> Another question:
> Is there any tool to analyze the number of SI, MS and LR frames in a MP3?
>
Frank, you just need a GTK enabled version of lame :-)
run lame -g on the mp3 file, scroll to the end, and then
click 'show' under the 'stats' pull down menu.
It shows the info you want, and any additional statistics
would be easy to add. You can also use to to examine
the mid/side bit allocation frame by frame.
You could test your ideas about near mono files
via the following:
Modify reduce_side() function in quantize-pvt.c to
be more aggressive. Right now it allocates at most
a 33/66 split between side channel and mid channel,
based on the side_channel_energy/total_energy ratio.
As Robert mentioned, a more aggressive split can
create artifacts. I think the problem is that
allocating just a few bits to the side channel
can produce audible glitches which will sound worse
than if 0 bits were used. But no one has done a
detailed study of this.
> -mm Use Mono
> -mi Use Intensity Stereo, MS-Stereo and LR-Stereo
> -mj Use MS-Stereo and LR-Stereo
> -ms Use LR-Stereo
> -ma Analyze FIle before any converting, select -mm, -mj or -ms
>
>
I think -ma would be beyond the scope of LAME. A
seperate analysis program should be written, and then a
GUI front end should run the analysis and make the selection.
This is similar to automatic level adjustment. A couple people
have expressed interest in adding a volume adjustment to
LAME, which is a fine, but the additional step of runing
some analysis on the file to determine the adjustment
should be left to a seperate program.
Mark
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