[mythtv] Ticket #9341: H264 doesn't play back watchably on Windows frontend

Jerry Rubinow jerrymr at gmail.com
Thu Dec 9 14:54:15 UTC 2010


On Thu, Dec 9, 2010 at 6:52 AM, James Courtier-Dutton <
james.dutton at gmail.com> wrote:

> On 7 December 2010 03:53, Robert McNamara <robert.mcnamara at gmail.com>
> wrote:
> > On Mon, Dec 6, 2010 at 7:50 PM, Jerry Rubinow <jerrymr at gmail.com> wrote:
> >> On Mon, Dec 6, 2010 at 10:37 PM, <noreply at mythtv.org> wrote:
> >>>
> >>> #9341: H264 doesn't play back watchably on Windows frontend
> >>>
> >>> Comment:
> >>>
> >>>  Your Ion box isn't even close to powerful enough to handle that
> content
> >>> in
> >>>  Windows, for which MythTV lacks hardware decode support.
> >>
> >> I considered this possibility but figured the CPU usage would be much
> >> higher, instead of just around 35%.  Shouldn't it be pegged?  In any
> case,
> >> thanks for the quick turnaround on the ticket.
> >> -Jerry
> >
> > You may wish to follow the progress of this ticket:
> >
> > http://svn.mythtv.org/trac/ticket/8620
> >
> > When Myth supports DXVA in Windows, you may have more hope.  As it
> > stands, however, Myth on Windows on ION with anything besides low to
> > moderate bitrate material, particularly H.264, will probably be a
> > recipe for disappointment.
> >
>
> I have an ION based small PC, and it plays back H.264 very nicely, but
> I run it on Linux mythfrontend.
>

For anyone following this or searching in the future, here is the upshot.
 nvidia drivers under Linux implement VDPAU, which does the heavy lifting on
the ION GPU.  VDPAU is only on Linux.  Under Windows, the equivalent is
DXVA, which myth doesn't make use of, although it's in development (see
http://svn.mythtv.org/trac/ticket/8620).  In the meantime, H.264 decode
under Windows is CPU-bound.

I mistakenly thought my CPU wasn't being maxed out because I forgot to take
into account I was running on a multi-core machine.  So one of my CPUs was
in fact being maxed out.

-Jerry
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