[mythtv-users] Any success with Intel graphics hardware and judderfree playback?

[Kenni Lund]

2012/10/4 William Powers <wepprop at gmail.com>:
>
> On Oct 3, 2012, at 3:49 PM, Kenni Lund <kenni at kelu.dk> wrote:
>
>> Hi list
>>
>> I'm considering replacing my main (ION-/Atom-based) frontend with a
>> Intel Ivy Bridge solution with integrated graphics, as a workaround
>> for #11115.
>>
>> I want to make sure that it works well before I purchase the new
>> hardware. Therefore I've hooked up my Ivy Bridge laptop to my TV with
>> a HDMI cable and have started testing.
>>
>> My initial testing were moderately positive, playback worked with any
>> OpenGL or regular playback profile (Slim/Normal/High Quality).
>>
>> However, I did see a few issues:
>> 1. A horizontal flickering line was consistently seen on some
>> recordings -> Likely fixable with some Xorg/driver parameter.
>> 2. Judder -> Fixable with http://www.mythtv.org/wiki/User_Manual:JudderFree
>> 3. Picture quality was slightly lower than when using VDPAU on the
>> same TV -> That I'll probably just have to live with.
>>
>> Judder was the first thing I tried to fix. Once I had Xorg and all
>> modelines configured, I ran into what at first sight appears to be a
>> bug in MythTV. Every time when MythTV starts playback and changes the
>> resolution from the desktop default 1920x1080 at 60Hz to 1920x1080 at 50Hz,
>> the picture gets moved vertically by an offset, causing a black bar at
>> the top of the screen while the bottom of the picture is missing:
>> http://postimage.org/image/wyf7m7rnt/
>>
>> It is supposed to look like this (notice the extra text in the bottom
>> of the screen):
>> http://postimage.org/image/4yfpfodl5/
>>
>> It's not an invalid modeline, the issue is only in MythTV, as
>> illustrated by the following picture:
>> http://postimage.org/image/m3dd9lsgb/
>>
>> So, I guess my question it: Has anyone succeded in creating a frontend
>> based on Intel-hardware with integrated graphics and with judderfree
>> playback?
>
> I have been very pleased with OpenGL playback on Sandy Bridge hardware.  Previously, it required jumping through some hoops to get a new enough version of the Mesa libraries, but a recent Fedora 17 install worked right out of the box.  I have no visible tearing with the X composite extension disabled.  Previously I got a single flickering line of green pixels at the bottom of the screen, which could be eliminated by offsetting the picture by one line, but the recent Fedora 17 install doesn't exhibit that behavior.

Yep, same experience here, worked out-of-the-box on an updated Arch Linux.

> I haven't seen any judder.

Ok, that can either be because that your screen is already running
with a refreshrate which matches (or is a multiply of) the framerate
of your video source or perhaps just because you don't notice it?
(like most people, who are used to watch video on a computer screen
:)) Playing back for example 25fps material on a screen running 60Hz
will *always* result in judder.

Anyway, can I ask you to do a very quick test to see if you hit the
same issue/bug as me? Go to Utilities / Setup -> Setup -> Appearance,
go to the “Video Mode Settings” page, and check “Separate video modes
for GUI and TV playback”. Now set:
GUI=Your native resolution (like 1920x1080)
Video output=Your native resolution (same as above)
Rate=Any
Aspect=Default

If you try to play some recording now, does it then displace the
picture like shown in my screenshots? To disable these settings again,
just untick the “Separate video modes for GUI and TV playback”
checkbox. I know that lots of factors come into play here, but if you
do hit the issue, at least I'll know that this is a generic issue,
which should be fixed. Thanks...

> The biggest problem for picture quality was picking a deinterlacer. I finally settled on GreedyHighMotion (2x) which, to my eye, looks as good as VDPAU Temporal, 2X.  However, it's a software interlacer and won't work with anything slower than a G620 and I recommend an i3 to be sure.

On my screen I can quite easily see a difference when running with
GreedyHighMotion 2x compared to VDPAU Temporal 2x. At least when I
look at some white text which is scrolling horizontally on a black
background. With VDPAU the text is sharp and clear, while with
GreedyHighMotion 2x the edge of the letters gets greyish and a bit
blurred. But I do agree that the picture quality with GreedyHighMotion
overall is quite good - just not as good as VDPAU, IMHO :)

Best regards
Kenni