[mythtv-users] Re: Considering a MythTV

[Jarod C. Wilson]

On Sunday, Jason Williams wrote:

> Hello everyone.

Hello.

> I’m leaning to MythTV for many reasons: Linux based, Integrated 
> Program Lineup and Scheduling, Great looking interface, runs on a 
> standardized system which would allow me to pull movies from the drive 
> (via Samba) and edit/clean them up etc…, free programming information 
> vs. ReplayTV subscription basis.  My second choice is TiVo for the 
> fact that it’s all configured already and is a known working product 
> (though I’ve yet to find a store display that will demonstrate it’s 
> video quality).  With anything on Windows running a distant and 
> insignificant last.

Good ordering! :)

> (I might use ShowShifter in my kids room for it’s simplicity, and ease 
> of reinstallation if he hoses it.)

MythTV can be made reinstallable with quite a bit of simplicity. Use 
mondorescue to generate a bootable full system restore CD. Boot off the 
CD, reinstall the system exactly as it was in no time whatsoever...

> Before I go into my questions, let me say that I don’t mind spending a 
> little money if it’s going to yield some significant benefit and 
> pleasure.  However, I do not wish to waste any money on anything that 
> will only yield marginally beneficial results.

Understood, and good that you're willing to spend some cash to do it 
right. :)

> Some concerns I have (sorry if any of these are covered, I searched 
> the archive and read a lot but finally my eyes got tired) :
>
> 1.	What is the video quality like?  I’m aware that even a VCR has a 
> lesser quality than broadcast TV, but I don’t use my VCR partly for 
> that reason.  VHS looks terrible, especially if the tapes been watched 
> a few times.  I expect that the quality will be near broadcast if not 
> equal to it.  Does anyone have any experience with both MythTV and 
> TiVo?  Can someone describe a comparison using quantifying terms other 
> than those like “awesome” or “sucks”?

Depends on your viewing device, input source, etc. Personally, I have a 
47" HDTV, and Comcast digital cable. I use a GeForce 4 MX for S-Video 
hookup to my TV, versus RCA Composite from my cable box to the TV. My 
capture card is a WinTV PVR-250, and using its highest quality setting, 
I get a substantially BETTER picture using MythTV than using my digital 
cable box. I believe some of the software involved in the video output 
process of MythTV actually cleans the picture up a bit. If you don't 
already have a tuner card, I HIGHLY recommend the PVR-250/350/Freestyle.

> 2.	While quality is important, so is file size.  I want to be able to 
> build a system that can store some music and downloaded/ripped movies 
> as well.  I’ve been unable to locate a good comparison of quality vs 
> size of the rtjpeg vs. mpeg2 vs. mpeg4 codecs.  Can anyone shed some 
> light on this?

Ah, well, in that case... The PVR-250 at its highest settings uses 
quite a bit more disk space, because it does hardware mpeg2 
compression, instead of software mpeg4. mpeg4 uses about 1/4 the disk 
space, if I recall correctly, but there is also an option in the latest 
rev of MythTV to transcode recordings from mpeg2 to mpeg4 after they 
are done (I haven't used it myself; I have plenty of disk storage to 
just use mpeg2).

> 3.	I’m thinking mpeg4 is going to give my quality vs size compromise 
> I’m looking for.  Are the mpeg4 files compatible with Windows?  If 
> not, what can be done to make them compatible?  I’ll most likely want 
> copy select programs over my network, clean up commercials etc.. then 
> save it back to the MythTV box so that it will concerve space.

You can use the mythmkmovie utility to convert recorded shows to a 
compatible file format.

mythmkmovie description:
MythMkMovie is an archiving assistant for use with MythTV. It will
produce a DiVX file for your viewing/archiving pleasure, and remove
the commercials in the process (IF you've gone through and removed
them when watching it in MythTV). It can be drivien from the command
line, or it also has a curses based interface to allow you to navigate
the files you have stored on your computer.

You don't even really need to do the commercial edits under Windows.

> 4.	I’m assuming that the TV Tuner will stay on one channel (3?) like a 
> VCR does and somehow you control the cable box?  It seems there are 
> ways to remote control the box.  Does anyone have any experience with 
> Comcast Cable inDallas,TX?  I’ve had this box since my provider was 
> TCI Cablevision.  I looked up some info on my box.  It is a Motorolla 
> for my Digital Cable.  The menu system indicates that it is a model 
> DCT, SW Ver. 15.22, IR Blast = No, Firmware 07.54, and RF Bypass = 
> On.  It does have a DB9 Female connector on the back of the unit.

There are ways to control it. I've got Comcast digital cable in 
Seattle, WA, though almost everything I actually watch comes through 
without the box, so I just go straight from the wall into my MythTV 
box. I'll have to muck with the box connection one of these days... (I 
have a Motorola DCT2224).

> 5.	Hardware Selection.  I have some items available to me already. 
> I’ve not decided if I will recycle them or just build an overpowered 
> system to ensure quality.  The expense will really dictate that.  
> Available to me is a:  P3-1000, 512+ SDRAM, Guillemot 3D DDR-DVI 
> (GeForce 256 DDR) with TV-Out, various NIC’s, and a SB Live!

If you plan on doing software encoding, that PIII-1GHz is NOT 
overpowered. It's about as little as I'd want for simultaneous software 
encoding and playback, if it'll even handle it.

 From the MythTV documentation (note the PIII-733):

Here are a few data points:

     * A PIII/733MHz system can encode one video stream using the MPEG-4 
codec using 480x480 capture resolution. This does not allow for live TV 
watching, but does allow for encoding video and then watching it later.
     * The developer states that his AMD1800+ system can almost encode 
two MPEG-4 video streams and watch one program simultaneously.
     * A PIII/800MHz system with 512MB RAM can encode one video stream 
using the RTJPEG codec with 480x480 capture resolution and play it back 
simultaneously, thereby allowing live TV watching.
     * A dual Celeron/450MHz is able to view a 480x480 MPEG-4/3300kbps 
file created on a different system with 30% CPU usage.
     * A P4 2.4GHz machine can encode two 3300Kbps 480x480 MPEG-4 files 
and simultaneously serve content to a remote frontend.

The second mode of operation is where MythTV is paired with a 
hardware-based video encoder, such as a Matrox G200 or a Hauppauge 
WinTV-PVR-250/350. In this mode, because the video encoding is being 
done externally, the CPU requirements are quite low. See the Video 
Capture Device section for details.


> I figure I’ll buy a Avermedia TV Studio for it’s high resolution and 
> remote, and either a DVD/CDRW combo or just a DVD for it.

I'm not at all impressed with my AverTV Studio card at all (the remote 
is mediocre too). I like my PVR-250 WAY better... If you want to 
minimize costs, use the PIII-1GHz, get a PVR-250 and a large hard 
drive. A PIII-1GHz is plenty w/the PVR-250. Transcode recordings to 
mpeg4 when they're done, and space shouldn't be an issue (though 
continuing to watch TV while a transcode is in process would probably 
not work).

Oh, the AverTV Studio also has some assorted audio issues...

> If I end up buying a DVD-RW it will go in my pc =)

My DVD-RW is in my Mac. :)

> 6.	It seems that I need a Ghz per tuner basically if I want to utilize 
> more than one function at a time?  So if I want two cards to be able 
> to watch (timeshift) and record something else, I will need at least 
> 2Ghz CPU?  I would like to be able to watch something and record 
> something else simultaneously if possible.  More than that is not 
> necessary.  Most of my watching will be of programs that ran when I 
> was not home.  As a single parent, I don’t get much time for TV until 
> the little man goes to bed.  That’s when I’m hoping to make the most 
> use of this system.  Maybe on the weekends also.

 From above:
* The developer states that his AMD1800+ system can almost encode two 
MPEG-4 video streams and watch one program simultaneously.

With software encoding, it would appear at least 2GHz would be 
necessary (remember that both the stream you're watching and the one 
you're recording are being encoded).

Even with a PVR-250 and a non-hardware-encoding tuner, I think your 
PIII-1GHz would be insufficient for watching and recording 
simultaneously. You might be able to do it with dual PVR-250s (or one 
PVR-250 and one Freestyle, since you don't need 2 remotes).

> 7.	Will the TV out on this card (Guillemot GeForce 256 DDR) be 
> sufficient for my quality concerns, or should I look into something to 
> convert the DVI to TV for me?  Or should I really consider something 
> else that’s on the market today?

It SHOULD be sufficient... But pre-GF4-series cards don't support the 
nvidia driver's overscan option. I'm extremely happy with the results 
I've had with my GeForce 4 MX 440's S-Video out.

> 8.	I may have missed this in the documentation, but I didn’t see where 
> the videos are stored.  I’d like to know this to plan my file system.

I can't recall. I use the Red Hat Linux 9 MythTV rpms, which use a 
different setting than the default one in a source-based install. It 
doesn't matter a huge amount though, because you can specify whatever 
storage locations you want for both live TV buffers and recordings 
(independent of one another).

> 9.	Are there any other concerns that a MythTV n00b should be aware of?

Be prepared to spend some time getting everything to work. Some 
distributions are easier to set MythTV up on than others, because some 
have pre-compiled packages for almost everything, while others must be 
installed predominantly from source. Red Hat Linux 9, as I mentioned, 
is one distribution that has software packages for almost everything 
you need, courtesy of Axel Thimm's ATrpms: 
http://atrpms.physik.fu-berlin.de/dist/rh9/

--Jarod

-- 
Jarod C. Wilson, RHCE

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html

MythTV, Red Hat Linux 9 & ATrpms documentation:
http://pvrhw.goldfish.org/tiki-page.php?pageName=rh9pvr250