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To: ariff@FreeBSD.org
From: Kazuhito HONDA <kazuhito@ph.noda.tus.ac.jp>
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Cc: freebsd-multimedia@FreeBSD.org
Subject: Re: patch for 24-bit soft volume and uaudio's tiny fix
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Hello,

From: Ariff Abdullah <ariff@FreeBSD.org>
Subject: Re: patch for 24-bit soft volume and uaudio's tiny fix
Date: Wed, 15 Feb 2006 16:30:02 +0800

> (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.

I tried to play and to record sound sources with converting between 16-bit
and 24-bit each other, endian, volume and sampling rate on my USB device.
It worked without a big problem. 

But sampling rate converter may be able to convert sampling rate 
for 16-bit sound stream only, so 24-bit sound stream is
always down-converted to 16-bit when its sampling rate is converted.
Because it is more than enough for 24-bit sound devices,
a sampling rate converter for 24-bit sound stream is necessary.

Sincerely yours,
Kazuhito HONDA