[mythtv] YV12 problem

Jean-Yves Avenard jyavenard at gmail.com
Wed Dec 12 22:49:27 UTC 2018


On Wed, 12 Dec 2018 at 5:02 pm, David Engel <david at istwok.net> wrote:

> On Wed, Dec 12, 2018 at 08:55:22AM +0100, Jean-Yves Avenard wrote:
> > From: David Engel <david at istwok.net>
> > Sent: Wednesday, 12 December 2018 07:26
> > To: Peter Bennett
> > Cc: Development of MythTV
> > Subject: Re: [mythtv] YV12 problem
> >
> >
> > > 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 you remove yv12 support software decoder won't work any longer.
> > Now in the TV world that's probably fine, but do we really want not to
> play those files?
> Please explain.  Without more context and being mostly ignorant of
> pixel format implilcations (though, I'm trying to correct that), I
> don't know what to make of this statement

TV broadcasts use exclusively mpeg2, h264 and h265.
Most embedded system like the fire2 have a hardware decoder for those.

So what you get out of the decoder will be a GPU based nv12 image.

For other codecs like say vp8, vp9, av1: you have to use a software decoder
and they will output yuv420 (if 8 bits).

I was just saying earlier that dropping yuv420, means you'll have to do a
conversion to nv12 right outside the decoder, so an extra memory allocation
and unnecessary copy.

All when converting any nv12 shader to do yv12 is trivial; you could even
use the same code for both.

BTW, the default browser by default on the fire2 is Firefox :)

Story goes that Bezos contacted our director personally asking if we could
port it in 2 weeks. The challenge was accepted.

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