[rtcweb] H.261 encoding samples at typical bitrates - sign language example

Basil Mohamed Gohar <basilgohar@librevideo.org> Tue, 03 December 2013 03:03 UTC

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Date: Mon, 02 Dec 2013 22:03:34 -0500
From: Basil Mohamed Gohar <basilgohar@librevideo.org>
Organization: Libre Video
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Subject: [rtcweb] H.261 encoding samples at typical bitrates - sign language example
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Let's let any further discussions about the usability of H.261, or any
other codec for that matter, use actual examples going forward.

The following is a VERY quick test of ffmpeg's h261 encoder in the
context of the IETF's rtcweb working group's discussion of an MTI
(mandatory-to-implement) video codec.

sine_irene_cif.y4m taken from derf's collection:

http://media.xiph.org/video/derf/y4m/sign_irene_cif.y4m

ffmpeg version N-58565-gc122e69

bitrate=64k,128k,256k,512k

ffmpeg -i sign_irene_cif.y4m -codec:v h261 -b:v $bitrate -g 30
sign_irene_cif.y4m-$bitrate.h261

http://media.basilgohar.com/rtcweb/sign_irene_cif.y4m-64k.h261
(real rate: 157.8kbits/s)

http://media.basilgohar.com/rtcweb/sign_irene_cif.y4m-128k.h261
(real rate: 165.6kbits/s)

http://media.basilgohar.com/rtcweb/sign_irene_cif.y4m-256k.h261
(real rate: 289.5kbits/s)

http://media.basilgohar.com/rtcweb/sign_irene_cif.y4m-512k.h261
(real rate: 541.8kbits/s)

I apologize for the bitrate inflation, but if I had more time I can
tweak the settings for a more accurate number.  These are simply the
rates that ffmpeg produced with such a short clip at the given requested
rates.
-- 
Libre Video
http://librevideo.org