Fw: Re: Massive sound changes / fix (24/32bit pcm support, new sampling rate converter, various fixes)

From: sebastian ssmoller (sebastian.ssmoller_at_gmx.net)
Date: 07/09/05

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    Date: Sat, 9 Jul 2005 10:26:16 +0200
To: current@freebsd.org, stable@freebsd.org

    just FYI ...

    regards,
    seb

    Begin forwarded message:

    Date: Sat, 9 Jul 2005 10:24:57 +0200
    From: sebastian ssmoller <sebastian.ssmoller@gmx.net>
    To: freebsd-multimedia@freebsd.org
    Subject: Re: Massive sound changes / fix (24/32bit pcm support, new
    sampling rate converter, various fixes)

    hi,
    i just wonna say: THX! really GREAT work! ... this improves sound
    quality on my boxes much !! ;-)

    THX,
    regards,
    seb

    > After sometimes, I've decided to release this (massive 4k lines) diff
    > to our sound driver. This need proper review and confirmation, before
    > it can be committed.
    >
    > Patches for both HEAD / RELENG_5 available at:
    >
    > http://staff.mybsd.org.my/skywizard/FreeBSD/sound/
    >
    > (Note the snd_RELTAG*.diff)
    >
    >
    > Whats New
    > =========
    >
    > 1. Support wide range sampling rate as low as 1hz up to int32 max
    > (which is, insane) through new feeder_rate, multiple precisions
    > choice (32/64 bit converter). This is indeed, quite insane, but it
    > does give us more room and flexibility.
    > 2. Support 24/32 bit pcm format conversion through new, much improved
    > feeder_fmt.
    >
    >
    > System wide changes
    > ===================
    >
    > 1. sys/soundcard.h
    > * Add definition for AFMT_(U|S)24_(B|L)E. This is somehow
    > contradict with OSS/Voxware definition of 24bit, but anyway...
    >
    >
    > General sound infrastructure changes
    > ====================================
    >
    > 1. ac97.c
    > * Slightly new method to detect mixer capabilities and resolution.
    > This mostly to help CT4730, but apparently it does help other
    > cards too (especially via8233x). This probably need futher test
    > and confirmation from other people with ac97 cards other than via
    > / es137x.
    > * Aggresive dac power wake up call, again, to help CT4730 (and
    > probably others).
    > 2. mixer.c / sound.c (high priority / grave severity)
    > * Fix super grave serious (call it whatever) panic/death during
    > driver unload on second attempt after failure on first (device
    > busy).
    > 3. buffer.c / dsp.c / sound.h
    > * Support for 24/32 AFMT
    > 4. feeder_rate.c
    > * New implementation of sampling rate conversion with 32/64 bit
    > precision, 1 - int32max hz (which is, ridiculous, yet very
    > addictive). Much improved / smarter buffer management to not
    > cause any missing samples at the end of conversion process
    > * Tunable sysctls for various aspect:
    > hw.snd.feeder_rate_ratemin - minimum allowable sampling rate
    > (default to 4000)
    > hw.snd.feeder_rate_ratemax - maximum allowable sampling rate
    > (default to 1102500)
    > hw.snd.feeder_rate_buffersize - conversion buffer size
    > (default to 8192)
    > hw.snd.feeder_rate_scaling - scaling / conversion method
    > (please refer to the source for explaination). Default to
    > previous implementation type.
    > 5. feeder_fmt.c / sound.h
    > * New implementation, support for 24/32bit conversion, optimized,
    > and simplified. Few routines has been removed (8 to xlaw, 16 to
    > 8). It just doesn't make sense.
    > 6. channel.c
    > * Support for 24/32 AFMT
    > * Fix wrong xruns increment, causing incorrect underruns statistic
    > while using vchans.
    > 7. vchan.c (high priority)
    > * Support for 24/32 AFMT
    > * Proper speed / rate detection especially for fixed rate ac97.
    > User can override it using kernel hint:
    > hint.pcm.<unit>.vchanrate="xxxx".
    >
    >
    > Hardware spessific changes
    > ==========================
    >
    > 1. als4000.c
    > * als4000 can't do 48k properly (perhaps it really can't at all!).
    > Set maxspeed to 44.1k instead.
    > * Add locking / MPSAFE
    > * Fix recording
    > 2. cmi.c
    > * remove busdma_lock_mutex and Giant from bus_dma_tag_create.
    > Nothing changes.
    > 3. es137x.c / es137x.h
    > * Register programming error during device initialization
    > especially for CT4730 / EV1938 chip, causing misconfigured mixer
    > (David Xu), crippled after power cycle (Kevin Oberman). Fixed.
    > * Incorporate locking/spdif patches from Jon Noack. Not all es137x
    > can really do spdif, clean it up a bit to only let few capable
    > chip.
    > * Convert all bus_space_(read|write) to use es_rd/es_wr, simmilar
    > with other drivers.
    > * Add tunable hw.snd.pcm<unit>.latency_timer sysctl to toggle pci
    > latency timer value on the fly. Much noise / pop / crackling
    > issues can be solved by increasing its value. Other people can
    > point out to use pciconf instead, but this is just and added
    > value specifically for braindead CT4730/EV1938.
    > 4. via8233.c
    > * Add locking / MPSAFE
    > * Add kernel hint option to disable DXS channels entirely. Report
    > from several skype users / Pav Lucistnik indicate that disabling
    > DXS fix lots of pop / crackling noise. To disable DXS, add
    > hint.pcm.<unit>.via_dxs_disabled="1" into /boot/device.hints.
    > NOTE: It is advisable to disable DXS entirely. Although DXS can
    > provide multiple concurrent access, doing so will cause more
    > harm than good (pop / crackling noise, sudden slowness,
    > overruns). There are few cases where this is considered
    > invalid, but I had to investigate more as this is not a
    > global issue. Use / enable vchans for multiple sound sources
    > (Please refer to vchans notes below).
    > 5. via82c686.c
    > * Add locking / MPSAFE. I don't have this card, so other people had
    > to confirm it. Anyway, the logic is correct.
    >
    >
    > Notes / Issues
    > ==============
    >
    > * Virtual Channels (vchans)
    > Enabling vchans can really, really help to solve overruns
    > issue. This is quite understandable, because it operate
    > entirely within its own buffering system without relying on
    > hardware interrupt / state. Even if you don't need vchan,
    > just enable single channel can help much.
    > * Feeder alignment is really a monster on its own, this should
    > be fixed or revamp in near future.
    > * Mixer infrastructure is really outdated, without support for
    > proper multichannel. Best candidate for hacking fest.
    > * The arrival of 24/32 also come with a price. Applications
    > that can do 24/32bit playback need to be recompiled (notably
    > mplayer). Use (recompiled) mplayer to experiment / test /
    > debug this various format using -af format=fmt. Note that
    > 24bit seeking in mplayer is a little bit broken, sometimes
    > can cause silence or loud static noise. Pausing / seeking
    > few times can solve this problem.
    > You don't have to rebuild world entirely for this. Simply
    > copy /usr/src/sys/sys/soundcard.h to
    > /usr/include/sys/soundcard.h would suffice. Few drivers also
    > need recompilation, and this can be done via
    > /usr/src/sys/modules/sound/.
    > Support for 24bit hardware playback is beyond the scope of
    > this changes. That would require spessific hardware driver
    > changes and currently I don't have any of it.
    > * Don't expect playing 9999999999hz is a wise decision. Be
    > reasonable. The new feeder_rate implemention provide
    > flexibility, not insanity. You can easily chewed up your CPU
    > with this kind of mind instability. Please use proper
    > mosquite repellent device for this obvious cracked brain
    > attempt. As for testing purposes, you can use (again)
    > mplayer to generate / play with different sampling rate. Use
    > something like mplayer -af resample=192000:0:0 files..
    >
    >
    > --
    >
    > Ariff Abdullah
    > MyBSD
    >
    > http://www.MyBSD.org.my (IPv6/IPv4)
    > http://staff.MyBSD.org.my (IPv6/IPv4)
    > http://tomoyo.MyBSD.org.my (IPv6/IPv4) 

    -- 
"Perfection is achieved, not when there is nothing left to add, 
but when there is nothing left to take away."  
--- Antoine de St. Exupery, Wind, Sand, and Stars, 1939 
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