[mythtv-users] Display weirdness

Sun Oct 18 01:26:53 UTC 2020

On Sat, Oct 17, 2020, 3:53 PM Greg Oliver <oliver.greg at gmail.com> wrote:

> On Sat, Oct 17, 2020 at 5:33 PM DryHeat122 <dryheat122 at gmail.com> wrote:
>
>> On Sun, Sep 13, 2020 at 12:59 AM Stephen Worthington <
>> stephen_agent at jsw.gen.nz> wrote:
>>
>>> On Sat, 12 Sep 2020 20:05:05 -0700, you wrote:
>>>
>>> [snip]
>>
>>
>>
>>> >Today a new problem cropped up.  From the program guide I started ESPN
>>> HD
>>> >from the "watch this channel" menu item to watch Lakers v Rockets.
>>> HDPVR2
>>> >started fine but the picture was shrunk to about half the size of the
>>> >monitor. Esc and try again, same result.  Rebooted, and same result.  I
>>> >noticed when it was starting from the program guide it showed the ESPN
>>> HD
>>> >icon, but another tv icon with SD below it.  So  somebody thinks they're
>>> >getting a SD signal. You can get HD video off component video outputs of
>>> >the HDPVR2, right?  Here's the kicker.  After watching the game on
>>> another
>>> >system, I went back and tried ESPN again on the Myth box as above. Now I
>>> >still get the TV/SD idon on startup but the picture is full screen.
>>> WTF?!?
>>>
>>> There can be a number of things that can cause this, including bugs.
>>> But the things to look at are how you have the config set up for
>>> playing video.  There are options that allow the video playback to
>>> change the video mode separately from the GUI screens - see Setup >
>>> Appearance > Separate modes for GUI and playback.  If that is set,
>>> then whenever you are playing video, the content of the video is
>>> matched against your playback profiles and the settings for the
>>> matching profile are applied.  This can also cause xrandr commands to
>>> be sent to the X display to get the display to change mode to a mode
>>> that matches the video that is being played.  Such mode changes can
>>> happen if the video being played changes mode in the middle (eg sport
>>> is 720p, but it changes to 1080i for the ad breaks).  The available
>>> mode changes are the modes that X lists in its Xorg.0.log file when it
>>> starts up.  You can get a problem that there are modes available that
>>> are not actually what you want for your screen.  So if the recording
>>> is 576p, for example, the matching mode may be only for displaying on
>>> 1/4 of the screen, when it should be set up to reprocess the frames to
>>> a 1080 screen size.  I have just been fighting a slightly different
>>> version of this problem where I do not want any interlaced modes used
>>> as when there is onscreen GUI overlaying video output, the GUI part of
>>> the display gets distorted by the interlacing.  The solution I am
>>> currently trying for this is to tell X not to use the EDID sourced
>>> modelines (and lots of other modeline sources) and just to use the
>>> modelines I have specified in my xorg.conf file.  I turned on this
>>> option:
>>>
>>> Section "Screen"
>>>   Option    "ModeDebug" "true"
>>> EndSection
>>>
>>> so that X logs details of all the modes it sees and edited the output
>>> of that to create the modelines I wanted, then disabled all the other
>>> modes.  Along the way, I had some modes from other sources still
>>> enabled that caused exactly what you are seeing where the video only
>>> used part of the screen.  After turning off those modes, it now seems
>>> to be working well, but it has only been a few days so far and I need
>>> to test it on various video files to be sure.
>>>
>>> You can find out what mode your screen currently is in by opening a
>>> terminal and using xrandr.  I hate xrandr - it is difficult to use and
>>> does not actually allow you to see the modes in the way they are
>>> reported in X's logs, but the required information is there.  So when
>>> you next have this problem, make sure you have the ModeDebug option on
>>> first, then run "xrandr" and see which mode has the * character by it,
>>> telling you that is the current mode.  Then match that to the modes
>>> reported in the X logs, and see if there is a problem.  You may need
>>> to disable that mode so a better one gets chosen, or you may need to
>>> use an xorg.conf option to set scaling for that mode so it will fill
>>> the full screen.  Your TV may also have a menu or remote key that will
>>> get it to display information about its current screen mode.
>>>
>>> BTW You have not said what video card you are using.  I am using an
>>> Nvidia GT1030, so things may work differently if you are using Intel
>>> or AMD.
>>>
>>
>> Found some time to get back to this issue.   All the problems with screen
>> sizing were resolved when I updated my Nvidia drivers (video card
>> is Geforce 8400 GS Rev. 2).  Now the issue is jankey/stuttering video/audio
>> when watching live TV.   It's odd because if I record these same channels
>> then play the recording everything is fine.  The only problem is when I'm
>> trying to watch live.
>>
>> I am still getting the SD symbol when I "watch this channel" on HD
>> channels where I encounter the stuttering.  Maybe it's occurring because
>> the system is trying to down-sample the HD to SD and the processor can't
>> keep up?
>>
>> I think this advice pertained to the screen size issue, but just in case
>> I checked setup and  "Separate modes for GUI and playback" is not enabled.
>> I also had a look at  Xorg.0.log for modes listed, and there don't seem to
>> be any except auto-select.  Here is the output of  cat Xorg.0.log | grep
>> mode:
>>
>> [     7.808] (==) Matched modesetting as autoconfigured driver 2
>> [     7.828] (II) LoadModule: "modesetting"
>> [     7.828] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so
>> [     7.829] (II) Module modesetting: vendor="X.Org Foundation"
>> [     7.832] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
>> [     7.841] (WW) Falling back to old probe method for modesetting
>> [     8.331] (==) NVIDIA(0): No modes were requested; the default mode
>> "nvidia-auto-select"
>> [     8.331] (==) NVIDIA(0):     will be used as the requested mode.
>> [     8.368] (II) UnloadModule: "modesetting"
>> [     8.368] (II) Unloading modesetting
>> [     8.375] (II) NVIDIA(0): Setting mode "DFP-0:nvidia-auto-select"
>> [     8.550] (**) Option "xkb_model" "pc105"
>> [     8.553] (**) Option "xkb_model" "pc105"
>> [     8.571] (**) Option "xkb_model" "pc105"
>>
>>
>> Maybe there are no modes because I don't have ModeDebug set as suggested,
>> but I'm not sure how to do that.
>>
>
> MythTV has long had live TV issues with stutttering, etc.  Just a shot in
> the dark - have you started live TV and immediately pressed back (left
> arrow) to see if it stops?
>
> Just making sure you have not tried this already - a lot of improvement
> was made by Peter Bennett a while back, but it still plays best when you
> let it (I'll call it, for simplicity) fill the buffers.
>
> If you have tried this, then please, disregard.
>
> -Greg
>

Have not tried that, but will.  So you mean start watching a channel, then
back it up a few times?

The odd thing is I never had this problem with 0.28 and 31 is running on
same hardware, except I now have SSDs which are faster storage. Only other
change was from hdpvr to hdpvr-2.

>
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