[mythtvnz] PVR-150 corruption

[Steven Ellis]

On 13/04/2009, at 6:27 PM, criggie wrote:

> Steven Ellis wrote:
>> On 13/04/2009, at 4:17 PM, criggie wrote:
>>> Hey all - I'm still having video corruption from my PVR-150 cards.
>>>
>>> I was kinda hoping the 0.21 upgrade and a matching kernel upgrade  
>>> would
>>> have fixed it.
>>>
>>> I've saved some stills and they're at
>>> http://criggie.dyndns.org/pictures/?gallery=pvr150
>>>
>>> Here's an exported video showing the problem - 1.5 MB
>>> http://criggie.dyndns.org/mythtv/TV1-second.avi
> ...
>
>> Are you getting any errors in the system log while this corruption
>> is occurring, or just before?
>
>
> Next weekend I will drop a windows HD in the machine and see what it
> sees.  Otherwise I need to swap around drives to free up a PCI slot  
> and
> then fit a DVB-T card.
>
>
> Yes - I sometimes get this, but its not correlated with channel  
> playback
> or anything.  The video stream corruption is ongoing as long as the
> channel is watched/recorded.
>
> Apr 13 17:26:36 bt kernel: ivtv0: All encoder VBI stream buffers are
> full. Dropping data.
> Apr 13 17:26:36 bt kernel: ivtv0: Cause: the application is not  
> reading
> fast enough.
>

You need to tweak a couple of buffer settings

Try putting the following in /etc/sysctl.conf

vm.min_free_kbytes=16384

Also how many analogue cards do you have as you might want to double  
the value to 32768.

The ivtv driver tries to compensate for a lot of bugs in the dma chips  
on the 150/500 series cards but sometimes it isn't enough. When it  
gets really bad a reboot is generally recommended.

Steve


Steven Ellis - Technical Director
OpenMedia Limited
email   - steven at openmedia.co.nz
website - http://www.openmedia.co.nz

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