NetBSD Problem Report #54973

From www@netbsd.org  Mon Feb 17 02:05:35 2020
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Date: Mon, 17 Feb 2020 02:05:34 +0000 (UTC)
From: jmcneill@invisible.ca
Reply-To: jmcneill@invisible.ca
To: gnats-bugs@NetBSD.org
Subject: audio regression with multi channel content and stereo hardware
X-Send-Pr-Version: www-1.0

>Number:         54973
>Category:       kern
>Synopsis:       audio regression with multi channel content and stereo hardware
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    isaki
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 17 02:10:00 +0000 2020
>Closed-Date:    Fri May 01 03:19:20 +0000 2020
>Last-Modified:  Fri May 01 03:19:20 +0000 2020
>Originator:     Jared McNeill
>Release:        9.99.46
>Organization:
>Environment:
NetBSD SEES 9.99.46 NetBSD 9.99.46 (GENERIC) #6: Sun Feb 16 21:45:07 AST 2020  jmcneill@SEES:/home/jmcneill/netbsd/cvs-src/sys/arch/amd64/compile/obj/GENERIC amd64
>Description:
When playing back a video file with 5.1 surround track using mpv, I noticed that there was sound but the speech was inaudible.

mpv uses libossaudio to detect hardware capabilities. It attempts to set the desired number of channels (6) with SNDCTL_DSP_CHANNELS, which is emulated using AUDIO_SETINFO and AUDIO_GETBUFINFO. This returns the number of emulated channels to userland, which is 6.

Since the source channel count is greater than hardware capabilities, the stream passes through audio_track_chmix_shrink. This function discards all but the front left and right channels. Unfortunately for 5.1 content, the voice is often carried in the center channel, so speech ends up being inaudible.

If the kernel is going to claim to support more channels than supported by the hardware, we need to downmix so this data is not lost.
>How-To-Repeat:
Use multimedia/mpv to playback a video with 5.1 surround audio on stereo audio hardware.
>Fix:

>Release-Note:

>Audit-Trail:

Responsible-Changed-From-To: kern-bug-people->isaki
Responsible-Changed-By: isaki@NetBSD.org
Responsible-Changed-When: Mon, 17 Feb 2020 14:37:40 +0000
Responsible-Changed-Why:
I take it.


From: "Tetsuya Isaki" <isaki@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/54973 CVS commit: src/sys/dev/audio
Date: Sat, 22 Feb 2020 05:51:39 +0000

 Module Name:	src
 Committed By:	isaki
 Date:		Sat Feb 22 05:51:39 UTC 2020

 Modified Files:
 	src/sys/dev/audio: audio.c

 Log Message:
 Limit the number of channels that userland apps can set (by AUDIO_SETINFO)
 to the number of channels supported by the hardware or less, if the hardware
 supports multi channels.
 - On monaural or stereo hardware, userland apps can always set 1ch or 2ch.
   The kernel (audio layer) can convert mono-stereo each other.
 - On 3ch (2.1ch) hardware, for example, userland apps can set 1, 2, or 3ch,
   but not 4ch or more.
 This allows userland apps to know actual number of channels supported by
 the hardware in the same way as before.
 PR kern/54973.


 To generate a diff of this commit:
 cvs rdiff -u -r1.42 -r1.43 src/sys/dev/audio/audio.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->feedback
State-Changed-By: isaki@NetBSD.org
State-Changed-When: Sat, 22 Feb 2020 05:56:37 +0000
State-Changed-Why:
sys/dev/audio/audio.c,v 1.43 will fix your problem.
Could you confirm it?


From: "Tetsuya Isaki" <isaki@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/54973 CVS commit: src/share/man/man4
Date: Sat, 28 Mar 2020 04:55:08 +0000

 Module Name:	src
 Committed By:	isaki
 Date:		Sat Mar 28 04:55:08 UTC 2020

 Modified Files:
 	src/share/man/man4: audio.4

 Log Message:
 Add description about channel limitation introduced in audio.c 1.43.
 PR kern/54973.


 To generate a diff of this commit:
 cvs rdiff -u -r1.101 -r1.102 src/share/man/man4/audio.4

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: Tetsuya Isaki <isaki@pastel-flower.jp>
To: gnats-bugs@netbsd.org
Cc: netbsd-bugs@netbsd.org,
	gnats-admin@netbsd.org,
	jmcneill@invisible.ca
Subject: Re: kern/54973 (audio regression with multi channel content and stereo hardware)
Date: Sun, 19 Apr 2020 13:30:05 +0900

 At Sat, 22 Feb 2020 05:56:38 +0000 (UTC),
 isaki@NetBSD.org wrote:
 > State-Changed-From-To: open->feedback
 > State-Changed-By: isaki@NetBSD.org
 > State-Changed-When: Sat, 22 Feb 2020 05:56:37 +0000
 > State-Changed-Why:
 > sys/dev/audio/audio.c,v 1.43 will fix your problem.
 > Could you confirm it?

 I'd like you to reply about this.
 Thanks,
 ---
 Tetsuya Isaki <isaki@pastel-flower.jp / isaki@NetBSD.org>

From: Jared McNeill <jmcneill@invisible.ca>
To: gnats-bugs@netbsd.org
Cc: 
Subject: Re: kern/54973: audio regression with multi channel content and
 stereo hardware
Date: Mon, 27 Apr 2020 23:21:35 -0300 (ADT)

 This now works correctly in -current. Thanks!

State-Changed-From-To: feedback->needs-pullups
State-Changed-By: isaki@NetBSD.org
State-Changed-When: Wed, 29 Apr 2020 02:07:38 +0000
State-Changed-Why:
Thank you for feedback!


From: "Martin Husemann" <martin@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/54973 CVS commit: [netbsd-9] src
Date: Thu, 30 Apr 2020 15:40:51 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Thu Apr 30 15:40:50 UTC 2020

 Modified Files:
 	src/share/man/man4 [netbsd-9]: audio.4
 	src/sys/dev/audio [netbsd-9]: audio.c

 Log Message:
 Pull up following revision(s) (requested by isaki in ticket #875):

 	sys/dev/audio/audio.c: revision 1.59
 	share/man/man4/audio.4: revision 1.102
 	share/man/man4/audio.4: revision 1.103
 	sys/dev/audio/audio.c: revision 1.43

 Limit the number of channels that userland apps can set (by AUDIO_SETINFO)
 to the number of channels supported by the hardware or less, if the hardware
 supports multi channels.
 - On monaural or stereo hardware, userland apps can always set 1ch or 2ch.
   The kernel (audio layer) can convert mono-stereo each other.
 - On 3ch (2.1ch) hardware, for example, userland apps can set 1, 2, or 3ch,
   but not 4ch or more.

 This allows userland apps to know actual number of channels supported by
 the hardware in the same way as before.

 PR kern/54973.

 Reinitialize the sticky parameters whenever the hardware format is changed.

 When the number of the hardware channels becomes less than the number of
 channels that sticky parameters remember, subsequent open("/dev/sound") will
 fail without this treatment.  This is for rev 1.43.

 Add description about channel limitation introduced in audio.c 1.43.
 PR kern/54973.

 Remove trailing whitespace.


 To generate a diff of this commit:
 cvs rdiff -u -r1.90 -r1.90.2.1 src/share/man/man4/audio.4
 cvs rdiff -u -r1.28.2.9 -r1.28.2.10 src/sys/dev/audio/audio.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: needs-pullups->closed
State-Changed-By: isaki@NetBSD.org
State-Changed-When: Fri, 01 May 2020 03:19:20 +0000
State-Changed-Why:
[pullup-9 #875] done.
Thank you for reporting!


>Unformatted:

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