Correction: The playback differences appeared in the Debian version of
Firefox 3.5.16; the nightly builds of Firefox play the video without
On Thu, February 17, 2011 12:19 pm, George Chriss wrote:
A cursory look suggests the problem originates in Firefox's internal
decoding, even using the most-recent nightly builds. Furthermore, the
problem only is apparent when the video is played from within a Commons
page ( http://is.gd/mWpoap
); viewing the video directly works just fine (
Comment #5 from Mozilla bug #531279 ( http://is.gd/m9pqZ5
) suggests the
problem might be somehow related to video re-scaling, but it might be
better to file a new bug and see what happens. I'd be happy to help
submit the bug report if needed.
On Thu, February 17, 2011 5:25 am, Lars Aronsson wrote:
In Firefox 3.6.13 on Linux, I can show Ogg Theora
videos just fine,
which is a great step forward from earlier versions a year ago.
But there are still bugs, where the playback just hangs. I have
no way to tell if this is a poorly encoded video or a browser bug
or something relating to my screen driver. All I know is that it
happens more often for videos with higher bitrate. As a programmer,
I could guess that there is some buffer competition, a combination
of buffer boundaries and time racing, that causes a deadlock.
I have no way to know the reason or whether it is unique to me.
Too few people watch videos in Wikipedia, so I have no user base
to draw conclusions from. The source code is available, but I
don't want to take the time to specialize in video decoding.
This headache is already taking far too much of my time.
For one video, I changed the encoding and this made the problem
occur less frequently for me. This 720 x 544 pixel, 15 minute
video was 116 MB when first encoded with "ffmpeg2theora" without
parameters, so to make it pass under the 100 MB limit I added
"-v 4" (lowercase v for video quality), to slightly reduce the
video quality. But it hanged just too often, and by encoding
with "-V 600" (uppercase V for bitrate, 600 kbit/s), it runs
a lot more smooth on my laptop. You can try either version at
Looking at these 1200 Dutch videos,
they are just 320x240 pixels, which is another way to get
smaller files and lower bitrates.
Is that something I should settle for? Will I live happier
and prosper if I scale all videos to half their size?
Maybe in 2-3 years time, when the 100 MB limit has been
lifted and Firefox 4.x offers a more mature video playback,
we can upload the same videos in better resolution?
Should we make this a recommendation? Do we have statistics
on the resolution and bitrate of the videos on Commons?
Who did the job with the Dutch films? How did they reason?
Lars Aronsson (lars(a)aronsson.se)
Aronsson Datateknik - http://aronsson.se
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