@@ -172,6 +172,10 @@
#
# 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)
+#
# @fixed-settings: use fixed settings for host input/output. When off,
# frequency, channels and format must not be specified
# (default on)
@@ -192,6 +196,7 @@
##
{ 'struct': 'AudiodevPerDirectionOptions',
'data': {
+ '*mixeng': 'bool',
'*fixed-settings': 'bool',
'*frequency': 'uint32',
'*channels': 'uint32',
@@ -432,6 +432,7 @@ 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"
@@ -500,6 +501,11 @@ 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
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 <DirtY.iCE.hu@gmail.com> --- Notes: Changes from v2: * removed #optional qapi/audio.json | 5 +++++ qemu-options.hx | 6 ++++++ 2 files changed, 11 insertions(+)