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[Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation)
From: |
Kővágó, Zoltán |
Subject: |
[Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation) |
Date: |
Sun, 25 Aug 2019 20:46:18 +0200 |
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: Kővágó, Zoltán <address@hidden>
---
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..dc7f9cb1e2 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.
#
+# @mixeng: use QEMU's mixing engine to mix all streams inside QEMU. When set to
+# off, fixed-settings must be also off. Not every backend compatible
+# with the off setting (default on, since 4.2)
+#
# @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': {
+ '*mixeng': 'bool',
'*fixed-settings': 'bool',
'*frequency': 'uint32',
'*channels': 'uint32',
diff --git a/qemu-options.hx b/qemu-options.hx
index ea0638e92d..8de6deb691 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= identifier of the backend\n"
" timer-period= timer period in microseconds\n"
+ " in|out.mixeng= use mixeng to mix streams inside QEMU\n"
" in|out.fixed-settings= use fixed settings for host
audio\n"
" in|out.frequency= frequency to use with fixed settings\n"
" in|out.channels= number of channels to use with fixed
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).
+@item in|out.mixeng=on|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=on|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
--
2.22.0
- [Qemu-devel] [PATCH 02/25] alsaaudio: port to the new audio backend api, (continued)
- [Qemu-devel] [PATCH 02/25] alsaaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 05/25] noaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 04/25] dsoundaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 06/25] ossaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 08/25] sdlaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 10/25] wavaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 07/25] paaudio: port to the new audio backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 11/25] audio: remove remains of the old backend api, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 13/25] audio: remove hw->samples, buffer_size_in/out pcm_ops, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 16/25] audio: add mixeng option (documentation),
Kővágó, Zoltán <=
- [Qemu-devel] [PATCH 17/25] audio: make mixeng optional, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 12/25] audio: unify input and output mixeng buffer management, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 14/25] audio: common rate control code for timer based outputs, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 15/25] audio: split ctl_* functions into enable_* and volume_*, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 19/25] audio: support more than two channels in volume setting, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 21/25] audio: basic support for multichannel audio, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 23/25] usb-audio: do not count on avail bytes actually available, Kővágó, Zoltán, 2019/08/25
- [Qemu-devel] [PATCH 20/25] audio: replace shift in audio_pcm_info with bytes_per_frame, Kővágó, Zoltán, 2019/08/25