In Isadora 3.0.8, we've added new capabilities for routing sound using the Sound Player actor, which will be extended to the Movie Player actors in the next release. This article will show you how to take advantage of this new feature.

About the Sound Player

The Sound Player actor is designed to play uncompressed AIFF and WAVE files imported in the Sound Samples section of the Media View. The files must be uncompressed because the goal of the Sound Player was to have it behave like a software sampler, where the start of playback after being triggered is as close to instantaneous as possible. Previous versions of Isadora did not allow you to play sound files with more than two channels. This limitation is lifted in Isadora 3.0.8.

New Features of the Sound Player

To start this tutorial, open Isadora 3.0.8 and add a Sound Player actor to the newly created file. You'll immediately see that the Sound Player actor has a new look.

Along the bottom you can see the new transport controls, which work in the same way as the transport controls in the Movie Player offered in previous versions of Isadora. 

You can double-click on the play bar at the left to jump to any point in the sound, or drag the two triangles above to change the play start and play length inputs. The transport controls on the right allow you to play, stop, pause and mute the sound.

Like the Movie Player, these transport controls are primarily designed to be used in a rehearsal situation where, for example, you need to mute the sound because the director needs to speak to the performers. For this reason, these controls are not persistent and will be cleared when you leave a scene. (For example, if you pause a sound and then return to the scene, the pause button will no longer be highlighted.)

In the top center part of the actor below the volume/pan indicator circle, you will see a graphic that is unfamiliar. This is the Matrix Router control that allows you to route the channels of the sound file to any output on your sound output device. In the next sections, we'll show you how to put that new feature to use.

Selecting Your Audio Output Device

As part of the new multi-channel audio support, Isadora 3.0.8 also introduces a new Audio View which allows you to choose an audio output device and to monitor the sound levels being sent to that device.

The Audio View is hidden by default in your new Isadora document. Go to the menu and choose View > Audio and you'll see something like this appear at the bottom of the window:

The controls in the Audio View allow you to:

  • select the audio output device.
  • specify the number of audio output channels to use on that device.
  • mute the sound on all channels.
  • open the system preferences for audio, allowing you to change the default audio device or the sample rate for a particular device.

In addition, you'll see a "VU Meter" for each channel of your device, which will allow you to monitor the audio level when sound is playing. (If you like your VU meters vertical instead of horizontal, then grab the five dots above this view and drag up to increase the height of this view.)

Selecting The Audio Output Device

The menu at the top left allows you to choose the Audio Output device.

By default, a new Isadora document will select the default audio output you've chosen for your system.

In the screen capture above, the default device is called MacBook Pro Speakers. Isadora will show you the number of channels and sample rate of the selected device right below the menu. In this case, the output device offers two channels and a 44.1 kHz sampling rate.

You can also see that it shows you a pair of "VU meters" that indicate the volume of the sound being sent to channels 1 and 2 of the audio device.

Specifying the Number of Channels

To the right of the audio output device menu is another menu that allows you to set the desired number of output channels. For example, if you're using an eight-channel audio output device but you only need four channels, then you would set this menu to four 4.

But you can also choose more channels than are available on the current device so that you can prepare multi-channel routings even when you're not connected to a multi-channel device.

Assuming your default device also offers only two channels of output (stereo), let's see what happens if we set the number of channels to 8.

You can see that Isadora has highlighted the number of channels and sample rate in yellow. This is to remind you that the device you've chosen doesn't actually offer 8 channels. When set up as shown above, Isadora will mix down the 8 channels to stereo so you can hear all the channels while you prepare your patch

When you're ready, you can simply connect your multichannel output device and select it in the audio output device menu. The number of channels and sample rate will return to their normal color to let you know that you actually have eight channels of output upon doing so.

Routing Sound

If you're following along, Isadora has selected the default output device and you have set the number of channels to 8. Now, you should import a stereo AIFF or WAVE file into your document, which should appear as sound #1 under the "Sound Samples" section like this:

As you can see above, the track we imported is a stereo file because it says (2 Trk) to the right of the file name. A four channel file would say (4 Trk), an eight channel file would say (8 Trk) and so on.

Now let's add a Sound Player actor and set the 'sound' input to '1' to choose the sound sample we've just imported. As soon as you do this, the Matrix Router thumbnail in the center of the actor will change to look like this:

The columns of this two dimensional grid represent the number of sound channels in the imported file, while the rows represent the number of output channels for the currently selected audio device. As you can see, there are two columns and eight rows, corresponding to our stereo file and the eight channels available for output.

The default routing is to send the odd numbered channels (in this case, channel 1) to the odd numbered outputs (1, 3, 5 and 7), and the evenly numbered channels (channel 2) to the even numbered outputs (2, 4, 6 and 8). To see this even more clearly, click the Matrix Router thumbnail to open the Matrix Router editor:

Now you can see the labels for the channels of the source sound file (1 and 2) across the top, and the labels for the audio output device (1 through 8) along the right. The routing points are grey because this is the default routing, but wherever you see a box with a number in it (e.g., 0.0) it indicates a connection between the source channel above and the output channel to the right.

Try moving your mouse over the grid, you'll see the "crosspoints" illuminate like this:

The indicator here tells you that clicking at the crosspoint over which you are hovering would connect channel 1 of the source audio file to output 2 of the audio device. If you click at this point and move the mouse outside the Matrix Router control you'll see that you've made a connection between channel 1 in the source and channel 2 on the sound output device like so.

Click again, but this time in column 2 and row 4 to send channel 2 of the source sound to channel 4 on the output device as shown below.

At this point, you've routed channels 1 and 2 of your stereo sound file to channels 2 and 4 of the audio output device. To see this in action, click the input trigger ('-') for the 'start' input of the Sound Player actor. You'll see the VU meters for channels 2 and 4 of your output device come to life as the sound is played. But you could also route the sound like this:

We worked with a two channel (stereo) file for this example, but the Sound Player is not limited to stereo files. For example, here's the Matrix Router setup for a four channel sound file with an eight channel output device.

Or the same four channel sound file setup for a stereo output device.

Matrix Router Editor: Controlling Volumes, Changing Settings and Seeing a Different View

Here are the other things you can do within the Matrix Router editor.

  • As previously shown, to add a crosspoint, click on that point in the Matrix Router display. If you continue to hold the mouse button down after you click, you can reduce the volume at that crosspoint by dragging the mouse down.
  • To delete an existing crosspoint, hold down the alt/option key and click it. The hover color will change to red while the alt/option key is down to let you know you're about to delete.
  • To adjust the volume, click on a crosspoint and drag the mouse up or down. Note that, by default, the value is given as the amount of attenuation in dB, ranging from 0.0 (full volume) to -∞ (silence).
  • You can also adjust the volume by clicking an existing crosspoint and using the small slider at the bottom right of the editor. You may also notice that the source and destination channels of the currently selected crosspoint are always shown to the right of this slider.
  • If you prefer to see the volumes as percentages, from 100% (full volume) to 0% (silence), then click the "%" button at the bottom of the editor. The current mode, either dB or %, is always shown at the top right of the matrix graphic.
  • You can also get a graphic view of the crosspoint configuration by clicking the circle button at the bottom left of the editor.
  • Finally, you can reset the routing points to the default by clicking the "X" button at the bottom of the editor.

One important thing to understand is what happens if you change devices and reduce the number of channels. Let's take the four channel to eight channel example from above, shown on the left. If you then go to the Audio View and change to a two-channel device, or set the number of channels to 2, the Matrix Router will change to look like it does on the right.

The yellow crosspoints and outputs indicate that they are invalid. If you played this sound in this configuration, only channels 1 and 2 from the source sound would be sent to outputs 1 and 2 of the audio output device. The remaining channels would be silent because they do not have a valid routing.

Interactive Control

You only need to read this section if you would like to interactively change the routing in real time, e.g., in response to a sensory input. The technique below might feel a bit complex if you are an Isadora novice. So please take your time!

You may have noticed that the 'routing' input has been changing as you adjusted the Matrix Router editor. That's because the routing is actually stored as a text string with the following format:

src:dst, src:dst,... or src:dst@vol, src:dst@vol,...

Where each src is the the number of the channel in the sound file and dst is the channel on the sound output device. The second variation shows how you can use the '@' sign and add a volume (percentages only at this time!) to determine the crosspoint volume.

For example this routing:

generates the routing string: 1:1@60.0, 1:2, 1:3@90.0, 1:4, 2:5, 2:6, 2:7@80.0, 2:8

What makes this interesting is that you can use various text actors in Isadora to send different routing strings into the 'routing' input and instantly change the routing or crosspoint volumes. For example, this patch uses three Keyboard Watcher actors, each coupled to a Trigger Text actor, to allow you to change the routing with the 'a', 's', and 'd' keys on your computer keyboard.

For each of the three instances above, we used the Matrix Router editor to setup the routing we wanted. Then we clicked in the 'routing' input and copied the routing string. Then we clicked in the 'input' of a Trigger Text actor and pasted the routing string there.

In this next example, we created a real-time mixer using the Text Formatter actor. The four input parameters of the Text Formatter generate a routing string that includes volume, allowing you to adjust the volume of each crosspoint in real time.

If you were to double-click the Text Formatter in this example, you'd see this formatting string

 "1:1@" P1 ", 2:2@" P2 ", 3:3@" P3 ", 4:4@" P4

The black text inside the double-quote characters is constant. But the Text Formatter will replace P1, P2, P3 and P4 (colored blue here for emphasis) with the input values 'param 1' through 'param 4' whenever any of those values change. When you do change one of those inputs, you end up with a routing string like this:

1:1@100, 2:2@66, 3:3@33, 4:4@10

where the numbers after the '@' signs specify the volume at the crosspoints. This can be fed directly into the 'routing' input of the Sound Player actor.