[mythtv-users] Deinterlacing and VAAPI in CentOS 7 ?

[Andrey Zhunev]

Hello Gary,


Wednesday, November 26, 2014, 10:29:40 AM, you wrote:

> On Wed, Nov 26, 2014 at 6:38 AM, Andrey Zhunev <a-j at a-j.ru> wrote:
> ....
>> Am I right assuming that xorg-x11-drv-intel is the issue? I guess EPEL
>> does not offer this package...

> My recollection is the package you want is (or was)
> named libva-intel-driver.  I do not believe it is in EPEL
> but I seem to recall the source is available from Intel's
> VAAPI repo at 01.org and was available via package
> in rpmfusion for previous RHEL revisions (7 is not
> yet available), but it seems possible that you might
> be able to try the F19 version (since RHEL 7 is "like"
> F19).


Oh, thanks! I may try the libva-intel-driver package for F19.

But before that, I would like to ask for an advise on below:


>> On the other hand, do I need VAAPI at all? I read earlier that
>> deinterlacing is not supported by VAAPI - at least by some early
>> versions of it. So maybe it is still the case, and getting VAAPI to
>> work won't help me to get deinterlacing running?

> The answer is "it depends".  The deinterlacing available
> depends on the specific GPU, but in general it is
> agreed that they are not as good as the nVidia ones.
> However, they may be "good enough", depending on
> your needs.

> Alternatively, depending (again) on the specific GPU
> you may want to attempt to let MythTV run the display
> in the modes that lets the display do the scaling and
> deinterlacing (many higher end TVs do a better job
> than some GPUs).  I seem to recall there is an article
> in the wiki on how to configure it.

> And, of course, as some people point out, software
> decoding can be as good, and sometimes better,
> than any particular hardware implementation (if your
> cpu is powerful enough).


I probably should have started with a story to explain the background.
So let me correct that mistake:


Previously, I had my mythbackend server running in the kitchen, acting
also as a frontend on a small (20-inch) kitchen TV. So all these
deinterlacing issues were not really critical, and I didn't care much.

In the living room, I had a larger TV with a dedicated frontend
machine, with an NVidia GT205 and VDPAU. It worked very good, at least
to my liking.


Now, I'm moving to a new location. The mackend machine will be
installed in a place where there's no TV or monitor at all. But there
is a nice way to route an HDMI cable from mythbackend directly to the
TV in the living room. I checked the distance - it is just 7 meters,
so I should be fine getting an average cable. This way I will avoid
the need for a dedicated frontend machine in the living room, and will
also have a screen in case if I happen to need to make some changes to
the backend machine in a single-user mode.


So the idea seems good. Now, I'm concerned about the video quality.
My CPU in the backend machine is an Intel Core i7-2600S. Normally, it
has really minimal load, so there should be plenty of power to do the
decoding in SW. 


My new TV for the living room is a SONY KDL50W705B. It's still in the
box, since the move is in progress. I'm about to install it - maybe in
a day or two... 
I didn't have a chance to see how good it will work with the built in
Intel graphics on my MythTV machine.
I suspect it won't be good until I teach my Myth machine to do
at least deinterlacing... But I can be wrong.


So now I see three options:

- Try the SW decoding while keeping stock CentOS drivers. I have no
idea how good this option is, or how to set up SW decoding properly...

- Try installing an Intel driver from Fedora 19 repo in order to use VAAPI.
Not sure it will work as good as the VDPAU on my previous dedicated
frontend machine... But sounds like a good candidate to me.

- Put an NVidia GT205 from my old frontend to the mythbackend machine.
Or maybe even get a newer NVidia card to do the job (will there any
benefit from a newer chip?).
This should work at least as good as the old setup. But the hassle
with NVidia drivers and the way they tend to update many things on the
system to their liking... Well, it will make it difficult to go back
to Intel video without reinstalling the OS, if a need will occur in
the future...

- Do nothing and see if the TV will be able to do deinterlacing with
an acceptable quality. As I said, I'm not even sure the TV will have
such an option.



Am I correct with my thinking?

Which of the options would you prefer?




--
Best regards,
 Andrey