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pcHDTV-5500 on Gentoo AMD64
PostPosted: Sun Jan 14, 2007 2:16 pm Reply with quote
swdrumm
 
Joined: 14 Jan 2007
Posts: 4




I've been struggling to get my pcHDTV-5500 card to work correctly on my Gentoo AMD64 box, but I'm running into the following problems:

1. ATSC / DVB doesn't work. The audio/video stream plays for 30-90 seconds and then becomes increasingly filled with errors until it grinds to a halt and locks the machine (xine) or quits (mplayer).

2. Under mplayer, I'm seeing the "Too many video packets in the buffer" problem discussed previously.

3. I also am getting the "a52 CRC check failed!" issue. Audio and video fall out of sync and the player eventually crashes. FWIW, my AC3 audio decoder is liba52.

4. On top of all that, when I installed the pcHDTV card, audio playback of disk-based video (AVI) and audio (MP3, OGG) files using mplayer, vlc, xmms, etc became erratic. The files will play, but every 2-3 minutes or so, the audio / video track slows WAY down for about 5 seconds, then resumes normal playback. It's most annoying. Wink

On the plus side, NTSC playback works great - no problems whatsoever.

My system is an AMD Athlon 64 3500 with 1GB of RAM, an nVidia graphics card and motherboard based audio (VIA VT8233). Kernel version is 2.6.18-gentoo-r4. CPU load rarely rises above 40% during DVB playback, so I think the system can handle the load.

I've tried two different HDTV antennas with the same results.

Any ideas? I'm frustrated enough to consider returning the card at this point and buying an HDTV, but I'd prefer to get the Linux solution working.

Thanks!

---
Scott Drumm
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PostPosted: Sun Jan 14, 2007 10:30 pm Reply with quote
flawlessdistortion
 
Joined: 12 Jan 2007
Posts: 6
Location: Chicago




I have a similar setup as you (athlon 3500 on gentoo 64), and have more or less been succesful in getting atsc playback to work using xine. I had many of the same issues as you, and it took me a while before I could separate antenna reception problems from software problems. I think the buffer problems you describe can be solved by simply increasing the buffer. Xine uses a default audio and video buffer which is insufficient for dvb streams at 720p and especially 1080i. Try increasing it - for the number of audio and video buffers, I have 1000 and 2000. I'm sure this is quite generous, but whatever. It works for me and I have not had the desire to try and find the exact limit.
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PostPosted: Mon Jan 15, 2007 8:59 am Reply with quote
swdrumm
 
Joined: 14 Jan 2007
Posts: 4




flawlessdistortion wrote:
I think the buffer problems you describe can be solved by simply increasing the buffer. Xine uses a default audio and video buffer which is insufficient for dvb streams at 720p and especially 1080i. Try increasing it - for the number of audio and video buffers, I have 1000 and 2000. I'm sure this is quite generous, but whatever. It works for me and I have not had the desire to try and find the exact limit.


With mplayer, increasing the buffer helped significantly - I cranked it up to 32768 at one point - which let me watch the premier of 24 last night. But it still started to run into problems every 10-15 minutes.

I'm wondering if the problem isn't my audio setup. The "a52 CRC check failed / error at resampling" seems to be the trigger event that causes everything to break. The help text from mplayer that says "Your system is too slow => most common cause is buggy audio driver" seems to be another clue.

What's your audio chipset?

Interestingly though, when I try mplayer -nosound, the feed plays for a few minutes and then quits. There's a % counter in the session window that starts at around 50% and then drops down to 0%, at which point playback stops.
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PostPosted: Mon Jan 15, 2007 10:54 am Reply with quote
flawlessdistortion
 
Joined: 12 Jan 2007
Posts: 6
Location: Chicago




did you have the a52 USE flag enabled when you compiled mplayer and its dependencies? For audio, I am using the emu10k1 drivers with my old creative soundblaster live.

Btw, 24 is the sh!t. Lol, jack bauer cannot be stopped!! Razz
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PostPosted: Mon Jan 15, 2007 12:14 pm Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




A52 errors usually just mean that you're getting garbled data. That's just the part that complains most when there is an error. Then mplayer gets confused and spews out that "system too slow" help text that is in this case completely wrong.

Make sure you're using the latest mplayer from svn. Older versions have known bugs with certain ATSC streams.
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PostPosted: Mon Jan 15, 2007 8:37 pm Reply with quote
swdrumm
 
Joined: 14 Jan 2007
Posts: 4




xyzzy wrote:
A52 errors usually just mean that you're getting garbled data. That's just the part that complains most when there is an error. Then mplayer gets confused and spews out that "system too slow" help text that is in this case completely wrong.

Make sure you're using the latest mplayer from svn. Older versions have known bugs with certain ATSC streams.


I'm running mplayer-1.0rc1 from Gentoo portage, which was compiled with the a52 use flag set. A few more questions:

1. How does the data get garbled? Is this an antenna / signal strength issue? I've tried two antennas (both in the attic) - maybe I need to move the antennas outside or install a pre-amp on the coax feed?

2. It looks like what's happening is that the a52 errors show up, then the video seizes up as it tries to resync with the audio track, at which point the video buffer overflows and crashes or mplayer grinds to a halt - usually with audio continuing on but no video. Why? There doesn't seem to be much fault-tolerance built into this setup.

3. I've been monitoring "azap -r <stream>" in a terminal window. Sometimes - but not always - the a52 errors are preceded by a loss of the tuner's FE_HAS_LOCK indicator. Is this indicative of poor signal reception or a defective card?

4. Why is this so difficult? Sounds like whining, but I know my server has a whole lot more horsepower than some $400 flat-panel HDTV. What gives?

Thanks!
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PostPosted: Mon Jan 15, 2007 8:45 pm Reply with quote
flawlessdistortion
 
Joined: 12 Jan 2007
Posts: 6
Location: Chicago




Try using Xine and see if you experience the same errors. This might help isolate your problem and tell you if it is something with mplayer or something with the signal. Btw, what commands are you using to watch dvb in mplayer? I never got that working...
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PostPosted: Mon Jan 15, 2007 9:09 pm Reply with quote
swdrumm
 
Joined: 14 Jan 2007
Posts: 4




flawlessdistortion wrote:
Try using Xine and see if you experience the same errors. This might help isolate your problem and tell you if it is something with mplayer or something with the signal. Btw, what commands are you using to watch dvb in mplayer? I never got that working...


OK, significant breakthrough tonight. After reading some of the older threads, it appears that my problems might be caused by the type / format / size of the incoming A/V stream.

Reason for the above assumption: All of the channels now work well - except FOX, which seems to have a history of problems. I'll investigate further tomorrow.

Oh, and the command I'm using is mplayer /dev/dvb/adapter0/dvr0 -cache 8192
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PostPosted: Tue Jan 16, 2007 1:32 am Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




swdrumm wrote:

I'm running mplayer-1.0rc1 from Gentoo portage, which was compiled with the a52 use flag set.

Too old! The major bug I found with the TS demuxer's PES type detection code that you can read about here (under A52 errors) is fixed in that one, but there was another bug. Certain channels would get messed up when played back live or from a pipe, but work if you played back from file. I'm not sure what that bug was, I just made some samples files and Nico fixed it. That bug still exists in rc1.

Quote:

1. How does the data get garbled? Is this an antenna / signal strength issue? I've tried two antennas (both in the attic) - maybe I need to move the antennas outside or install a pre-amp on the coax feed?

That would be one way. If you have a poor signal, either too weak, too much noise, mutli-path interference (reflections off buildings), etc., you will get garbled data. If you use the latest drivers, you can get the SNR in dB. If it's less than 20 dB your signal is marginal.

It's also possible to get interference in the card itself. Inside a computer is really bad place for an analog demodulator. Tons of EMI. Stuff like nvidia video cards are known to cause problems with reception. You might try moving the card as far away from other cards as you can or paring your computer down to a minimum of hardware to see if that fixes the problem.

Quote:

2. It looks like what's happening is that the a52 errors show up, then the video seizes up as it tries to resync with the audio track, at which point the video buffer overflows and crashes or mplayer grinds to a halt - usually with audio continuing on but no video. Why? There doesn't seem to be much fault-tolerance built into this setup.

Pretty much. mplayer doesn't handle garbled TS streams very well at all.

Quote:

3. I've been monitoring "azap -r <stream>" in a terminal window. Sometimes - but not always - the a52 errors are preceded by a loss of the tuner's FE_HAS_LOCK indicator. Is this indicative of poor signal reception or a defective card?

Poor signal or interference problems in your computer.

Quote:

4. Why is this so difficult? Sounds like whining, but I know my server has a whole lot more horsepower than some $400 flat-panel HDTV. What gives?

All that hoursepower is the problem. Every part of an HDTV is designed to be able to demodulate ATSC signals. They pay carefull attention to reducing EMI and providing clean power supply rails to the analog section. Your computer's CPU, motherboard, video card, and power supply have not done this. In general, you could say that the more powerfull they are, the more noise they create, and the harder they make it for analog hardware like an ATSC demodulator to work correctly.
Quote:

All of the channels now work well - except FOX, which seems to have a history of problems. I'll investigate further tomorrow.

Could be mplayer has a problem with FOX's data. Could also be you have worse reception for that station. I couldn't get my FOX station either, becuse it's much farther away, until I made a new antenna.
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pcHDTV-5500 on Gentoo AMD64
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