patch for 24-bit soft volume and uaudio's tiny fix

[Ariff Abdullah]

On Sat, 17 Dec 2005 19:46:04 +0800
Ariff Abdullah <skywizard at MyBSD.org.my> wrote:
> On Sat, 17 Dec 2005 03:37:15 +0900 (JST)
> Kazuhito HONDA <kazuhito at ph.noda.tus.ac.jp> wrote:
> > Hello,
> > 
> > We have already had a soft volume, feeder_volume_s16().
> > But it is of 16 bit.  So 24-bit sound streams are
> > always downgraded to 16-bit before soft volume 
> > even though a sound device has a 24-bit port.  
> > Thus 24-bit soft volume is necessary.
> > 
> > This mail has a patch for 24-bit soft volume.
> > I tried to use it with `SB Live! 24-bit external'
> > and it worked.
> > 
> > And the patch includes a fix of tiny mistakes in uaudio.c, too.
> > 
> 
> uaudio.c: Obvious mistake that need to be fixed.
> 
> feeder_volume.c: Ok, looks good. My concern is endianess issue, but
>                  this can be ignored for now. I need to examine it
>                  first.
> 
> channel.c: Changes against feeder building process is a bit
> sensitive,
>            some brute testing need to be done here.
> 
(Especially to Kazuhito-san), Latest patchsets (rev. 091) contain:

1) 16/24/32bit feeder_volume
2) 16/24/32bit vchan mixing (default to 16, use sysctl or vchanformat
   kernel hint to toggle it).
3) Smarter (I would say *perfect*) format scoring during format
   chaining.
4) Endian/sign-free format conversion
5) Various fixups, especially on hardware, DMA buffer alignment
6) Samples processing are moving towards endian-safe, we just need to
   enclose varios PCM_READ/WRITE/CLAMP (sound.h) within BYTE_ORDER
   ifdefs.

My concern is 24bit alignment. This patchset enforce strict alignment
based on bytes-per-sample, so if the so called "24bit" hardware can
really do 24bit alignment, it is pretty much OK. Otherwise, we
probably need to swap AFMT_S24_XX -> AFMT_S32_XX within specific
driver implementation.


--
Ariff Abdullah
FreeBSD
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