[mythtv-users] Can't get my projector to work with Myth

[Allen Edwards]

On Sun, Mar 3, 2019 at 5:21 AM Andrew Stadt <acstadt at stadt.ca> wrote:

> On 2019-03-02 11:42 p.m., Allen Edwards wrote:
>
> <snipped>
>
> I think the problem is that I misread the specification on the projector.
> While it says that it does 1080p, the maximum data rate is 1280x720 so the
> 1080p must be with an analog input.  Same with the monitor. It has a native
> resolution of 1280 x 1024.  Per the recommendation of everyone here, I set
> the TV up from my initial setup of 1280x720 to 1920x1280 when I upgraded to
> Mythbuntu-16.
>
> Option         "metamodes" "VGA-0: nvidia-auto-select +0+0, HDMI-0:
> 1920x1080 +1280+0"
>
> When I was running Mythbuntu-8 which drove the projector and the TV just
> fine, I had everything set to 1280x720 as that is all the TV signal is
> anyway.
>
> So now I have to decide if I want to use the TV at 1920x1080 or downres so
> I can use the projector a few times a year or find some way to have the
> computer auto detect without turning the TV black. I believe there was also
> an issue with the Sony sending bad EDID data. I just read something about
> auto detecting 1360x768 instead of something useful.  Might be a different
> model but I recall there was an issue. Maybe there is a way to have X pick
> between 1280x720 and 1920x1024???
>
> The video card is "GeForce GTX 750 Ti"
>
> Well, I think I am at least understanding why it doesn't work.
>
> Allen
>
>
> I don't think I ever set up a frontend where I hadn't had to tweak the
> xorg.conf for the specific screen ( monitor, tv, projector, etc ) at least
> a little ( ok, the Android frontend on my Shield went surprisingly easy ).
>
> Whether it be dealing with overscan, underscan, adjusting mode lines for
> some specific resolutions/frame rates, or dealing with an older xorg that
> couldn't handle the device not being there when it came out of suspension,
> bad EDIDs, etc.
>
> The issue is that these adjustments are generally specific to that device
> and don't just work for all of them.
>
> For one of my frontends, which has a primary output device (TV), and a
> secondary I only use a few times a year (Projector), I ended up creating an
> xorg.conf which has two SERVERLAYOUT sections, each of those two sections
> specify their own DEVICE, SCREEN and MONITOR sections.
>
> Most of the time, my frontend auto logs in the myth user, and
> automatically starts "startx --layout TV". For the couple times a year I
> use the projector, I logout then, log in manually, and "startx --layout
> PROJECTOR".
>
> FWIW: I tweaked the xorg.conf for the separate devices individually, till
> I had everything the way I wanted it for that output device, and then
> combined them, makes testing a lot easier as well.
>
> Of course none of this solves your immediate issue, just a suggestion on
> how you can run both configs going forward when you do get it working.
> Stephan Worthington already gave some pretty good advice in that category.
>
> Andrew.
>
Let me explain what I did for the last decade.  I had a VGA display which
is a small Samsung monitor.  For the other I had a 1080x720 output to a DVI
splitter which went to the TV and the Projector.  The splitter faked the
HDCP data so that a source like a DVD player thought there was only one
device connected.  I would play whatever I wanted and it would show up on
whichever display was on. That was on Mythbuntu8 with an old slow video
card but it worked fine.  That system died. There was no problem having the
same setting for both the TV and the Projector and in fact Myth had no idea
there were two displays connected to the single DVI port.  This DVI
splitter was quite expensive and violated the HDCP standard, which is why
it worked.  I originally bought it so that my new DVD player would work
with my old projector that had no HDCP so without this device, I could no
longer watch DVDs once my old DVD player died. That projector died and I
bought the Panasonic.  Point is, Myth worked fine with a single setup and
two displays on the DVI port and one on the RGB port.

New system is Mythbuntu 16 and the video old card is too slow.  I got lots
of tearing. Big step backward.  A friend gave me the 750 ti card and now I
am using HDMI and get digital sound into the TV.  Can't go back to the old
setup because in the process of doing something I fried the audio decoder I
was using to get audio to the TV.  Anyway, I am happy with the hdmi into
the TV so that is good.

That is the history.  The goal now is to be able to unplug the TV and plug
in the Projector and have it work. The obvious solution is to change
 Option   "metamodes" "VGA-0: nvidia-auto-select +0+0, HDMI-0: 1920x1080
+1280+0"
to
 Option   "metamodes" "VGA-0: nvidia-auto-select +0+0, HDMI-0: 1280x720
+1280+0"

It is not at all clear to me what benefit I am getting from using 1920x1080
on 1280x720 source material but someone on this list convinced me to do it
that way and it works well so I would prefer not to change.

What I wonder is, would X figure it out if I did something like this?
Option "metamodes" "VGA-0: nvidia-auto-select +0+0, HDMI-0: 1280x720,
1920x1080 +1280+0"
or maybe it has to be this
Option "metamodes" "VGA-0: nvidia-auto-select +0+0, HDMI-0:
1920x1080,1280x720  +1280+0"

Allen
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