[mythtv-users] High end, state of the art Myth Frontend

Andre Newman mythtv-list at dinkum.org.uk
Mon Sep 30 08:30:13 UTC 2013


On 19 Sep 2013, at 00:57, Jean-Yves Avenard <jyavenard at gmail.com> wrote:

> On 19 September 2013 02:55, Andre Newman <mythtv-list at dinkum.org.uk> wrote:
>> Well, I've upgraded from a 9400GT, to a GT220, a GT430 (ugh) to a GT640 and each step of the way picture quality has improved in various ways. Yes I've gone back and tried to old cards (this week actually) and yes the newer ones are better, my girlfriend has commented "what's wrong with the picture" when I went back to the GT220 last week trying out another old LGA775 board that doesn't seem to like the GT640, doesn't like the 220 much either!
> 
> now we're entering the placebo realm....
> 
> Must be the quality of the digital cable you're using , the signal is purer !
> 
> Decoding will be identical between all those cards, and Advanced 2X
> will be identical to all the cards supporting it.
> Now cards like the GT4xx or GT6xx have extra post-processing options,
> but they aren't enabled by default.
> 
> I'm willing to bet that if you did a bit for bit comparison between
> all those cards, using the same options, you'll find identical data.

So I bought an Asus mini ITX motherboard and an i3-4340, 3.6Ghz with a HD4600 gpu.

Initial impression is that cpu decoding works very well, plays 50Mbps H264 4:2:2 broadcast HD video very nicely, cpu usage wibbles around 80%, blurays and regular HD broadcasts around 50% on one core and 15% on the other.

I had some trouble with lip sync being  massively out of adjustment range but a few lines in rc.local and a modprobe.d/ file fixed all that.

/bin/chmod -R ug+rw             /proc/asound
/bin/chown -R root:audio        /proc/asound


echo 2048 >/sys/class/rtc/rtc0/max_user_freq
echo 2048 >/proc/sys/dev/hpet/max-user-freq

and:

options nvidia                  	NVreg_EnableMSI=1
options nvidia_319_updates 	NVreg_EnableMSI=1
options snd_hda_intel           	enable_msi=1 bdl_pos_adj=32

The bdl_pos_adj thing seems to bring all the different audio codecs to the same lip sync, without that I need a different adjustment for ac3 as mp2 as dts and truehd.

De-interlacing was a little disappointing with the hd4600, maybe the drivers aren't there yet but every de-int I tried resulted in combing, tearing or a very blurry image on any interlaced motion, interlaced film and drama stuff was fine but that's an easy de-interlace. I tried vaapi too but that looked very torn, maybe I need newer drivers than an up to date Ubuntu 12.04.3 install, 3.8 kernel.

So for now the gt640 went in too and is configured for ffmpeg decode and vdpau advanced 2x de-interlacing which looks very nice. I haven't done a proper test but I'm not seeing a lot of difference between vdpau decode and ffmpeg decode, time for a proper test next week I hope.

One unexpected fringe benefit of a modern motherboard, the boot time is great, it's all up and running in 15 or so seconds from switch on to mythtv screen and no screens of scrolling bios wibble just an Asus logo followed by the mythbuntu loader, nice to have that in the living room.

Andre

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