[mythtv] YV12 problem

Peter Bennett pb.mythtv at gmail.com
Tue Dec 11 22:27:21 UTC 2018

On 12/11/18 3:13 PM, Peter Bennett wrote:
> Hi David
> Please can you point me to the patches that you are planning to 
> install, or specific instructions on which commits you will reverse, 
> so that I can do a test.
> Here are close-up photos of the screen from current master with UYVY 
> and YV12 when using fire stick (non-4k) or "mi box s" or other devices 
> that do not support high precision opengl es.
> Screen using YV12 checked ---> https://imgur.com/lbfyEWQ
> Screen using YV12 unchecked (i.e. using UYVY) ---> 
> https://imgur.com/dLoMUau
> If you send me your patches I will test with those and see how the 
> picture looks.
> Peter

I have tried your patch on ticket #13358. It produces the jagged result 
(https://imgur.com/dLoMUau) on the Fire TV (non-4k), without any ability 
to fix it.

I agree that the code you are removing is flawed, as stated by Mark. I 
recommend that we change the default for the "enable YV12" setting  to 
be "false" for everybody, which bypasses that flawed code and achieves 
the same effect as removing it. The users of fire tv non-4k, mi box s, 
or other android devices that do not support high precision can still 
enable that check box to fix the jaggies, albeit with flawed code that 
does not properly support kernel deinterlace. However, using Linear 
blend deinterlace with YV12 is better than looking at that jagged picture.

If somebody can come up with better code that supports these android 
devices without the jaggies, we can then remove that faulty YV12 code.

If my recommendation is not taken and the code is removed, then we need 
to remove the setting from the frontend setup for enabling/disabling 
YV12, since that will no longer have any effect. I will also need to 
update the wiki to remove the recommendations around YV12 for android.


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