From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B643C32755 for ; Mon, 23 Sep 2019 13:09:49 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 03ECD20835 for ; Mon, 23 Sep 2019 13:09:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 03ECD20835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56336 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCO68-00008S-2u for qemu-devel@archiver.kernel.org; Mon, 23 Sep 2019 09:09:48 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54519) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iCO4q-0007fy-Nf for qemu-devel@nongnu.org; Mon, 23 Sep 2019 09:08:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iCO4o-0005Nh-FL for qemu-devel@nongnu.org; Mon, 23 Sep 2019 09:08:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56424) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iCO4o-0005NZ-7h for qemu-devel@nongnu.org; Mon, 23 Sep 2019 09:08:26 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7936AA2667F; Mon, 23 Sep 2019 13:08:25 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-117-142.ams2.redhat.com [10.36.117.142]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 65AA210016EB; Mon, 23 Sep 2019 13:08:22 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id E59FE113864E; Mon, 23 Sep 2019 15:08:20 +0200 (CEST) From: Markus Armbruster To: =?utf-8?B?S8WRdsOhZ8OzLCBab2x0w6Fu?= Subject: Re: [PATCH v4 15/24] audio: add mixing-engine option (documentation) References: <68c4b4bd438e9cb5c97aed32ee31e3dabd96cbf6.1568927990.git.DirtY.iCE.hu@gmail.com> Date: Mon, 23 Sep 2019 15:08:20 +0200 In-Reply-To: <68c4b4bd438e9cb5c97aed32ee31e3dabd96cbf6.1568927990.git.DirtY.iCE.hu@gmail.com> (=?utf-8?B?IkvFkXbDoWfDsywgWm9sdMOhbiIncw==?= message of "Thu, 19 Sep 2019 23:24:23 +0200") Message-ID: <87sgonma7v.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.68]); Mon, 23 Sep 2019 13:08:25 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" "K=C5=91v=C3=A1g=C3=B3, Zolt=C3=A1n" writes: > This will allow us to disable mixeng when we use a decent backend. > > Disabling mixeng have a few advantages: > * we no longer convert the audio output from one format to another, when > the underlying audio system would just convert it to a third format. > We no longer convert, only the underlying system, when needed. > * the underlying system probably has better resampling and sample format > converting methods anyway... > * we may support formats that the mixeng currently does not support (S24 > or float samples, more than two channels) > * when using an audio server (like pulseaudio) different sound card > outputs will show up as separate streams, even if we use only one > backend > > Disadvantages: > * audio capturing no longer works (wavcapture, and vnc audio extension) > * some backends only support a single playback stream or very picky > about the audio format. In this case we can't disable mixeng. > > However mixeng is not removed, only made optional, so this shouldn't be > a big concern. > > Signed-off-by: K=C5=91v=C3=A1g=C3=B3, Zolt=C3=A1n > --- > > Notes: > Changes from v1: >=20=20=20=20=20 > * renamed mixeng to mixing-engine > > qapi/audio.json | 5 +++++ > qemu-options.hx | 6 ++++++ > 2 files changed, 11 insertions(+) > > diff --git a/qapi/audio.json b/qapi/audio.json > index 9fefdf5186..0535eff794 100644 > --- a/qapi/audio.json > +++ b/qapi/audio.json > @@ -11,6 +11,10 @@ > # General audio backend options that are used for both playback and > # recording. > # > +# @mixing-engine: use QEMU's mixing engine to mix all streams inside QEM= U. When > +# set to off, fixed-settings must be also off. Not every= backend > +# compatible with the off setting (default on, since 4.2) > +# Last sentence no verb. Which backends are compatible? What happens when you try the off setting with incompatible backends? > # @fixed-settings: use fixed settings for host input/output. When off, > # frequency, channels and format must not be > # specified (default true) > @@ -31,6 +35,7 @@ > ## > { 'struct': 'AudiodevPerDirectionOptions', > 'data': { > + '*mixing-engine': 'bool', > '*fixed-settings': 'bool', > '*frequency': 'uint32', > '*channels': 'uint32', > diff --git a/qemu-options.hx b/qemu-options.hx > index bbfd936d29..395427422a 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -433,6 +433,7 @@ DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, > " specifies the audio backend to use\n" > " id=3D identifier of the backend\n" > " timer-period=3D timer period in microseconds\n" > + " in|out.mixing-engine=3D use mixing engine to mix st= reams inside QEMU\n" > " in|out.fixed-settings=3D use fixed settings for hos= t audio\n" > " in|out.frequency=3D frequency to use with fixed set= tings\n" > " in|out.channels=3D number of channels to use with f= ixed settings\n" > @@ -503,6 +504,11 @@ Identifies the audio backend. > Sets the timer @var{period} used by the audio subsystem in microseconds. > Default is 10000 (10 ms). >=20=20 > +@item in|out.mixing-engine=3Don|off > +Use QEMU's mixing engine to mix all streams inside QEMU. When off, > +@var{fixed-settings} must be off too. Not every backend is fully > +compatible with the off setting. Default is on. > + > @item in|out.fixed-settings=3Don|off > Use fixed settings for host audio. When off, it will change based on > how the guest opens the sound card. In this case you must not specify