[mythtv] A need for advanced player settings

Kyle Rose krose at krose.org
Fri May 27 15:17:43 UTC 2011

> You run both the front and backend on something as slow as an atom?
> I am impressed.  I wouldn't try that.

The machine is more than powerful enough to handle it. With VDPAU
decoding, I never see the CPU more than half loaded even with krb5p
(it typically maxes out at 100% of one core with a kworker thread
grinding on bulk decryption). The problem does not occur even in this
mode with the ringbuffer tweaks I made.

> Does your video card have any ability to help with the decoding or is
> the poor atom stuck with all the work?

I neglected to specify that it is an NVidia ION machine with VDPAU
working flawlessly.

> Which kernel version and filesystem?

Ubuntu Natty's 2.6.38-9. ext4.

> I know ext3 had some performance
> issues in the past that were fixed in more recent kernels, although not
> all of them of course.  Of course NFS shouldn't really be related to that.

The machine never uses more than 3% of CPU when reading from the local
SSD. AFAICT, the machine is an order of magnitude more than powerful
enough to handle the stream, as illustrated by my successful tweaks to
the buffer settings. In fact, I would be willing to bet that the same
phenomenon would occur on my other frontend (my Core i7 desktop) with
the default settings, because the pausing appears to be more a
property of the media file itself than of the playback hardware. If
anyone wants an 8GiB media file for testing, I would be willing to
make it available. :-)

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