[mythtv-users] fps drops with DRM sync and bob

Hamish Moffatt hamish at cloud.net.au
Sun Jun 3 14:15:52 UTC 2007


On Sun, Jun 03, 2007 at 11:54:46PM +1000, Hamish Moffatt wrote:
> The new machine is using DRM sync apparently, and with bob enabled it's
> not doing well; it claims 24.96 fps for a while, but then that drops off
> and it starts dropping frames. The audio quality decreases noticeably.
> 
> 'video_output' mean = '40071.23', std. dev. = '574.40', fps = '24.96'
> 2007-06-03 23:38:48.698 NVP: 800 interlaced frames seen.
> 'video_output' mean = '40070.97', std. dev. = '35.61', fps = '24.96'
> 'video_output' mean = '40070.87', std. dev. = '41.36', fps = '24.96'
> 'video_output' mean = '40070.78', std. dev. = '32.52', fps = '24.96'
> 'video_output' mean = '40859.13', std. dev. = '3338.62', fps = '24.47'
> 2007-06-03 23:39:01.720 NVP: Video is 3.06932 frames behind audio (too slow), dropping frame to catch up.
> 2007-06-03 23:39:01.721 NVP: Video is 3.02697 frames behind audio (too slow), dropping frame to catch up.
> 2007-06-03 23:39:02.155 NVP: Video is 3.03393 frames behind audio (too slow), dropping frame to catch up.
> [..]
> 'video_output' mean = '42333.96', std. dev. = '18130.41', fps = '23.62'
> 'video_output' mean = '41686.57', std. dev. = '18624.15', fps = '23.99'

And even before it goes off the rails, the picture shimmers badly.
My output is 720p @ 50 Hz, btw.

FWIW, switching to audio sync makes things even more entertaining;

2007-06-04 00:03:11.062 Using audio as timebase
2007-06-04 00:03:11.062 Video timing method: DRM
2007-06-04 00:03:11.062 Refresh rate: 19980, frame interval: 40000
'video_output' mean = '40064.78', std. dev. = '95.55', fps = '24.96'
'video_output' mean = '40070.39', std. dev. = '75.88', fps = '24.96'
'video_output' mean = '40070.98', std. dev. = '31.91', fps = '24.96'
2007-06-04 00:03:26.951 NVP: 400 interlaced frames seen.
'video_output' mean = '39870.29', std. dev. = '2000.35', fps = '25.08'
'video_output' mean = '40071.84', std. dev. = '90.21', fps = '24.96'
'video_output' mean = '40070.27', std. dev. = '94.98', fps = '24.96'
'video_output' mean = '39870.21', std. dev. = '1992.80', fps = '25.08'
2007-06-04 00:03:42.960 NVP: 800 interlaced frames seen.
'video_output' mean = '40070.83', std. dev. = '38.52', fps = '24.96'
'video_output' mean = '40070.87', std. dev. = '47.04', fps = '24.96'
'video_output' mean = '39870.67', std. dev. = '1994.86', fps = '25.08'

Now the fps jitters around 25Hz with huge standard deviation.


confused,
Hamish
-- 
Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>


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