From: "Kővágó Zoltán" <dirty.ice.hu@gmail.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org, Michael Roth <mdroth@linux.vnet.ibm.com>,
Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 1/6] qapi: qapi for audio backends
Date: Wed, 17 Jun 2015 15:53:00 +0200 [thread overview]
Message-ID: <55817BBC.60904@gmail.com> (raw)
In-Reply-To: <87fv5q317m.fsf@blackfin.pond.sub.org>
2015-06-17 15:37 keltezéssel, Markus Armbruster írta:
> "Kővágó Zoltán" <dirty.ice.hu@gmail.com> writes:
>
>> 2015-06-17 13:48 keltezéssel, Markus Armbruster írta:
>>> "Kővágó Zoltán" <dirty.ice.hu@gmail.com> writes:
>>>
>>>> 2015-06-17 09:46 keltezéssel, Markus Armbruster írta:
>>>>> Copying Eric for additional QAPI schema expertise.
>>>>>
>>>>> My questions inline, pretty sure they show my ignorance.
>>>>>
>>>>> "Kővágó, Zoltán" <dirty.ice.hu@gmail.com> writes:
> [...]
>>>>>> +##
>>>>>> +# @AudiodevPaOptions
>>>>>> +#
>>>>>> +# Options of the pa (PulseAudio) audio backend.
>>>>>> +#
>>>>>> +# @server: #optional PulseAudio server address
>>>>>> +#
>>>>>> +# @sink: #optional sink device name
>>>>>> +#
>>>>>> +# @source: #optional source device name
>>>>>
>>>>> Who picks the defaults, QEMU or PA?
>>>>
>>>> PA
>>>
>>> Is there a way to explicitly ask for the PA default? Something like
>>> source=default?
>>
>> Not really right now. The default is a NULL pointer (pulseaudio api
>> wise), so unless we add an arbitrary keyword (like default), it's not
>> possible to ask explicitly for the default. (But omitting them will
>> choose the default, of course.)
>
> Treating an empty string like NULL should get us a way to ask for the
> default, and a way to document the default concisely, like (default '')
> plus a suitable explanation what '' means.
>
> I'm not saying you should do that. I'm saying whatever you do, document
> what happens when an optional parameter is absent :)
>
>>>>>> +#
>>>>>> +# Since: 2.4
>>>>>> +##
>>>>>> +{ 'struct': 'AudiodevPaOptions',
>>>>>> + 'data': {
>>>>>> + '*server': 'str',
>>>>>> + '*sink': 'str',
>>>>>> + '*source': 'str' } }
>>>>>> +
>>>>>> +##
>>>>>> +# @AudiodevWavOptions
>>>>>> +#
>>>>>> +# Options of the wav audio backend.
>>>>>> +#
>>>>>> +# @path: #optional path of the wav file to record
>>>>>> +#
>>>>>> +# Since: 2.4
>>>>>> +##
>>>>>> +{ 'struct': 'AudiodevWavOptions',
>>>>>> + 'data': {
>>>>>> + '*path': 'str' } }
>>>>>
>>>>> Who picks the default?
>>>>
>>>> It defaults to "qemu.wav"
>>>
>>> Make it
>>>
>>> # @path: #optional path of the wav file to record (default 'qemu.wav')
>>>
>>>>>> +
>>>>>> +
>>>>>> +##
>>>>>> +# @AudiodevBackendOptions
>>>>>> +#
>>>>>> +# A discriminated record of audio backends.
>>>>>> +#
>>>>>> +# Since: 2.4
>>>>>> +##
>>>>>> +{ 'union': 'AudiodevBackendOptions',
>>>>>> + 'data': {
>>>>>> + 'none': 'AudiodevNoOptions',
>>>>>> + 'alsa': 'AudiodevAlsaOptions',
>>>>>> + 'coreaudio': 'AudiodevNoOptions',
>>>>>> + 'dsound': 'AudiodevDsoundOptions',
>>>>>> + 'oss': 'AudiodevOssOptions',
>>>>>> + 'pa': 'AudiodevPaOptions',
>>>>>> + 'sdl': 'AudiodevNoOptions',
>>>>>> + 'spice': 'AudiodevNoOptions',
>>>>>> + 'wav': 'AudiodevWavOptions' } }
>>>>>> +
>>>>>> +##
>>>>>> +# @AudioFormat
>>>>>> +#
>>>>>> +# An enumeration of possible audio formats.
>>>>>> +#
>>>>>> +# Since: 2.4
>>>>>> +##
>>>>>> +{ 'enum': 'AudioFormat',
>>>>>> + 'data': [ 'u8', 's8', 'u16', 's16', 'u32', 's32' ] }
>>>>>> +
>>>>>> +##
>>>>>> +# @AudiodevPerDirectionOptions
>>>>>> +#
>>>>>> +# General audio backend options that are used for both playback
>>>>>> and recording.
>>>>>> +#
>>>>>> +# @fixed-settings: #optional use fixed settings for host DAC/ADC
>>>>>> +#
>>>>>> +# @frequency: #optional frequency to use when using fixed settings
>>>>>> +#
>>>>>> +# @channels: #optional number of channels when using fixed settings
>>>>>> +#
>>>>>> +# @format: #optional sample format to use when using fixed settings
>>>>>
>>>>> Are these guys used when @fixed-settings is off?
>>>>
>>>> No.
>>>
>>> If @fixed-settings, are the other three all required? If not, what are
>>> their defaults?
>>
>> No, they all have defaults: 44100 Hz, 2 channels and s16 format.
>
> Okay, this sort of explains why you have @fixed-settings.
>
> My first thought was that @fixed-settings is redundant, because we can
> have any of @frequency, @channels, @format imply fixed settings. Except
> that doesn't let you ask for the *default* fixed settings, as you have
> to specify at least one.
>
> What's the default for @fixed-settings?
It's on by default.
> What if I specify frequency, channels or format together with explicit
> fixed-settings: false?
They will be ignored.
The audio system currently work like this: when an audio frontend wants
to open an output with some format (frequency, channels, format) it
checks fixed-settings. If it's false, it will just open the stream with
the frontend specified settings. If it's true, it'll convert it into the
format specified by @frequency, @channels, @format, then pass this
converted/recoded stream to the backend.
>
>> I
>> guess I should also document it...
>
> Yes, please.
>
>>>>>> +#
>>>>>> +# @buffer: #optional the buffer size (in microseconds)
>>>>>
>>>>> @buffer suggests this is a buffer, not a buffer length given as time
>>>>> span. @buffer-len?
>>>>
>>>> Ok. (It used to be called buffer-usecs before I changed everything to
>>>> 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': 'int',
>>>>>> + '*buffer-count': 'int' } }
> [...]
>
next prev parent reply other threads:[~2015-06-17 13:53 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 12:49 [Qemu-devel] [PATCH v2 0/6] -audiodev option Kővágó, Zoltán
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 1/6] qapi: qapi for audio backends Kővágó, Zoltán
2015-06-17 7:46 ` Markus Armbruster
2015-06-17 10:54 ` Kővágó Zoltán
2015-06-17 11:48 ` Markus Armbruster
2015-06-17 12:07 ` Kővágó Zoltán
2015-06-17 13:37 ` Markus Armbruster
2015-06-17 13:53 ` Kővágó Zoltán [this message]
2015-06-17 16:06 ` Markus Armbruster
2015-06-18 0:21 ` Kővágó Zoltán
2015-06-18 8:51 ` Markus Armbruster
2015-06-17 15:50 ` Eric Blake
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 2/6] qapi: support nested structs in OptsVisitor Kővágó, Zoltán
2015-06-17 7:50 ` Markus Armbruster
2015-06-17 8:41 ` Gerd Hoffmann
2015-06-17 11:01 ` Kővágó Zoltán
2015-06-17 11:50 ` Markus Armbruster
2015-06-17 15:47 ` Eric Blake
2015-06-17 11:18 ` Markus Armbruster
2015-06-17 12:11 ` Kővágó Zoltán
2015-06-17 13:41 ` Markus Armbruster
2015-06-17 14:02 ` Kővágó Zoltán
2015-06-17 16:10 ` Markus Armbruster
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 3/6] opts: do not print separator before first item in qemu_opts_print Kővágó, Zoltán
2015-06-17 7:53 ` Markus Armbruster
2015-06-17 9:02 ` Kevin Wolf
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 4/6] qapi: AllocVisitor Kővágó, Zoltán
2015-06-17 7:56 ` Markus Armbruster
2015-06-17 12:01 ` Kővágó Zoltán
2015-06-17 13:42 ` Markus Armbruster
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 5/6] audio: use qapi AudioFormat instead of audfmt_e Kővágó, Zoltán
2015-06-17 8:01 ` Markus Armbruster
2015-06-17 11:05 ` Kővágó Zoltán
2015-06-17 11:51 ` Markus Armbruster
2015-06-17 16:01 ` Eric Blake
2015-06-16 12:49 ` [Qemu-devel] [PATCH v2 6/6] audio: -audiodev command line option Kővágó, Zoltán
2015-06-17 8:13 ` Markus Armbruster
2015-06-17 11:18 ` Kővágó Zoltán
2015-06-17 12:27 ` Markus Armbruster
2015-06-17 13:25 ` Kővágó Zoltán
2015-06-17 16:13 ` Markus Armbruster
2015-06-18 6:54 ` Gerd Hoffmann
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