[Qemu-devel] [PATCH v3 4/8] qapi: qapi for audio backends

[Kővágó, Zoltán]

This patch adds structures into qapi to replace the existing
configuration structures used by audio backends currently. This qapi
will be the base of the -audiodev command line parameter (that replaces
the old environment variables based config).

This is not a 1:1 translation of the old options, I've tried to make
them much more consistent (e.g. almost every backend had an option to
specify buffer size, but the name was different for every backend, and
some backends required usecs, while some other required frames, samples
or bytes). Also tried to reduce the number of abbreviations used by the
config keys.

Some of the more important changes:
* use `in` and `out` instead of `ADC` and `DAC`, as the former is more
  user friendly imho
* moved buffer settings into the global setting area (so it's the same
  for all backends that support it. Backends that can't change buffer
  size will simply ignore them). Also using usecs, as it's probably more
  user friendly than samples or bytes.
* try-poll is now an alsa and oss backend specific option (as all other
  backends currently ignore it)

Signed-off-by: Kővágó, Zoltán <address@hidden>

---

Changes from v2 patch:
* documentation fixes
* rename mmap -> try-mmap, buffer -> buffer-len
* id is now required
* converted into flat unions
* renamed alsa's and oss's in an out, because it was incompatible with
  with flat union

Changes from v1 patch:
* every time-related field now take usecs (and removed -usecs, -millis suffixes)
* fixed inconsisten optional marking, language issues

Changes from v2 RFC patch:
* in, out are no longer optional
* try-poll: moved to alsa and oss (as no other backend used them)
* voices: added (env variables had this option)
* dsound: removed primary buffer related fields

Changes from v1 RFC patch:
* fixed style issues
* moved definitions into a separate file
* documented undocumented options (hopefully)
* removed plive option. It was useless even years ago so it can probably safely
  go away: 
https://lists.nongnu.org/archive/html/qemu-devel/2012-03/msg02427.html
* removed verbose, debug options. Backends should use trace events instead.
* removed *_retries options from dsound. It's a kludge.
* moved buffer_usecs and buffer_count to the global config options. Some driver
  might ignore it (as they do not expose API to change them).
* wav backend: removed frequecy, format, channels as AudiodevPerDirectionOptions
  already have them.

 Makefile         |   4 +-
 qapi-schema.json |   3 +
 qapi/audio.json  | 250 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 255 insertions(+), 2 deletions(-)
 create mode 100644 qapi/audio.json

diff --git a/Makefile b/Makefile
index 3f97904..ac566fa 100644
--- a/Makefile
+++ b/Makefile
@@ -257,8 +257,8 @@ $(SRC_PATH)/qga/qapi-schema.json 
$(SRC_PATH)/scripts/qapi-commands.py $(qapi-py)
                "  GEN   $@")
 
 qapi-modules = $(SRC_PATH)/qapi-schema.json $(SRC_PATH)/qapi/common.json \
-               $(SRC_PATH)/qapi/block.json $(SRC_PATH)/qapi/block-core.json \
-               $(SRC_PATH)/qapi/event.json
+               $(SRC_PATH)/qapi/audio.json  $(SRC_PATH)/qapi/block.json \
+               $(SRC_PATH)/qapi/block-core.json $(SRC_PATH)/qapi/event.json
 
 qapi-types.c qapi-types.h :\
 $(qapi-modules) $(SRC_PATH)/scripts/qapi-types.py $(qapi-py)
diff --git a/qapi-schema.json b/qapi-schema.json
index 2a3cfe3..f1896f4 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -5,6 +5,9 @@
 # QAPI common definitions
 { 'include': 'qapi/common.json' }
 
+# QAPI audio definitions
+{ 'include': 'qapi/audio.json' }
+
 # QAPI block definitions
 { 'include': 'qapi/block.json' }
 
diff --git a/qapi/audio.json b/qapi/audio.json
new file mode 100644
index 0000000..e00f082
--- /dev/null
+++ b/qapi/audio.json
@@ -0,0 +1,250 @@
+# -*- mode: python -*-
+#
+# Copyright (C) 2015 Zoltán Kővágó <address@hidden>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or later.
+# See the COPYING file in the top-level directory.
+
+##
+# @AudiodevNoOptions
+#
+# The none, coreaudio, sdl and spice audio backend have no options.
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevNoOptions',
+  'data': { } }
+
+##
+# @AudiodevAlsaPerDirectionOptions
+#
+# Options of the alsa backend that are used for both playback and recording.
+#
+# @dev: #optional the name of the alsa device to use (default 'default')
+#
+# @try-poll: #optional attempt to use poll mode, falling back to non polling
+#            access on failure (default on)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevAlsaPerDirectionOptions',
+  'data': {
+    '*dev':      'str',
+    '*try-poll': 'bool' } }
+
+##
+# @AudiodevAlsaOptions
+#
+# Options of the alsa audio backend.
+#
+# @alsa-in: options of the capture stream
+#
+# @alsa-out: options of the playback stream
+#
+# @threshold: #optional set the threshold (in microsecods) when playback starts
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevAlsaOptions',
+  'data': {
+    'alsa-in':    'AudiodevAlsaPerDirectionOptions',
+    'alsa-out':   'AudiodevAlsaPerDirectionOptions',
+    '*threshold': 'int' } }
+
+##
+# @AudiodevDsoundOptions
+#
+# Options of the dsound audio backend.
+#
+# @latency: #optional add extra latency to playback in microseconds (default
+#           10000)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevDsoundOptions',
+  'data': {
+    '*latency': 'int' } }
+
+##
+# @AudiodevOssPerDirectionOptions
+#
+# Options of the oss backend that are used for both playback and recording.
+#
+# @dev: #optional file name of the oss device (default '/dev/dsp')
+#
+# @try-poll: #optional attempt to use poll mode, falling back to non polling
+#            access on failure (default on)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevOssPerDirectionOptions',
+  'data': {
+    '*dev':      'str',
+    '*try-poll': 'bool' } }
+
+##
+# @AudiodevOssOptions
+#
+# Options of the oss audio backend.
+#
+# @oss-in: options of the capture stream
+#
+# @oss-out: options of the playback stream
+#
+# @try-mmap: #optional try using memory mapped access, falling back to non
+#            memory mapped access on failure (default off)
+#
+# @exclusive: #optional open device in exclusive mode (vmix won't work)
+#             (default off)
+#
+# @dsp-policy: #optional set the timing policy of the device (between 0 and 10,
+#              where smaller number means smaller latency but higher CPU usage)
+#              or -1 to use fragment mode (option ignored on some platforms)
+#              (default 5)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevOssOptions',
+  'data': {
+    'oss-in':      'AudiodevOssPerDirectionOptions',
+    'oss-out':     'AudiodevOssPerDirectionOptions',
+    '*try-mmap':   'bool',
+    '*exclusive':  'bool',
+    '*dsp-policy': 'int' } }
+
+##
+# @AudiodevPaOptions
+#
+# Options of the pa (PulseAudio) audio backend.
+#
+# @server: #optional PulseAudio server address (default: let PulseAudio choose)
+#
+# @sink: #optional sink device name (default: let PulseAudio choose)
+#
+# @source: #optional source device name (default: let PulseAudio choose)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevPaOptions',
+  'data': {
+    '*server': 'str',
+    '*sink':   'str',
+    '*source': 'str' } }
+
+##
+# @AudiodevWavOptions
+#
+# Options of the wav audio backend.
+#
+# @path: #optional name of the wav file to record (default 'qemu.wav')
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevWavOptions',
+  'data': {
+    '*path': 'str' } }
+
+
+##
+# @AudioFormat
+#
+# An enumeration of possible audio formats.
+#
+# Since: 2.4
+##
+{ 'enum': 'AudioFormat',
+  'data': [ 'u8', 's8', 'u16', 's16', 'u32', 's32' ] }
+
+##
+# @AudiodevDriver
+#
+# An enumeration of possible audio backend drivers.
+#
+# Since: 2.4
+##
+{ 'enum': 'AudiodevDriver',
+  'data': [ 'none', 'alsa', 'coreaudio', 'dsound', 'oss', 'pa', 'sdl', 'spice',
+            'wav' ] }
+
+##
+# @AudiodevPerDirectionOptions
+#
+# General audio backend options that are used for both playback and recording.
+#
+# @fixed-settings: #optional use fixed settings for host input/output.  When
+#                  off, frequency, channels and format must not be specified
+#                  (default on)
+#
+# @frequency: #optional frequency to use when using fixed settings
+#             (default 44100)
+#
+# @channels: #optional number of channels when using fixed settings
+#            (default 2)
+#
+# @voices: #optional number of voices to use (default 1)
+#
+# @format: #optional sample format to use when using fixed settings
+#          (default s16)
+#
+# @buffer-len: #optional the buffer size in microseconds
+#
+# @buffer-count: #optional number of buffers
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevPerDirectionOptions',
+  'data': {
+    '*fixed-settings': 'bool',
+    '*frequency':      'int',
+    '*channels':       'int',
+    '*voices':         'int',
+    '*format':         'AudioFormat',
+    '*buffer-len':     'int',
+    '*buffer-count':   'int' } }
+
+##
+# @AudiodevCommonOptions
+#
+# Captures the common configuration of an audio backend.
+#
+# @id: identifier of the backend
+#
+# @driver: the backend driver to use
+#
+# @in: options of the capture stream
+#
+# @out: options of the playback stream
+#
+# @timer-period: #optional timer period (in microseconds, 0: use lowest
+#                possible)
+#
+# Since: 2.4
+##
+{ 'struct': 'AudiodevCommonOptions',
+  'data': {
+    'id':            'str',
+    'driver':        'AudiodevDriver',
+    'in':            'AudiodevPerDirectionOptions',
+    'out':           'AudiodevPerDirectionOptions',
+    '*timer-period': 'int' } }
+
+##
+# @AudiodevBackendOptions
+#
+# Options of an audio backend.
+#
+# Since: 2.4
+##
+{ 'union': 'Audiodev',
+  'base': 'AudiodevCommonOptions',
+  'discriminator': 'driver',
+  'data': {
+    'none':      'AudiodevNoOptions',
+    'alsa':      'AudiodevAlsaOptions',
+    'coreaudio': 'AudiodevNoOptions',
+    'dsound':    'AudiodevDsoundOptions',
+    'oss':       'AudiodevOssOptions',
+    'pa':        'AudiodevPaOptions',
+    'sdl':       'AudiodevNoOptions',
+    'spice':     'AudiodevNoOptions',
+    'wav':       'AudiodevWavOptions' } }
-- 
2.4.3