For a slightly thorough explaination, please refer to
[1] http://people.freebsd.org/~ariff/SOUND_4.TXT.html .
Summary of changes includes:
1 Volume Per-Channel (vpc). Provides private / standalone volume control
unique per-stream pcm channel without touching master volume / pcm.
Applications can directly use SNDCTL_DSP_[GET|SET][PLAY|REC]VOL, or for
backwards compatibility, SOUND_MIXER_PCM through the opened dsp device
instead of /dev/mixer. Special "bypass" mode is enabled through
/dev/mixer which will automatically detect if the adjustment is made
through /dev/mixer and forward its request to this private volume
controller. Changes to this volume object will not interfere with
other channels.
Requirements:
- SNDCTL_DSP_[GET|SET][PLAY|REC]_VOL are newer ioctls (OSSv4) which
require specific application modifications (preferred).
- No modifications required for using bypass mode, so applications
like mplayer or xmms should work out of the box.
Kernel hints:
- hint.pcm.%d.vpc (0 = disable vpc).
Kernel sysctls:
- hw.snd.vpc_mixer_bypass (default: 1). Enable or disable /dev/mixer
bypass mode.
- hw.snd.vpc_autoreset (default: 1). By default, closing/opening
/dev/dsp will reset the volume back to 0 db gain/attenuation.
Setting this to 0 will preserve its settings across device
closing/opening.
- hw.snd.vpc_reset (default: 0). Panic/reset button to reset all
volume settings back to 0 db.
- hw.snd.vpc_0db (default: 45). 0 db relative to linear mixer value.
2 High quality fixed-point Bandlimited SINC sampling rate converter,
based on Julius O'Smith's Digital Audio Resampling -
http://ccrma.stanford.edu/~jos/resample/. It includes a filter design
script written in awk (the clumsiest joke I've ever written)
- 100% 32bit fixed-point, 64bit accumulator.
- Possibly among the fastest (if not fastest) of its kind.
- Resampling quality is tunable, either runtime or during kernel
compilation (FEEDER_RATE_PRESETS).
- Quality can be further customized during kernel compilation by
defining FEEDER_RATE_PRESETS in /etc/make.conf.
Kernel sysctls:
- hw.snd.feeder_rate_quality.
0 - Zero-order Hold (ZOH). Fastest, bad quality.
1 - Linear Interpolation (LINEAR). Slightly slower than ZOH,
better quality but still does not eliminate aliasing.
2 - (and above) - Sinc Interpolation(SINC). Best quality. SINC
quality always start from 2 and above.
Rough quality comparisons:
- http://people.freebsd.org/~ariff/z_comparison/
3 Bit-perfect mode. Bypasses all feeder/dsp effects. Pure sound will be
directly fed into the hardware.
4 Parametric (compile time) Software Equalizer (Bass/Treble mixer). Can
be customized by defining FEEDER_EQ_PRESETS in /etc/make.conf.
5 Transparent/Adaptive Virtual Channel. Now you don't have to disable
vchans in order to make digital format pass through. It also makes
vchans more dynamic by choosing a better format/rate among all the
concurrent streams, which means that dev.pcm.X.play.vchanformat/rate
becomes sort of optional.
6 Exclusive Stream, with special open() mode O_EXCL. This will "mute"
other concurrent vchan streams and only allow a single channel with
O_EXCL set to keep producing sound.
Other Changes:
* most feeder_* stuffs are compilable in userland. Let's not
speculate whether we should go all out for it (save that for
FreeBSD 16.0-RELEASE).
* kobj signature fixups, thanks to Andriy Gapon <avg@freebsd.org>
* pull out channel mixing logic out of vchan.c and create its own
feeder_mixer for world justice.
* various refactoring here and there, for good or bad.
* activation of few more OSSv4 ioctls() (see [1] above).
* opt_snd.h for possible compile time configuration:
(mostly for debugging purposes, don't try these at home)
SND_DEBUG
SND_DIAGNOSTIC
SND_FEEDER_MULTIFORMAT
SND_FEEDER_FULL_MULTIFORMAT
SND_FEEDER_RATE_HP
SND_PCM_64
SND_OLDSTEREO
Manual page updates are on the way.
Tested by: joel, Olivier SMEDTS <olivier at gid0 d org>, too many
unsung / unnamed heroes.
use patches so far:
+ Envy24:
- fix: broken init data for M Audio Delta DiO 2496
- add: support for M Audio Delta 44
- add: support for M Audio Delta 1010LT
Tested by: Dominique Goncalves, dominique.goncalves at gmail.com
- add: support for Terratec EWX 2496
Tested by: Stefan Sperling, stsp at stsp.name
- add: support for M Audio Delta 66
Tested by: Richard Bown, richard.bown at blueyonder.co.uk
- add: support for M Audio Delta 1010
Tested by: Andrew Reilly, areilly at bigpond.net.au
+ Envy24HT:
- add: support for Terrasoniq TS22PCI
- fix: M-Audio Revolution 5.1 sound volume is very low
Reported by: Oliver Hartmann, ohartman at zedat.fu-berlin.de
Andrey Slusar, anrays at gmail.com
Tested by: Andrey Slusar, anrays at gmail.com
Rusu Silviu, arol.the at gmail.com
- fix: M-Audio Revolution 7.1 sound is distorted and very quiet
Reported by: Olev Hannula, hannula at gmail.com
Tested by: Olev Hannula, hannula at gmail.com
Stanislav Belansky, stanislav at icmail.ru
- fix: Terratec PHASE 22 codec is power-off due to wrong init data
Reported by: Philipp Ost, pj at smo.de
Tested by: Philipp Ost, pj at smo.de
+ SpicDS:
- fix: AK4381 produce hiss sound on 192kHz sample rate
- fix: stupid bug with volume control for AK4396
Submitted by: Konstantin Dimitrov <kosio.dimitrov@gmail.com>
Neither me nor Ariff have access to any of this hardware, so all tests
have been made by Konstantin and Artem. Commit message mostly written
by Konstantin.
envy24:
- Add test code to support rear line-in input on 'Terratec DMX 6fire'
audio card. This code is also intended to be used in the future for
support of cards, that have I2C-to-GPIO expanders wired between the
control line of the audio codec and the Envy24, however such cards
are too complex and i can't add that support without hardware sample
of such board, i've already tried and failed.
envy24ht:
- Add support for 'AudioTrak Prodigy HD2'.
- Add support for 'AudioTrak Prodigy 7.1 XT'.
- Add support for 'ESI Juli@' (Works ok, DAC volume is hard-coded for
the time being, so 'mixer vol ...' doesn't work, only 'mixer pcm
...' works). [1]
- Fix bug in the init data for M-Audio Revolution 5.1, that
results in distorted sound.
- Add software volume control (now 'mixer pcm' works, thanks to Ariff).
- Add support for more samples rates - 176.4kHz and 192kHz.
- Fix problem with the 192kHz samples rate playback when 24.576MHz
crystal is used on the board instead of 49.152MHz crystal.
spicds:
- Add support for Asahi Kasei flagship DAC - AK4396 (used in AudioTrak
Prodigy HD2).
Submitted by: Konstantin Dimitrov <kosio.dimitrov@gmail.com>
Tested by: Artem Antonov [1]
Reviewed by: ariff
yet. More commits to follow.
I got no response from the author, but since the driver is BSD licensed
I don't think he will complain. :-)
I got it from http://people.freebsd.org/~lofi/envy24.tar.gz
Written by: Katsurajima Naoto <raven@katsurajima.seya.yokohama.jp>
