From: Ruslan Bilovol <ruslan.bilovol@gmail.com>
To: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Clemens Ladisch <clemens@ladisch.de>,
Felipe Balbi <balbi@kernel.org>, Daniel Mack <zonque@gmail.com>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/5] USB Audio Gadget refactoring
Date: Wed, 27 Jul 2016 00:38:41 +0300 [thread overview]
Message-ID: <CAB=otbTr8iRnxp6y74URZA7qWp=vLdi738cThj4uhWB7co534Q@mail.gmail.com> (raw)
In-Reply-To: <CABb+yY35-o6MDcwZ2kFJYAN2dkow4T7zQJgAGnhSW27vY29cPg@mail.gmail.com>
On Tue, Jul 26, 2016 at 11:53 AM, Jassi Brar <jassisinghbrar@gmail.com> wrote:
> On Tue, Jul 26, 2016 at 7:01 AM, Ruslan Bilovol
> <ruslan.bilovol@gmail.com> wrote:
>> On Fri, Jul 15, 2016 at 10:43 AM, Clemens Ladisch <clemens@ladisch.de> wrote:
>>>>> On Tue, May 24, 2016 at 2:50 AM, Ruslan Bilovol
>>>>> <ruslan.bilovol@gmail.com> wrote:
>>>>>> it may break current usecase for some people
>>>
>>> And what are the benefits that justify breaking the kernel API?
>>
>>
>> Main limitation with current f_uac1 design is - it can be used only on systems
>> with real ALSA card present and can have only exact number of
>> channels / sampling rate as sink card has.
>> Yet it is not flexible - can't do audio processing between f_uac1 and the card.
>> Also if someone wants to bind f_uac1 it to another sound card he has to
>> unload g_audio or reconfigure it through configfs - that means USB
>> reenumeration on host device.
>>
>> If you have a "virtual sound card", audio processing is done in userspace
>> and is more flexible. You even don't need to have a real sound card and
>> can use some userspace application for playing/capturing audio samples.
>> Moreover, existing f_uac2 (that is USB Audio Class 2.0 function
>> implementation) already uses approach of "virtual sound card"
>>
> While I agree the virtual sound card approach is the right way, I am
> not sure if we should break the userspace api that the existing UAC1
> driver exposes. Maybe we should add another virtual-sound-card
> exposing UAC1 driver
This approach is quite easy to implement and I though about it when
started to work on this patch series, but due to my lazyness I wanted
to get some comments before doing extra work.
> ... and hopefully very similar to (or just port
> of) the f_audio_source.c from android.
Current patch series reuses code from f_uac2 (in u_audio) and
makes it in some sense similar to f_audio_source.c.
The f_audio_source.c implementation has additional functionality
like more accurate data transferring (w.r.t timings), that can be
ported to u_audio separately.
Best regards,
Ruslan
prev parent reply other threads:[~2016-07-26 21:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-23 23:50 [RFC PATCH 0/5] USB Audio Gadget refactoring Ruslan Bilovol
2016-05-23 23:50 ` [RFC PATCH 1/5] usb: gadget: f_uac2: remove platform driver/device creation Ruslan Bilovol
2016-05-23 23:50 ` [RFC PATCH 2/5] usb: gadget: f_uac2: split out audio core Ruslan Bilovol
2016-05-23 23:50 ` [RFC PATCH 3/5] usb: gadget: f_uac1: drop volume/mute functionality Ruslan Bilovol
2016-05-23 23:50 ` [RFC PATCH 4/5] usb: gadget: f_uac1: switch to u_audio core utilities Ruslan Bilovol
2016-05-23 23:50 ` [RFC PATCH 5/5] usb: gadget: f_uac1: add capture support Ruslan Bilovol
2016-06-08 8:03 ` [RFC PATCH 0/5] USB Audio Gadget refactoring Ruslan Bilovol
2016-07-14 21:38 ` Ruslan Bilovol
2016-07-15 7:43 ` Clemens Ladisch
2016-07-26 1:31 ` Ruslan Bilovol
2016-07-26 8:06 ` Clemens Ladisch
2016-07-26 21:22 ` Ruslan Bilovol
2016-07-26 8:53 ` Jassi Brar
2016-07-26 12:02 ` Krzysztof Opasiak
2016-07-26 21:55 ` Ruslan Bilovol
2016-07-26 21:38 ` Ruslan Bilovol [this message]
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