[Wikivideo-l] Size and bitrate

[George Chriss]

Correction: The playback differences appeared in the Debian version of
Firefox 3.5.16; the nightly builds of Firefox play the video without
hesitations.


On Thu, February 17, 2011 12:19 pm, George Chriss wrote:
> 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
>>
>>
>>
>> _______________________________________________
>> Wikivideo-l mailing list
>> Wikivideo-l at lists.wikimedia.org
>> https://lists.wikimedia.org/mailman/listinfo/wikivideo-l
>>
>
>
> --
>
>
>
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