[mythtv-users] stutter while recording two programs at once

Brad DerManouelian myth at dermanouelian.com
Tue Aug 29 21:51:11 UTC 2006

On Aug 29, 2006, at 10:15 AM, Steven Adeff wrote:

> On 8/29/06, Tony Lill <ajlill at ajlc.waterloo.on.ca> wrote:
>> Brad DerManouelian <myth at dermanouelian.com> writes:
>>> I've got an AMD64 box with a SATA II drive formatted as JFS  
>>> dedicated
>>> to recorded programs. music, photo, videos are on a separate SATA
>>> drive and the system runs from a PATA drive - all are 7200 RPM with
>>> 8MB buffers.
>>> I've got a PVR-350 and an HD-5500 card in the box which is also my
>>> frontend. I'm getting weird stuttering when recording on both tuners
>>> at the same time. The HD stream looks perfect but the stream from  
>>> the
>>> PVR-350 will show a single frame from about a second before the
>>> current position. It happens intermittently but often enough to be
>>> REALLY annoying. I've found that it's in the recording this way  
>>> since
>>> the rogue frames happen at the same place when I play back every
>>> time. I have a feeling it MIGHT only be happening when watching a
>>> program and recording two others at the same time. I had anticipated
>>> 3GB/sec on the SATAII drive would be enough bandwidth to watch 1,
>>> record 2. Is this not the case? Is there a good way to test? Do I
>>> finally need to submit and start transcoding every program I watch
>>> and deal with sub-par quality?
>> Are you getting any messages from the ivtv driver about your
>> application not reading fast enough? Look in
>> /var/log/messages.
>> There's a known problem where database access slows
>> things down enough to cause dropped frames. It's more likely to  
>> happen
>> in the first minute of the recording, 'cause it hits the database  
>> more
>> often then.
> it may also be a pci latency issue, I had similar occur with a PCI ATA
> card I'm using for part of my RAID array once I changed the latency
> this went away.

The only thing that looks like an error or warning in my /var/log/ 
messages is:
Aug 27 16:11:13 mythtv kernel: ivtv0: Unreasonably low latency timer,  
setting to 64 (was 32)

Oh.. and ssh attacks attempted and failed on my system. :)

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