ETC Television Center User Manual
This manual was written by Dave Linnenbank.
First Edition, April 2017
Welcome to The ETC Television Center (or simply ETC to her friends)! Time is money so let’s get you up and running…
Along with this card, there are two main items in the box you just opened.
Follow these steps to make your sound visual.
HDMI Outport to a powered-up HDMI® monitor.
9VDCpower port, the leftmost port on the back of ETC. The top row’s Status LED will indicate progress, glowing light blue as ETC is booting up, and then white when things are operational. Your connected monitor will also show the boot up process.
Audio Inport, and turn up the top row’s Audio Input Gain knob. (Feel free to crank it; you won’t hurt ETC’s ears.) As long as an audio signal is coming in, you should start getting pictures on your HDMI display.
Again, welcome to the world of ETC! As this video instrument has an inherent range and can work for different people in different ways, let us start by talking about what it is and where on Earth (or beyond!) it came from. We’ll then look at some of the basic concepts in play and make sure we are speaking the same language. Then we’ll close with a word on using this guide, preparing you to go forth and visually multiply. So back to our origin story…
We at Critter & Guitari (hello!) have released video boxes before, and we are still rather fond of those devices. Their intended use was simple:
While ETC preserves this “self-service” approach, a number of other modes and options are present.
Yes! Once ETC is connected and powered up (see chapter zero), it will automatically begin creating visuals with the factory modes.
Yes! You can cycle forwards and backwards through ETC’s current visual modes by pressing the two Mode Selector buttons on the bottom left of the front panel (around the eyeball icon). Each valid patch on the USB stick is loaded as a mode, and the preloaded factory content provides a survey of unique visual effects.
Yes! The knobs and buttons on ETC’s front panel provide direct access to the inner workings of ETC and each available visual mode. To expand your control options, you can connect a pedal to ETC’s
Foot Switch port, or even wire up a MIDI controller to the
MIDI In port, etc.
Yes! If audio is running into ETC, a couple of knob tweaks should get you a steady stream of responsive visuals.
Yes! Do you use a digital audio workstation (DAW) or performance software, like Ableton Live? Gib mir fünf! You can send MIDI to ETC from your DAW, both to directly control ETC’s parameters in an automated way and to create synchronized changes that match your music. In other words, you can now use ETC to take the music you are playing and create a generated, beat-driven video accompaniment. Your audience will thank you (and I hope you are getting a cut of the bar).
Yes! The bottom row of ETC has a dedicated Screenshot button (with a camera icon). Pressing this button will capture the current output of ETC to an image file on the USB drive. And if you are a hacker-type, you could even craft a mode that injects the most recently captured screenshot back into the current output. Think feedback, recursion, or something less imaginable.
Yes! Modes can be made to use still images from within the mode’s file structure. You might even find some examples of this in our ETC modes repository.
Yes! All of ETC’s modes are written in Python using the graphics library of Pygame. This means that for the brave, every mode on your USB drive could be edited. And for the truly bold, new modes of your own can be created.
Exactly! ETC is a vehicle for creating visuals. You may want that in a live performance environment, or you might wish to capture and edit the output. Perhaps you want someone to operate ETC throughout your set, or maybe you yourself just lean over and switch scene presets ever song or two. You might want to get out a text editor and code a custom mode, but you can just as easily download new modes that others have written. Any of these choices are valid as long as they serve your purposes!
Our introduction and the sticker on the back of ETC have already hinted at certain ideas and the terms we are using to express them. Let’s take a moment to be clear about the concepts in play.
An ETC mode is a method for creating visuals. In audio terms, you could think of each mode as a patch. The mode can be switched instantaneously from the front panel. Each available mode lives on the attached USB drive along with any support files it may need.
In building the initial factory modes, we have considered modes as falling into two broad categories:
To make things easy to read, a factory mode whose name start with
S - is scope mode, and one beginning with
T - is a trigger mode. But as the descriptions above suggest, there is plenty of wiggle room as modes can readily blend these ideas or go off in completely new directions. Thinking in the scope/trigger paradigm to start is a good way to both help you understand the factory modes and organize your own ideas for new modes or new even categories.
As for the controls of ETC, we think of them as falling into a couple of categories.
An ETC scene is essentially a preset. Each scene stores which mode was being used along with the values of all five knobs (including the four foreground controls and the Background Color knob) and whether the Auto Clear Toggle button is enabled or disabled.
The next chapter will explore how to put all of these ideas into action, but understanding modes versus scenes (and foreground controls versus background controls) will let us hit the ground running.
Certain chapters (such as this one!) are relevant to everyone. But depending on how you plan to use ETC, some information may prove more valuable to you.
Just realize that how you use ETC today may be very different from how you use it a week from now. This is to say feel free to skip information that isn’t of use to you today; you may find that later chapters appreciate in value over time.
Up to this point, we have talked about getting ETC plugged in and running, we have discussed some ways to use the device, and we have covered the concepts that underpin the system. So now we should get on with it and make some pretty pictures.
In this chapter, we will walk through ETC from the user’s perspective, with hands fixed on the hardware controllers and eyes on the back panel’s ports. This will naturally address the role and relation of each control within ETC’s structure. Taken as a whole, we will be painting our own picture of ETC’s functions and general operation.
So let’s grab the knobs, push the buttons, and watch the pictures, now, as they fly through the air…
The top row of ETC has a number of system-level controls and the only direct feedback element that faces the user. We will take these items from left to right.
The Shutdown button is a trigger that does exactly what its name implies: it tells ETC to begin shutting the system down.
When ETC is connected to power, the system automatically begins booting up (as described in chapter zero). When you are done using ETC or need to power it down for a moment, hold down the Shutdown button for two seconds or so. During the shutdown process, the Status LED will go from white to pink, and once the unit is ready to be safely unplugged from power, the light will finally go out .
The Status LED is a light that illuminates in various colors to reflect either the state of the ETC hardware, or to indicate that a particular action is being taken or a type of message was just received.
When the Status LED is glowing in one of these colors, it is indicating the following hardware state:
And when the Status LED is showing one of these colors, it is relaying the following information:
The On Screen Display button is a toggle that calls up an overlay of current system information.
Information is displayed in two columns. On the left side are:
The right column includes:
Pressing the On Screen Display button a second time will toggle the display back off screen.
The Audio Input Gain knob does nothing to affect the internal video system or change the audio that you hear, but it is probably the most consequential control for ETC. This knob scales the incoming audio level before it is processed by ETC for use in the current visual mode. The purpose of this knob is to adjust the strength of the audio signal and scale it into an appropriate range for visualization.
The appropriate setting for this knob will depend on the type of signal you are connecting and the mode you are using. For example:
Audio Inport? Then you will probably need a higher gain setting for this relatively weak signal.
While the second row is the most sparsely populated, its two controls are really the glue that hold transitions together for ETC. These background controls set global parameters that are held steady not matter what mode you are in or if you recall a scene.
The Background Color knob allows you to set the “canvas color” on top of which mode paints its scene. Turning this knob cycles through the available colors.
The Auto Clear Toggle button is a nice toggle effect available in all situations. This is easier explained with a brief word on how ETC carries out its drawing functions.
Each ETC mode contains one
draw function, which is triggered 30 times per second to generate 30 frames per second (FPS) of output. The default behavior for a drawing program like this is to clear the screen right before the
draw function is run. (This clearing results in the color set by the Background Color knob covering the screen.) But breaking the rules can be interesting.
The Auto Clear Toggle button allows us to disable this clearing function. When clearing has been toggled off, each new frame of video draws on top of the previous frame, which can create a “hall of mirrors,” recursive effect. Hitting the Auto Clear Toggle button again restores the normal clear function.
So there is a dependent relationship between the Auto Clear Toggle button and the Background Color knob. When clearing has been toggled off, the Background Color knob has no effect since the background is never getting painted. When the button is toggled back to normal clearing behavior, the set background color will be applied again.
The third row consists of four numbered knobs. Formally, we could call them Foreground 1 Control knob,Foreground 2 Control knob, etc. Or we could be more collegial and simply call them foreground knob
3 and foreground knob
4. Either would be appropriate.
Each of these foreground controls represents a top-level parameter within the mode. This could be a single parameter that controls one discrete element of the mode, or it could be several parameters wrapped into a true “macro” function. While we don’t know the specifics for each mode (see the factory modes reference for that type of per-mode information), we know that each patch should have four top-level controls, and that these knobs pull the strings to make each mode its own instrument.
We spoke in chapter one about the difference between modes and scenes, but an additional word is appropriate here on how the foreground knobs behave when moving between modes and scenes.
When you load a different mode, the current values of the foreground knobs are maintained for the new mode that is loaded. In other words, if you just turned foreground knob
1 to 3 o’clock and foreground knob
3 is set to 10 o’clock, ETC will supply those exact same settings to any successive modes that you load.
If the foreground knobs are assigned consistently across different modes you are using, this can offer more stable transitions between modes. For example, if you have loaded several modes that use foreground knob
4 as a uniform color selection parameter, then that setting would be interpreted similarly as you switch from mode to mode, using that same color value across successive modes. And even if your modes assign their foreground knobs in completely different ways, ETC’s behavior will at least preserve your settings when you switch over to another mode and then back to your original selection.
When you load a different scene, the current values of the foreground knobs are ignored in favor of the settings stored in the scene. In other words, loading a scene will load the scene’s stored foreground control values into ETC, leaving no connection (for the moment) between the values currently used by the software engine and the physical position of the foreground control knobs.
As we discussed in the concepts portion of chapter one, each scene is basically a snapshot of ETC’s current mode state. This includes the mode that is being used as well as the value of each of the foreground controls at the time the scene was captured (and the values of the Background Color knob and the Auto Clear Toggle button). While turning the foreground knobs and switching between modes offers an “organic” experience, loading a scene is a relatively abrupt act, jumping directly to settings that were stored at another time, in another place. This is by design.
Turning a foreground knob is always an absolute gesture: as soon as a change in the knob’s value is detected, it will be applied to ETC’s video engine. This holds true after a scene has been loaded. By turning a foreground knob, the new value there will take over, replacing the scene’s stored value and restoring the connection between the physical control and the software. Again, this may be an abrupt gesture at first — particularly if the stored value and the current knob position are on opposite sides of the control range. But once the knob is turned, all successive tweaks will create smooth value transitions.
And as for how to switch between different modes and scenes (and store new scenes), well it’s funny that you ask…
The top bottom of ETC has a number of navigation and action-based options, all in the form of tasteful maple buttons. We will look at each niblet, going from left to right.
The Mode Selector buttons are first up. This pair of trigger buttons on the far left around the eyeball icon allow you to step backward (left) or forward (right) through the modes that are currently loaded on your USB drive.
The Scene Selector buttons are next. This pair of trigger buttons around the clapperboard icon allow you to step backward (left) or forward (right) through all stored scenes.
The Scene Save button follows the Scene Selector buttons. This trigger button with the floppy disk icon (remember those?) takes various performance values — your current mode selection, the values of all four foreground controls, the background color setting, and the state of the Auto Clear Toggle button — and stores them to a new scene. This new scene is placed at the end of the scene list.
Additionally, pressing and holding the Scene Save button for about two seconds will delete the most recently loaded scene. So if you called up a scene and wanted to re-save it with some adjustments, first hold the Scene Save button down for a couple seconds to delete the original scene. Once you have found settings you are happy with, then press and release the Scene Save button as usual to write the new scene into memory. (Just release that the new scene will be placed at the end of the current scene list.)
The Screenshot button is a trigger with a camera icon. When pressed, the output of the current video mode is captured to a still image file on ETC’s USB drive. Screenshots created will not include the On Screen Display, even if this overlay is currently visible via the
HDMI Out port.
Output files are number from zero (
0), are saved as JPEG files (for example,
1.jpg, and so forth), and share the specs of ETC’s video output: 1280 pixels wide, 720 pixels high, and a resolution of 72 pixels per inch (PPI).
To access these files, first safely shutdown ETC. You can then connect its USB drive to your own computer. All screenshots will be located in the
Grabs folder in the drive’s root (or top) directory.
The Trigger button is on the bottom right of the panel, and its icon is a rectangle containing an X, marked for action! Pressing this button triggers an assigned visual function within most modes. This trigger action is the equivalent of having audio from the
Audio In port cross the threshold. It is most commonly used in trigger modes (as discussed in chapter one), but any mode can connect a function to the threshold behavior.
Pressing the Trigger button will also fill ETC’s buffer of recently received samples with a sine wave. Together with the threshold trigger behavior described above, these two functions make the Trigger button a useful substitute when you do not have audio flowing into ETC. With that being said, many modes can also make use of these trigger messages to supplement incoming audio signals so do try it with all kinds of modes.
Most of the ports are on the back of ETC, and many of them have already come up in our conversation, but we’ll take a moment to touch on each of them with any information relevant to this conversation of general functionality.
9VDC power port is made for the power supply including with ETC. As with all Critter & Guitari instruments, the power supply’s output specifications are as follows: 9VDC, 1000mA, and a tip with center-positive polarity. If you are uncertain whether a power supply will work with ETC, don’t plug it in to find out.
HDMI Out port serves as the video output for ETC.
Next is an unlabeled microSD card slot. This slot comes preloaded with a card that serves as the internal microcomputer’s root disk. We do not recommend ejecting or otherwise manipulating this card as nothing good will come of it.
MIDI In port is for connecting an external MIDI controller. Information on ETC’s MIDI implementation is found in chapter three.
Audio In port is a
-Mono-(phonic) 1/4" input for audio signal. This audio is made available to your modes in two ways. First, a list of the most recent 100 samples is always available for drawing purposes. And second, the incoming audio is continually assessed to determine if it exceeds a threshold level (roughly 80% of maximum possible amplitude), highly useful for commencing a function.
Foot Switch port is a 1/4" jack. It is intended to be connected to a keyboard sustain-/damper-style pedal.
If scenes are stored on your USB drive, an “on” message received at the
Foot Switch port advances to the next stored scene. If no scenes are present on the USB drive, each message loads the next available mode instead. In both cases, this action “wraps around,” going from the last available scene/mode back to the first one, and so on.
ETC assumes that any connected foot switch has a “normally open position” (positive polarity).
Finally, the two USB ports reside on the right side panel. We already mentioned the tiny USB drive that comes with ETC and must be connected for the device to properly boot up. For more information on working with the USB drive and its formatting, see chapter three.
If you need more USB ports, you could connect a hub to one of these ports. That hub and any other devices you connect should be class compliant, meaning that is doesn’t require a special software driver to be installed. This will help to ensure compatibility with ETC.
Note that we aren’t discussing how to produce certain types of images or effects. While the controls offered by ETC are always the same, each mode is unique its own right and can be used in ways that even we can’t imagine. Do consult the factory modes reference for a sense of the included options and their range. And if those provided options aren’t enough, then continue with us to the next chapter.
First, we are glad you made it this far! And just in case you skipped straight to this chapter, be sure to go back and read chapter two! We are assuming that general operation of ETC is fairly clear at this point. So with that out of the way, let’s proceed.
In this chapter, we are going outside of ETC itself to focus on how it interacts with the wider world. While ETC can be run successfully with its factory modes and its own on-board controls, you can definitely expand this performance device with new modes and/or additional sources of control. Here we will see ways to grow ETC’s range in each of these dimensions.
We will start with some basics, looking at the folder structure used by ETC’s USB drive, where your modes and screenshots all live. If you want to load additional modes or simply download your screenshots, you will need to work with the USB drive (and your own computer) to place the new modes and their support files in the right place. Second, we will look at accessing the USB drive by connecting it to your computer. And finally, we’ll look at ETC’s MIDI implementation. This will be useful if you want to connect external MIDI — including USB MIDI — controllers to ETC, or even if you pair ETC with an external sequencer.
If you are searching for additional modes of expression, you have come to the right place. Let’s make ETC that bigger boat…
As has been mentioned, ETC will only properly work while a USB drive is attached to it. Modes are run directly from this attached USB drive. (While not mission-critical, scenes and screenshots are also stored to this drive.) This could be the flash drive included with ETC or another USB disk that is appropriately set up. Some rules apply:
Modesat its top-level. (This name is case-sensitive.) All modes to be loaded must live here, as detailed below.
Grabsfor housing screenshots that are taken, a file called
Scenes.csvfor recording all scenes that are stored, and a
MIDI-Channel.txtfile that sets the incoming MIDI channel that ETC listens to. If absent, these items may be automatically created when needed.
The following is an example directory listing of an ETC-ready USB drive. You can see four modes here, each with a required
main.py file, as well as the
Grabs folder and a
Grabs\ 0.jpg 1.jpg 2.jpg MIDI-Channel.txt Modes\ S - Circle Scope Connected\ main.py S - Feynman\ main.py main.pyc T - Density Cloud\ main.py main.pyc T - Spanish Flash Cards\ font.ttf main.py main.pyc spanish.py spanish.pyc Scenes.csv
A couple items worth noting here about the modes:
main.pyfile. As long as these Python script files contain the minimum requirements for an ETC mode, they will all be treated as valid modes and loaded when the device starts up. (For information on programming or editing modes, see chapter four.)
main.pycfiles. These intermediary files are automatically created by the Python compiler in ETC. These files can speed up future interpretations of their script, but the PYC files are not required or needed. (The first mode listed here has no
main.pycfile, suggesting that it is a new mode which has not yet been run by ETC.)
Whether you want to load new modes, download some of your screenshots, or edit the
Scenes.csv file or the modes themselves, any of these actions requires accessing the files on ETC’s USB drive. One way to do that is connecting the USB drive to a computer. We will discuss that here. (A second way to edit modes is with the USB Wi-Fi interface [a separate purchase] for wireless access. We will cover that in the chapter four.)
If the USB drive is currently connected to ETC, you must first shut down the unit by holding the Shutdown button for a couple seconds. You will then see the Status LED turn pink while the system is shutting down, and then the LED will go dim. Only when the Status LED has gone out is it safe to disconnect the USB drive.
When using the included USB drive, be sure it is flipped the right way before connecting to your computer. The drive that comes with ETC has an extremely low profile, consisting of the bottom half of most standard USB connectors/cables. As such, it is possible to plug the drive in upside down. This is generally harmless but is better avoided.
Be sure that the exposed pins — I think of them as teeth — are facing “up,” toward wherever the top of a connected USB cable would go. (On Mac laptops, for example, the pins should face upward, toward the sky.)
Once the drive is connected and seen by your computer, it would appear somewhat like the following.
The top level of my USB drive, whose disk name is
ETC, is shown above. This root-level does indeed contain the
Grabs folder, where three screenshots have been stored. Now would be a good time to move those images to your computer for your own use.
A suggestion about screenshots. While you could copy files to your computer and leave them in place on the USB drive, a better practice is to regularly remove your screenshots from the USB drive. It is easy to run out of space on the USB drive by amassing screenshots, either slowly or quickly. Instead of running low on space without realizing it, just remove these images regularly.
Also at the top level is the
Scenes.csv file. This file of comma-separated values is readable if you open it in a text editor, with each line looking something like this:
These values represent:
Mode, Foreground 1 Control knob, Foreground 2 Control knob, Foreground 3 Control knob, Foreground 4 Control knob, Background Color knob, Auto Clear Toggle button
If you are brave and interested, you could try editing these scenes values or simply reordering the lines. But you might want to make a local copy of the file first, just in case. (If things get out of hand, you can always just deleted the
Scenes.csv. When a new file is needed, ETC will create it.)
Inside of the top-level
Modes folder, the four modes are selected (with blue coloration), and their contents are exposed. So in the example shown above, the four modes available on ETC would be
S - Circle Scope Connected,
S - Feynman,
T - Density Cloud, and
T - Spanish Flash Cards. And once more, the practice with factory modes is that a leading
S - indicates a scope mode while a leading
T - signifies a trigger mode (see chapter one).
When working with these modes, you will most likely want to work with their folders rather than handling the files within each folder. For example:
Modesfolder. (And if you downloaded a ZIP file, make sure that you have decompressed it to a folder before moving it to ETC’s USB drive.)
In short, if you aren’t editing the files themselves, then working with the files within the mode’s folder can only cause problems.
Finally, note that any other folders or files located on the USB drive will likely be ignored by ETC. This means you could keep a backup folder of working modes on the USB drive while editing the “live” versions. Or this could be handy for having different “set lists” of modes or even different scene files. The set list idea would be to duplicate either your
Modes folder or
Scenes.csv file, and then rename the version that you would like to save for future use. Just make sure that the proper files and folders have the proper names before you hit the stage!
MIDI In port suggests, external MIDI controllers can be connected to it. In addition to devices connect by regular(/old-fashioned) five-pin DIN connectors, USB MIDI devices can also be used with ETC. To ensure compatibility, we suggest that you select a class compliant USB MIDI controller. Any controller that requires the installation of a driver may, at best, not work as expected.
To properly interact with ETC, we need to know the MIDI implementation of this device. To begin with, ETC only listens to incoming MIDI messages that are on the specified channel (by default, MIDI channel 1). And only a small subset of MIDI messages has an actual effect on ETC’s operating modes.
In other words, your controller may send some messages that ETC doesn’t recognize, and that’s okay. These messages won’t produce any effect on ETC, but they won’t create any problems either so don’t worry with “disabling active sensing,” etc. etc.
Let’s start by examining the different type of messages that ETC uses. We will also end with a word on changing the incoming MIDI channel that ETC responds to.
Incoming control change messages using controller numbers
25 have an effect on ETC. The following knobs correspond to the listed controller number:
21> Foreground 1 Control knob
22> Foreground 2 Control knob
23> Foreground 3 Control knob
24> Foreground 4 Control knob
25> Background Color knob
Each incoming message’s value replaces the current value of the respective controller. So even if foreground knob 2 is turned all the way to the right, an incoming controller message of number
22 with a value
0 will change foreground controller 2’s value to zero. Once you move the Foreground 2 Control knob again, its control will be restored.
Program change messages received by ETC switch to the scene specified by the message’s value. So if a program change message with a value of
1 is received, ETC will switch to its first stored scene, and a program change message with value
4 would switch to the fourth scene, etc.
If no scenes are stored on ETC, then these program change messages will similarly map to the loaded modes. So a program change message with value
1 would switch to the first mode,
9 to the ninth mode, etc.
All incoming note messages (again, on the global MIDI channel) are received by ETC. It provides information on these note messages in two ways:
Any mode can use either or both of these status data.
Additionally, the last MIDI note (pitch
127) is used to toggle that state of the auto clear function, acting in the same manner as each press of the Auto Clear Toggle button. So any note on message with pitch
127 toggles the current state (if it was on, it switches off, and vice versa).
ETC also understands a couple of MIDI system real-time messages. Many sequencers support this clocking method, but it is simple enough that you could build it into other environments as well (such as Pure Data [read: for Organelle], Max, Reaktor, etc.).
MIDI’s concept for system real-time messages is that a timing clock message is received 24 times per quarter note for the purposes of synchronization. Accordingly, each time ETC receives a timing clock message, an internal counter is increased by one step. After the 24th step, the counter returns to its low position and counts upward again. Additionally, any real-time start message that is received triggers also causes the counter to be reset on the next clock beat.
This internal counter value of ETC is accessible to any mode that wishes to use it. By using select steps of the counter, you can create effects that are rhythmically synchronized to your liking.
And please note that MIDI clock messages are system MIDI messages. That means that these messages will be received and used regardless of ETC’s current global MIDI channel.
Earlier we noted a file called
MIDI-Channel.txtat the top level of the USB drive. This plain text file should contain only a single number. If the number is between
16, then ETC will listen only to that specified MIDI channel for incoming MIDI messages, and all other channels will be ignored.
Setting the contents of the text file to
0 (the number zero) will switch ETC to a kind of omni mode, telling the device to ignore the MIDI channel of incoming message and to respond to everything it receives. As an example, this might be preferable if you are using a MIDI controller that has both keys and/or knobs (typically transmitted on channel 1) and drum pads (often sent on channel 10).
Finally, if this
MIDI-Channel.txt file is deleted or not readable, ETC will default to MIDI channel 1 when it boots up.
Well, here we are. The place where dreams and/or ETC modes are made.
First of all, this chapter may not be for you. If we may say so ourselves, ETC is rather functional and expressive without getting into coding. So if you are comfortable with using ETC and would rather stick with the artistic side of your brain, that is great. Focus on what is going to benefit you the most, and go in peace. If you ever want to come back, we will be here. Waiting.
And while this chapter focuses on how ETC works and the methods available to you within this framework, we are not going to teach you how to code. We don’t have enough pages or Red Bull to do that here. But don’t despair. Now more than ever, there is a bounty of resources available that will help you learn about programming in general and about particular languages (such as Python). Searching the internet, the library, or even local computer classes on offer will give you some good leads and help you find a way forward to start programming.
Now, if you enjoy coding already (or are considering it), or if you have some video ideas that you need to express, then let’s proceed. Just pull that lever to pop the hood.
In this chapter, we will start with the concepts and requirements for any ETC mode. Each mode doesn’t require much, but talking about what does need to be there will give us a good picture of how ETC operates. We will then outline ETC’s application program interface (API). Beyond the required pieces, these are the available functions and properties that you can make use of in any mode. Finally, we will look at connecting to ETC for the purpose of editing modes directly while the device is running. This can be done via the optional USB Wi-Fi interface, which is an additional purchase.
So this is the road before us. We have already seen how ETC handles; now let’s change the oil and what make him purr…
A word or two on how ETC actually does its work will go a long way. We will spend a moment on the languages at play and the system behavior of ETC, and then we will talk about the basic requirements of a mode.
As was said early on, ETC’s modes are written in Python using the graphics library of Pygame. So Python is the programming language in use, and the graphics library executing the drawing comes from Pygame.
Python has a rich standard library with numerous modules, any of which can be used in your modes. A full list of modules can be found in Python’s documentation. Going through the factory modes, you will see such modules as
time in use. To learn more about how any of the library modules work or more about Python itself, the documentation link above is a wonderful place to start.
Pygame is a set of Python modules that were originally written for video game development. ETC is using the graphics library of Pygame to create our visuals. A full list of available modules can be found in Pygame’s documentation under the Reference section. Some of the factory modes make use of additional libraries such as
pygame.gfxdraw, but other graphics-related modules could be used as well.
Pygame renders its graphical output to a surface. This is how we connect our Python scripts to our Pygame output, which we will see in the next section.
When ETC starts up, it identifies all valid modes within the USB drive’s
Modes folder. And it then loads all of these modes simultaneously. This parallel behavior is what makes switching between modes so instantaneous and smooth, but it also adds a couple of things worth considering:
setup()), realize that this memory will be taken up even when another mode is called up and generating output.
Modesfolder) during testing.
Each mode has only four basic requirements for successfully being loaded and to (hopefully) produce graphical output:
importstatement. So any ETC mode script should begin with…
setup()will get called automatically when the mode is loaded. This is a clean way to run any operations that are only needed once, before video is being rendered.
draw()is the function that is run 30 times per second (think 30 frames per second [fps]) to paint each frame of video output. Common activities here including taking in any control changes since the last frame, redrawing with updated audio information, executing changes based on any trigger or other messages received, etc. etc.
screen. This surface is what gets sent out for display via the HDMI port.
Taking all of these points into consideration, here is a very simple example ETC mode…
import pygame def setup(screen, etc): pass def draw(screen, etc): size = 640 position = (510, 500) color = (255, 0, 0) pygame.draw.circle(screen, color, position, size, 0)
Walking through this basic
main.py example, we start by loading the
pygame module, as outlined above in step one. We then define a
setup() function. This one is blank, but it is good to have as a placeholder for use when necessary.
Next comes the
draw() function. The first three lines of the function are defining local variables that are used in calling the
pygame.draw.circle() function. And as the first argument in the example indicates, this function is pointing at the
screen surface, getting our draw messages out of ETC through the HDMI output port.
That is about the simplest mode we could make, and its result is equally simple — a red circle is drawn near the middle of the screen, each and every frame, forever. This example offers the basic framework for examining the factory modes and for understanding how to structure your own modes. Our only suggestion is an obvious one: you should probably send different images out of ETC from time to time.
Having walked through the general framework and requirements of ETC’s modes, it’s time to take a look at the API available when working with ETC. The
etc object contains a number of variables, all of which can be accessed from any mode:
etc.audio_in- A list of the 100 most recent audio levels registered by ETC. These values are stored as 16-bit, signed integers, ranging from a minimum of -32,768 to a maximum of +32,767.
etc.audio_trig- A boolean value indicating whether or not incoming audio has exceeded the fixed threshold level (approximately 80% of maximum) since the last frame was drawn via the
etc.bg_color- A tuple of three integers representing the red, green, and blue components of the current background color.
etc.knob1- A float representing the current value of the Foreground 1 Control knob.
21on the current global MIDI channel will replace the value of foreground knob 1, until the knob is moved again.
etc.knob2- A float representing the current value of the Foreground 2 Control knob.
22on the current global MIDI channel will replace the value of foreground knob 2, until the knob is moved again.
etc.knob3- A float representing the current value of the Foreground 3 Control knob.
23on the current global MIDI channel will replace the value of foreground knob 3, until the knob is moved again.
etc.knob4- A float representing the current value of the Foreground 4 Control knob.
24on the current global MIDI channel will replace the value of foreground knob 4, until the knob is moved again.
etc.lastgrab- A Pygame surface that contains an image of the last taken screenshot taken (via the Screenshot button). This surface has dimensions of 1280 by 720, matching the full size of the screenshot.
etc.lastgrab_thumb- A Pygame surface that contains a thumbnail image of the last taken screenshot taken (via the Screenshot button). This surface has dimensions of 128 by 72.
etc.midi_notes- A list representing the 128 various MIDI note pitches. Each value in this list indicates whether that note is current on or not. For example, you could create a threshold function that executes when “middle C” (MIDI note 60) is being held down with something like…
if etc.midi_notes : yourFunctionHere()
etc.midi_note_new- A boolean value indicating whether or not at least one new MIDI note on message was received since the last frame was drawn (via the
etc.midi_clk- An integer representing ETC’s internal MIDI clock. As explained in chapter three, this is an implementation of MIDI’s real-time messages. The
etc.midi_clkvalue starts at
1and increments each time a timing clock message is received. After the counter reaches its maximum value of
24(or whenever a real-time start message is received), the counter will reset on the next tick to
if (((etc.midi_clk-1)%6)==0) : yourFunctionHere()
etc.mode- A string of the current mode’s name.
etc.mode_root- A string of the file path to the current mode’s folder. This will return something like
/USBdriveName/Modes/CurrentModeFolder. This can be useful when images, fonts, or other resources need to be loaded from the mode’s folder. (The
setup()function would be an appropriate place to do this.)
Along with all of these variables, the
etc object does have one function worth mentioning as well:
etc.color_picker()- This function translates the value of the Foreground 4 Control knob into a color. When called, this function returns a tuple of three integers representing the red, green, and blue components of this color. In the factory modes, you will often see a local variable (usually
color) being set by this function, like so…
color = etc.color_picker()
This represents the API components that are available to you, the aspiring ETC mode editor/writer. Remember that for any variable whose value is based on a hardware controller, changing scenes may override the value in use for a time (for more information on scenes, see chapter two). And since the
draw() function is called for each and every video frame produced, querying any of the variables within the
draw() function is an effective way to dynamically update your mode’s output.
Finally, we are not telling you how to make modes. We aren’t telling you what is a good idea, and even our mode categories (scope versus trigger) admit to being limited. This is where you and your ideas come in.
We leave it to you to have a working knowledge of Python, to come up with some ideas for tweaks or completely new modes, and to try and make it work. Even if you don’t nail it the first time, chances are you will come across some happy accidents as you go. As always, it’s along the way that art gets made.
In chapter three, we looked at the format of the USB drive as well as how to add new modes and work with files and folders by connecting the drive to a computer. Now that you are acquainted with the basics of making and editing modes for ETC, you could simply plug ETC’s USB drive into your computer whenever you want to edit or create new modes. This would work just fine…
But this workflow — power down ETC, unplug its USB drive, connect the USB drive to your computer, find and edit the file of interest… — well, even six steps in, you still wouldn’t have seen the result of your work. This could be a pain for creating new modes from scratch, much less for fine tuning a few settings. So we’ve come up with a more convenient workflow for all of us.
To let you keep ETC running and allow you to edit its primary scripts (the
main.py files of each mode), we have made ETC ready to work with the USB Wi-Fi interface, which is available as an additional purchase.
Using the USB Wi-Fi interface with ETC requires just a little configuration. You need to create a file named
WiFi.sh and place it at the root level of the USB drive. This shell script will prompt ETC to create its own ad hoc Wi-Fi network with a network name and password of your choosing. A template version of the file would look like this…
#!/bin/bash create_ap wlan0 eth0 NETWORK_NAME PASSWORD &
(From this link, you can download a template version of the
After either downloading this file or pasting the above two lines into a text editor, please take the following actions:
NETWORK_NAMEto the network name (read: SSID) that you want ETC to create.
PASSWORDto the password that you want ETC to use for this new network.
WiFi.sh. (Double-check that your text editor does not add an additional file extension to the end of the filename, such as
.txt.) Make sure that a copy of this file is saved to the top level of ETC’s USB drive.
Once ETC has booted up, you should be able to find and connect to ETC’s Wi-Fi network just as you would any other network. In the example below, I have named ETC’s network
Note that if you are connecting to the internet via Wi-Fi, switching over to ETC’s Wi-Fi network will also take you “offline.” This would limit your access to wholesome online resources, such as this manual and the Critter & Guitari site in general. If possible, connecting to the internet by other means (such as an ethernet cable or Bluetooth) could allow you to stay online while connected to ETC.
Once you are connected to ETC’s Wi-Fi network, open your web browser and visit http://192.168.12.1:8080/static/index.html.
This is the landing page of ETC’s web console. The simple navigation bar in the very top line offers us two pages:
Screen Grabs. The page we are on is the default Editor page, showing a list of the loaded modes on the left, a few function options beneath that list, and a friendly code editor on the right of the screen. By clicking on one of the modes, we will load that mode for viewing and/or editing.
The right side of the window is indeed a code editor, complete with line numbers and syntax highlighting/coloring. You can edit as you would with any basic text editor. After making changes, we will need the functions beneath the mode list. Three functions are available:
reloadrefreshes the list of available modes. You won’t need this too often.
savewrites the file you were editing back to the USB drive with any changes you have made.
save newcreates a new mode as a copy of the mode currently loaded in the code editor. After clicking
save new, a dialog box appears asking you to name the new mode before its folder is written.
So after altering the mode script in the code editor, click
save to commit those changes. This will also cause ETC to reload the current mode, immediately showing you the visual result of your changes via the HDMI output.
By clicking on the
Screen Grabs link in the upper navigation bar, the Screen Grabs page is loaded.
This page displays thumbnails of all stored screenshots. So still using our example file structure from chapter three, here we can see our three screenshots from the USB drive’s
Grabs folder. By clicking on any of these thumbnail images, a larger preview is presented.
If you want to save a screenshot to your computer, right-click on either the thumbnail or the larger image preview, and then select the context menu option for saving the image. (Both images link to the full resolution version.)
That covers the general overview of ETC’s web console. While some functions must still be done by connecting the USB stick to your computer (see chapter three), the web console allows you both to quickly sample all of the screenshots you have taken and to program on the fly, seeing the results as you go. If you plan on doing your own tweaks and/or programming with ETC, you may want to consider the USB Wi-Fi interface as a small cost yielding a large convenience.
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