[mythtv-users] Glitches in firewire capture from DCT-6200

David Rudder drig at noses.org
Fri Dec 16 23:55:24 EST 2005


Are you sure this isn't a drive-speed issue?  Check hdparm -v 
/dev/<device>.  Also, make sure you have at least a 7200 RPM drive.   
The dct-6200 will send out an mpeg stream.  I think MythTV just copies 
it to disk.  So, there's very little CPU or memory involved. 

You can try running test-mpeg2 (from the libiec61883 package).  It 
outputs the raw mpeg stream from the 6200.  If it gets the same 
corruption you see in myth, then you know it's not a myth issue.
test-mpeg2 > file.mpg
wait maybe 30 seconds, then hit ctrl-c.  mplayer file.mpg should display 
the file.

-Dave

Azmat wrote:

>I've been using this script in a cron job for the last week, but I'm
>still seeing glitching.  Its mostly occurring at the start of a show
>and then clears up in the middle.  Is it possible that I might need to
>use a faster processor or bump up my RAM?  Right now I'm running an
>Athlon XP 2400+ with 1G of RAM.  Thanks in advance for the help.
>
>Azmat
>
>On 12/9/05, Steve Adeff <adeffs at gmail.com> wrote:
>  
>
>>there was a thread a while back regarding this. You can search on Gossamer for
>>more info. basically you want to run this bash script. It will set the p2p or
>>broadcast connection to 1 depending on what your machine will use. From what
>>I've found bcast is prefered when available, which is why it comes second
>>(since its one or the other) p2p is sometimes only available and when this is
>>the case its fine. data_rate doesn't need to be 3, but it increases speed if
>>your using firewire for capture and not just channel changing. I have it run
>>before mythbackend starts when I run it via init.d and I've found it resets
>>sometimes so I run it hourly as a cron job.
>>
>>oh, and the -n # is which node it is. In case you have more than one firewire
>>connection have it run for each connection as well.
>>
>>#!/bin/bash
>>plugctl -n 2 opcr[0].channel=63
>>plugctl -n 2 opcr[0].n_p2p_connections=1
>>plugctl -n 2 opcr[0].bcast_connection=1
>>plugctl -n 2 opcr[0].data_rate=3
>>
>>--
>>Steve
>>
>>On Friday 09 December 2005 14:52, Azmat wrote:
>>    
>>
>>>Here's my plugreport output:
>>>Host Adapter 0
>>>==============
>>>
>>>Node 0 GUID 0x0000d10080357942
>>>------------------------------
>>>libiec61883 error: error reading oMPR
>>>libiec61883 error: error reading iMPR
>>>
>>>Node 1 GUID 0x4279358080357942
>>>------------------------------
>>>libiec61883 error: error reading oMPR
>>>libiec61883 error: error reading iMPR
>>>
>>>Node 2 GUID 0x000f9ffffe103008
>>>------------------------------
>>>oMPR n_plugs=1, data_rate=2, bcast_channel=63
>>>oPCR[0] online=1, bcast_connection=0, n_p2p_connections=0
>>>        channel=63, data_rate=0, overhead_id=0, payload=376
>>>iMPR n_plugs=0, data_rate=2
>>>
>>>On 12/9/05, Steve Adeff <adeffs at gmail.com> wrote:
>>>      
>>>
>>>>On Friday 09 December 2005 12:44, Azmat wrote:
>>>>        
>>>>
>>>>>Hi,
>>>>>
>>>>>My mythtv system is running on an AMD Athlon XP 2400+ (2 GHz) with 1G
>>>>>RAM, a PVR-350 and firewire capture from my Motorola DCT-6200 cable
>>>>>box.  Whenever I do firewire capture from the box through Myth, the
>>>>>recording exhibits a audio/video glitching.  The picture will
>>>>>momentarily become pixelated and there will be a brief skip.  I can
>>>>>tell the glitch is in the recording because when I rewind and playback
>>>>>it is reproducible.  There is no pattern or regularity to the
>>>>>glitching.  Sometimes it will be at the start of the show and will
>>>>>disappear in the middle, only to reappear later.  It doesn't prevent
>>>>>me from recording shows, but is just become a huge annoyance that I'd
>>>>>like to take care of.  Does anyone have any idea what might be wrong?
>>>>>Do you think a faster processor would help?
>>>>>
>>>>>Thanks in advance,
>>>>>
>>>>>Azmat
>>>>>          
>>>>>
>>>>run plugreport and paste the output.
>>>>
>>>>--
>>>>Steve
>>>>        
>>>>
>>>--
>>>
>>>
>>>Azmat
>>>      
>>>
>
>
>--
>
>
>Azmat
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