[RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[Takashi Sakamoto]

Hi,

This is request-for-test (RFT) to the ALSA control service programs for
Digidesign Digi 002/003 family and Tascam FireWire series. The programs
are available in 'topic/services-for-dg00x-tascam' of below repository,
and the RFT is corresponding to Pull Request #1:

* https://github.com/alsa-project/snd-firewire-ctl-services/

Background
----------

The models in above family and series are already supported by drivers in
ALSA firewire stack for their isochronous packet stream functionality.
Although the drivers allow userspace applications to process PCM frames
and MIDI messages in the packet streaming, they doesn't support the other
functionalities such as volume control since it can be achieved by any
usespace applications of Linux firewire subsystem.

The service programs added by this patchset are for the supplemental
functionality to control the models by asynchronous packet transaction or
to process a part of data transferred by the isochronous packet stream.

In detail, please read README.rst in the repository[1]. You can see some
illustrations.

How to build
-------------

The project depends on several libraries in below repositories:

* glib[2]
* alsa-gobject v0.1.0[3]
* libhinawa v2.0.0[4]

Before building it, please install them with gobject-introspection support.

The project is written by Rust programming language[5] and packaged by
cargo[6]. To build, just run below commands in the environment to connect
to internet:

```
$ git clone https://github.com/alsa-project/snd-firewire-ctl-services.git -b topic/services-for-dg00x-tascam
$ cd snd-firewire-ctl-services
$ cargo build
```

All of required crates are downloaded automatically, then start build.

Executables
-----------

The added executables are listed below:

 * snd-firewire-digi00x-ctl-service
 * snd-firewire-tascam-ctl-service

When running, the programs add and maintain control elements, then enter
event loop to dispatch events. Thes elements are visible and manipulable
for any userspace applications. The program dispatch any manipulation
event for transactions to control actual device. For console model and
FE-8 in Tascam FireWire series, the program adds and maintains port in
ALSA Sequencer.

They have command line options. For all models of Digi 002/003 family, the
executable has an option for the numerical ID of sound card.

```
Usage:
  snd-firewire-digi00x-ctl-service CARD_ID

  where:
    CARD_ID: The numerical ID of sound card.
```

For models of Tascam FireWire series except for FE-8, the executable should
run with 'snd' as its first option and the numerical ID of sound card as
second option. Tascam FE-8 is supported by the service program but not
supported by ALSA firewire stack since it doesn't handle isochronous
packet streaming. For FE-8, the executable should run with 'fw' as its
first option and the numerical ID of firewire character device.

```
Usage:
  snd-firewire-tascam-ctl-service SUBSYSTEM ID

  where:
    SUBSYSTEM: The name of subsystem; 'snd' or 'fw'
    ID: The numerical ID of sound card or fw character device
```

It's easy to run the executables by cargo, like:

```
$ cargo run --bin snd-firewire-digi00x-ctl-service 2
```

Receiving SIGTERM signal terminates the event loop, then the program
finishes.


Access permissions for relevant character devices
--------------------------------------------------

The executables manipulate below character devices to dispatch, convert, and
emit event from end to end. The '%u' is the numerical number in each
subsystem:

 * ALSA control character device (/dev/snd/controlC%u)
 * ALSA hwdep character device (/dev/snd/hwC%uD%u)
 * Linux firewire character device (/dev/fw%u)

Additionally, the service program for Tascam FireWire series manipulates ALSA
sequencer character device (/dev/snd/seq) to handle events of control
surface for console model. Users should pay enough attention to access
permission for the above character devices when running the service program.

Feedback
--------

Any feedback is welcome. For questions, please use mailing list in alsa-devel
or alsa-users[7]. For issues, please use service of github.com[8].

Issues
------

The name of control elements are not fixed yet since the convention of
name for element set is not clear yet for recording equipment.

Users may feel inconvenience to which channel corresponds to which physical
port. Furthermore, in the case that element set includes several elements,
it's unclear that which element corresponds to which physical port as well.
ALSA control core has no feature for the above issues at present.

[1] https://github.com/alsa-project/snd-firewire-ctl-services
[2] https://gitlab.gnome.org/GNOME/glib
[3] https://github.com/alsa-project/alsa-gobject/
[4] https://github.com/alsa-project/libhinawa
[5] https://www.rust-lang.org/
[6] https://doc.rust-lang.org/cargo/
[7] https://www.alsa-project.org/wiki/Mailing-lists
[8] https://github.com/alsa-project/snd-firewire-ctl-services/issues


Regards

Takashi Sakamoto

Re: [RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[Jaroslav Kysela]

Dne 07. 07. 20 v 14:56 Takashi Sakamoto napsal(a):


> They have command line options. For all models of Digi 002/003 family, the
> executable has an option for the numerical ID of sound card.
> 
> ```
> Usage:
>    snd-firewire-digi00x-ctl-service CARD_ID
> 
>    where:
>      CARD_ID: The numerical ID of sound card.
> ```

It's better to handle both card number and the card id string. In the latter 
case, the user may create independent environment and use udev or 
modprobe.conf configurations to address the devices. The card number may 
change when the plug-and-play devices are randomly connected / disconnected.

snd_card_new() - third argument.

						Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

Re: [RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[Takashi Sakamoto]

Hi Jaroslav,

On Tue, Jul 07, 2020 at 03:15:53PM +0200, Jaroslav Kysela wrote:
> Dne 07. 07. 20 v 14:56 Takashi Sakamoto napsal(a):
> > They have command line options. For all models of Digi 002/003 family, the
> > executable has an option for the numerical ID of sound card.
> > 
> > ```
> > Usage:
> >    snd-firewire-digi00x-ctl-service CARD_ID
> > 
> >    where:
> >      CARD_ID: The numerical ID of sound card.
> > ```
> 
> It's better to handle both card number and the card id string. In the latter
> case, the user may create independent environment and use udev or
> modprobe.conf configurations to address the devices. The card number may
> change when the plug-and-play devices are randomly connected / disconnected.
> 
> snd_card_new() - third argument.

Thanks for the comment and I also think it good idea for users to have
fixed configuration since the numerical ID of sound card differs
depending on system environment.

At the same time, I like to keep the specification of service programs
as small as possible. The numerical ID of sound card is enough to
identify target sound card, and it's sole way for it.

If implementing the idea, I need to add enough instructions about the
mechanism of card id string in kernel land so that users can utilize
it without any puzzle. Actually, the mechanism heavily depends on kernel
loadable module domain and I think it better not to consider that the
users are enough friendly to the domain.

Actually there are good tools to identify the numerical ID of user's
sound card, and usage of such tools are more friendly than module
manipulation and option documentation.

For future, I have a plan to write system service to handle udev
event and launch the service programs automatically. For the case,
the event includes enough information to construct arguments for
the service program, therefore no need to handle mapping information
and extra care of the card id string.

At last, the most of drivers in ALSA firewire stack don't support the
card id string, except for my initial work for bebob and fireworks
driver. If ALSA control core had a feature to change card id string
dynamically for existent card instance by ioctl command, or it had a
feature to maintain mapping between card id string and the other
identification such as system-wide or bus-wide UUID, I would be
willing to implement them to the drivers. At present, it's outside
of my work scope.


Thanks

Takashi Sakamoto

Re: [RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[Jaroslav Kysela]

Dne 08. 07. 20 v 16:44 Takashi Sakamoto napsal(a):
> Hi Jaroslav,
> 
> On Tue, Jul 07, 2020 at 03:15:53PM +0200, Jaroslav Kysela wrote:
>> Dne 07. 07. 20 v 14:56 Takashi Sakamoto napsal(a):
>>> They have command line options. For all models of Digi 002/003 family, the
>>> executable has an option for the numerical ID of sound card.
>>>
>>> ```
>>> Usage:
>>>     snd-firewire-digi00x-ctl-service CARD_ID
>>>
>>>     where:
>>>       CARD_ID: The numerical ID of sound card.
>>> ```
>>
>> It's better to handle both card number and the card id string. In the latter
>> case, the user may create independent environment and use udev or
>> modprobe.conf configurations to address the devices. The card number may
>> change when the plug-and-play devices are randomly connected / disconnected.
>>
>> snd_card_new() - third argument.
> 
> Thanks for the comment and I also think it good idea for users to have
> fixed configuration since the numerical ID of sound card differs
> depending on system environment.
> 
> At the same time, I like to keep the specification of service programs
> as small as possible. The numerical ID of sound card is enough to
> identify target sound card, and it's sole way for it.
> 
> If implementing the idea, I need to add enough instructions about the
> mechanism of card id string in kernel land so that users can utilize
> it without any puzzle. Actually, the mechanism heavily depends on kernel
> loadable module domain and I think it better not to consider that the
> users are enough friendly to the domain.
> 
> Actually there are good tools to identify the numerical ID of user's
> sound card, and usage of such tools are more friendly than module
> manipulation and option documentation.
> 
> For future, I have a plan to write system service to handle udev
> event and launch the service programs automatically. For the case,
> the event includes enough information to construct arguments for
> the service program, therefore no need to handle mapping information
> and extra care of the card id string.
> 
> At last, the most of drivers in ALSA firewire stack don't support the
> card id string, except for my initial work for bebob and fireworks
> driver. If ALSA control core had a feature to change card id string
> dynamically for existent card instance by ioctl command, or it had a
> feature to maintain mapping between card id string and the other
> identification such as system-wide or bus-wide UUID, I would be
> willing to implement them to the drivers. At present, it's outside
> of my work scope.

The id can be changed via sysfs:

$ LC_ALL=C ls -la /sys/class/sound/card0/id
-rw-r--r--. 1 root root 4096 Jul  3 11:58 /sys/class/sound/card0/id

I believe that we should offer tools and let users to select the usage way.

					Jaroslav

> 
> 
> Thanks
> 
> Takashi Sakamoto
> 


-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

Re: [RFT] ALSA control service programs for Digidesign Digi 002/003 family and Tascam FireWire series

[Takashi Sakamoto]

Hi,

On Tue, Jul 07, 2020 at 09:56:51PM +0900, Takashi Sakamoto wrote:
> How to build
> -------------
> 
> The project depends on several libraries in below repositories:
> 
> * glib[2]
> * alsa-gobject v0.1.0[3]
> * libhinawa v2.0.0[4]
> 
> Before building it, please install them with gobject-introspection support.
> 
> The project is written by Rust programming language[5] and packaged by
> cargo[6]. To build, just run below commands in the environment to connect
> to internet:
> 
> ```
> $ git clone https://github.com/alsa-project/snd-firewire-ctl-services.git -b topic/services-for-dg00x-tascam
> $ cd snd-firewire-ctl-services
> $ cargo build
> ```
> 
> All of required crates are downloaded automatically, then start build.

I merged the above topic branch into master branch. Please use HEAD of master
branch if you're interested in it.


Thanks

Takashi Sakamoto