> Date: Thu, 13 Jan 2000 11:37:53 +0100
> From: Marc de Lange <[EMAIL PROTECTED]>
>
> I am interested is VBR encoding so when I discovered LAME I started to play
> with it.
>
> For relative low quality I used -V 7 and didn't specify a minimum bit rate.
> To increase the quality I changed to -V 5 and added -b 64 (or something
> comparable). After upgrading from 3.50 to 3.58 I saw that a low pass filter
> was applied (cutting above 15,xxx Hz and decreasing above 12,xxx Hz) in
> this case.
>
> My first question is: is this automatic filter also in 3.50 (there was no
> output on the screen that told me about the filter in this version).
>
> I discovered that this low pass filter was induced by the bit rate setting
> and independent from the VBR quality setting. I thought that the point
> where this filter isn't used is somewhere around 112.
>
I think this is another mistake on my part. The automatic
lowpass filters are intended for high compression MPEG2 type
encodings and not for VBR since no one has really tested them
and figured out the best tuning for high bitrates.
They were being used in VBR, unless you specified a min
bitrate larger than 64kbs. This wouldn't be that
bad, except for the fact that the filter parameters were
a little aggressive - they were left over from some unfinished
MPEG2 tests :-(
This will soon be fixed in CVS, and I'll put out a 3.61 tonight.
In the new version, VBR will only use the sfb21 filter
(just like 44.1kHz/128kbs encoding) if the quality setting
is >= 5.
All filters, including the sfb21 filter are disabled with -k.
Mark
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