From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:32862) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ghWOA-0005I3-So for qemu-devel@nongnu.org; Thu, 10 Jan 2019 04:12:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ghWOA-0005aQ-3N for qemu-devel@nongnu.org; Thu, 10 Jan 2019 04:12:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38500) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ghWO9-0005Zx-TH for qemu-devel@nongnu.org; Thu, 10 Jan 2019 04:12:34 -0500 From: Markus Armbruster References: <65a00798-9a26-b0bb-b70a-cfd292169123@redhat.com> Date: Thu, 10 Jan 2019 10:12:27 +0100 In-Reply-To: <65a00798-9a26-b0bb-b70a-cfd292169123@redhat.com> (Eric Blake's message of "Wed, 9 Jan 2019 19:43:51 -0600") Message-ID: <8736q098qs.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 43/52] audio: add mixeng option (documentation) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: dirty.ice.hu@gmail.com, qemu-devel@nongnu.org, Gerd Hoffmann Eric Blake writes: > On 12/23/18 2:52 PM, K=C5=91v=C3=A1g=C3=B3, Zolt=C3=A1n wrote: >> This will allow us to disable mixeng when we use a decent backend. >>=20 >> 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 >>=20 >> 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. >>=20 >> However mixeng is not removed, only made optional, so this shouldn't be >> a big concern. >>=20 >> Signed-off-by: K=C5=91v=C3=A1g=C3=B3, Zolt=C3=A1n >> --- >> qapi/audio.json | 5 +++++ >> qemu-options.hx | 6 ++++++ >> 2 files changed, 11 insertions(+) >>=20 >> diff --git a/qapi/audio.json b/qapi/audio.json >> index 56d8ce439f..180bf207a8 100644 >> --- a/qapi/audio.json >> +++ b/qapi/audio.json >> @@ -184,6 +184,10 @@ >> # >> # General audio backend options that are used for both playback and rec= ording. >> # >> +# @mixeng: #optional use QEMU's mixing engine to mix all streams inside= QEMU. > > The #optional tag is no longer necessary (the docs generator figures it > out from the '*mixeng' name below). In fact, the qapi generator had special code to detect and reject #optional tags for some six months (from commit 1d8bda128d2 to 67ab1ce9263), just to ensure patches in flight don't add them. This one has been in flight for even longer. [...]