Hi Harry,
> At no point to I think Ctlra will *require* also using TCC. It just
so happens that they complement each other well for my use-cases.
That seams to be a good approach. If the architecture allows to put
Ctlra drivers into runtime loaded object files, it does not matter which
compiler is used and if it turns out that TCC is the best for our needs
on a platform, fine.
> That proposal looks really good. It basically means, from a Ctlra
POV, that Ctlra is plain old C code, and exposes generic events.
No, not generic events. The Ctlra using apllications should receive a
specific event. If you turn the gain Knob on a controller, the
application should be able to now that this is the Knob labeled with
"Gain" grouped for Deck A. This might be done by a generic event + a
link into a manifest file, which may also include a photo of the
controller. This metada of each event should be optimized to be
translated into a OSC address, this should be a mandatory part of Crtra.
So we need a document like this:
https://github.com/fabb/SynOSCopy/wiki
> The application can interpret those in whatever way it wants - OSC,
JS/Mixxx, or however OpenAV stuff will end up doing this. It keeps Ctlra
just generic events, and allows the application to solve the mapping
problem in its own way. That sounds logical and a good abstraction,
which is exactly what Ctlra aims for.
Yes, that is right. Today in case of midi, the user has to figure out
which midi key is doing what. With a Ctlra enabled controller this
issue should be gone. The mapping solution can for example show the
photo of the controller, and highlight the place of action.
But even without the photo, the user knows exactly how to enable a knob
LED, using the OSC name-space as address.
> In order to progress this idea, I'll post code up ASAP, which makes
the generic Ctlra events available in a callback as part of the
CtlraController class. After that, the Mixxx/JS components must be
designed / worked on to fully enable Ctlra in Mixxx.
Thank you :-)
I think for the OCS Plug and Play stuff we just need to rethink the API
a bit.
I would like to do something like this
https://github.com/mixxxdj/mixxx/blob/lv2_support2/src/effects/lv2/lv2manifest.cpp
in Ctlra as well.
(Sorry, I am not completely though the API so this might be wrong)
We need a kind of generic data point enumerator expression for every
event, which is able to discover all controller features.
Every data point should have a function for examine like
ctlra_dev_get_osc_namespace() and ctlra_dev_get_picture_location()
Will this work? Does this fit to the ctlra goals?
Kind regards,
Daniel
Am 09.07.2017 um 13:18 schrieb Harry van Haaren:
On Sun, Jul 9, 2017 at 11:21 AM, Daniel Schürmann <dasch...@mixxx.org
<mailto:dasch...@mixxx.org>> wrote:
Hi Harry, Hi Be,
here some comments:
IMHO arguing about If C or JS is easier will not lead us ahead in
this discussion.
Good point - apologies for the rat-hole.
> As noted above, we can take TCC off the table for Mixxx's use
case. Personally I still love it - and it has radically changed
how I think about programming in C - but perhaps its just not a
good fit for Mixxx. I can work with that.
I am afraid a mandatory TCC based Ctlra solution will prevent it
from being successful.
At no point to I think Ctlra will *require* also using TCC. It just so
happens that they complement each other well for my use-cases.
Only a solution that works nice Windows as well as on non X86
based architectures will be accepted as a new standard.
TCC supports a variety of targets; and despite no official releases,
the git repo is pretty active: http://repo.or.cz/w/tinycc.git
For me, the key is here to be modular. Similar to LV2 each driver
Ctlra driver can be shipped with a source file and a meta-data
file which should contain a recipe to turn the source file into a
*.so or a dll. In a future advanced step, the hosts Ctlra library
code should be responsible to read the recipe and do what it
should be done to turn it into a binary.
I'm not sure what the benefit is here - i see a pretty complex
workflow, but no ultimate gain that TCC doesn't already provide. But I
said I'd drop the TCC idea and discuss other options.
> Lets find a better solution for novice / casual users who don't
want to compile anything.
The compile step itself is not the issue. If we look for example
to OpenGL Shading Language, where we also have a compiler step no
one noticed.
Good point.
>> Even if we have a ctlra controller in Mixxx, we need to adapt
the signals to Mixxx Control Objects using xml or js files.
> Why XML or JS? I see many more options, and just because we have
existing infrastructure for a similar case doesn't mean its always
the correct solution.
Just because Mixxx is using it right now. It is IMHO not in the
responds of Ctlra to convert controller events into application
commands.
OK - then lets investigate this option more. Keep in mind that my JS
experience is limited, and that I'm not particularly familiar with
QT/Mixxx's JS engine capabilities.
I'll post a PR asap that exposes Ctlra events to Mixxx, and then see
what kind of JS magic is required on top to expose that to the JS
mapping scripts.
> I'm still not convinced it is possible for any point-and-click
system to fully map most controllers **in a maintainable way**. ...
This is should be out of scope of Ctlra.
Absolutely yes - this is outside the scope of Ctlra - at this point we
are talking about the integration of Ctlra + Mixxx in particular. This
was noted by a few developers at the LAC too, that device access is
only a part of the problem. Providing a good mapping mechanism is the
harder part. But we need step 1 (Ctlra device access) before step 2
(easy/powerful mappings).
IDEA:
Thinking of all of this again, I think this Ctlra project is a
great chance to fix some issues, existing standards have.
* Midi: Midi is that successfully, because it is defined up to the
Application layer for a Midi-Keyboard. Reusing this for other
types of controllers works, but pushes it down to the Presentation
Layer.
* OSC: OSC fails to define the Application layer. It is promoted
to be a Midi successor, but it even has no standard way to even
transport good old midi messages. There are approaches to fix this
in some OSC namespaces, but this is somehow stucked.
It would be grate If we could get back to the state of original
Midi Plug-And-Play behaviour for Midi-Keyboard for all type of
controllers using Ctlra. If we do this along with a OSC namespace
for Ctlra, this will be a great benefit and probably a very
successfully.
Lets see!
On a Midi-Keyborad you know exactly which phsical key is pressed
an how just looking to the midi Message.
This can be done for Ctlra as well, I we define a message like
"Gain Knob Deck A 56 %" So a new controller will be instantly
usable for Mixxx with a basic default mapping. This is probably
not sufficient, but putting a new function on "Gain Knob Deck A"
can be done by existing mapping solutions.
Yes, simple "static" mapping schemes can be easily handled by mapping
event IDs to ControlProxy objects. As Be pointed out, the difficult
point is layering multiple functionalities over each other in a
user-workable way.
I have these Architectures in mind:
OpenAV setup:
HID-Controller
V
Ctlra Driver
V
Cltra Lib
V
C Mapping
V
OpenAV App
Mixxx setup:
HID-Controller
V
Ctlra Driver
V
Cltra Lib
V
Controller Proxy
V
XML / *js mapping
V
Mixxx engine
Gnereic OSC setup:
HID-Controller
V
Ctlra Driver
V
Cltra Lib
V
OSC Wrapper (process)
V
UDP/TCP
V
OSC to OSC mapper
V
UDP/TCP
V
OSC enabled DAW
What do you think?
That proposal looks really good. It basically means, from a Ctlra POV,
that Ctlra is plain old C code, and exposes generic events. The
application can interpret those in whatever way it wants - OSC,
JS/Mixxx, or however OpenAV stuff will end up doing this. It keeps
Ctlra just generic events, and allows the application to solve the
mapping problem in its own way. That sounds logical and a good
abstraction, which is exactly what Ctlra aims for.
In order to progress this idea, I'll post code up ASAP, which makes
the generic Ctlra events available in a callback as part of the
CtlraController class. After that, the Mixxx/JS components must be
designed / worked on to fully enable Ctlra in Mixxx.
Thanks for all the input - we seem to be converging on a solution,
great! -Harry
Am 09.07.2017 um 06:52 schrieb Be:
Hi Harry,
I read the paper for the presentation at LAC 2017 that you linked
on IRC:
http://musinf.univ-st-etienne.fr/lac2017/pdfs/01_C_E_137795.pdf
<http://musinf.univ-st-etienne.fr/lac2017/pdfs/01_C_E_137795.pdf>
Going along with what I mentioned in my previous post, I do not
think Ctlra should be aware of the "userdata". IMO that should be
left to the application and its scripting environment.
On 07/08/2017 08:36 PM, Be wrote:
On 07/08/2017 06:51 PM, Harry van Haaren wrote:
3. The programming language. It is a lot easier to find
someone who
knows JavaScript, or at least kinda knows JavaScript enough
to get
by for a small project, than it is to find someone who
knows C. For
people with minimal or no prior programming experience,
higher level
languages are much easier to learn.
Surely anybody somewhat proficient in JS can figure out what
this (link below) does?? Programming is programming - logical
thinking. I don't think that the C code there is "harder" than
achieving the same in JS. Keep in mind we're not asking people
to do pointer-magic here - its basic arithmetic, and calling a
functions.
https://github.com/openAVproductions/openAV-Ctlra/blob/master/examples/vegas_mode/z1.c#L45
<https://github.com/openAVproductions/openAV-Ctlra/blob/master/examples/vegas_mode/z1.c#L45>
C is more difficult to learn than JavaScript. There are a lot of
details in that code that you simply don't have to think or know
about with JavaScript. To a novice developer who knows nothing
about C, they'd have to answer these questions:
> if(e->slider.id <http://slider.id> ==
NI_KONTROL_Z1_SLIDER_LEFT_FADER) {
What is the difference between "->" and "."?
> uint32_t iter = (int)((d->volume+0.05) * 7.f);
1. What is a uint32_t? Why should I use that instead of a
different number type?
2. What is that "(int)" doing?
3. Why is there a ".f" after the "7"?
That's just the tip of the iceberg of understanding a few lines
of code. Fully mapping controllers requires considerably more
complex logic than that.
So, I think it would make more sense to expose Ctlra to
Mixxx's
existing JavaScript environment for controller mapping.
There would
only need to be two capabilities added for this to work:
1. Scripts would be able to register JavaScript callback
functions
that would be called when particular Ctlra events are
passed to Mixxx.
2. Scripts would need to have a way to send output messages to
Ctlra. There should be a way to freeze/unfreeze the sending of
output messages so many outputs could be updated
simultaneously in a
single HID packet.
I have written a proposal for how to do this with MIDI:
https://mixxx.org/wiki/doku.php/registering_midi_input_handlers_from_javascript
<https://mixxx.org/wiki/doku.php/registering_midi_input_handlers_from_javascript>
<https://mixxx.org/wiki/doku.php/registering_midi_input_handlers_from_javascript>
<https://mixxx.org/wiki/doku.php/registering_midi_input_handlers_from_javascript>
It would be great if we could create JS APIs that are almost
identical for MIDI and Ctlra.
I'm still not sold on the idea of wrapping all of Ctlra up in
JS callbacks and then exposing it to Mixxx. Its possible, but I
fail to see why this should be the holy-grail of how mappings
should work. I should probably do up a design-doc or video on
how I think *eventually* the Ctlra / Mixxx UX for mapping a
controller would look: and if I can figure out the technical
parts, it will be pretty revolutionary in how it enables novice
users to create unique mappings. Punch line is to present the
functionality (multi-layered bindings) in a way that is easily
consumed by "ordinary" humans, and provide a doc + video
explaining it. Give me a few weeks - some POC Ctlra + Mixxx
code first, then onwards to the exact mapping UX.
I'm still not convinced it is possible for any point-and-click
system to fully map most controllers *in a maintainable way*.
Years ago, device specific hacks were added to Mixxx in C++ to
make the XML system work with MIDI signals for jog wheels.
Someone please correct me if I am wrong, but my understanding is
that the JS engine was added to avoid the need for such
compiled-in device specific hacks. Almost all mappings submitted
for inclusion in Mixxx recently have been done mostly or
entirely in JS. Traktor has an elaborate point-and-click mapping
system and users complain how awful it is to work with (refer to
https://djworx.com/what-do-you-want-from-traktor-pro/
<https://djworx.com/what-do-you-want-from-traktor-pro/> for
example).
I have previously thought about designing a GUI that used tabs
to organize different layers of functionality. But this would
break down quickly for handling the interaction of multiple
layers and create a mess even worse than Traktor's mapping GUI.
For example, consider a cue button that uses the cue_default
ControlObject normally but start_stop while a shift button is
held. You could define a layer that the unshifted button belongs
to and another layer that the shifted button belongs to. Okay,
easy enough. Now you want to make that side of the controller
able to be toggled between deck 1 & deck 3. How would you
accomplish this? With a simple layering system, you could create
4 different layers:
Deck 1 unshifted
Deck 1 shifted
Deck 3 unshifted
Deck 3 shifted
Then you'd need to copy & paste all those 4 layers for the other
side of the controller with decks 2 & 4! It would be possible to
hack support for toggling decks into Mixxx so the mapping could
deal with a virtual deck and Mixxx would maintain the state of
which deck is active, but that would only handle this specific
use case. And you'd still need to copy & paste for the left &
right sides of the controller.
What if I want pushing a button to use the beatloop_activate
ControlObject when no loop is active but use reloop_toggle when
a loop is active? I'd need to create a layer for a loop being
enabled and a layer for no loop enabled, then somehow tell Mixxx
to switch between them when that state changes. Then I'd have to
duplicate both those layers for deck 1 & deck 3. Now I want
pressing that button to act differently when shift is pressed --
and act differently depending on whether a loop is active. When
shift is pressed, I want to use reloop_toggle with no loop
active and reloop_andstop with a loop active. With a GUI
layering system, I'd need layers for:
Deck 1, loop disabled, no shift
Deck 1, loop disabled, shift
Deck 1, loop enabled, no shift
Deck 1, loop enabled, shift
Deck 3, loop disabled, no shift
Deck 3, loop disabled, shift
Deck 3, loop enabled, no shift
Deck 3, loop enabled, shift
And again copy and paste for decks 2 & 4. Now there are 16
layers for pushing this button! What if you wanted to remap it?
Maintaining even this example would be a pain, and that's just
one component of the controller. Programming an entire mapping
this would would be awful.
Also consider how you could implement
https://mixxx.org/wiki/doku.php/standard_effects_mapping
<https://mixxx.org/wiki/doku.php/standard_effects_mapping>
for the Kontrol X1, S2, S4, and S5 with such a system. Again,
you could hack all that logic into the C++ side of Mixxx like
the deck toggling case, but then what would you do to implement
something like the effects mapping for the Pioneer DDJ-SB2:
https://mixxx.org/wiki/doku.php/pioneer_ddj-sb2#effects
<https://mixxx.org/wiki/doku.php/pioneer_ddj-sb2#effects>
(particularly the Mixxx 2.1 mapping).
This video talks about the uselessness of visual diagramming
languages like UML, and I think much of what is said about
visual diagramming languages in this applies to programming with
a GUI as well:
https://www.youtube.com/watch?v=4_SvuUYQ5Fo
<https://www.youtube.com/watch?v=4_SvuUYQ5Fo>
That said, if you have revolutionary ideas for how to design a
GUI for mapping controllers that could actually handle all the
complexity above and not be a huge pain to work with, please
share. I'd love to be proven wrong... but I think it's more
likely that you'd waste time that could be better spent making
Mixxx do other cool things or writing a new OpenAV application.
Thanks for your input again - good points raised. -Harry
On 07/06/2017 04:57 PM, Harry van Haaren wrote:
Hi All,
First of all - this is my first post to the Mixxx-devel
list, so
a brief intro is in order;
I'm Harry van Haaren, developer of the OpenAV audio
software,
bit of a music/tech/linux head :)
I've recently been working on improving controller
support in
Linux audio land, in particular
what I call "modern USB HID" controller devices (think DJ
controllers like Akai/NI/Abletons range).
I've developed the Ctlra library as OpenAV, which provides
access to these hardware devices
on Linux. The library allows hotplug and various other
"advanced" features like accessing
screens on devices.
I'd like to integrate Ctlra into Mixxx - to provide
access to
hardware currently not available
to Linux users, and also to provide hotplug support to
those
controllers. I've created a blueprint
on Launchpad[1], and written an introduction on Ctlra
and how I
propose to integrate it in Mixxx[2].
Finally, there is a documentation page on what Ctlra
itself
achieves here[3], and the source is here[4].
If you have an interest in hotplug of controllers,
controller
support or hardware on Linux,
do have a read of the wiki page and others, and I'd
appreciate
your input on the ideas!
Thanks for all your efforts on Mixxx so far, onwards
and upwards!
-Harry of OpenAV
[1]
https://blueprints.launchpad.net/mixxx/+spec/ctlra-controller-support
<https://blueprints.launchpad.net/mixxx/+spec/ctlra-controller-support>
<https://blueprints.launchpad.net/mixxx/+spec/ctlra-controller-support>
<https://blueprints.launchpad.net/mixxx/+spec/ctlra-controller-support>
[2] https://www.mixxx.org/wiki/doku.php/ctlra_support
<https://www.mixxx.org/wiki/doku.php/ctlra_support>
<https://www.mixxx.org/wiki/doku.php/ctlra_support>
<https://www.mixxx.org/wiki/doku.php/ctlra_support>
[3] http://openavproductions.com/doc/ctlra.html
<http://openavproductions.com/doc/ctlra.html>
<http://openavproductions.com/doc/ctlra.html>
<http://openavproductions.com/doc/ctlra.html>
[4] https://github.com/openAVproductions/openAV-ctlra
<https://github.com/openAVproductions/openAV-ctlra>
<https://github.com/openAVproductions/openAV-ctlra>
<https://github.com/openAVproductions/openAV-ctlra>
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