[MPlayer-dev-eng] How should we fix this? (Fwd: Re: [MPlayer-users] -lameopts q=9 high bitrate?)

[D Richard Felker III]

----- Forwarded message from D Richard Felker III <dalias at aerifal.cx> -----

Date: Sat, 1 Mar 2003 21:55:40 -0500
To: "MPlayer user's list." <mplayer-users at mplayerhq.hu>
Subject: Re: [MPlayer-users] -lameopts q=9 high bitrate?
In-Reply-To: <3E615FF5.2030008 at fatooh.org>
User-Agent: Mutt/1.3.25i
From: D Richard Felker III <dalias at aerifal.cx>
Precedence: list
Reply-To: "MPlayer user's list." <mplayer-users at mplayerhq.hu>

[Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
On Sat, Mar 01, 2003 at 05:35:49PM -0800, Corey Hickey wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hi,
> 
> 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
> this:
> mencoder ocean11.vob -aid 128 -ovc frameno -oac mp3lame -lameopts q=9 \
> -ofps 23.976 -o q9.avi
> 
> -------------DATA--------------
> -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.

Yes, I noticed this too... 10l to someone!!! Lame expects a quality
parameter in the range 0-9, but mplayer takes a quality number in the
range 0-9 then adds 1 to it before passing it to lame!! I'd like to
change this, but I don't want to alter the existing behavior without
discussing it first...

Rich

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