920x1080?
> >
>
> This is where it gets a little tricky to understand and frustrating
> when you learn that it's all irrelevant. The only way to get an HD
> signal out of a decoder box is if the provider lets it through, and
> you have a way to capture it. Theoretically, FCC rules require a cable
> operator (don't know if this applies to satellite) to give you a
> firewire-equipped decoder if you ask for it, which would allow you to
> capture HD streams over firewire without needing a capture card.
> However, they are only required to send OTA channels. You still can't
> record cable HD programs in HD.

Let me see if I'm understanding this correctly.  Firewire-equipped decoder 
boxes don't push out the pay channels through the firewire port?... only the 
OTA channels?

I could buy a DirecTV HD receiver modified with a firewire port 
(http://www.169time.com/).  They're expensive, but they're available.  If what 
I said above is true for cable providers, I don't think the same holds true (at 
least, based on the info from 169time.com) for DirecTV recievers modified with 
a firewire port... I hope!  This may be the route I go, but will I be able to 
use MythTV with this type of setup?


> It would be possible, I suppose, if you had a decoder box that sent
> DVI/HDMI/component outs and a capture device that supported one of
> those, but I've never seen one.

The new DirecTiVo HD10-250 unit I recently purchased has HDMI and component out 
but, you're right, I've yet to find a capture card with any type of digital 
input.  Actually, I take that back.  There are a few cards out there 
(http://www.stream-video.com/drcstream.htm and 
http://www.canopus.us/us/products/dvrex-rt_professional/pt_dvrex-rt_professional.asp),
 but I don't think they're supported under Linux. :-(


> The chip on the Hauppage card might support 720p encoding, but you
> need to give it a 720p signal to encode. That isn't possible with the
> current inputs.

Understood.  This is all begining to make more sense now.


> > 3. Are there any hardware encoding cards supported under Linux to encode the
> >captured streams to MPEG4?  If so, does MythTV support this?  I know there's 
> >a
> >Matrox USB device that can do this, but I would prefer something
> internal to the PC.
> >
>
> Another poster noted one, but I'm not sure this is where you want to
> go. Transcoding video takes a ton of system resources. Myth can
> transcode recordings later (conveniently skipping commercials) if disc
> space is an issue. Otherwise, there's not much point in trying to do
> real-time MPEG-4.

I wanted to do MPEG4 encoding to lessen the amount of disk space used by my 
recordings.  However, at the same time, I would also like to perform multiple 
recordings at once on the back end.  As you noted, the recordings are performed 
on the BE, and this will tax the CPU on the BE if the encoding isn't handled by 
hardware.  This is why I'd like an MPEG4 hardware encoder, if it's available.

Another gentleman by the name of Brian Steele responded to my post, also.  He 
noted:

You are correct, they are hardware tuners and they don't perform any hardware 
encoding.  The reason they don't need to do this is that ATSC video is already 
encoded and compressed into MPEG2 before it is broadcast.  The video recorded 
by the HD-3000 and Air2PC cards is just streamed over the bus directly to the 
hard disk with very little CPU involvement.  I have two HD-3000 cards and can 
record with both at the same time while using less than 5% of a 3Ghz Pentium4 
CPU.  Playback on the other hand, requires quite a bit of CPU time.  I average 
about 85-90% CPU usage when playing back 1080i HDTV.


That said, why would anyone need a hardware encoder if the stream is passed 
through the PCI bus and dumped directly to the hard disk as an MPEG2 formatted 
file?  And where does ATSC come in to play?  I thought the signals we receive 
in the US are NTSC.  Please forgive my ignorance.


> Also, I don't know of many (any, really) success stories of people
> getting USB devices to work.

 I'm tryi

Re: [mythtv-users] Various questions

[kteague]

> > 
> >
> > After reviewing these products, I was under the impression that they're
> > hardware *tuners* that do not perform any hardware encoding (which is left
> > to the CPU/software). They have a new HD-5000 card that appears to boast
> > more features than the previous card, with limited hardware support for
> > demux'ing, but it doesn't appear as if it does full hardware encoding. This
> > card is also able to receive unencrypted digital signals, so I believe my
> > type of setup will fall under this category, and I should be able to use
> > this card (if it's not simply just a tuner).
> >
> >
> > http://mythic.tv/product_info.php?products_id=46&osCsid=7c5c1287a18541561a83e932b1d7c8fd
> >
> > 
> 
> 
> 
> You are correct, they are hardware tuners and they don't perform any
> hardware encoding. The reason they don't need to do this is that ATSC video
> is already encoded and compressed into MPEG2 before it is broadcast. The
> video recorded by the HD-3000 and Air2PC cards is just streamed over the bus
> directly to the hard disk with very little CPU involvement. I have two
> HD-3000 cards and can record with both at the same time while using less
> than 5% of a 3Ghz Pentium4 CPU. Playback on the other hand, requires quite a
> bit of CPU time. I average about 85-90% CPU usage when playing back 1080i
> HDTV.


Thanks for the info, Brian.  So I assume you're not using an nVidia card with a 
hardware MPEG2 decoder?  Or, are you using an nVidia card, and its' MPEG2 
decoder just doesn't cut it?

- Ken


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Re: [mythtv-users] Various questions

[Dewey Smolka]

Just wanted to add a few things to earlier posts.


On 9/22/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Good day Ladies and Gent's,
>
> 1. From what I've gathered, since the DirecTV receivers have tuners in them, 
> I do not need a tuner for my MythTV box.  Is this correct?
>

You don't need a tuner per se, but you need a capture device. The
Hauppage cards have tuners in them, but they also capture over S-vid,
and RCA. I've never played with a DirectTV decoder, but I believe
those are the only two outs you can really use in Myth, besides the
coax.

Generally, you're not going to find a capture device without a tuner in it.

> 2. I would like to record HD stuff, however, it appears that the only way to 
> do this is
>via encoding with CPU overhead (no hardware encoders), as there are
no video capture >cards (supported under Linux) that can perform
hardware HD encoding.  I did some
>reasearch on chipsets used on the Hauppauge PVR-500, and it appears
the maximum
>encoding resolution they support is SD.  Now this is where it becomes
very confusing.
> The chipset used on the card is a Conexant CX23416.  The product brief
>(http://www.conexant.com/servlets/DownloadServlet/102074B.pdf?FileId=996)
states
>that it supports hardware encoding of 720x480, yet, just below that,
it says it also
>supports "HDTV MPEG Capture".  So, does this card also perform
hardware encoding
>of 1280x720, or even 1920x1080?
>

This is where it gets a little tricky to understand and frustrating
when you learn that it's all irrelevant. The only way to get an HD
signal out of a decoder box is if the provider lets it through, and
you have a way to capture it. Theoretically, FCC rules require a cable
operator (don't know if this applies to satellite) to give you a
firewire-equipped decoder if you ask for it, which would allow you to
capture HD streams over firewire without needing a capture card.
However, they are only required to send OTA channels. You still can't
record cable HD programs in HD.

It would be possible, I suppose, if you had a decoder box that sent
DVI/HDMI/component outs and a capture device that supported one of
those, but I've never seen one.

At the moment, at least as far as I'm aware, the only HD you can
capture is OTA, or OTA channels through a digital cable decoder.

The chip on the Hauppage card might support 720p encoding, but you
need to give it a 720p signal to encode. That isn't possible with the
current inputs.

> 3. Are there any hardware encoding cards supported under Linux to encode the
>captured streams to MPEG4?  If so, does MythTV support this?  I know there's a
>Matrox USB device that can do this, but I would prefer something
internal to the PC.
>

Another poster noted one, but I'm not sure this is where you want to
go. Transcoding video takes a ton of system resources. Myth can
transcode recordings later (conveniently skipping commercials) if disc
space is an issue. Otherwise, there's not much point in trying to do
real-time MPEG-4.

Also, I don't know of many (any, really) success stories of people
getting USB devices to work.

> 4. Output -- does MythTV output through the capture card?... or through the 
> video
>card?... or do I have my choice?  I would like to use DVI and keep
everything in the
>digital domain.
>

Either, if you have a PVR-350 with on-board decoder. But you're better
off going through the video card (and, yes, it should be an nvidia).
The DVI on the fx5200 works very well with minimal configuration.


> 5. With the front end/back end arch., where are the encoder cards installed?  
> In the >front or back end?
>

The BE manages capture cards and the master database for scheduling,
recordings, and serving content to FEs. The FEs play live TV and
recorded content delivered from the BE through Myth, play other media
mounted locally or on the network (MythVideo, MythMusic), and can set
up recording schedules.

If a box has a capture card in it, it has to be set up as a BE. If you
have more than one BE, then one has to be set up as the Master,
meaning that it controls the MySQL database that make the whole thing
run.

The easiest way to start is with everything in one box. Once you get
all the bits working together how you want, then you can start
worrying about adding FEs and slave BEs.

Keep in mind, though, that if you're using hardware-encoding cards,
you don't need a particularly powerful system to do recording. Even
with an HD card, since that basically just dumps an MPEG stream to a
very, very large file. The horsepower is needed to play back content,
particularly HD.


> 6. With the FE/BE arch., can the programs be recorded on the FE, then x-fer'd 
> to the
>BE when the program is done recording?  I fear that a temporary
network failure could
>disrupt a program recording.  Having it record on a small FE box,
then x-fer'd later (or
>in chunks as the program is recording) to the BE, it can take
advantage of resuming a
>failed upload to the BE.  Streaming the data has its limit

Re: [mythtv-users] Various questions

[Brian Steele]

On 9/22/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
After
reviewing these products, I was under the impression that they're
hardware *tuners* that do not perform any hardware encoding (which is
left to the CPU/software).  They have a new HD-5000 card that
appears to boast more features than the previous card, with limited
hardware support for demux'ing, but it doesn't appear as if it does
full hardware encoding.  This card is also able to receive
unencrypted digital signals, so I believe my type of setup will fall
under this category, and I should be able to use this card (if it's not
simply just a tuner).http://mythic.tv/product_info.php?products_id=46&osCsid=7c5c1287a18541561a83e932b1d7c8fd


You are correct, they are hardware tuners and they don't perform any
hardware encoding.  The reason they don't need to do this is that
ATSC video is already encoded and compressed into MPEG2 before it is
broadcast.  The video recorded by the HD-3000 and Air2PC cards is
just streamed over the bus directly to the hard disk with very little
CPU involvement.  I have two HD-3000 cards and can record with
both at the same time while using less than 5% of a 3Ghz Pentium4
CPU.  Playback on the other hand, requires quite a bit of CPU
time.  I average about 85-90% CPU usage when playing back 1080i
HDTV.

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Re: [mythtv-users] Various questions

[Bill Omer]

Newer D* receivers have both DVI and HDMI outputs.  The D* HD10-250 (POS) I just 
bought has an HDMI port and comes with a HDMI -> DVI cable.  Are there any 
cards that can support either a DVI or HDMI input?
 


Sadly ... no.  Not yet anyway.  Sure would be nice though, since I can't 
get any OTA HD signals where I live.



-Bill Omer

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Re: [mythtv-users] Various questions

[kteague]

Thanks so much for the quick replies!

> Sort of.  You need a card that can capture from s-video or composite
> since this is the only output you can get from your DirecTV receiver
> (unless they offer one with firewire).  Most cards that have this (PVR 
> series from Hauppauge, etc) also have a tuner so you basically are
> getting both for the price.

Newer D* receivers have both DVI and HDMI outputs.  The D* HD10-250 (POS) I 
just bought has an HDMI port and comes with a HDMI -> DVI cable.  Are there any 
cards that can support either a DVI or HDMI input?


> You can record HD without software encoding using an HD-3000 or Air2PC 
> card.  But these work with over-the-air HD signals from an Antenna.
> These have nothing to do with your DirectTV system, which, per #1, must
> be captured using S-video/composite input to your capture card (software
> or hardware)

After reviewing these products, I was under the impression that they're 
hardware *tuners* that do not perform any hardware encoding (which is left to 
the CPU/software).  They have a new HD-5000 card that appears to boast more 
features than the previous card, with limited hardware support for demux'ing, 
but it doesn't appear as if it does full hardware encoding.  This card is also 
able to receive unencrypted digital signals, so I believe my type of setup will 
fall under this category, and I should be able to use this card (if it's not 
simply just a tuner).

http://mythic.tv/product_info.php?products_id=46&osCsid=7c5c1287a18541561a83e932b1d7c8fd


> Yes.  I believe the Plextor cards can do hardware MPEG-4 encoding on Linux.

Hmm, I'm on their web site right now, and all I can see are external devices.  
Anything in the form of an internal card?  Again, I'm still trying to keep 
everything within the digital domain.


> Video card.  Highly recommend nVidia card of some kind since ATI has
> poor linux support.

I felt this pain and suffering when I was gaming on my Linux box.  I opted to 
dump the ATI card and bought an nVidia. :-)


Richard,

Great explainations of how the FE/BE work, and thanks for the warm welcome.  
Thanks so much!  And thanks to the rest of you who made suggestions regarding 
video cards!

- Ken



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Re: [mythtv-users] Various questions

[Kevin Kuphal]

Mickey Chandler wrote:


At 02:10 PM 9/22/2005, Kevin Kuphal wrote:
>Video card.  Highly recommend nVidia card of some kind since ATI has
>poor linux support.

Your mileage may vary on this one.  I'm using an ATI 9200 card in my 
Myth box and have had excellent results with livna keeping the ATI 
fglrx rpm package up to date with the kernel.  I'm running 
2.6.12-1.1447_FC4 and have a current fglrx build in place.


On the other hand, if you insist on compiling from source, then yes, I 
also thought that ATI was a bit slow off the blocks to start 
supporting the 2.6 kernels (although I think this was more of a 
problem with the changing to the newer GCC version than the kernel 
itself).  I will also note that if you're trying to go completely OSS 
with your Myth box then the ATI drivers aren't for you (as witnessed 
by the "fglrx: module license 'Proprietary. (C) 2002 - ATI 
Technologies, Starnberg, GERMANY' taints kernel." line you'll find in 
dmesg after boot up).


I think the big thing is that ATI does not support XvMC at all which, 
for some systems, maybe the only way for them to get hardware MPEG-2 
decoding in order to playback HDTV content effectively.


Kevin
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Re: [mythtv-users] Various questions

[Mickey Chandler]

At 02:10 PM 9/22/2005, Kevin Kuphal wrote:
>Video card.  Highly recommend nVidia card of some kind since ATI has
>poor linux support.

Your mileage may vary on this one.  I'm using an ATI 9200 card in my 
Myth box and have had excellent results with livna keeping the ATI 
fglrx rpm package up to date with the kernel.  I'm running 
2.6.12-1.1447_FC4 and have a current fglrx build in place.


On the other hand, if you insist on compiling from source, then yes, 
I also thought that ATI was a bit slow off the blocks to start 
supporting the 2.6 kernels (although I think this was more of a 
problem with the changing to the newer GCC version than the kernel 
itself).  I will also note that if you're trying to go completely OSS 
with your Myth box then the ATI drivers aren't for you (as witnessed 
by the "fglrx: module license 'Proprietary. (C) 2002 - ATI 
Technologies, Starnberg, GERMANY' taints kernel." line you'll find in 
dmesg after boot up).


--
Mickey Chandler
Chief Operating Whizard
Whizardries, Inc.: 
Our new site:  



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Re: [mythtv-users] Various questions

[Richard Bronosky]

[EMAIL PROTECTED] wrote:

Good day Ladies and Gent's,

Long time lurker, first time poster with a few questions up my sleeve regarding hardware requirements for my type of setup.  


Service Provider: DirecTV (from here on, referred to as D*)
Video Format: NTSC
Receiver: Any HD capable D* receiver
Television: Westinghouse LVM-37w1

1. From what I've gathered, since the DirecTV receivers have tuners in them, I 
do not need a tuner for my MythTV box.  Is this correct?

2. I would like to record HD stuff, however, it appears that the only way to do this is 
via encoding with CPU overhead (no hardware encoders), as there are no video capture 
cards (supported under Linux) that can perform hardware HD encoding.  I did some 
reasearch on chipsets used on the Hauppauge PVR-500, and it appears the maximum encoding 
resolution they support is SD.  Now this is where it becomes very confusing.  The chipset 
used on the card is a Conexant CX23416.  The product brief 
(http://www.conexant.com/servlets/DownloadServlet/102074B.pdf?FileId=996) states that it 
supports hardware encoding of 720x480, yet, just below that, it says it also supports 
"HDTV MPEG Capture".  So, does this card also perform hardware encoding of 
1280x720, or even 1920x1080?

3. Are there any hardware encoding cards supported under Linux to encode the 
captured streams to MPEG4?  If so, does MythTV support this?  I know there's a 
Matrox USB device that can do this, but I would prefer something internal to 
the PC.

4. Output -- does MythTV output through the capture card?... or through the 
video card?... or do I have my choice?  I would like to use DVI and keep 
everything in the digital domain.
  
with the PVR-350 you have a choice, but the output on that card is 
analog.  So if you want DVI out, you must use a video card with DVI out.

5. With the front end/back end arch., where are the encoder cards installed?  
In the front or back end?
  
A back end is be definition a machine that does capturing.  A front end 
is by definition a machine that displays output.  Most people use a 
single machine as a front end + back end.  You can have multiple FEs, 
BEs, and/or FE+BEs.

6. With the FE/BE arch., can the programs be recorded on the FE, then x-fer'd 
to the BE when the program is done recording?  I fear that a temporary network 
failure could disrupt a program recording.  Having it record on a small FE box, 
then x-fer'd later (or in chunks as the program is recording) to the BE, it can 
take advantage of resuming a failed upload to the BE.  Streaming the data has 
its limits.
  
Since FEs don't record, your question is invalid.  An FE+BE can record.  
It can record to a local volume or a network mounted volume, which can 
be another MythTV box.  It sounds like that is what you are wishing to 
do.  Or, you may be wanting to move the recording to a remote volume 
after recording is complete use a batch script, which again is 
possible.  (This isn't a Microsoft product.  You are in complete control.)

7. With the video scaling capabilities, could I get MythTV to constantly 
upscale all signals to 1080p?  For example, lets say I'm watching SDTV (480i), 
will it upscale that to 1080p?  Then, lets say I change to a channel that's 
outputting HDTV (720p or 1080i), will it automatically know to upscale those to 
1080p?... or will I have to fiddle with MythTV each time I switch channels that 
output different scan rates?

I think that's it for now.  Please be nice to this newbie :-)  I've been trying 
to do my research on this project between working 2 jobs and school.  Thanks!

- Ken
  
I don't know enough about your other questions to answer.  Good luck, 
and welcome to the community.


--


Thank you for your time,
--==<< R i c h a r d   B r o n o s k y >>==--

Nearly all viruses and spyware are designed to use Microsoft internet products.  
Protect yourself by avoiding Internet Explorer & Outlook/Outlook Express.

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Re: [mythtv-users] Various questions

[Kevin Kuphal]

[EMAIL PROTECTED] wrote:


Good day Ladies and Gent's,

Long time lurker, first time poster with a few questions up my sleeve regarding hardware requirements for my type of setup.  


Service Provider: DirecTV (from here on, referred to as D*)
Video Format: NTSC
Receiver: Any HD capable D* receiver
Television: Westinghouse LVM-37w1

1. From what I've gathered, since the DirecTV receivers have tuners in them, I 
do not need a tuner for my MythTV box.  Is this correct?
 

Sort of.  You need a card that can capture from s-video or composite 
since this is the only output you can get from your DirecTV receiver 
(unless they offer one with firewire).  Most cards that have this (PVR 
series from Hauppauge, etc) also have a tuner so you basically are 
getting both for the price.


2. I would like to record HD stuff, however, it appears that the only way to do this is via encoding with CPU overhead (no hardware encoders), as there are no video capture cards (supported under Linux) that can perform hardware HD encoding.  I did some reasearch on chipsets used on the Hauppauge PVR-500, and it appears the maximum encoding resolution they support is SD.  Now this is where it becomes very confusing.  
 

You can record HD without software encoding using an HD-3000 or Air2PC 
card.  But these work with over-the-air HD signals from an Antenna.  
These have nothing to do with your DirectTV system, which, per #1, must 
be captured using S-video/composite input to your capture card (software 
or hardware)



3. Are there any hardware encoding cards supported under Linux to encode the 
captured streams to MPEG4?  If so, does MythTV support this?  I know there's a 
Matrox USB device that can do this, but I would prefer something internal to 
the PC.
 


Yes.  I believe the Plextor cards can do hardware MPEG-4 encoding on Linux.


4. Output -- does MythTV output through the capture card?... or through the 
video card?... or do I have my choice?  I would like to use DVI and keep 
everything in the digital domain.
 

Video card.  Highly recommend nVidia card of some kind since ATI has 
poor linux support.



5. With the front end/back end arch., where are the encoder cards installed?  
In the front or back end?
 

They are installed where a mythbackend process runs.  This can be on a 
standalone master backend, a combination frontend/backend or even a 
slave backend working with a master.



6. With the FE/BE arch., can the programs be recorded on the FE, then x-fer'd 
to the BE when the program is done recording?  I fear that a temporary network 
failure could disrupt a program recording.  Having it record on a small FE box, 
then x-fer'd later (or in chunks as the program is recording) to the BE, it can 
take advantage of resuming a failed upload to the BE.  Streaming the data has 
its limits.
 

It is usually best to have all backends write to common disk using an 
NFS mount.  This avoids problems where the slave goes offline taking 
recordings with it.



7. With the video scaling capabilities, could I get MythTV to constantly 
upscale all signals to 1080p?  For example, lets say I'm watching SDTV (480i), 
will it upscale that to 1080p?  Then, lets say I change to a channel that's 
outputting HDTV (720p or 1080i), will it automatically know to upscale those to 
1080p?... or will I have to fiddle with MythTV each time I switch channels that 
output different scan rates?
 


Not sure.  Someone else might answer this better.

Kevin
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[mythtv-users] Various questions

[kteague]

Good day Ladies and Gent's,

Long time lurker, first time poster with a few questions up my sleeve regarding 
hardware requirements for my type of setup.

Service Provider: DirecTV (from here on, referred to as D*)
Video Format: NTSC
Receiver: Any HD capable D* receiver
Television: Westinghouse LVM-37w1

1. From what I've gathered, since the DirecTV receivers have tuners in them, I 
do not need a tuner for my MythTV box.  Is this correct?

2. I would like to record HD stuff, however, it appears that the only way to do 
this is via encoding with CPU overhead (no hardware encoders), as there are no 
video capture cards (supported under Linux) that can perform hardware HD 
encoding.  I did some reasearch on chipsets used on the Hauppauge PVR-500, and 
it appears the maximum encoding resolution they support is SD.  Now this is 
where it becomes very confusing.  The chipset used on the card is a Conexant 
CX23416.  The product brief 
(http://www.conexant.com/servlets/DownloadServlet/102074B.pdf?FileId=996) 
states that it supports hardware encoding of 720x480, yet, just below that, it 
says it also supports "HDTV MPEG Capture".  So, does this card also perform 
hardware encoding of 1280x720, or even 1920x1080?

3. Are there any hardware encoding cards supported under Linux to encode the 
captured streams to MPEG4?  If so, does MythTV support this?  I know there's a 
Matrox USB device that can do this, but I would prefer something internal to 
the PC.

4. Output -- does MythTV output through the capture card?... or through the 
video card?... or do I have my choice?  I would like to use DVI and keep 
everything in the digital domain.

5. With the front end/back end arch., where are the encoder cards installed?  
In the front or back end?

6. With the FE/BE arch., can the programs be recorded on the FE, then x-fer'd 
to the BE when the program is done recording?  I fear that a temporary network 
failure could disrupt a program recording.  Having it record on a small FE box, 
then x-fer'd later (or in chunks as the program is recording) to the BE, it can 
take advantage of resuming a failed upload to the BE.  Streaming the data has 
its limits.

7. With the video scaling capabilities, could I get MythTV to constantly 
upscale all signals to 1080p?  For example, lets say I'm watching SDTV (480i), 
will it upscale that to 1080p?  Then, lets say I change to a channel that's 
outputting HDTV (720p or 1080i), will it automatically know to upscale those to 
1080p?... or will I have to fiddle with MythTV each time I switch channels that 
output different scan rates?

I think that's it for now.  Please be nice to this newbie :-)  I've been trying 
to do my research on this project between working 2 jobs and school.  Thanks!

- Ken




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