Hi,
I'd like to know our audio specification. i.e.,
what encoding the kernel accepts?
This table shows the status of current implementation, not current
documentation.
audioplay(1) audio(4) AUDIO_GETENC(*1)
------------------------------------------------------------
s8 accept accept not support
s16{be,le} accept accept supported(*2)
s24{be,le} accept reject not support
s32{be,le} accept accept not support
u8 accept accept not support
u16{be,le} ? ? supported by emulation
u24{be,le} ? reject? not support
u32{be,le} ? ? not support
mulaw accept accept(ifdef) supported by emulation
note:
*1 The mismatch of AUDIO_GETENC is described in PR/52585.
*2 On LE, s16le is supported natively and s16be is by emulation.
On BE, s16be is supported natively and s16le is by emulation.
Even if the hardware does not support slinear16 natively.
memo:
o I confirmed that audioplay(1) accepts u8.wav, s{16,24,32}le.wav,
s8.au, s{16,24,32}be.au, and mulaw.au.
But I don't know about u{16,24,32}.
o I confirmed that audio(4) rejects s24{le,be} by audioplay(1).
Is this result expected (= well-planned)?
I don't say that "audio(4) does not accpet 24bit, let's add it."
Before rev1.26, auconv.c supported 8/16bit only.
After rev1.27, auconv.c supports {8,16,24/24,24/32,32} but mostly
broken (see PR/52586) but no one noticed it because most of them
was dead code.
It's better to clarify the specification before implementing.
I'm not an audio man, so I don't know details but,
Will audio(4) support ulinear{16,24,32} or slinear24 ? i.e.,
is it worth to pay the maintainance cost to keep supporting it?
Thanks,
---
Tetsuya Isaki <is...@pastel-flower.jp / is...@netbsd.org>
