[mythtv-users] mythtv-users Digest, Vol 40, Issue 81

[Andrew Casper]

Greg -

This doesn't sound like a drive issue. It sounds like an issue with  
firewire and very close to a problem I'm having too. There is some  
discussion about firewire chipsets and some being better than others.  
I have tried a couple and still have issues.

To debug, I recommend watching the log files. When I watch a  
problematic channel, my backend log will have  over and over again.  
I'm thinking that it might be something in how my cable company  
encrypts channels. There was also some discussion in the developer's  
list about an issue with the firewire memory buffer (RingBuffer in  
your logs) and possibly an issue with the kernel.

http://www.gossamer-threads.com/lists/mythtv/dev/171329#171329

I would also watch your frontend and backend logs for firewire speed.  
Channels will request a speed and override the speed set in  
mythtvsetup. In my case, I saw that a channel change issued a 200  
speed command.

Broadcast mode has to be done in just the right order. You probably  
want to compile the 6200ch script in the contrib directory. Then stop  
your frontend, stop your backend, run mythtvsetup and set the  
firewire input to broadcast and the correct speed and channel change  
script, then shutdown your myth box, pull the power on your 6200,  
plug in and re-power the 6200, and finally re-power your myth box.  
You might want to reset your 6200 while it is powered off - just hold  
the power button until the front display finishes a dance of dashes.

In my case, I get 6 HD local un-encrypted channels perfectly, 4 HD  
movie channels with an occasional glitch, and 4 premium HD channels  
that throw so many "Firewire: Got out of sync TS Packet" error that  
my backend finally crashes.

Good luck and keep me posted

- Andrew

On Jul 18, 2006, at 7:48 PM, mythtv-users-request at mythtv.org wrote:

> Message: 7
> Date: Tue, 18 Jul 2006 15:09:15 -0600 (CST)
> From: greg at nodecam.com
> Subject: Re: [mythtv-users] Motorola 6200 firewire high def artifacts
> 	- Help	me	debug?
> To: Discussion about mythtv <mythtv-users at mythtv.org>
> Message-ID: <59796.198.169.6.69.1153256955.squirrel at mail.nodecam.com>
> Content-Type: text/plain; charset=iso-8859-1
>
>> I am also trying to solve an issue with a Motorola firewire box.
>> Could you describe the artifacts you are seeing. Do they crash your
>> backend? Have you tried switching from a point-to-point connection to
>> a broadcast connection? Have you tried increasing the firewire speed
>> in MythTVSetup.
>
> Basically it's like a skip in the stream - the whole screen goes very
> blocky, then resolves itself.  When watching the NHL playoffs, it was
> doing it every 10-20 seconds during play, making the game unwatchable.
>
> I can't get broadcast working, and firewire speed is set to 400  
> already
> (though I'll have to check on that to confirm)
>
> The backend is still stable though, it's just frustrating not being  
> able
> to really use the system to record high def sports.
>
> I did some benchmarking on the hard drives, and they seem to be  
> able to do
> sequential writes plenty fast for HD - I'm wondering if I have a bad
> firewire cable.  I guess replacing that is my next logical step.
>
> Greg

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