Apple

I am already aware of most of this material. Unfortunately, none of this material seems to answer my questions.

Here's how I see it. The whole AudioUnit rendering process seems to be equivalent to using callbacks in AudioQueue (at least logically, and even programmatically in many ways). Just a bunch of different functions (So that part will, I believe, slip right into my existing code (doubtless after lots of aggravation on my part). I can also appreciate that Xcode might be a pain. These are all details which I believe I can handle.

However, as far as I can tell (and please correct me if I am wrong) none of these examples illustrate what I actually need and what I listed in my original email:

* How to get "signals" from Logic into the plugin - not external MIDI signals (which I can already do) but signals from the Logic software track into which the plugin is plugged. These would probably be called something like Logic "internal MIDI events" or something similar. There must be some function (functions?) to get these.

* How to get output generated by the plugin (created by the rendering) directed to the same instrument track (for instance, so it can be processed by EXISTING effects processors supplied with Logic, which I do NOT want to write).

* How to connect my plugin to automation.

Presumably all this involves figuring out how to fit into the AUGraph structure in LogicPro.

I already have a classy stand-alone synth - fancy GUI, nice DSP processing routines, etc etc etc. What I need is really simple and basic - bare-bones function calls that allow me to do what is listed above. I don't want C++ classes (I'm not using C++), I don't want convenience routines. All these things are just wrappers around C (objective C) functions. I want the relevant functions.

Again, thanks for your response, and (hopefully) for additional responses.

Perhaps, as a final comment, it will be necessary for me to pay an Apple engineer to help me with this. It is a sign of my desperation that I am actually willing to do this if I could be sure that, after spending the money, I would have my answer (and if Apple even offers this service). I'd even enroll in a course (if such a thing exists).

Anyway, thanks again.

Steve

BTW, just to indicate the paucity of available material on this subject, when I google "programming an au plugin for logic pro" I'm getting back references to my forum postings.

On Apr 13, 2015, at 12:23 PM, Christian Rober <email@hidden> wrote:

I would start with building, installing, running and setting debugger breakpoints in the example AudioUnits in this sample project (look for the different Render, Parameter and MIDIEvent/StartNote calls):

https://developer.apple.com/library/prerelease/mac/samplecode/sc2195/Introduction/Intro.html

While doing that I would refer to this for clarification of both the higher level design and some notable details:

https://developer.apple.com/library/mac/documentation/MusicAudio/Conceptual/AudioUnitProgrammingGuide/Introduction/Introduction.html

You will probably also want the Core Audio helper code files. They are partially included in the sample projects above, but it may best to "install" it in a more accessible/global location that is conducive to your workflow. Among other things, these give helpful c++ base classes for bootstrapping your own Audio Unit via the AU API:

https://developer.apple.com/library/ios/samplecode/CoreAudioUtilityClasses/Introduction/Intro.html

One word of warning: getting the Xcode project/workspace configured for audio units can be tricky and has a few gotchas, especially with respect to older hosts. For example, there are many cases where the older component manager-based code paths require strict matching of properties and strings across multiple files.

I create mine from scratch and pattern-match the sample code environments, others copy and alter the existing ones. Do whichever works the best for you.

Good luck.

--Christian

On Mon, Apr 13, 2015 at 11:34 AM, Steven Brawer <email@hidden> wrote:

I apologize in advance if this topic has been discussed or if this is not the correct forum. And if I am asking too much.
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I have created a complex and sophisticated synthesizer with objective C, Cocoa and AudioQueue. (For just onesimple example, frequencies, amplitudes and timbres can fluctuate on sub-millisecond up to seconds time scales. There is no start/end latency.) The synth receives MIDI signals from a LogicPro external MIDI track and outputs to standard out (which is piped back to a Logic audio track via an audio interface). Objective C classes organize the modules of the project, while time-critical variables and calculations use C. There is no C++ (which I know). It runs in X-code.
I would like to make this synth an au plugin app for LogicPro, and am looking for MINIMAL help or examples to guide me. I think I need only a few things. POINT ME TO THE APPROPRIATE FUNCTIONS (see below) and I will figure out the rest. I'm just asking for a few words. I will use audio graphs if necessary.
1. What is the C/Obj C function (or functions) needed to capture signals from the Logic software tracks into which the plugin is inserted? (These would replace/expand MIDI signals with Logic signals.)
2. What is the C/Obj C function (or functions) to send the output directly to the instrument track?
3. What is the C/Obj C function (or functions) required for automation?
4. How do I create the app bundle and where do I put it?
5. I have been informed that Audio Queue cannot be used in an au plugin. Is this true? Is there an alternative that operates in essentially the same manner?
Currently, the synth is for my own personal use for composing opera and songs using custom instrumental sounds. I am not fooling around. See soundcloud.com/steven-brawer for a sci-fi opera composed entirely with Logic 9.
I use XCode 5.1.1, Logic Pro 10.0.7, OSX 10.8.5. I plan to upgrade to Yosemite, Logic 10.1 and the most recent XCode when I see from the forums that things have settled down sufficiently.
Thank you in advance.

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