Re: [Qemu-devel] [PATCH 02/11] audio: basic support for multi backend audio

[Markus Armbruster]

"Zoltán Kővágó" <address@hidden> writes:

> On 2019-07-10 06:06, Markus Armbruster wrote:
>> "Kővágó, Zoltán" <address@hidden> writes:
>> 
>>> Audio functions no longer access glob_audio_state, instead they get an
>>> AudioState as a parameter.  This is required in order to support
>>> multiple backends.
>>>
>>> glob_audio_state is also gone, and replaced with a tailq so we can store
>>> more than one states.
>>>
>>> Signed-off-by: Kővágó, Zoltán <address@hidden>
>>> ---
>> [...]
>>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>>> index bfa5681dd2..23196da3fe 100644
>>> --- a/hmp-commands.hx
>>> +++ b/hmp-commands.hx
>>> @@ -819,16 +819,17 @@ ETEXI
>>>  
>>>      {
>>>          .name       = "wavcapture",
>>> -        .args_type  = "path:F,freq:i?,bits:i?,nchannels:i?",
>>> -        .params     = "path [frequency [bits [channels]]]",
>>> +        .args_type  = "path:F,freq:i?,bits:i?,nchannels:i?,audiodev:s?",
>>> +        .params     = "path [frequency [bits [channels [audiodev]]]]",
>>>          .help       = "capture audio to a wave file (default 
>>> frequency=44100 bits=16 channels=2)",
>>>          .cmd        = hmp_wavcapture,
>>>      },
>>>  STEXI
>>> -@item wavcapture @var{filename} [@var{frequency} [@var{bits} 
>>> [@var{channels}]]]
>>> +@item wavcapture @var{filename} [@var{frequency} [@var{bits} 
>>> [@var{channels} [@var{audiodev}]]]]
>>>  @findex wavcapture
>>> -Capture audio into @var{filename}. Using sample rate @var{frequency}
>>> -bits per sample @var{bits} and number of channels @var{channels}.
>>> +Capture audio into @var{filename} from @var{audiodev}. Using sample rate
>>> +@var{frequency} bits per sample @var{bits} and number of channels
>>> +@var{channels}.
>>>  
>>>  Defaults:
>>>  @itemize @minus
>>    @item Sample rate = 44100 Hz - CD quality
>>    @item Bits = 16
>>    @item Number of channels = 2 - Stereo
>>    @end itemize
>>    ETEXI
>> 
>> Defaults for the other optional arguments are listed here.  Why not for
>> @audiodev?
>
> There's no default listed because there's no default when you use the
> -audiodev options, since there's no good default.  When you don't use
> -audiodev, it'll use the implicitly created audiodev which doesn't have
> a name, so it can't be specified.

Double-checking to avoid misunderstandings: there is a default
*behavior*, but no default *value*, i.e. there is no VALUE that makes
audiodev=VALUE give you the same behavior as no audiodev.  Correct?

>                                    But I agree that this situation
> should be documented somehow.

Yes, please.

>>> diff --git a/qemu-options.hx b/qemu-options.hx
>>> index 9621e934c0..0111055aa4 100644
>>> --- a/qemu-options.hx
>>> +++ b/qemu-options.hx
>>> @@ -1978,6 +1978,11 @@ can help the device and guest to keep up and not 
>>> lose events in case
>>>  events are arriving in bulk.  Possible causes for the latter are flaky
>>>  network connections, or scripts for automated testing.
>>>  
>>> +@item audiodev=@var{audiodev}
>>> +
>>> +Use the specified @var{audiodev} when the VNC client requests audio
>>> +transmission.
>>> +
>> 
>> What's the default?
>
> It's the same story as wav_capture.
>
> Regards,
> Zoltan