Commit Graph

7 Commits

Author SHA1 Message Date
Pedro F. Giffuni
fe267a5590 sys: general adoption of SPDX licensing ID tags.
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.
2017-11-27 15:23:17 +00:00
Hans Petter Selasky
3f9dcc588d Declare the "snd_fxdiv_table" once. This shaves around 24Kbytes of
binary data from sound.ko and the kernel.

MFC after:		3 days
2017-05-25 05:23:47 +00:00
Hans Petter Selasky
0f86d40bf5 Increase the allowed maximum number of audio channels from 31 to 127
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
2017-05-24 21:42:48 +00:00
Ariff Abdullah
96831ae59b - Increase dynamic range of filter coefficients from 28bit to 30bit.
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)
2009-07-05 18:15:06 +00:00
Ariff Abdullah
0162436974 Slightly increase amount of bandwidth of resampling filter for
feeder_rate_quality=3. This have the benefit of reducing aliasing
artifacts due to alias masking.

Spectrogram analysis:

 o Old preset (100:36:0.90)
	http://people.freebsd.org/~ariff/z_comparison/z_q3_old.png

 o New preset (100:36:0.92):
	http://people.freebsd.org/~ariff/z_comparison/z_q3_new.png

Approved by:	re (kib)
2009-07-02 10:02:10 +00:00
Ariff Abdullah
164e1f20ec - Add a way to change filter oversampling factor through
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.
2009-06-15 04:31:34 +00:00
Ariff Abdullah
0f40c3f162 Move all sound related scripts to its own 'sound' subdir.
Suggested by:	jmallett
2009-06-10 06:49:45 +00:00