[mythtv] still getting jitter/speed pulsing
krose+mythtv at krose.org
Fri Dec 31 20:13:54 UTC 2004
I was wrong about setting Bob correctly getting rid of the jittery
playback: it was the lack of a control that led me to believe it was
The difference appears to be that the jitter happens only in the
presence of both Xv output and the new ffmpeg code. I don't know how
the two can possibly be related, which is part of the reason I'm
having a hard time figuring out where to start debugging this.
I added a few Jitterometers in AVSync, and found a potentially
interesting difference between X11 and Xv output.
'prepare1' sd0fmean = '12.87', mean = '8.21', std. dev. = '1.06', fps = '121802.68'
'vsync1' sd0fmean = '11.00', mean = '4.67', std. dev. = '0.51', fps = '214132.76'
'vout1' sd0fmean = '17.59', mean = '14254.70', std. dev. = '2506.94', fps = '70.15'
'prepare2' sd0fmean = '10.90', mean = '7.83', std. dev. = '0.85', fps = '127713.92'
'vsync2' sd0fmean = '12.76', mean = '3.81', std. dev. = '0.49', fps = '262467.19'
'vout2' sd0fmean = '13.14', mean = '15888.00', std. dev. = '2088.11', fps = '62.94'
'video_output' sd0fmean = '2.15', mean = '33318.28', std. dev. = '716.07', fps = '30.01'
'prepare1' sd0fmean = '9.16', mean = '7.82', std. dev. = '0.72', fps = '127877.24'
'vsync1' sd0fmean = '103.59', mean = '12139.34', std. dev. = '12575.42', fps = '82.38'
'vout1' sd0fmean = '9.75', mean = '3117.61', std. dev. = '304.00', fps = '320.76'
'prepare2' sd0fmean = '12.86', mean = '7.06', std. dev. = '0.91', fps = '141643.06'
'vsync2' sd0fmean = '25.75', mean = '12002.08', std. dev. = '3090.27', fps = '83.32'
'vout2' sd0fmean = '10.26', mean = '2886.44', std. dev. = '296.08', fps = '346.45'
'video_output' sd0fmean = '43.54', mean = '33651.20', std. dev. = '14652.30', fps = '29.72'
Note that the first vsync seems to vary a *lot*. I would expect vsync
in Xv to take more time, since the frames actually display quicker so
mythfrontend is spending more time idle; but the standard deviation is
as high as the mean, which suggests something funky is going on there.
What I don't understand is why vsync would start acting up just
because I started using Xv output: I'm using GL sync in both cases.
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