[mythtv-users] Shuttering sound with PVR-250

Alexander Varakin avarakin at optonline.net
Thu Oct 14 01:44:40 UTC 2004

CPU usage is about 5% on this backend.
It seems like the memory might be the culprit: I have 128 MB only and 
mythbackend takes about 60 MB.
I am not running X on this box and there is not much else running on 
this box, so I was hoping that 128 MB will be ok.
Looks like I have to add some memory.

Yan-Fa Li wrote:

> Your AMD is practically about 400% faster than the P3, so you're going 
> to have work a bit.  Maybe you're swapping under load, you don't say 
> how much mem you have, have you checked that ?  Verify what DMA the 
> drive is running at.
> hdparm -i /dev/hda
> will tell you if it's running in dma mode and what mode.  For example:
>  Model=IC35L120AVV207-1, FwRev=V24OA66A, SerialNo=VNVD09G4CTX3DT
>  Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
>  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=52
>  BuffType=DualPortCache, BuffSize=7965kB, MaxMultSect=16, MultSect=16
>  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=241254720
>  IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
>  PIO modes:  pio0 pio1 pio2 pio3 pio4
>  DMA modes:  mdma0 mdma1 mdma2
>  UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
>  AdvancedPM=yes: disabled (255) WriteCache=enabled
>  Drive conforms to: ATA/ATAPI-6 T13 1410D revision 3a:  2 3 4 5 6
> See the asterisk near UDMA5.  That's the speed it's running at.  Maybe 
> your drive isn't enabling DMA for some reason.
> That's a pretty old box, so it's probably running at UDMA33, which 
> normally isn't a problem but might be in your case.  If you can afford 
> it, drop a $20 UDMA100 card into a spare PCI slot and see if that helps.
> Did you turn off X ?  Have your disabled all unecessary daemons ?  
> What kind of network card are you using ?  Maybe it's consuming too 
> much processor.  Basically when you use an old PC you have to do a lot 
> of fine tuning.  Try compiling some of your components specifically 
> for P3 instead of i386 or i686, and turning on -mmmx as an 
> optimization.  I always like to install an i686 optimized glibc on a 
> pentium class box as this speeds up all user space programs :)
> Yan
> avarakin at optonline.net wrote:
>> Hi,
>> I had a perfectly working Myth setup on my Athlon XP 2000+ PC.
>> I built a new headless Myth backend using old 667MHz  PIII PC and I 
>> am getting shuttering sound and incomplete recordings if I record and 
>> watch at the same time. I watch recordings using a different PC.
>> If I record a program and then watch it later, all works fine, so 
>> there might be some kind of competition between recording and playing 
>> thread of the backend.
>> When I play a recording with damaged sound and do a seek, then sound 
>> becomes normal for a few seconds and then shutters again.
>> My environment is:
>> Debian unstable
>> Myth 0.16 from repository
>> PIII 667MHz
>> stock kernel 2.6.7
>> PVR-250 with CK driver version 99
>> Thanks,
>> Alex
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