[MPlayer-users] -lameopts q=9 high bitrate?

Corey Hickey bugfood-ml at fatooh.org
Sun Mar 2 02:35:49 CET 2003


I've been doing a bit of audio testing with mencoder and mp3lame, and I
noticed that -lameopts q=9 produces a bitrate approximately equal to
q=3, and higher than q=4 - q=8.

I don't know if this is a bug in the encoder or a deficiency in my
understanding of the q option. In the manpage:

q=<0-9>             quality (0-highest, 9-lowest) (only for VBR)

which leads me to expect that (for the same algorithmic quality), q=0
should have the highest bitrate, and higher numbers should have
subsequently lower bitrates, with q=9 being the lowest.

I've run a few benchmarks on an entire movie's worth of audio, like
mencoder ocean11.vob -aid 128 -ovc frameno -oac mp3lame -lameopts q=9 \
-ofps 23.976 -o q9.avi

-lameopts q=0
Audio stream:  170.113 kbit/s  (21264 bps)  size: 148744032 bytes 
6995.088 secs

-lameopts q=1
Audio stream:  163.290 kbit/s  (20411 bps)  size: 142778256 bytes 
6995.088 secs

-lameopts q=2
Audio stream:  115.562 kbit/s  (14445 bps)  size: 101045376 bytes 
6995.088 secs

-lameopts q=3
Audio stream:  111.978 kbit/s  (13997 bps)  size: 97905528 bytes 
6994.608 secs

-lameopts q=4
Audio stream:  108.211 kbit/s  (13526 bps)  size: 94618032 bytes 
6995.088 secs

-lameopts q=5
Audio stream:  104.563 kbit/s  (13070 bps)  size: 91428744 bytes 
6995.088 secs

-lameopts q=6
Audio stream:   98.830 kbit/s  (12353 bps)  size: 86415984 bytes 
6995.088 secs

-lameopts q=7
Audio stream:   94.756 kbit/s  (11844 bps)  size: 82853040 bytes 
6995.088 secs

-lameopts q=8
Audio stream:   91.150 kbit/s  (11393 bps)  size: 79700256 bytes 
6995.088 secs

-lameopts q=9
Audio stream:  111.979 kbit/s  (13997 bps)  size: 97905960 bytes 
6994.608 secs
----------------END DATA-----------------

 From q=0 to q=8, the bitrates decrease as expected, except that q=9 is
almost the same as q=3.


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