From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Henningsson Subject: Re: [RFC PATCH] Inverted internal mic Date: Tue, 28 Feb 2012 15:19:16 +0100 Message-ID: <4F4CE264.7040008@canonical.com> References: <4F4C9714.1080307@canonical.com> <4F4CA438.90103@canonical.com> <4F4CD1AF.2050409@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by alsa0.perex.cz (Postfix) with ESMTP id 8619E24675 for ; Tue, 28 Feb 2012 15:19:18 +0100 (CET) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: ALSA Development Mailing List , kailang@realtek.com, 903853@bugs.launchpad.net List-Id: alsa-devel@alsa-project.org On 02/28/2012 02:22 PM, Takashi Iwai wrote: > At Tue, 28 Feb 2012 14:07:59 +0100, > David Henningsson wrote: >> Ok. My question was more about the following: When I look at >> patch_realtek.c, I can find functions alc271_fixup_dmic and >> alc269_fixup_stereo_dmic. I have also seen machines having ALC268 and >> ALC272X that have this internal mic behaviour. Is there a way we can >> know the corresponding processing coefficients to set for ALC268 and >> ALC272X as well? > > AFAIK, no, it was specific to the codec model. Ok, then we can only hope for Kailang to supply this information if possible. And if not possible we could attempt the workaround (when/if we agree on it...) for these devices as well? >>> Note that in alsa-lib, the HD-audio "default" is already set up to >>> copy left-channel for mono streams. You can see a line setting >>> "route_policy" to "copy" in HDA-Intel.conf. >>> >>> Thus, when ALSA apps run without PA, it'd work in both stereo and >>> mono. >> >> Assuming the right channel is muted, yes. But not in the current >> implementation. > > It should work no matter whether the right channel is muted or not. > The plug layer will use only the left channel when a mono stream is > recorded since route_policy=copy is set. Remember that it's about > "default" PCM, not about "hw" PCM that PA uses. We don't touch "hw" > intentionally because it's really intended to be a raw access. I'm talking about recording an internal mic in *stereo*, as I just wrote below. Or don't you agree that is a valid and probably fairly common use case? >> By not making a change in the ALSA layer, it will still be broken for >> any ALSA apps who record the Internal Mic as a stereo signal. They will >> get a broken result as the right channel will be phase inverted. That's >> why I think this is better dealt with in the ALSA layer. >> Would a zeroed right channel be less broken than a phase inverted right >> channel? I think so. -- David Henningsson, Canonical Ltd. http://launchpad.net/~diwic