>
> I have briefly tried the "--voice" mode and the "normal" mode when
> encoding a purely voice signal (with background noise) at 8kbps, and
> have been very impressed with the difference. I would like to compress
> the signal more... but 8 is as low as it goes.
>
> The "nomal" mode renders the voice absolutely unintelligible (I assume
> the encoder tries too hard to preserve the background).
>
As others have pointed out, --voice is the same as
lame --noshort --lowpass 12
and I imagine the main differece between this and the default is that
that at 8kbs, the default lowpass value is not very good. It is based
on a simple formula.
Alfred Weyers did some detailed tests a while ago suggesting some low
bitrate corrections, but this hasn't made it back into LAME
If you dont mind, can you try:
lame -h --noshort --lowpass 12
lame -h --lowpass 12
lame -h --lowpass 10
lame -h --lowpass 8
and let us know which sounds the best? I'd like to verify the best
filter level for this bitrate and also verify that --noshort really is
helpfull for voice encoding. The short block encoding is much better
now than when Gabriel first added --voice.
>
> I have read most of the past articles on "--voice" but they don't tell
> me all I wish to know. I am also starting with a 11K/samples per sec
> file (mono) and having to up-sample it to 44.1K before I can process it.
> Has anyone considered allowing different input sample rates (ie: the
> standard 16, 22.05, 24, 32, 48) as well as 44.1 ?
>
Which version are you using? LAME can take any samplerate for input.
(if you are feeding lame raw pcm data, it will assume the sample rate
is 44.1, unless you add -s 11)
Mark
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