> 1) With my encoder (64kbps stereo CRC), every fricative is almost painful to
> listen to, as the pink noise bursts end up being narrow band filtered (due
> to lack of bits - only the MDCT coeffs closest to the pole are making it
> into the bitstream), and there are occasional weird high frequency blips and
> arpeggiation which are very annoying.
>
> 2) LAME (-m s -h -b 64 -p --resample 44.1) (we use CRC and I haven't enabled
> LSF yet) sounds pretty good. There are occasional minor glitches, but
> that's to be expected at this bitrate. However, LAME (as above plus -k to
> turn off the filters) sounds pretty similar to what I'm getting. I note
> that without the forced resampling, LAME will attempt to downsample to
> 22050.
>
> 3) FhG (-br 64000 -qual 9 -crc -no-is -esr 44100) sounds very good. (Man,
> is it slow, though.) Again, without the forced MPEG-1 sampling rate, the
> mp3enc31 will attempt to use 22050.
>
The main difference between FhG and LAME is probably the lowpass
filters. Try different values of --lowpass. The compression ratio
you are using (about 22x) is not commonly used, and the LAME's
default guess at a lowpass setting wont be very good.
Why do you disable the 22050 downsampling? This is done based on the
idea that encoding at 22khz is better than encoding at 44khz and
removing have the specturm with filters.
FhG is probably using joint stereo? This will increase the
bandwidth by 10-20%.
The main difference between LAME and ISO is that the ISO
code has serious flaws in several major components. jstereo,
filtering and other advanced features help, but you gotta fix
the bugs first!
> some filtering as well, though there's no way to disable it and see for
> sure. Are there really just not enough bits for this type of signal at this
> bitrate? Why does Layer-II do so much better a job with this type of
> signal? Do other codecs (AAC/MPEG-4) hand this kind of signal better as
You rate FhG as 'very good', and Layer II as 'good'. So I'm assuming
layer III beats layer II. The thing layer III adds to layer II is: 1)
MDCT transform (lossless to roundoff), 2) entropy coding (lossless),
3) bitreservoir (prevents wasting of bits) and 4) the ability to do
more advanced noise shaping. #1,2 and 3 can only improve the
quality. The only way I can see layer II out-perform layer III is if
#4 is not tuned properly for the desired compression.
> well? And what is the capital of Assyria?
>
during which century?
Mark
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