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 Post subject: hdhomerun dual tuner
PostPosted: Tue May 24, 2011 12:39 pm 
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Joined: Tue Nov 14, 2006 2:55 pm
Posts: 245
Location: South Jersey
Has anyone experienced mpeg blocking on the hdhomerun? Can you offer any advice to resolve it?

Using hdhomerun_config I originally had a signal stregth (ss) of 80-85%. I had comcast come out and boost it. I'm now at 94-98% but I'm *still* getting mpeg blocking.

Any advice is appreciated. Thanks, -Abs

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R6.04, dual core 3ghz, 3 gig memory, Zotac 8400 passive heat sink dvi/hdmi out video, 500 gig sata, dual tuner hdhomerun, streamzap remote

Abby


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 Post subject:
PostPosted: Wed May 25, 2011 9:10 pm 
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Joined: Tue Nov 14, 2006 2:55 pm
Posts: 245
Location: South Jersey
When the mpeg blocking errors happen I see this in the backend log:

mythbackend.log:2011-05-22 21:31:24.511 [ac3 @ 0xb6cf28c0]frame CRC mismatch
mythbackend.log:2011-05-22 21:31:24.512 [ac3 @ 0xb6cf28c0]frame sync error
mythbackend.log:2011-05-22 21:31:24.513 AFD Error: Unknown audio decoding error
mythbackend.log:2011-05-22 21:31:24.521 [mpeg2video @ 0xb6cf28c0]00 motion_type
at 24 52
mythbackend.log:2011-05-22 21:31:24.581 [ac3 @ 0xb6cf28c0]frame CRC mismatch
mythbackend.log:2011-05-22 21:31:24.582 [ac3 @ 0xb6cf28c0]frame sync error
mythbackend.log:2011-05-22 21:31:24.583 AFD Error: Unknown audio decoding error
mythbackend.log:2011-05-22 21:31:24.587 [mpeg2video @ 0xb6cf28c0]ac-tex damaged
at 67 5
mythbackend.log:2011-05-22 21:31:24.590 [mpeg2video @ 0xb6cf28c0]invalid mb type
in I Frame at 10 17
mythbackend.log:2011-05-22 21:31:24.598 [mpeg2video @ 0xb6cf28c0]skipped MB in I
frame at 76 34
mythbackend.log:2011-05-22 21:31:24.602 [mpeg2video @ 0xb6cf28c0]ac-tex damaged
at 43 37
mythbackend.log:2011-05-22 21:31:24.608 [mpeg2video @ 0xb6cf28c0]invalid mb type
in I Frame at 92 39

Anyone know what all this means?

Thanks, Abs

_________________
R6.04, dual core 3ghz, 3 gig memory, Zotac 8400 passive heat sink dvi/hdmi out video, 500 gig sata, dual tuner hdhomerun, streamzap remote

Abby


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 Post subject:
PostPosted: Wed May 25, 2011 9:40 pm 
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Joined: Thu Mar 25, 2004 11:00 am
Posts: 9551
Location: Arlington, MA
Corrupted MPEG2 stream most likely.

This can happen for any of several reasons.

- Bad signal from the broadcasters.

- The HDHomeRun maybe freaking out for some reason, possibly over heating or corrupt firmware.

- Networking problems causing either delays and thus buffer over/under runs or loss of data due to noise.

- The PC may not be able to keep up for some reason. Again this could produce buffering problems in various places.

To diagnose...

- Bad signal - you would most likely see artifacts on a TV too

- Overheating, check if it's warm or hot to the touch, firmware ... I'd probably just (re)upgrade to the current version.

- For networking, try isolating just the PC and HDHomeRun on their own switch with different cables, and just record something to minimize the load on the PC.


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 Post subject:
PostPosted: Thu May 26, 2011 9:07 am 
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Joined: Tue Nov 14, 2006 2:55 pm
Posts: 245
Location: South Jersey
Thanks tjc.

bad signal >> comcast came out and rewired the house. There was noise and it is gone. HDHomerun still burps tho.

HDH freaking out >> I haven't checked if its too hot but I doubt it is. Plus its debugging tools show no errors and strong incoming signal.

Networking >> My lan is 100mbs. The signal from one feed is 9 - 12 mbs. I guess this could possibly be an issue.

Overheating >> the pc gets pretty hot. It has three fans going all the time so perhaps I need to think about better cooling.

Thanks, -Abs

_________________
R6.04, dual core 3ghz, 3 gig memory, Zotac 8400 passive heat sink dvi/hdmi out video, 500 gig sata, dual tuner hdhomerun, streamzap remote

Abby


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 Post subject:
PostPosted: Thu May 26, 2011 6:53 pm 
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Joined: Thu Mar 25, 2004 11:00 am
Posts: 9551
Location: Arlington, MA
Well 100mbps or GigE gear doesn't necessarily mean you get that. For example a bad cable or a loose connection could trip a QOS trigger and cause it to negotiate down. I had big problems with this when I first ran the line from the office to the TV, one of the connectors was badly crimped and the cable wouldn't do 100baseT. Even with known good or pre-made cables I occasionally have to reseat the connections and reset a switch to keep everything talking at full speed, typically after stuff gets moved around and connections get disrupted.

Anyway that's just one possibility. Typically this kind of problem is because you're losing blocks somewhere in the chain. Either because they're not making it from A to B, not making it there in time (e.g. due to errors and resend) leading to a buffer underflow, or the buffers are overflowing because they're not being consumed fast enough (not being written to disk, not being read from the remote device, ...).

At the very least check the cables, a friend had network problems not to long ago shortly after getting a couple kittens. It turned out that they'd been sampling the cables, which were clearly not all that tasty because they hadn't chewed them enough to be obvious, just enough to break a wire or two... The cables had a few dozen little pinholes where they dangled down behind his machine.


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