Log in Register FAQ Memberlist Search pcHDTV Forum Index
pcHDTV Forum

pcHDTV Forum Index -> mythTV wiith the HD-2000 card -> pchdtv + mythtv + comcast = dollor capitis
Post new topic  This topic is locked: you cannot edit posts or make replies. View previous topic :: View next topic 
pchdtv + mythtv + comcast = dollor capitis
PostPosted: Sun Apr 23, 2006 11:06 pm Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




Dollor capitis is latin for headache.

So far every single step in the installation has been painful, and I'm still don't have everything working. Sad

I already have Mythtv 0.19 configured with one analog capture card and a frontends, so I thought this would be fairly easy.

In my first attempt I put the pcHD3000 in the same machine as the analog card. It took me a while to figure out which devices I needed and what settings to use in myth, and evern when I did figure it out, myth was unable to find or tune any channels. This is of course because Compost (oops, that's supposed to be comCAST) doesn't transmit channel identifiers on their channels.

Ok, after some reading up I realize that I need to use atscscan to find the channels, then record some programming from each to figure out what they are. (This btw, took quite a while to figure out, since there are no real instructions, just posts from people that made it work somehow.)

Next problem: which frequency table to choose? Well, there are only so many, so I wrote a small script, started it up and went to bed.

Ok, so in the morning I found that I have more choices than I wanted, but one of the channel scans revealed a few more channels than the others, so I picked that one. I tried tuning a few channels and playing data from /dev/dvb/adapter0/dvr0. At first I had absolutely no luck, probably because most channels are encrypted. However, eventually I found a channel, which immediately revealed problem #3 (4?): The signal was all garbled!

Back to the drawing board (actually, this board): After reading up I noticed that it seems that the signal quality was going down significantly when I started capturing data. It seems more people has had this problem, and blamed it on poor power supplies. My mythbackend computer is cobbled together by old parts, so it's quite possible that the power supply is not very good. So, I moved it to my file server and fired up another mythbackend...

On a side note, when you select "delete all capture cards" in the mythtv setup program, it deletes all capture cards on all clients, not just the ones you can see. (It doesn't show capture cards on other backends.)

At this point I wrote a small script which would tune in every channel and capture 30 seconds of data from /dev/dvb/adapter0/dvr0. This of course takes a while, so I ran it while I was at work. The results were encouraging: I was able to identify a number of channels and update my channel.conf with the proper callsigns. The garbling was much less than it had been in the previous computer! I was thinking that this was perhaps going to work! Smile

I re-ran the script a couple of times, because I wasn't able to indentify all the channels I saw in the first run. However, after the fourth run my file server was starting to act sluggish and killing off processes randomly. At first I thought this was because of the kernel upgrade to 2.6.15.5, but after I looked around a little I realized that the kernel memory usage was going up a couple of Mb every time I did "cat /dev/dvb/adapter0/dvr0". Sad

After the reboot I found a mythtv option that keeps the device open in between recordings, which I figure will reduce the memory leak to only happen *once*, which would be acceptable. So I figured I would scan through all the rest of the channels manually using mythtv this time, while keeping a watchful eye on /proc/meminfo. So I went to myth-setup and imported my freshly updated channels.conf, thinking that this would allow me to tune in and identify channels properly. Unfortunately I was sadly mistaken, it seems that mythtv completely failed to update the "serviceid" column in the database, so when I tune to a channel, all I get is black. *sigh*

I'm no stranger to SQL, so I went into the database and updated the serviceid for a few channels, so I could at least record the channels I cared about most, namely KINGDT and KOMODT. And FINALLY I can actually tune in channels, but my moment of triumph was all too brief as mythfrontend hung. Repeated attemts created some odd results: In one case the audio kept playing while stuttering, in other cases I would get black screens but most often it would just hang after a few seconds of displaying the picture.

This is where the story catches up with the present. Our hero is currently debating weather to use the pcHDTV card for target practice or to try making it work again. As I am writing this I noticed that mythtv has decided to record "Crossing Jordan" in all-digital SD using the pcHDTV card. Hesitently I activate the recording and to my surprise: it works! The picture is still garbled every few seconds, but perhaps the new power supply that is currently being shipped to me will fix that.

I need to do some more experimenting to find out if this latest success is because SD channels work and HD channels don't, or perhaps it's just that watching things "live" doesn't work too well? Either way, this is by far the worst experience I've had with any hardware I've bought. Installing hardware should not be an epic journey spanning across time and space, it should be simple. So, let me finish this post with some constructive ranting:

To the makers of pchdtv: Put some more capacitors on the card to stabilize the power, right now it's stupid how sensetive it is.
To the makers of mythtv: Please make the channel configurating work better and easier. And at least add a confirmation dialog that explains what will happen to "delete all capture cards".
To the DVB driver guys: memory leaks are not cool, ok?
To comcast: Get your asses in gear and listen to the FCC!

/Hubbe
View user's profile Send private message
PostPosted: Mon Apr 24, 2006 2:23 am Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




Hmm, KINGDT, KOMODT, I think this might help you find some channels. The Sea-Tac cam on channel 89.12 is gone now, but most of it is still right. I fixed that memory leak some time ago, you just need to update your drivers.
View user's profile Send private message
PostPosted: Mon Apr 24, 2006 2:40 am Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




Thanks, the channel list will help.
I'm not too worried about the driver issue right now since the "keep device open" option seems to keep it in check.
Also, it's starting to look like the playback issue is because of bandwidth or similar issues. Digital SD playback works fairly well, and if I record a HD channel, I get quite a lot of garble in the picture, but mplayer can at least play the generated .mpg file, mythtv cannot. Sad

Interestingly, the preview image works better than the actual playback.
It looks like mythtv is serving the file from the master backend instead of the machine that has the disk drive though. That might be because the master backend is also the computer with the pchdtv card right now. Still, reading 2Mb/s over NFS and writing it out over TCP shouldn't be that hard to do over full duplex 100Mbit ethernet...

Storing my HD recordings on the same machine as the PCHDTV card might help. Or maybe it's just time to move to gigabit networking...
View user's profile Send private message
PostPosted: Mon Apr 24, 2006 6:26 am Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




It sounds like your trouble may lie in the video display. For HD viewing a good video card and the correct driver are needed. In my case, I have a nVidia 6600GT, but had trouble viewing HD content until I installed the nVidia driver.
I have a Dell laptop with Intel i810 graphics that will not display HD, but I can watch SD with it all day long.

MythTV has display settings that you can change and check for improvement. They're in Utilities/Setup > Setup > TV Settings > Playback

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
View user's profile Send private message
PostPosted: Mon Apr 24, 2006 2:33 pm Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




I don't think that's it. I have a gforce 5700 and a geforce 4800. both with nvidia drivers. I haven't tried using XvMC yet, because of a driver installation conflect for the XvMC library, but I will probably try that shortly.

As I said before, mplayer is quite capable of displaying the recorded files, even though they have quite a lot of garble in them.
View user's profile Send private message
PostPosted: Mon Apr 24, 2006 4:44 pm Reply with quote
patman
 
Joined: 30 Mar 2006
Posts: 8
Location: Portland, OR




hubbe wrote:
I don't think that's it. I have a gforce 5700 and a geforce 4800. both with nvidia drivers. I haven't tried using XvMC yet, because of a driver installation conflect for the XvMC library, but I will probably try that shortly.

As I said before, mplayer is quite capable of displaying the recorded files, even though they have quite a lot of garble in them.


I'm having a similar problem, using OTA (for the maybe 3 channels I can actually get a lock on), I get acceptable quality with no errors.

Using my comcast cable with QAM tuning, I get a lot of errors.

I don't have another HD tuner for comparison. Are you able to get acceptable quality via another HD tuner on the same cable outlet, and so rule out problems with your cable connection?

By "errors" I mean that either mythtv or mplayer playback complains about bad data (in the broadcast stream). mythtv ends up displaying glitches in the video, and skips or has odd sounds in the audio, mplayer will eventually stop or crash.

I'm running fedora core 5, mythtv .19-fixes (via svn as of April 23 2006).

I have basic cable, no cable box. The comcast tech came by today, as my reception was bad on one channel, he verified all my signals were good, and found that I was using a bad connecting cable (to my TV, it was receiving OTA signal and cable via that cable, and causing ghosts on channel 6, I am very close to the broadcast anntenae). He checked that my signal quality at 621Mhz was good (that is OPB QAM frequency).

He did call in to verify that officially I'd need to get digital cable at about $55 /mo, plus a cable box at $5 /mo to get "comcast HD", even though I can almost get it fine now (I don't want to pay the extra $$ and don't want more channels at this point in time - I don't even have an HD display yet, just a computer monitor for now).

I was thinking of trying to move the card around, to see if intereference is causing any problems. I also thought about adding an attenuator (lower the signal coming in?) to see if that changes anything.

Also have you seen this qamscan script? There is another one also titled qamscan (check google):

http://www.gossamer-threads.com/lists/engine?do=post_attachment;postatt_id=8140;list=mythtv

Above found in this thread:

http://www.gossamer-threads.com/lists/engine?do=post_view_printable;post=149939;list=mythtv

Please post if you make any progress ...

-- Patrick
View user's profile Send private message Visit poster's website
PostPosted: Thu Apr 27, 2006 10:11 am Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




Today I received the new 500W power supply I ordered. With it installed, the pchdtv captures comcast QAM channels like a champ! However, I am still not able to view the HDTV signals in mythtv.

I have two computers which I would like to view HDTV on: One is a Athlon XP 1900+, 1Gb RAM, Geforce 4800 with latest nvidia drivers. The other is an Athlon XP 3000+, 2Gb RAM, Geforce5700 with latest nvidia drivers.

The first computer also has the pcHDTV capture card, and it can *almost* play HDTV, it will play for half a second, stutter, then play another half a second or so.

The second computer is connected to the first one through full-duplex 100Mbit ethernet (one switch in between). When I play the HDTV recording, it will show only one frame, then freeze the picture while continuing to play the audio. If I skip forward, it will show a new frame, then freeze the picture again. The second computer is quite capable of playing the recorded files with mplayer, but it doesn't seem to work with mythtv.

I still have some fiddling to do, because I haven't tried all the settings standard/libmpeg2/xvmc yet, and I also haven't figured out if there is a way to apply deinterlacing and filters to SD broadcasts but not to HD broadcasts, or how to tell mythfrontend to change to a particular resolution depending on the resolution of the incoming broadcast.

Ideally I would like to deinterlace and filter analog broadcasts only, for digital broadcasts I would like mythtv to change to the approperiate resolution and have my projector handle the deinterlace.

...the journey continues...
View user's profile Send private message
PostPosted: Thu Apr 27, 2006 11:27 am Reply with quote
patman
 
Joined: 30 Mar 2006
Posts: 8
Location: Portland, OR




hubbe wrote:
Today I received the new 500W power supply I ordered. With it installed, the pchdtv captures comcast QAM channels like a champ! However, I am still not able to view the HDTV signals in mythtv.


What power supply are you now using? link?

I'm using the power supply that came with my Antec Sonata II case.

I am wondering if the antec power supply is causing my problems, there was a similar question here:

http://www.pchdtv.com/forum/viewtopic.php?t=1077&start=0&postdays=0&postorder=asc

Both the sonata II and the overture II use this power supply:

http://www.antec.com/us/productDetails.php?ProdID=26450

hubbe wrote:
I still have some fiddling to do, because I haven't tried all the settings standard/libmpeg2/xvmc yet, and I also haven't figured out if there is a way to apply deinterlacing and filters to SD broadcasts but not to HD broadcasts, or how to tell mythfrontend to change to a particular resolution depending on the resolution of the incoming broadcast.


In my limited experience with 3Ghz Intel + nvidia, xvmc is required for decent HD playback.

-- Patrick
View user's profile Send private message Visit poster's website
PostPosted: Thu Apr 27, 2006 1:17 pm Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




patman wrote:
What power supply are you now using? link?


I'm using this one: http://www.newegg.com/product/product.asp?item=N82E16817194003

patman wrote:
In my limited experience with 3Ghz Intel + nvidia, xvmc is required for decent HD playback.


I have tried that without any success. However, I didn't have much time this morning to test things like turning off filters and deinterlacing. (How does deinterlacing work with XvMC anyways? My guess is that it doesn't.)

I suspect that at least one of my computers is too slow to do any filtering or deinterlacing on an 1080i signal, but my projector has a native resolution of 720p, which means that I need to do *some* sort of deinterlacing. I think ths solution is to make mythtv change resolution to 1080i when playing a 1080i signal, so that the projector will do the deinterlacing. (Hopefully the projector won't object to doing de-interlacing on signals coming from the VGA port.)

The same approach could work for SD signals as well.
View user's profile Send private message
PostPosted: Thu Apr 27, 2006 11:02 pm Reply with quote
patman
 
Joined: 30 Mar 2006
Posts: 8
Location: Portland, OR




OK, I replaced my new Antec SmartPower 2.0 450w power supply, this one:

http://www.antec.com/us/productDetails.php?ProdID=26450

With a new Antec NeoHE 500, this one:

http://www.antec.com/us/productDetails.php?ProdID=28500

And QAM tuning is now working OK.

So, these power supplies are somehow noisy, or the hd3000 is not properly shielded (or such).

Note that the SmartPower 2.0 450w is included in the Sonata II and Overture II, both of them make nice HTPC cases.

-- Patrick
View user's profile Send private message Visit poster's website
PostPosted: Sun Apr 30, 2006 12:52 am Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




Success at last.

It took a while, but it now seems like I can record HDTV from comcast and play it back in mythtv. It turned out that one of the last stumbling blocks was that I had compiled mythtv before I installed the latest nvidia drivers, this caused XvMC to not work.

I did discover a few more interesting tidbits though.

First of all, I wasn't sure how well the BOB deinterlacing was going to work, so I was planning to set up MythTV to change resolution to the same resolution as the recording and let my projector do the deinterlacing. However, it turns out that this doesn't work so well as the frame switch sometimes happens on odd fields. This causes fields to be displayed in the wrong order and makes the picture jittery. However, it turns out that this isn't really an issue as the BOB deinterlacing works quite well for HDTV signals.

Now I just need to buy more disk. Smile

I'm still having some problems with SD signals though. Since I have a geforce4, I activated the XvMC hack that allows for color overlays. This work s very well on any wide-screen signal. For SD tv however, there is flickering on the sides of the picture every time the overlay is updated. (Which is quite often if you use close captioning) The flickering is blue and very annoying. I hacked the mythtv source a little so that it wouldn't use the overlay hack when displaying SD signals. This works, but the overlay becomes jittery because it is now subject to the "bob" deinterlacing. Sad
View user's profile Send private message
PostPosted: Tue May 09, 2006 12:31 am Reply with quote
hubbe
 
Joined: 23 Apr 2006
Posts: 9




On the off chance that anybody else on this planet has as as much trouble with getting things to work as I have, I would liket to share some settings in mythtv that I have found to work:

1) Unless you have a very very fast cpu, use XvMC when displaying HDTV
2) Use BOB deinterlacing with XvMC, it's currently the only thing that works
3) BOB deinterlacing works better if you enable "OpenGL vsync"
4) If you use nvidia drivers, it's a good idea to ENABLE the vsync settings with 'nvidia-settings', otherwise you get "tearing"
5) If you have a nvidia 4/5 card, I highly recommend the UseChromaKey hack described on the mythtv wiki.
6) If you use UseChromaKey, the black sidebars will flicker when playing back SD, this can be fixed by editing videoout_xv.cpp and changing this:
Code:

        XFillRectangle(XJ_disp, XJ_curwin, XJ_gc, dispx,
                       dispy + boboff, dispw, disph - 2 * boboff);

to this:
Code:

        XFillRectangle(XJ_disp, XJ_curwin, XJ_gc,
                       (dispxoff > dispx ? dispxoff : dispx),
                       (dispyoff > dispy ? dispyoff : dispy)+ boboff,
                       (dispxoff > dispx ? dispwoff : dispw),
                       (dispyoff > dispy ? disphoff : disph)- 2 * boboff);

7) Using AC3 pass-through in conjunction with "OpenGL vsync" can cause stuttering audio, but enabling "Agressive sound buffering" can help.

My system is an Athlon XP1900+ with an GeForce4 4200 hooked up to a 720p projector and the coax spdif on my nforce1 motherboard is hooked to an JVC 6.1 receiver.
View user's profile Send private message
pchdtv + mythtv + comcast = dollor capitis
  pcHDTV Forum Index -> mythTV wiith the HD-2000 card
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
All times are GMT - 7 Hours  
Page 1 of 1  

  
  
 Post new topic  This topic is locked: you cannot edit posts or make replies.  


Powered by phpBB © 2001-2003 phpBB Group
Theme created by Vjacheslav Trushkin