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<div class="moz-cite-prefix">On 10/09/2018 10:03 AM, Allen Edwards
wrote:<br>
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cite="mid:CAH8UtKNgESVsZ615WXDkBn8t6Y7goixJDF2jBTajk4RRpF9nTw@mail.gmail.com">
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<div dir="ltr">On Tue, Oct 9, 2018 at 6:31 AM Stephen
Worthington <<a href="mailto:stephen_agent@jsw.gen.nz"
moz-do-not-send="true">stephen_agent@jsw.gen.nz</a>>
wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">On Tue, 9
Oct 2018 13:39:14 +0100, you wrote:<br>
<br>
>On Mon, 8 Oct 2018 at 15:27, Peter Bennett <<a
href="mailto:pb.mythtv@gmail.com" target="_blank"
moz-do-not-send="true">pb.mythtv@gmail.com</a>> wrote:<br>
>><br>
>> The speed up and slow down problem is likely
related to the audio. It<br>
>> tries to vary the video rate to keep in sync with
audio. If it is<br>
>> getting bad audio timestamps or bad information
from the audio driver<br>
>> this can happen. Run with -v playback and look at
the log for<br>
>> confirmation. If this is the case I suggest trying
different audio<br>
>> settings. Also there is a setting you can try. Run
mythfrontend with -O<br>
>> AVSyncAveraging=60. The minimum and default value
is 4. You can try<br>
>> different values. Higher values will smooth out the
speed changes but<br>
>> may cause lip sync problems.<br>
><br>
>Thanks for the tip, I turned on the playback logging and
here is a<br>
>link to part of the log during a couple of minutes of
watching a<br>
>pre-recorded program. <a
href="http://paste.ubuntu.com/p/4c6nPpYTwC/"
rel="noreferrer" target="_blank" moz-do-not-send="true">http://paste.ubuntu.com/p/4c6nPpYTwC/</a><br>
><br>
>Not sure what all these messages indicate, some, like
this one :-<br>
><br>
>Oct 8 21:34:03 mustard mythfrontend.real:
mythfrontend[18401]: W<br>
>CoreContext audio/audiooutputalsa.cpp:243
(IncPreallocBufferSize)<br>
>ALSA: Try to manually increase audio buffer with: echo
128 | sudo tee<br>
>/proc/asound/card1/pcm7p/sub0/prealloc<br>
><br>
>are obvious and I have attended to this now but not yet
tested.<br>
>Others such as this one could be fixed (the device is
owned by root<br>
>and mode 600) so that is where I was going to go next (1
step at a<br>
>time right ?)<br>
><br>
>Oct 8 21:34:05 mustard mythfrontend.real:
mythfrontend[18401]: E<br>
>CoreContext vsync.cpp:358 (TryInit) VSYNC: RTCVideoSync:
Could not<br>
>open /dev/rtc: #012#011#011#011eno: Permission denied
(13)<br>
<br>
This is what I did to fix the /dev/rtc problem. The
/dev/rtc device<br>
is a link to /dev/rtc0, so I created a file<br>
/etc/udev/rules.d/10-local-rules and put this in it:<br>
<br>
# Allow MythTV (mythtv group) access to the rtc hardware for<br>
mythfrontend to use it for timing.<br>
KERNEL=="rtc0", GROUP="mythtv", MODE="0660"<br>
<br>
So now my rtc devices look like this:<br>
<br>
<a class="moz-txt-link-abbreviated" href="mailto:root@mypvr:/etc/udev/rules.d#">root@mypvr:/etc/udev/rules.d#</a> ll /dev/rt*<br>
lrwxrwxrwx 1 root root 4 Oct 8 04:30 /dev/rtc ->
rtc0<br>
crw-rw---- 1 root mythtv 249, 0 Oct 8 04:30 /dev/rtc0<br>
<br>
and mythfrontend is happy:<br>
<br>
mythplayer.cpp:1832 (InitAVSync) Player(11): Video timing
method: RTC<br>
_______________________________________________<br>
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<div>Can you enlighten me as to how widespread this problem
is? Specifically, would my new Mythbuntu 14 have this
problem? Watching DWTS last night the playback was
terrible. Much worse than the same hardware with Mythbuntu
8, my pre upgrade version. I thought it might be fixed with
the new 750 video card which I plan to give another try at
installing today but this post makes me wonder. Some of the
dance moves were impossible, nobody can move that fast
without "special powers". Do I need to do something to my
system to fix timing?</div>
<div><br>
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<div>Allen</div>
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<br>
</blockquote>
Run with -v playback and check for messages that say something like
"video is xx frames behind audio, dropping frame to catch up". You
can also try the setting mentioned above (-O AVSyncAveraging=60). I
have written a new synchronization routine to help with some of
these issues, but I don't know if it will help in your case. Let me
know if you get the dropping frame messages or if the
AVSyncAveraging works.<br>
<br>
Peter<br>
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