[Wikivideo-l] Size and bitrate

[George Chriss]

Hi Lars,

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 (
http://is.gd/gn0BEr ).

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.

Sincerely,
George



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
> 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
>
>
>
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>


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