[mythtv-users] frontend video smoothness

Paul Gardiner lists at glidos.net
Tue May 19 07:54:00 UTC 2020


On 18/05/2020 17:54, John Pilkington wrote:
> On 18/05/2020 16:50, Jim Abernathy wrote:
>> I now have an easy way to test multiple frontends very quickly 
>> switching between them to compare which is best.
>>
>> And as all of you know the best can be different depending on which 
>> video, which format, etc. I've found a short scene where the camera 
>> pans past a number of people, and that motion makes the pan seem 
>> slightly jerk, but not bad, certainly it doesn't prevent enjoyable 
>> viewing of the program.
>>
>> Hardware:
>>
>> Backend common for all frontends. Core i7 Ubuntu 18.04 server Mythtv 
>> v31. All video captured is MPEG2 USA OTA HD 1080i (1920x1080 at 30hz). 
>> Average bit rate is 10Mb/s.
>>
>> Frontends:
>>
>> 1. Core i7 with Nvidia GT 1030 fanless GFX card
>>
>> 2. Nvidia Shield TV running mythfrontend and leanfront.
>>
>> 3. RP3B+ with MPEG2 license.
>>
>> I would have guess before hand that the PC with the GT1030 would be 
>> the best, but it wasn't.
> 
> Using DVB-T/T2 in the UK I find that the Leanfront on a 4K Firestick is 
> excellent when it works, but it still seems to need purely progressive 
> content and that often can't be guaranteed.  I have GT710s, which are 
> less capable than your GT1030, and they lack smoothness in panning when 
> using nvdec hardware decoding.  But with i5 4-core 3 GHz software 
> decoding, playback is as smooth as I get from DLNA or the leanback on 
> appropriate content.  I haven't seen what newer and cheaper devices can 
> do, but I'm sceptical.  I think you ought to try software decoding on 
> your i7.

That worries me a little. I still have an old nvidia ION based frontend 
that seems to play everything I throw at it perfectly, but I'm still on 
v29 and using vdpau. I hope the rendering rewrite hasn't caused any 
regression.

> And I recently noticed that the leanfront seems to work well with live 
> DVB-T mpeg2 material, while recordings now have good audio but the video 
> pauses briefly about once a second and sync is terrible...

That sounds like the TV being driven at the wrong frame rate, either a 
24fps movies played with the TV running at 25fps or vice versa. I'm 
finding leanfront really very nice to use these days, but that is one 
constant pain, having to do the strange vulcan nerve pinch on the 
firestick control to get 24fps.

Paul G.


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