[theora] Drop Frames

Patrick Byrne pbyrne at frontier.co.uk
Tue Jan 22 01:59:27 PST 2008


Hi,

Last night I encoded a movie at a variety of different bitrates:

ffmpeg2theora-0.20.exe -V 300 1am_zzzz01a.avi -o v300.ogg
ffmpeg2theora-0.20.exe -V 50 1am_zzzz01a.avi -o v50.ogg
ffmpeg2theora-0.20.exe -V 100 1am_zzzz01a.avi -o v100.ogg
ffmpeg2theora-0.20.exe -V 200 1am_zzzz01a.avi -o v200.ogg
ffmpeg2theora-0.20.exe -V 400 1am_zzzz01a.avi -o v400.ogg
ffmpeg2theora-0.20.exe -V 500 1am_zzzz01a.avi -o v500.ogg

The source is a 20GB 4 minute 15 second uncompressed avi (1280x720) with 
no sound.


21/01/2008  18:37        32,412,109 v300.ogg
21/01/2008  19:21        32,199,484 v50.ogg
21/01/2008  20:05        32,257,144 v100.ogg
21/01/2008  20:55        32,318,099 v200.ogg
21/01/2008  21:39        32,586,514 v400.ogg
21/01/2008  22:23        32,942,370 v500.ogg

..why is there so little blessed difference between the file sizes?



My player reports:

v50.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=50000 quality=0 pixfmt=4:2:0

v100.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=100000 quality=0 pixfmt=4:2:0

v200.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=200000 quality=0 pixfmt=4:2:0

v300.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=300000 quality=0 pixfmt=4:2:0

v400.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=400000 quality=0 pixfmt=4:2:0

v500.ogg THEORA pwh=1280x720 fps=30.00 fwh=1280x720 ofsxy=0x0 
bitrate=500000 quality=0 pixfmt=4:2:0

..but according to the file sizes, they all have a bitrate of about 253 
kbps - what am I missing here?


Thanks

- Patrick



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