Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
in the PCM feeder mixer. Without this change a value of 32 channels is
treated like zero, due to using a mask of 0x1f, causing a kernel
assert when trying to playback bitperfect 32-channel audio. Also
update the AWK script which is generating the division tables to
handle more than 18 channels. This commit complements r282650.
MFC after: 3 days
This cause dramatic effect in overall precision and conversion quality
by pushing down most aliasing artifacts around -180 dB.
Spectrogram analysis/comparison:
http://people.freebsd.org/~ariff/z_comparison/z_28vs30/
- Guard against possible 64bit overflow during accumulation process by
slightly normalize and saturate sample and coefficient multiplication,
possible during extreme 32bit downsampling (eg. 380KHz -> 8KHz) with
custom preset that require more than ~7000 taps filter (which is
overkill).
- Add knobs through FEEDER_RATE_PRESETS to set dynamic range of filter
coefficients/accumulator and prefered polynomial interpolator:
COEFFICIENT_BIT:X
(where 1 <= X <= 30, default: 30)
ACCUMULATOR_BIT:X
(where 32 <= X <=64, default: 58)
INTERPOLATOR:I
(where I = ZOH, LINEAR, QUADRATIC, HERMITE, BSPLINE,
OPT32X, OPT16X, OPT8X, OPT4X, OPT2X)
Approved by: re (kib)
FEEDER_RATE_PRESET "OVERSAMPLING_FACTOR:X .. .." where
X = log2(oversampling factor).
- Lower down default filter oversampling factor from 128
(log2 = 7) to 32 (log2 = 5), saving worth of 80 Kb.
The use of better polynomial interpolator will raise
its conversion quality/accuracy to match (or slightly
better) with previous settings.
- Bump driver version.
