Add beaglebone audio applications

ideas/beaglebone-audio-applications.rst

@@ -3,5 +3,112 @@
 Beagle Bone Audio Applications
 ###############################
 
-Porting multi-channel sound card drivers to recent kernels
-***********************************************************
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+.. card:: 
+    
+    **Porting multi-channel sound card drivers to recent kernels**
+    ^^^^^
+
+    Goal: Porting sound card drivers to recent kernels.
+
+    As part of this project you will develop and/or update kernel audio drivers for some soundcards 
+    currently available for the BeagleBoard series of SBCs. The objective is to have support for the 
+    latest TI kernel (> 5.10) and for some of the most recent TI SoC, such as the Sitara AM6xxx series 
+    that is on the `SK-AM62 <https://www.ti.com/tool/SK-AM62>`_ board and the TDA4VM that is on the 
+    `BeagleBone AI-64 <https://beagleboard.org/ai-64>`_.
+
+    1. The Bela and BelaMini capes feature a TLV320AIC3104 codec (stereo I/O) controlled via I2C and connected to the McASP clock and data lines. This could be used in older kernels and architectures (e.g.: up to 4.14 on Sitara AM3358) with the simple-audio-card driver and a relevant device tree fragment. It has to be tested whether it still works on more recent kernels and SoCs.
+    2. A multi-channel version (BelaMiniMultichannelExpander) combines 1x TLV320AIC3104 and 3xTLV320AIC3106 to achieve 8in/8out; this is supported via a `Bela-specific library <https://github.com/BelaPlatform/Bela/blob/master/core/I2c_MultiTLVCodec.cpp>`_ but there is no kernel support for it yet.
+    3. The Bela cape Rev C adds an ES9080Q 8-channel DAC which is also connected to the McASP; this is supported via a `user-space Bela-specific library <https://github.com/BelaPlatform/Bela/blob/master/core/Es9080_Codec.cpp>`_, but there is no kernel support for it yet.
+    4. The CTAG capes have an AD1938 codec (4in / 8out) which is controlled via SPI, has an on-board crystal oscillator and are connected to the McASP data and clock lines. This has its own device driver which has been fixed up a few times over time (most recently `here <https://forum.bela.io/d/2578-ctag-face-support-in-linux-5-x-kernel/18>`_, AFAIK) but its features are limited and needs to be tidied up and tested on newer kernels.
+
+    - **Software Skills:** C, Linux, Kernel
+    - **Possible Mentors:** rma, henrix, giuliomoro, jluthra
+    - **Expected Size of Project:** 350 hrs
+    - **Rating:** Medium
+    - **Upstream Repository:** where available, listed above
+    - **References:** 
+        - https://github.com/BelaPlatform/Bela
+        - https://learn.bela.io/products/
+
+    ++++
+
+.. card:: 
+
+    **IP Media Streaming**
+    ^^^^
+
+    - **Goal:** Building on a Beagle GSoC project of 2017 and 2020, the idea is to extend / add audio network streaming capabilities using the AVB and / or the Ravenna / AES67 standards.
+    - **Software Skills:** C/C++, Linux, Kernel
+    - **Possible Mentors:** rma, henrix
+    - **Expected Size of Project:** 350 hrs
+    - **Rating:** Medium
+    - **Upstream Repository:** TBD
+    - **References:** 
+        - https://niklaswan.github.io/GSoC-Overview 
+        - https://elinux.org/BeagleBoard/GSoC/BeagleBoneAVB
+
+    ++++
+
+.. card:: 
+
+    **Bela audio driver for common audio APIs**
+    ^^^^
+
+    Bela uses its own custom audio API which bypasses ALSA altogether. When adding support for Supercollider and Csound, 
+    we had to add a new audio driver to these pieces of software to call into Bela’s C API. In order to make the process 
+    of adding Bela support to more programming languages in the future easier, we could think of simply adding Bela support 
+    to some common audio backend libraries, so that a single effort can be reused across several pieces of software that 
+    use that same library. Examples of such libraries are: portaudio, rtaudio and jack and there may be more. In this 
+    project you’ll write a Bela driver for one or more of these libraries and build at least one application that uses 
+    the library (e.g.: ChucK, which uses RtAudio or Pure Data, which uses portaudio). You will need a good knowledge of C 
+    and build systems. Upon successful completion, the project will make it easier to add more applications and programming languages to Bela.
+
+    - **Goal:** Improve the portability of Bela code across audio APIs/ Hardware Skills: Minimal
+    - **Software Skills:** C / make Possible Mentors: giuliomoro
+    - **Expected Size of Project:** 350 hrs
+    - **Rating:** Medium
+    - **Upstream Repository:** 
+        - https://github.com/BelaPlatform/Bela
+        - https://github.com/thestk/rtaudio
+        - https://github.com/PortAudio/portaudio
+
+    ++++
+
+.. card:: 
+
+    **Live patching of Pure Data on embedded devices**
+    ^^^^
+
+    Pure Data (Pd) is a visual data-flow language for audio applications and it is one of the several languages supported 
+    by Bela. Pd ships as a cross-platform software with a C backend and a Tcl/Tk GUI (replaced by HTML5 in the PurrData project). 
+    When running Pd on Bela, the user can leverage the analog and digital I/Os of the board to integrate audio processing with 
+    the physical connectivity capabilities of the board. Bela provides access to a browser-based IDE for programming the board 
+    but, since a desktop environment is not available, the current workflow for using Pure Data on Bela consists in editing the 
+    patch on the host computer and then copying it over to Bela where it gets executed.
+
+    One of the limitations of this two-step workflow is that the immediateness of the live-patching behaviour of Pd is lost. In this project, 
+    the student will leverage the fact that Pd communicates with its GUI via a socket to run the GUI on the host computer while running the 
+    audio backend on Bela. This requires a number of adaptations to Pd, including:
+
+    - managing the GUI startup process to allow GUI and audio backend to be started separately and connect to each other
+    - allowing access to paths on the remote device
+    - loading patches through the GUI instead of from the backend
+    - delegating some of the functionalities currently handled in the backend to the GUI
+
+    Knowledge of C is required as part of the work will take place in the audio backend, however there will be need to operate on the 
+    GUI side as well. A good starting point for the project would be last year's GSoC project which managed to run PurrData entirely 
+    in the browser. At the end of a successful project we should be able to submit a pull request in the upstream Pure Data or Purr 
+    Data repositories. The benefits of this contribution will not be exclusive to Bela, but can benefit the Pd community at large, 
+    making it easier to use Pure Data on embedded devices.
+
+    - **Goal:** Allow live patching of Pd on embedded devices. Hardware Skills: Minimal
+    - **Software Skills:** Javascript/HTML, possibly using Svelte as a framework
+    - **Possible Mentors:** giuliomoro
+    - **Expected Size of Project:** 350 hrs
+    - **Rating:** Medium
+    - **Upstream Repository:** 
+        - http://github.com/pure-data/pure-data/
+        - https://git.purrdata.net/jwilkes/purr-data/
+        - https://gist.github.com/hugonxc/75e0bb838b1953cfa52fa87045bf5b98#file-gsoc2020_hugocarvalho_purrdata-md
+
+    ++++
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