[mythtv-users] High timestretch speeds with VDPAU

John P Poet jppoet at gmail.com
Sat Dec 13 23:20:26 UTC 2008


On Sat, Dec 13, 2008 at 11:05 AM, David Engel <david at istwok.net> wrote:
> On Fri, Dec 12, 2008 at 09:36:33AM -0800, Brad DerManouelian wrote:
>> On Dec 12, 2008, at 9:23 AM, David Engel wrote:
>> > I like to watch most news and talking heads shows and occasionally
>> > some sports at fairly high timestretch speeds.  I'd like to hear if
>> > anyone has been able to achieve at or near 2x timestretch speeds using
>> > VDPAU on H.264/HD-PVR recordings?  I'd particularly like to hear what
>> > speeds others can get on 9300/9400 IGP systems since that's what I've
>> > been eyeing for a frontend upgrade.
>> > [...]
>>
>> On 13.5 Mbps 720p content, I can time stretch to 1.25, but 1.3+ has
>> audio dropouts that make it too annoying to use. I haven't seen much
>> mention of time stretching with VDPAU so I don't know if it's been
>> optimized at all. There's likely some work still left to be done with
>> it.
>
> With which GPU is that?  If your drop off for 1080i is comparable to
> mine with my 9500, that wouldn't leave you much room to do anything
> more than 1.0x.  I don't know that there's much optimization Myth can
> do.  I would expect the timestretch speed to be almost entirely
> dependent on the speed of the GPU, but I'll defer to Mark Kendall who
> appears to be the MythTV expert on VDPAU.
>
> Could someone with an integrated 9300 or 9400 please see what maximum
> timestretch speed they can reach.  I can't imagine either would beat
> an add-in 9500, though.

David,

I am using:

http://www.newegg.com/Product/Product.aspx?Item=N82E16813128363&Tpk=N82E16813128363
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115054&Tpk=e8600
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231209

I am slightly over-clocking the E8600, but I doubt it makes any
difference for VDPAU.

My default recording profile for my HD-PVR is:   avg: 12500, max: 19200.

With all that and VDPAU enabled, max timestretch I could get up to
with it still watchable was 1.75x.  It is not so much that it started
to stutter, but the visual artifacts got too annoying beyond that.

Hope that helps,

John
-- 
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