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

["Zoltán Kővágó" <dirty.ice.hu@gmail.com>]

On 2019-07-10 06:06, Markus Armbruster wrote:
> "Kővágó, Zoltán" <dirty.ice.hu@gmail.com> 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 <DirtY.iCE.hu@gmail.com>
>> ---
> [...]
>> 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.  But I agree that this situation
should be documented somehow.

> 
>> 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