[Wikivideo-l] Size and bitrate

[Lars Aronsson]

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
http://commons.wikimedia.org/wiki/File:M%C3%A4n_och_maskiner_1936.ogv

Looking at these 1200 Dutch videos,
http://commons.wikimedia.org/wiki/Category:Media_from_Open_Beelden
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 at aronsson.se)
   Aronsson Datateknik - http://aronsson.se