[Jack-Devel] About ALSA drivers for Firewire sound devices

HI,

I'm a newbie for this project. I'm a ALSA/FFADO developer and currently
working for ALSA drivers of some firewire devices.

[alsa-devel] [RFC v3] [PATCH 00/52] Enhancement for support of firewire
devices
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

And call for testing in 'Linux Audio Devel':
[LAD] Call for testing (final): ALSA driver for some firewire devices
http://lists.linuxaudio.org/pipermail/linux-audio-dev/2014-January/034662.html

The drivers have almost the same streaming functionality as FFADO has.
The drivers are for some devices so-called 'GenericAVC', based on
Fireworks/BeBoB/OXFORD.

Currently they aren't going to be merged to upstream. i have some
discussion about adjustment between the new drivers and related projects.

At first, to PulseAudio.

[pulseaudio-discuss] 'Failed to find a working profile' for firewire
sound devices
http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-January/019685.html


Next, to FFADO.
http://sourceforge.net/mailarchive/forum.php?thread_name=52D8EE54.1040500%40sakamocchi.jp&forum_name=ffado-devel


Finally, to JACK... I have no issue to JACK :p

JACK is still a good friend to Firewire sound devices. But I inform
three points to you.

1. Daisy-caining
With FFADO backend, jackd can handle some firewire devices. But with
ALSA backend, jack can't. This rule is still applied to the new drivers.

When users want to use several ALSA PCM devices for firewire sound
devices, they must write ALSA configuration with 'multi' plugin. See in
detail:
http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html#pcm_plugins_multi


2. conflict between ALSA/FFADO streaming functionality
Both starts streaming. But generally, one device can handle a pair of
streams (in and out).  So FFADO/ALSA can conflict for streaming.

To prevent this, I post a patch to FFADO. If this patch is applied, when
at least one of connected firewire devices is streaming, jackd with
FFADO backend fails to start streaming.

[FFADO-devel] Adjustment between FFADO/ALSA for Firewire drivers
http://sourceforge.net/mailarchive/message.php?msg_id=31856195

Here I have to mention about MIDI functionality. When users use ALSA
MIDI functionality, the new drivers also start streaming because
firewire streaming includes both of PCM samples/MIDI messages.

Some graphical JACK application such as 'patchage' displays ALSA MIDI
ports when jackd is running. But users can't do this. Vise versa, when
users use any ALSA MIDI ports, then jackd always failed.


3. control for internal mixer
The new drivers don't give this functionality. So users still need
applications for it, like FFADO Mixer.


Regards

Takashi Sakamoto

1391007973.15012_0.ltw:2,a <52E918DA.6020303 at sakamocchi dot jp>