Software Lab NMC
Lab 1: Making Music with Pd in Satellite CCRMA
Lab write-up due on Tuesday, July 12 at 9AM
(For the lab write-up, answer all the questions asked below, and include pd patches of your solutions.)
For this lab you need your [Satellite CCRMA kit], a computer to program it, and some headphones with a mini 1/8" stereo jack. During this lab, you will start to use your kit.
- 1 The Satellite CCRMA setup
- 2 Powering Up For The First Time
- 3 Starting Audio And Pd
- 4 Optional: Programming Linux
- 5 Halt Your Board Properly When Finished!
- 6 Install
- 7 Download the Lab Patches to Your Home Directory
- 8 Play Around With the Patches
- 9 Short questions
- 10 Key Repeat
- 11 Design a different musical interaction
- 12 The Community
The Satellite CCRMA setup
Included in your kit you should have
- Satellite CCRMA Hardware (Beagle Board + microSDHC memory card + Arduino Nano + solderless breadboard) - One 5V power adaptor to plug into the Beagle Board - One Ethernet cable for external communication - Arduino Nano - One GT Max adjustable-length USB cable
If you are missing something, please go get it before assembling your kit. Use the USB cable to connect the Arduino to the Beagle Board. Make sure you plug the micro SDHC memory card fully into its seat so that it looks as shown inside the red box:
Powering Up For The First Time
Plug the Ethernet port of the Satellite CCRMA into your laptop. Then plug in the 5V power supply into the Beagle as shown below. You should see some lights turn on, flickering every now and then. This means that Satellite CCRMA is booting up.
Connect To Satellite CCRMA
In order to see what your Satellite CCRMA kit is doing and program it, you need to log in to it. To do so, follow these instructions.
After you login, you will see the prompt ccrma@satellite:~$ This means that you are logged into a computer named "satellite" as the user "ccrma", and you are currently in the directory ~, which is the shortcut for your home directory.
Avoid Powering Down the Board Without Halting it First!
Would you take the battery out of your laptop and unplug its power adaptor without shutting down? I don't think so! The same goes for Satellite CCRMA, at least when you can avoid it, because it is a small computer running linux.
Now we will test the halt procedure. Run the halt command as superuser by typing sudo halt at the Satellite CCRMA prompt. Then you will again have to type in the password temppwd in order to have the privilege to run this command. The SSH connection will be closed, but it will still be 20 seconds or so before Satellite CCRMA has completely shut down. (Note: The command sudo reboot would instead have caused Satellite CCRMA to reboot itself.)
Wait an extra entire minute to ensure that Satellite CCRMA is shut down. However, it will not power itself off. To do this, you need to disconnect the 5V power adaptor from the hub.
Getting Comfortable With Satellite CCRMA
Turn on Satellite CCRMA again using the same procedure as before where you plug the power into the USB hub. After about 30 seconds, the board should be booted up again, so you can log in again by running the command
ssh -X email@example.com
Run the command pwd to find out the current directory. You will find that you are in the ccrma subdirectory of the directory /home.
Type the ls command to see what is in the current directory. The blue items are subdirectories of the current directory. You can change directories using the cd command. For instance, to change into the pd_lecture subdirectory, you should run the command
Now again type pwd to make sure that you understand where you are! Run the ls command to see what files are in here.
Starting Audio And Pd
Start up the Jack audio server by executing the command qjackctl & at the terminal and clicking on the Start button. In order to be able to hear audio, you will need to plug a pair of ear buds, headphones, or loudspeakers into the 1/8" (2.54mm) jack labeled AUDIO OUT on the beagleboard.
Optional: Programming Linux
We don't actually expect you to do anything here, we are just providing some more information that is maybe helpful for you linux gurus. Since ccrma@satellite runs ubuntu linux on an OMAP chip, many standard software packages have been compiled for it. This is why we were easily able to install software such as Jack, Audacity, ChucK, Faust, Jacktrip, and the Arduino software.
If you are lucky, you can install your favorite software using the apt-get utility. To get a list of packages available on the OMAP's ARM architecture, type
sudo apt-cache pkgnames
You will notice that this list is way too long to look at. You can pipe it to the text file using the command
sudo apt-cache pkgnames > packages.txt
and then look at it using emacs packages.txt, or you search for a particular package, such as
sudo apt-cache pkgnames | grep emacs.
Or, you can compile linux software yourself on the Beagleboard. The gcc, g++ tools etc. are already installed.
Type the df command. You can see that there is not a whole lot more than 1GB available on the SD card, so you should only install software if you decide that you need it.
Halt Your Board Properly When Finished!
Remember to shut down your board when you are done before powering it off! (Of course as Spencer pointed out, if you are operating truly autonomously, of course you cannot login and run the halt command. Nevertheless, if it is not too inconvenient please try to shut down properly if you can. If you do not, then you may find that your SD memory card becomes corrupted.) As described above, you can do this by executing the command sudo halt and then waiting 30 seconds before disconnecting the power cables.
If you will use your own laptop, install Pd extended v0.41.4. Make sure that you install the extended version so that you have all of the objects that you need.
If you're running Pd using a desktop machine on the CCRMA network, make sure that you followed the instructions in this lecture for configuring Pd.
Download the Lab Patches to Your Home Directory
- Download the patches into your 250a directory and uncompress the archive: software_lab_pd.zip
Play Around With the Patches
- Open the patch labeled myinstrument. Play around with this patch. You should be able to exhaust its musical potential in a matter of minutes; reflect on its strengths and limitations.
- Also try to understand how it works as a piece of software. (But please don't get hung up on the arcana - as always, if you get stuck, ask for help rather than waste time.)
- Right-click or option-click on any object to get a contextual menu including "help," which opens that object's help patch.
- Right-click on a blank portion of a Pd patch. Now when you select "help" you get a list of Pd's built-in objects, arranged by category.
- In the upper right hand corner of each Pd window is a "help" menu. This accesses the Pd tutorials as well as some online reference documentation.
Why is the following patch a bad idea?
Make a patch that shows how to connect some objects together to calculate the function 1-x where x is an input number. Save the patch in a file called OneMinus.
- What happens when you hold down a key? The behavior may depend on what operating system you are running.
- Is the behavior desirable on your system? What operating system are you running?
Design a different musical interaction
Here are some ideas of changes that might make the patch more interesting:
- Involve more QWERTY keys
- Involve the mouse (see the [MouseState] object)
- Load in a larger collection of samples.
- Implement a mechanism to switch among banks of samples
- Multiple gestures to one result: design a way for the parameters of each triggered note to depend on multiple key presses. For example, maybe only the space bar triggers notes, and all the other keys determine parameters of notes.
- Make your patch automatically generate a bassline as a function of the key presses
- Set multiple parameters modally, as volume works in the sample patch
- Use chording: keep track of all the keys that are currently pressed, and use only that information to set the parameters for each note.
- One gesture to multiple results
- Use the "metro" object to trigger a steady stream of notes. Now you have two new parameters: repetition rate, and whether the metro is on or off.
- Use the "counter" object to step through a cycle (of samples, parameter settings, etc.)
- You could combine "metro" and "counter" to build a rudimentary sequencer that can step through a rhythmic pattern
- Invent a mechanism to record short sequences of keypresses and play them back in time.
- Incorporate looping or other interactive controls over the soundfile playback
- Use Pd's "spigot" object to route control information to different parts of your patch at different times
- Use some additional signal processing such as a filter, delay line, reverb, tremolo, etc. This gives you more parameters to control.
- Polyphony: make it so the patch can play multiple samples at the same time. (Hint: put multiple copies of "play-sample" in your patch)
- Use a totally different form of sound synthesis, such as FM, granular, or physical modeling.
We recommend that you pick one or a small number of these and work on it in depth, iterating on both the program/test/debug cycle as well as the design/implement/play cycle to craft something that has actual musical potential or is at least more fun to play. If you have an existing idea for your class project, you could use this lab to start thinking about implementing some of the modes and mappings. By all means, if you're inspired to try something else, go for it. If you'd rather spend today getting more of a broad sense of Pd's capabilities, feel free to work on many of these suggestions.
There is a large, dedicated, and very generous community of Pd users on the Internet. Do some web searching (e.g., with a search engine, or else starting from some more specific resources) and look for interesting externals and/or patches. Download, install, and play with at least one. Can you incorporate it into what you programmed in the previous part?
For more help in finding resources, don't forget to look on the PID Links page.