Hello,

I've tried with both lame 3.93.1 and 3.94b with these options:

lame-3.94b -q2 -V2 --vbr-new --athtype 3 --ns-sfb21 2 --nspsytune -Z --scale 0.98 -X0 -mm --resample 22.05 --lowpass 12.0 -b08 -B40 tmp.wav tmp-B40.mp3

With lame-3.93.1 I get see this:

Resampling: input 44.1 kHz output 22.05 kHz
Using polyphase lowpass filter, transition band: 11114 Hz - 11381 Hz

Notice, it's close, and I missed it at first. But later, I changed the lowpass to 16 and then to 19.5 and had no changes! When I removed the resampling option (and changing b08 to b32 after the warning message about MPEG types, bitrates, and frequencies), I was able to change the lowpass as I would expect.

With lame 3.94b I get the same exact message and behaviour as above, but with an additional message about the stereo to mono conversion.

Autoconverting from stereo to mono. Setting encoding to mono mode.

Am I missing something, or is there a specific reason why the resampling to 22.05 causes lowpass to stop working? Any ideas for workarounds?

Synergy

A digital audio file sampled at 22050 Hz can only contain frequencies up to 11025 Hz. In your output, you have effectively disabled lowpassing, because its minimum band is above the maximum frequency.

So there's nothing wrong with lowpassing, it's just pointless to set the lowpass higher than the maximum frequency. =P You can't keep what's not there.

Ok, I checked. The -mm switch sets the mode to mono. That's why yer getting a mono encoding.

Once again, another "tweaked" commandline ...

Thanx reporting. This is not a bug of the filtering, but the bug of printing the config.

This is fixed just now to the CVS and this will be included in LAME 3.95.