[mythtv-users] 23.976fps choppy playback

Wil nodenet at hotmail.com
Wed Jan 11 22:06:02 UTC 2012


I got a few BR movies for xmas so I thought I'd try ripping them to see if
they would playback properly. Unfortunately the playback was a bit choppy
leading to numerous tests with out any real conclusion as to what the
problem is. So I thought I'd try posting here to see if there are any useful
suggestions.

 

I'm primarily using JYA's 0.24 fixes repo for HD audio and also JYA's
modeline for 1920x1080 at 23.976 although I have tested some other frame rates
as well. In addition to the OSD of the display I have a frame rate tester
which confirms the actual frame is 23.975634 over 1000 frames using gl sync
api calls. With verbose frontend logging on I can see that the audio is
stated to be running slowly and that frames are being dropped to compensate.
With HD audio enabled it reaches a point where after a min or two of
playback the discontinuity between audio and video leads to an almost
complete breakdown in playback where audio and video seem to be continually
trying to get back in sync but never quite succeeding. I'm not sure if this
is with all the rips but I have seen the frame drops on a lot of them and so
concentrated on 1 in particular (VC-1 video, DTS audio, AC3 commentary)
where I know to look out for it at certain points. All the rips were created
with makemkv 1.7 and I have not been able to validate whether or not makemkv
is the source of the issue although I did re-rip my test movie without HD
audio to test if that was the problem essentially leaving the defaults
ticked. Unfortunately DumpHD will not work my drive so I was not able to
test that as it would have been my preferred option. Playback at 59.989 fps
seemed a lot better, playback at 24 fps did not seem to help. Mythfrontend
logging and makemkv all state the video is VC-1 23.976fps.

 

I have JYA's repo on my backend and frontend, both have different kernels,
different nvidia hardware and drivers and both seem to suffer with the same
playback problems (with/without hd audio and also without hdmi audio). I
also have an original 0.24 fixes frontend with the original ION chipset
(other frontend is an ION2) which has the same issues. I am using storage
groups for the movies but I copied the test movie across to one of the
frontends and tried local playback which did not help. I'm not sure if the
storage groups need to be totally disabled but I did read a post that
suggested there may be some associated playback issues. In addition to
adjusting a variety of nVidia related settings I tried regular ffmpeg
playback on the backend but the results were still the same. 

 

I did try some other stuff too but really wanted to see if this rings a bell
with anyone as my time to test things has sort of run out.

 

Will

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