[mythtv-users] HD-3000 recording corruption

[Brian Wood]

On Mar 30, 2006, at 2:41 PM, Steven Ihde wrote:

> On Wednesday 29 March 2006 07:22, Craig Partin wrote:
>> This is the first time I have been stumped in over two years of  
>> mythtv
>> use.  I got my HD-3000 working just fine tuning QAM stations over
>> cable in myth.  The system works flawlessly and reliably except that
>> QAM recordings get trashed when anything else is happening on the
>> system.  It records beautifully when nothing else is happening.  This
>> happens on all channels, HD and SD.  I can playback 1080i content  
>> with
>> XVMC just fine, even with bob.
>
> I've been debugging a similiar problem with my HD-3000.  In my case  
> it appears
> to have something to do with the video card.  When I play video (with
> anything -- xine, mythtv, mplayer), any QAM recording in progress  
> will get
> trashed.
>
> The interesting thing is that it doesn't appear to have anything to  
> do with
> data transfer to the hard drive.  Rather the HD-3000 actually loses  
> the
> signal lock.  I can verify this by shutting everything down  
> (mythbackend,
> etc.), and running "azap" to tune a channel.  As azap prints status  
> lines,
> they all show excellent signal strength in the range fd00-ff00, and
> FE_HAS_LOCK.  As soon as I start playing any video with xine, the  
> signal
> strength drops, and FE_HAS_LOCK disappears.  The larger the xine  
> window, the
> worse the problem.  If I shrink the xine window down to a tiny size,
> FE_HAS_LOCK comes back and the signal strength improves.  The  
> amount of
> signal loss seems directly related to the size of the video  
> window.  It's not
> related to data transfer that I can see -- it behaves the same  
> whether I
> simply tune the card without recording, or if I use "azap -r" and
> "cat /dev/dvb/adapter0/dvr0" to record.
>
> My card is an nVidia 6200 AGP.  I switched back to my old Radeon  
> 9200SE, and
> found that it did not have this issue!  Signal strength stays  
> essentially
> constant even when playing video, and the QAM recording is crystal  
> clear.
> However I can't really use the Radeon because of the TV-out fiasco  
> with
> Radeon, and besides my CPU is too slow to do the job without XvMC,  
> which the
> Radeon doesn't support.
>
> Anyway, I don't have a solution, but since elsewhere in the thread you
> indicated that the PCI latency fix didn't work for you, I wonder if  
> you might
> be having a similar issue to me.
>
> BTW, my mobo has a Via KT600 chipset.  I'm planning on upgrading  
> the whole
> system to a mobo with an Intel chipset and a CPU that can do the  
> job without
> XvMC at some point.

I have the same problem with a P4 2.4 Ghz. system w/Intel mobo (Dell  
machine). I also had the same trouble when I was playing with a  
Athlon64 3700+.

Same symptom, solid lock with azap 'till I tried to play the video,  
then the lock came and went, and the video was alternately good and bad.

I was assuming I had a good signal due to the zero BER, but I have  
since learned that the HD-3000 card will report a zero BER when  
connected to a tree.