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blocky sound and HD video paused until -> pressed
PostPosted: Mon Aug 18, 2008 11:37 am Reply with quote
harryr
 
Joined: 18 Aug 2008
Posts: 11
Location: Broken Arrow, OK




In mythbuntu using 5500 pcHDTV card I am using OTA HD antenna. When trying to watch live TV, I get HD coming in but it plays only briefly then stalls. Sound is very blocky. The video updates with -> arrow press and maybe gets out a few frames before stalling again. I know this means I am attempting to use both frontend and backend at once which takes alot of resources. I noticed (by running 'free' in a terminal window) that my 1-Gbyte RAM may be all used and maybe I'm into virtual memory with an infinite swapping loop but supposedly, from mythbuntu hardware requirements, this should work with 1 Gbyte RAM.

FWIW, I downloaded tst.ts from pcHDTV support site and this plays fine using xine. So, I suppose that means I can use my PC as an HD frontend only.

How can I find out if I'm hitting a hardware or software limit, as well as what that (those) limit(s) is (are), when trying to watch live TV?
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PostPosted: Mon Aug 18, 2008 1:58 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




It is the frontend that is the most taxing on a MythTV system. It has to display the HD video, where the backend just dumps the video stream to a file.

You could test it by scheduling a recording, and then watching the recording later. Make sure that it is a true HD show.

Since it is the displaying of the HD video that consumes the system resources, you usually have to hand off some of the video processing to your video card. The best card for this in a nVidia video card, 6200 thru 8800. NVidia uses XvMC for displaying HD, although some other graphics chips support it too.

http://www.mythtv.org/wiki/index.php/XvMC

Also adjust the deinterlacing in the Setup-->TV settings-->Playback section. BOB deinterlacing is what works for most people.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
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PostPosted: Wed Aug 20, 2008 9:54 am Reply with quote
harryr
 
Joined: 18 Aug 2008
Posts: 11
Location: Broken Arrow, OK




Thank you for the response waterhead. I did do a recording of HDTV programming and when I tried to play it back in myth-frontend I got the same problems I mentioned in my first post. I did enough fast-forward testing to convince me the recording (backend) is ok. I think my video card is ATI, I know it is not Nvidia. Maybe my 1st-generation 64bit Athlon is too slow to do it all by itself?

I never found BOB deinterlacing in the 9 pages of Playback section. I found a page which mentioned XvMC but didn't understand what to do with it. Myth seems way too advanced for me, one who is used to telling TIVO to record "soccer" and then I watch it later at my convenience.

FWIW, I have little time to invest in this especially since I just broke my clavicle falling off my bicycle Sunday afternoon. So, If I seem slow to act upon your very-welcome suggestions it's not because I am uninterested.

So, my next testing, when I can get to it, seems to logically bypass myth and see if my recorded HDTV program is playable over xine.
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PostPosted: Mon Sep 01, 2008 10:00 am Reply with quote
harryr
 
Joined: 18 Aug 2008
Posts: 11
Location: Broken Arrow, OK




After spending lots of time with no success I am reaching the point that maybe I got lied to? Maybe the minimum hardware requirements to playback HDTV programming are much more than is advertised?
My system: AMD 64bit 3800+ 2.4 GHz processor (apparently not even enough processing power to play HD on its own?) Video card is R420 Radeon X800 PRO/GTO. I downloaded the latest linux fglrx driver (8.2) from ati.com and followed instructions to install but xvinfo still didn't give any info on my video device. aticonfig was used to install options to xorg.conf but wait someone said that was *not* the way to go. Are you sensing my frustration? Anyway, I have learned to admit my pride and suck it up and pay more $ to get hardware which is supposed to work. I took your advice waterhead and ordered an Nvidia 6200 video card.
FWIW I have not been able to use the dtv tools provided by pcHDTV. dtvsignal # just stalls and gives no info. dtvscan can't find any channels, which I know are there because my TV can see several fine and says the signal is 85-92% strength. dtvscan ends with an error TUNING FRONTEND: Invalid argument. Maybe this error is due to dtvscan not able to find a single DTV active channel?
I did find that after installing mythbuntu I needed to also install libc6-dev package which was necessary to get dtvsignal and dtvscan to compile. (my contribution back in case anyone needs this tidbit of info).
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PostPosted: Mon Sep 01, 2008 11:39 am Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




You should install the dvb-utils package, and use that to scan for channels. Follow this MythTV How-To. It is for cable channels, but the process is the same.
http://www.mythtv.org/wiki/index.php/Adding_Digital_Cable_Channels_%28For_ATSC/QAM_Tuner_Cards_--_USA/Canada%29

Instead of using the us-Cable-HRC-center-frequencies-QAM256 and us-Cable-IRC-center-frequencies-QAM256 files, use the us-ATSC-center-frequencies-8VSB file, for OTA broadcasts. It is located in this folder:

/usr/share/doc/dvb-utils/examples/scan/atsc/

Use this command to scan:
Code:
 scan /usr/share/doc/dvb-utils/examples/scan/atsc/us-ATSC-center-frequencies-8VSB

You cannot scan if the mythbackend is running. So shut it down with this command:
Code:
sudo /etc/init.d/mythtv-backend stop

The output of scan will give all of the successful channels at the end. Just copy this to a text file and save it as channels.conf. Make a folder in your home directory called .mplayer (don't forget the "dot", it makes it hidden), and place a copy of the channels.conf file in it. You can then watch HDTV with mplayer using the name of the TV station, as it is written in the channels.conf file. Of course, you need to have mplayer installed.

To see the manual for mplayer, enter this command:
Code:
man mplayer

The syntax to play dvb channels with mplayer is this:
Code:
mplayer dvb://[card_number@]channel [options]

if you only have one card, it will automatically chose it, and I don't know too much about adding options. My first channel in my file is "MPTV-HD", followed by the tuning specifics. To watch it in mplayer, I would enter this command:
Code:
mplayer dvb://MPTV-HD

That's it! Some of the channel names have spaces in them. It seems it will not accept spaces in the terminal, so I edited them and replaced the spaces with a dash. Now mplayer can tune those channels too.

You can also watch HDTV with Kaffeine. It does not do it out-of-the-box, but it is fairly easy to set up. If interested, let me know. I'll explain further.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
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PostPosted: Mon Sep 01, 2008 12:49 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




I also have a solution for scheduling recordings with MythTV. It is not quite as simple as telling it to record "soccer" , but almost.

First, I am using only the Over-The-Air transmitted schedule guide. This sometimes only gives me 12 hours of listings, not much for advanced scheduling.

In MythTV, go to Manage Recordings-->Schedule Recordings-->Custom Record.
Here you can tell it to record everything with the word "soccer" in the tile. Give it a rule name, soccer sounds good. Not go to the third line, and arrow right until you get to "Match words in the title". Now go to the next line and hit enter. The lower box will now have "program.title LIKE 'CSI:%''. Replace CSI with soccer, and select store. It now has stored it for future use.

Now you can call it back up, in the same screen. This time hit the "Record" button, and in the first line arrow left until it says "Record at any time on any channel". Arrow down to the "[Save these settings]" line and hit enter again. It should now record every show with the word soccer in the title.

I have just set up two new recording rules. One for The Big Bang Theory, and the other for How I Met Your Mother. When I set them up yesterday, the OTA guide didn't have them listed (more than 24 hours). I just noticed now that they have been scheduled to record, because they just appeared on the OTA guide.

If you want to use the OTA guide, here's how:
In the initial mythtv-setup section, go to:
Capture cards-->
(select card)
Recording Options
Uncheck "Open DVB card on demand"
Check "Use DVB card for active EIT scan"

Then:
Video Sources-->
Listings Grabber-->
Transmitted guide only (EIT)

I hope you get this working.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
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PostPosted: Mon Sep 01, 2008 1:13 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




One more thing that I forgot.

To change the deinterlacer setting (Bob 2x), go to this screen:
Utilities/Setup-->
Setup-->
TV Settings-->
Playback-->

On the third screen in the Playback section, you will find the Playback Profiles. You may need to experiment to find the best profile, try cpu-- and High Quality. Next to the different rez levels there is an Edit button. This takes you to two config screens, the second having the choice of deinterlacing methods. The primary one is the important one.

With my new install, I have backed away from using XvMC. I found that my nVidia 6600 card needed an extra power supply hooked to it, I had totally missed it! I now get a better picture without XvMC. I am using ffmpeg & XVideo for all of the Profile settings.

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
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PostPosted: Fri Sep 05, 2008 10:38 am Reply with quote
harryr
 
Joined: 18 Aug 2008
Posts: 11
Location: Broken Arrow, OK




[Subject line SOLVED]
I installed mythbuntu from scratch again after I decided I had made too many changes in mythtv setup to know where I had gone. One change I made in the new install was to leave the open-source ATI graphics driver in place instead of requesting the proprietary driver from ATI.com. Then another change I made was instead of trying to configure Mythtv with software from the install disk, the first thing I did after the install was to abort the myth configuration and instead run the full software apt-get update and upgrade. I rebooted and then ran the mythtv-setup. My card and drivers were all recognized, the scan found all the OTA channels too. I changed very little from the defaults. The video was clean and responsive through 4X speed. At 8X it got blocky which is understandable. It was rewarding to watch live HD TV with pause and fast forwarding through commercials.
[end of Subject line: SOLVED]

Im currently using my CRT for display which is not the full ???? x 1080 widescreen resolution, so the next step is to hook up my 1080i HD TV and see if it works there with full resolution.

I signed up for SchedulesDirect so I'd like to get that going as the basis of my recording rules. I did set up the "soccer" rule per your instructions but for some reason the SchedulesDirect programming didn't happen. I also checked to include EIT updates but that didn't work either. So, no programming info was present. The window messages scrolled off too fast. I went to /var/log/mythtv and expected the backend myth log file to have some mythfilldatabase info but it wasn't in there. I ran out of time to investigate this further.

This process is painstaking and I have some ideas for the mythtv designer(s) to make this a more user-friendly experience. That's another subject though.
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PostPosted: Fri Sep 05, 2008 2:55 pm Reply with quote
waterhead
 
Joined: 24 Apr 2005
Posts: 299




For the tuner to get OTA guide data, it can't be in use. It will actually use the tuner to tune into the channels for the guide data. Apparently, it can't do this if you are using the tuner. You should initially get some data, then it will fill in if the MythTV box sits unused for a while.

I don't think that you can use both EIT and Schedules Direct. Since you have already signed up for it, set MythTV up to use that.

To output it to your TV will possibly be another trying experience. I don't know how easy the ATI configuration screen is for this, especially if you want dual outputs. It may be best (easiest) to only have the HDTV connected and configured. I have heard that if you don't have the correct configuration, that you can damage your HDTV. I don't mean to scare you, just to warn you.

I do output one of my MythTV boxes to a 19" 720P TV. But I did have to use the VGA port, so I'm not getting true HDTV. It's only 19", so I don't really notice.

Still, I'm glad that you got a working system. As for the lack of simplicity in the MythTV setup process, I doubt that that will change. Mythbuntu makes it as painless as possible. You should try installing it ,say on Fedora, from the repos. This is my preferred setup, but I was unable to get my last Fedora/MythTV install to work. So I resorted to Mythbuntu, just so that I would have a working MythTV setup. I really HATE Ubuntu and it's derivatives, but having a fully functional MythTV box trumped wanting to use Fedora.

There are so many different MythTV hardware configurations, that all of the software configuration options are necessary. It has got a bit more complicated with the last release. It has taken me a while to figure out the Playback Profiles. I now create my own profile so that I can more accurately control the HD video playback. Remember that this is really a Do-It-Yourselfer's hobby project. If you want everything done for you, there is always windoze media center.

WHOA! This turned into a long post. Thank that huge Foster's Ale can of beer that I cracked open before I started this post. Wink

Just keep toying with your setup, and you will eventually find what works for you. Just keep notes on any changes that you make, as they will come in handy when you completely bork the system, and have to do a fresh install.

Edit: If you are interested in a forum where MythTV and it's various configuration intricacies are actively discussed, I recommend the Linux HTPC section of the AVS Forums:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=76

_________________
Mythbuntu 8.04
Intel D875PBZ main board
Pentium4 3.06Ghz
1024GB RAM
nVidia 6600GT
pcHDTV HD-3000
Air2PC PCI
MythTV 0.21
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blocky sound and HD video paused until -> pressed
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