sdlaudio: add -audiodev sdl,out.buffer-count option

Currently there is a crackling noise with SDL2 audio playback.
Commit bcf19777df: "audio/sdlaudio: Allow audio playback with
SDL2" already mentioned the crackling noise.

Add an out.buffer-count option to give users a chance to select
sane settings for glitch free audio playback. The idea was taken
from the coreaudio backend.

The in.buffer-count option will be used with one of the next
patches.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 9315afe5-5958-c0b4-ea1e-14769511a9d5@t-online.de
Message-Id: <20210110100239.27588-3-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 32 insertions, 1 deletions

diff --git a/qapi/audio.json b/qapi/audio.json
index 072ed79def..9cba0df8a4 100644
--- a/qapi/audio.json
+++ b/qapi/audio.json
@@ -302,6 +302,37 @@
     '*server': 'str' } }
 
 ##
+# @AudiodevSdlPerDirectionOptions:
+#
+# Options of the SDL audio backend that are used for both playback and
+# recording.
+#
+# @buffer-count: number of buffers (default 4)
+#
+# Since: 6.0
+##
+{ 'struct': 'AudiodevSdlPerDirectionOptions',
+  'base': 'AudiodevPerDirectionOptions',
+  'data': {
+    '*buffer-count': 'uint32' } }
+
+##
+# @AudiodevSdlOptions:
+#
+# Options of the SDL audio backend.
+#
+# @in: options of the recording stream
+#
+# @out: options of the playback stream
+#
+# Since: 6.0
+##
+{ 'struct': 'AudiodevSdlOptions',
+  'data': {
+    '*in':  'AudiodevSdlPerDirectionOptions',
+    '*out': 'AudiodevSdlPerDirectionOptions' } }
+
+##
 # @AudiodevWavOptions:
 #
 # Options of the wav audio backend.
@@ -385,6 +416,6 @@
     'jack':      'AudiodevJackOptions',
     'oss':       'AudiodevOssOptions',
     'pa':        'AudiodevPaOptions',
-    'sdl':       'AudiodevGenericOptions',
+    'sdl':       'AudiodevSdlOptions',
     'spice':     'AudiodevGenericOptions',
     'wav':       'AudiodevWavOptions' } }