Stereo line-in capture broken in alsa-lib 1.0.10 for "simple mixer" cards.

dapper-updates candidate

Hi Matt, Colin,

Recently I was made aware of ticket #1000 [0] in which quite a few
6.06.1 users of AC'97 codecs are not able to record audible stereo
microphone input. A bug report has been filed [1] to track the
resolution of this issue for 6.06.1. A straightforward fix [2] is
available in a newer upstream version of alsa-lib (1.0.11, so 6.10 is
not affected, nor are earlier Ubuntu versions).

Attached please find a SRU debdiff against 6.06.1's alsa-lib source package.

$ debdiff alsa-lib_1.0.10-2ubuntu4.dsc alsa-lib_1.0.10-2ubuntu4.1.dsc
|diffstat
 alsa-lib-1.0.10/debian/changelog | 11 ++++++++++
 alsa-lib-1.0.10/debian/patches/00list | 1
 debian/patches/25_fix_stereo_line_capture.dpatch | 24
+++++++++++++++++++++++
 3 files changed, 36 insertions(+)

[0] https://launchpad.net/distros/ubuntu/+ticket/1000
[1] https://launchpad.net/distros/ubuntu/+source/alsa-lib/+bug/62855
[2]
http://hg-mirror.alsa-project.org/alsa-lib?cmd=changeset;node=71eb744cd5be42cd7ebd14edf5f3f2e2da6ba35d;style=gitweb

Thanks,
--
Daniel T. Chen <email address hidden>
GPG key: 0xC88ABDA3

diff -u alsa-lib-1.0.10/debian/changelog alsa-lib-1.0.10/debian/changelog
--- alsa-lib-1.0.10/debian/changelog
+++ alsa-lib-1.0.10/debian/changelog
@@ -1,3 +1,14 @@
+alsa-lib (1.0.10-2ubuntu4.1) dapper-proposed; urgency=low
+
+ * Add debian/patches/25_fix_stereo_line_capture.dpatch that fixes
+ inaudible recording of stereo microphone input. Patch backported
+ from 1.0.11 referenced at
+ http://hg-mirror.alsa-project.org/alsa-lib?cmd=changeset;node=71eb744cd5be42cd7ebd14edf5f3f2e2da6ba35d;style=raw
+ (Closes Ubuntu ticket #1000, bug #62855). Thanks, Jeff Meininger
+ and others.
+
+ -- Daniel T Chen <email address hidden> Thu, 28 Sep 2006 17:34:12 -0400
+
 alsa-lib (1.0.10-2ubuntu4) dapper; urgency=low

   * debian/patches: Add:
diff -u alsa-lib-1.0.10/debian/patches/00list alsa-lib-1.0.10/debian/patches/00list
--- alsa-lib-1.0.10/debian/patches/00list
+++ alsa-lib-1.0.10/debian/patches/00list
@@ -16,0 +17 @@
+25_fix_stereo_line_capture
only in patch2:
unchanged:
--- alsa-lib-1.0.10.orig/debian/patches/25_fix_stereo_line_capture.dpatch
+++ alsa-lib-1.0.10/debian/patches/25_fix_stereo_line_capture.dpatch
@@ -0,0 +1,24 @@
+#! /bin/sh /usr/share/dpatch/dpatch-run
+## 25_fix_stereo_line_capture.dpatch by <email address hidden>
+##
+## All lines beginning with `## DP:' are a description of the patch.
+## DP: Fixes stereo line capture bug in simple mixer API:
+## DP: http://hg-mirror.alsa-project.org/alsa-lib?cmd=changeset;node=71eb744cd5
+## DP: be42cd7ebd14edf5f3f2e2da6ba35d;style=gitweb
+
+@DPATCH@
+
+diff -ru alsa-lib-1.0.10.orig/src/mixer/simple_none.c alsa-lib-1.0.10/src/mixer/simple_none.c
+--- alsa-lib-1.0.10.orig/src/mixer/simple_none.c 2005-08-24 05:41:16.000000000 -0500
++++ alsa-lib-1.0.10/src/mixer/simple_none.c 2005-12-02 07:39:24.000000000 -0600
+@@ -768,7 +768,9 @@
+ if (cchannels > 1) {
+ if (simple->ctls[CTL_CAPTURE_ROUTE].elem ||
+ (simple->ctls[CTL_CAPTURE_SWITCH].elem &&
+- simple->ctls[CTL_CAPTURE_SWITCH].values > 1)) {
++ simple->ctls[CTL_CAPTURE_SWITCH].values > 1) ||
++ (simple...

On Thu, Sep 28, 2006 at 05:54:50PM -0400, Daniel T. Chen wrote:
> Hi Matt, Colin,
>
> Recently I was made aware of ticket #1000 [0] in which quite a few
> 6.06.1 users of AC'97 codecs are not able to record audible stereo
> microphone input. A bug report has been filed [1] to track the
> resolution of this issue for 6.06.1. A straightforward fix [2] is
> available in a newer upstream version of alsa-lib (1.0.11, so 6.10 is
> not affected, nor are earlier Ubuntu versions).

Excellent job on this proposal; it had everything I needed.

The update itself seems fine; my only reservation is that the original bug
doesn't seem serious enough to justify the inherent risk factors of an
update. It seems that it would affect only a very small number of users (on
particular hardware and doing stereo audio capture?).

--
 - mdz

Matt Zimmerman wrote:

> The update itself seems fine; my only reservation is that the original bug
> doesn't seem serious enough to justify the inherent risk factors of an
> update. It seems that it would affect only a very small number of users (on
> particular hardware and doing stereo audio capture?).

As I understand it, the bug affects the vast majority of PC audio
hardware. Most on-board audio chipsets use the buggy "simple mixer" and
so do the majority of consumer-grade PCI sound cards. (Higher-end
[Audigy] and other specialty audio hardware use different mixer code and
are not affected.)

I suppose any update is a risk factor, but the changes to the existing
package are minimal and completely isolated. This is much less of a
risk than upgrading the whole library to 1.0.11 would be.

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Hi Matt,

Matt Zimmerman wrote:
> The update itself seems fine; my only reservation is that the original bug
> doesn't seem serious enough to justify the inherent risk factors of an
> update. It seems that it would affect only a very small number of users (on
> particular hardware and doing stereo audio capture?).

As Jeff mentioned in the follow-up to bug 62855, a significant number of
"AC'97" users are affected. Considering that there is zero possibility
of backward breakage by applying this fix for stereo audio capture and
that Ubuntu will soon have an audio-centric sister project, IMO it seems
sensible to include this fix in dapper-updates.

Thanks,
- --
Daniel T. Chen <email address hidden>
GPG key: 0xC88ABDA3
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On Wed, Oct 04, 2006 at 12:16:23AM -0400, Daniel T. Chen wrote:
> Hi Matt,
>
> Matt Zimmerman wrote:
> > The update itself seems fine; my only reservation is that the original bug
> > doesn't seem serious enough to justify the inherent risk factors of an
> > update. It seems that it would affect only a very small number of users (on
> > particular hardware and doing stereo audio capture?).
>
> As Jeff mentioned in the follow-up to bug 62855, a significant number of
> "AC'97" users are affected. Considering that there is zero possibility
> of backward breakage by applying this fix for stereo audio capture and

Only a tiny fraction of users are likely to be using stereo audio capture at
all. With a little more context from the file, though, it seems clear that
only those users will be affected by the patch.

Let's go ahead with this update.

> that Ubuntu will soon have an audio-centric sister project, IMO it seems
> sensible to include this fix in dapper-updates.

Is this sister project committed to deriving from Dapper? Typically it
makes more sense to start from the most recent version, which will soon be
Edgy.

--
 - mdz

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Hi Matt,

Matt Zimmerman wrote:
> Let's go ahead with this update.

Great! Per SRU guidelines, I've uploaded an alsa-lib source package,
with the debdiff applied, to dapper-proposed.

> Is this sister project committed to deriving from Dapper? Typically it
> makes more sense to start from the most recent version, which will soon be
> Edgy.

I've just chatted with Cory, and he assures me that UbuntuStudio
(formerly Mubuntu) will derive from Edgy (to be precise: < _MMA_> Yes.
All our testing will be done with Edgy with an actual release planed for
+1). At the time (prior to more detailed consultation with him), I was
under the impression that 6.06.1 LTS had been chosen as the base.

Thanks,
- --
Daniel T. Chen <email address hidden>
GPG key: 0xC88ABDA3

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Accepted into dapper-proposed. Please proceed to the Test phase of StableReleaseUpdates.

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QA team et al.,

Per SRU policy, I've tagged Ubuntu bug report 62855 after Colin has
accepted alsa-lib (1.0.10-2ubuntu4.1) into dapper-proposed. I've tested
the fix locally, and it resolves the issue reported in 62855.

Jeff, <email address hidden>, please verify the fix in dapper-proposed.
Please ask others affected (see Ubuntu ticket 1000, too) to also test.

Thanks,
- --
Daniel T. Chen <email address hidden>
GPG key: 0xC88ABDA3
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Verified that sound output and microphone capture are not broken by this update.

Hello everyone,

Will this fix be ever moved to dapper-updates?

It is not entirely clear whether the SRU procedure is completed on the testing side, though I presume Simon's comment above is sufficient.

This report has been marked "In progress" without any assignee for a long time now, and there is no recent comment. Can we consider that the SRU procedure is achieved and close this report ?

Thanks in advance.

Fixed in every alsa-lib release post-6.06. Added tag just to cover the corner case that additional verification is necessary.