Hello
I would vote for a default 14Hz high pass filter, removable with the -k
option.
Why an high pass filter:
*theorical minimum audible freq for humans is 20Hz (also very discutable)
*most soundcards are unable to reproduce less than 20Hz frequencies
*most speakers are unable to reproduce less than 19Hz freq
*most (if not all) headphones are unable to reproduce such low freq (even if
their specs tell they are)
*ISO doc recommends an high pass filter
*even if it's a small part of the spectrum, it's still a few bits usable for
other more critical parts.
why a 14Hz high pass filter and not a 20Hz one:
because the lowest tone produced by a true musical instrument is 16Hz (it's
from organ).
Perhaps it would be better to use an higher high-pass filter (20Hz?) for
very low bitrates like 24 or 32k streaming, perhaps an
auto-changing-default, like the low-pass one?
perhaps:
high_pass_freq=(15+compression_ratio/4) (this seems like a good
compromise)
Regards,
Gabriel Bouvigne - France
[EMAIL PROTECTED]
icq: 12138873
MP3' Tech: www.mp3-tech.org
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