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How to use the software. . . DIGITAL LIGHTING CONTROLLER Part 3 – by Nicholas Vinen Christmas is just about here! Have you got your Digital Lighting Controller ready yet? In the first two articles we explained how the Digital Lighting Controller works and how to build it. This third article explains how to use the software – primarily the Windowsbased sequencing program. A s it turns out, the majority of the time spent developing this project involved writing software – both the firmware and the sequencing utility. We only had space for a quick rundown of the software functions last month. Here is a more detailed explanation. Audio conversion As previously stated, the Digital Lighting Controller supports audio files in the WAV format, with 16 bits per sample, mono or stereo, in one of the supported sample rates (11.025kHz, 12kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz or 48kHz). If you have an MP3 file (or other format) that you want to play or sequence using this device, you can use third party software to convert it to WAV. This is also necessary if you want to use a WAV which contains compressed data (eg, Law or aLaw). There are many pieces of software capable of doing so. The best is probably Audacity (http://audacity.sourceforge.net/). It is available for Windows, Mac OS X and Linux/Unix and can be downloaded and used at no charge. All you need to do is open the audio file and then use the File->Export command to save it as a WAV. This WAV file can then be loaded into the sequencing software. Note that it only handles simple WAV files (one chunk, etc). This is because it uses the same WAV routines as the master unit does, so if you can open the file in the Windows software then it should work on the master unit 66  Silicon Chip too. Even so, it doesn’t hurt to check that the master unit will play the WAV before you begin sequencing it. Operation and additional features Sequences can be created with or without audio. Sequences with audio have a .lsq file extension, those without have a .lsn extension. The master unit scans the memory card for any files with a .wav or .lsn extension. WAV files are played with or without an accompanying .lsq lighting sequence. If there is no sequence, the lights are all switched off as the audio plays. If an .lsn file is encountered instead, the audio output plays silence while the lighting sequence is displayed. In either case, after the sequence is finished, it moves onto the next file (unless you use the single file playback buttons on the remote control). Since the last article was published, we added a “mute” command which can be triggered from either compatible remote control. It immediately sets the audio volume to zero and is cancelled by pressing mute again, changing the volume or else pressing play. It can be re-mapped to other infrared codes like the other remote control commands. Note that a sample configuration file, showing all the main options, will be included with the HEX file and source code downloads. Limitations Because the sequences are stored compressed (reducing siliconchip.com.au Fig.1: the main window, showing the WAV audio data at the top and the sequence below. The blue rectangle shows the current selection while the green line is the playback cursor. The simulated light state is shown at the bottom. The main sequence display, in the middle, represents the brightness of each light over time with strips of colour. Note that some of the toolbar buttons are disabled. If you move the mouse cursor over them, you’ll find out why. file size and memory card I/O), there is one minor restriction. Light ramps (when the brightness slowly fades up or down over time) have a minimum and maximum time period. The possible range is about 0.016 to 8.2 seconds. It’s unlikely you will need to go outside this range and if you do, the software will automatically adapt. For long ramps, it will substitute a series of evenly spaced “set brightness” commands to give a similar effect. Still, it is a good idea to avoid very short or long ramps since they can complicate further sequence manipulation. Sequencing software To install the Windows sequencing software, simply Fig.2: the settings dialog which provides a few options for tweaking the behaviour of the program. Most of the settings only need to be changed once. siliconchip.com.au Fig.3: the lights dialog, accessible via settings, which allows you to name each light channel and select the colour in which it will be displayed. December 2010  67 Fig.4: the Custom Ramp dialog allows you to create light ramps with a specific profile. Once a profile has been set up, it can be repeated many times on different channels at different times. download and run the executable file. It will ask you a few questions (such as where to put the files) but most users can ignore the questions (leaving the options at their defaults) and just click the “Next” button until the installation is complete. The first time you run the sequencing software, it is a good idea to go to the Settings screen (Edit––>Settings) and adjust the options. The most important is the audio delay. To set it, select a WAV file which has an obvious beat and then create a new sequence for it. Use the Play command (on the toolbar or in the menu) to play the file and watch the playback cursor (a green vertical line) as it moves across the display. The beats should be visible as spikes in the WAV display at the top of the window. As the playback cursor reaches each spike, you should hear the beat simultaneously. If the playback cursor reaches the spike before the beat sounds, increase the delay. If the beat sounds before the playback cursor reaches the spike, decrease it. The possible range is ±1000ms (±one second). Repeat until it is correct. The rest of the settings are explained in Table 1 at right. Having set them to your satisfaction, you are ready to create sequences. The rest of this article is dedicated to explaining the various controls, commands and options which you can use in choreographing your light display to the music. Mouse controls The mouse wheel zooms in or out on the sequence, centred on the portion under the mouse cursor. Rolling it up zooms in while rolling it down zooms out. Note that this is true even while you are dragging a selection (see below). Right clicking in the WAV display (at the top) or sequence display (below it) re-centers the display on that location. Right-dragging (ie, right-clicking and holding) in either area pans the display left or right. Panning can also be accomplished using the scroll bar, at the bottom of the window. 68  Silicon Chip Fig.5: with the Cascade dialog you can create a pattern of lights across multiple channels. The lights flash in the specified pattern at the selected interval. Table 1 – Settings Monitor Gamma Used to display light brightness accurately. The default is 1.6, common values are 1.6 – 2.2. Make backup files If on (the default), each time you save over a sequence, the old file is kept with a different extension (maximum of ten backups). Associate file extensions If on (defaults to off), sequence files can be opened by double-clicking them in Windows Explorer. SD Card Drive This is auto-detected but may need to be changed. The “Publish” command copies the sequence to this drive. Eject After Publish If on (the default), after publishing a sequence, the memory card is “ejected” so that it can be immediately removed. Audio delay compensation Some sound drivers do not accurately report the playback position. If the audio synchronisation is off, adjust this value. Maximum undo Undo records are kept forever until they use memory up more than this much memory, when the oldest undo records are discarded. Loop playback Can also be set on the toolbar. If on, when playback reaches the end of the selected section, it starts again from the beginning. Scroll to follow Can also be set on the toolbar. If on, when the playback cursor playback cursor approaches the edge of the window, the display scrolls to follow it. Lights Selects which light channels are available and sets the associated names and colours. By default, the first eight are enabled. siliconchip.com.au Fig.6: Beat Detection provides an automated hueristic for detecting beats in the music and causing lights to flash in time with them. It operates similarly to Cascade but the flash times are determined by the music, rather than a simple interval. The mouse is used to define the selection initially and can also be used to adjust it. The selection is a portion of the sequence, outlined in blue. Most commands which manipulate the sequence only change the portion within the selection. To make a selection, move the mouse into either the WAV display or sequence display and hold the left button down. You can then “drag out” an area to select it. If you click the button rather than dragging the mouse then this will select a single time point in the sequence. In this case, the “Play Selection” command will play from that point until the end of the sequence and the “Paste” command will paste the copied data beginning at that point. When dragging a selection, you can also move the mouse Table 2 – Custom Ramp options Fig.7: Spectrum Analysis operates like Beat Detection but it breaks the audio up into multiple frequency bands and controls each lighting channel based on the audio within the separate bands. vertically to select one or more light channels simultaneously. Once a selection has been made, you can drag the edges, changing the time span or the range of light channels selected. A double-arrow cursor indicates when the mouse is in the right location to change the selection. While using the mouse to create or adjust a selection, Table 3 – Cascade options Order The order in which channels are flashed. “Low to high” starts with the first selected channel and then moves to higher channels, wrapping back around to the first. “High to Low” is the opposite. “Ping pong” alternates between the previous two. “Random” creates an arbitrary pattern. Type Ramp Up increases brightness over time, Ramp down decreases it. Peak ramps up and then down while Trough ramps down and then up. Brightness Defines the brightness at the salient points for the given ramp type. Effect Normally the ramp is stretched to fill the selection. Start and End Delay allow for padding. Peak/Trough delay, if set, create a brightness plateau in those modes. When Flash is selected the light simply turns on for the selected On Time. With fade, the beginning and end are ramped, according to the Rise time and Fall time settings. Brightness The peak brightness of each light flash. Interval The time between flashes being triggered on subsequent channels. This can be shorter than the On time if desired and the flashes will overlap. Timing Symmetry Available in Peak and Trough modes. The up and down ramps take the same time with 50% symmetry while other values emphasise one or the other. siliconchip.com.au December 2010  69 The up and down arrows also move the selection up and down, selecting a different set of light channels. If shift is held down at the same time then rather than moving the selection, it is extended. If the Control key is held down while pressing the left and right arrows, the display scrolls left or right. In this mode the shift key can also be used for larger increments. Dialogs Fig.8: Automatic Sequencing is a feature which allows you to quickly and easily generate a sequence for a piece of music, based on beat detection and spectrum analysis. It can be further modified or used as-is. if you move the mouse cursor off the left or right edge of the sequence area, the display will automatically scroll in that direction. The light channel selection can be altered without affecting the selection time span by clicking on the light names at the left side of the window. Holding down shift or control while clicking on the light names allows you to select a range or group of them. This allows you to manipulate a number of channels at once, eg, to create a Cascade (more on this later). It is also possible to adjust the amount of space available for WAV data display at the top of the screen. Move the mouse over the line dividing the WAV and sequence area and drag it up or down. You can use the same technique to adjust the left/right split between the light names and the sequence data. Keyboard controls In addition to the keyboard shortcuts (shown in the menus), there are some extra keyboard controls which perform basic functions such as changing the selection. The arrow keys, in combination with shift and control, allow you to move the current selection or scroll the display. The left and right arrows by themselves move the selection left and right and if shift is held down at the same time, it moves in larger increments (x10). Moving the selection with the keyboard allows you easily make fine timing adjustments. Table 4 – Beat Detection options Sensitivity Previews Some options are common to several dialogs. If “Live Preview” is turned on then the selected operation is performed immediately so that you can see what its result will be. If you then cancel the dialog, the changes are undone. Table 5 – Spectrum Analysis options Frequency range The upper and lower ends of the frequency bands. This range is broken into enough logarithmic steps for the selected light channels. Stereo If “Left to right” or “Right to left” are selected then the light channels are divided in half, one set using left channel audio and the other right channel audio. Otherwise, the selected channel is used for all bands. Frequency order Determines the order in which the resulting bands are mapped onto the light channels. Response The Flash and Fade modes work similarly to Cascade. The Sensitivity control works similarly to Beat Detection. For “Brightness tracks volume”, instead of flashing, the brightness of each light channel varies continuously, tracking the audio level in each frequency band. Scale brightness by intensity In Flash/Fade mode, this causes the brightness to be modulated by the intensity of each transient. Scale duration by intensity In Flash/Fade mode, this causes the On Time and if appropriate, Rise and Fall times, to be modulated by the intensity of each transient. Timing As for Beat Detection. Determines the transient energy required to trigger a light flash. Minimum inter- Once a beat has been detected, any transients val are ignored for this period after it. The equivalent maximum BPM (Beats Per Minute) are shown. Delay While much of the sequencing work is done in the main program window, the software also includes a number of “dialogs”. These are windows which pop up when certain options are selected, allowing you to enter additional parameters. The available dialogs are: Settings, Lights, Custom Ramp, Cascade, Beat Detection, Spectrum Analysis and Automatic Sequencing. The first two are used to alter the behaviour of the program while the others manipulate the sequence in some way. One thing they all have in common are the “OK” and “Cancel” buttons. Either button will close the dialog, but pressing “Cancel” also discards any changes made since it was opened. You can only have one dialog open at any time. For dialogs that manipulate the sequence, only the selected portion is affected, except in the case of Automatic Sequencing which always operates on the whole file. Thus, most of these dialogs are unavailable while there is no selection. Each light flash is offset by this amount (±) from the detected transient. Most commonly used in “Fade” mode to compensate for the initial ramp. Effect, Timing, As with Cascade. The “Multiple Lights” settings Multiple Lights are only available if more than one light channel has been selected. 70  Silicon Chip siliconchip.com.au COMMANDS The software supports many commands which are accessible via the menu or the toolbar. While most of them are self-explanatory, the following are worth elaborating. File->Publish Sequence This copies the loaded sequence onto your memory card along with the accompanying WAV file (if appropriate). The memory card drive letter is set automatically but you should check the Settings before using this feature and adjust it if necessary. Edit->Paste Special Normally when you copy and then paste sequence data, the data is copied exactly. The only change normally made is when the selection into which it is being pasted is smaller than what was copied, in which case some of the data is omitted. However, the Paste Special menu provides five ways to paste data that also manipulate it in some way. If Paste Stretch is used, the duration of the data copied will be lengthened or shortened to fit the current selection, time-stretching it. Paste Mix and Paste Merge allow the sequence data in the copy buffer to be combined with the data within the current selection. In the case of “Merge”, the brightest light value will dominate at any given time. This is useful in a case where you want to leave the existing sequence as it is but add new lighting commands on top. “Mix” is similar but the resulting brightness is the product of the existing and pasted brightnesses. This is especially useful with the Custom Ramp option as it allows you to take a series of light flashes (or ramps, etc) and apply a ramp over the top which modulates their brightness over time. This effect is shown within the selection in Fig.1. Edit->Copy Buffer Storage Normally, if you perform a “Cut” or “Copy” command, the contents of the copy buffer are replaced with the selected data and thus lost. Sometimes you need to be able to store multiple sequence sections in order to paste them later, in a different order. Copy Buffer Storage gives you nine additional holding locations. First, copy or cut the data in the normal manner, then store the contents of the copy buffer using this menu. The contents can be retrieved later and then pasted as usual. Edit->Selection Storage This menu allows you to store the location of the current selection so that you can recall it later. After making a selection, store it in one of the nine locations. It can then be restored any time. The stored selection includes both the light channels and time span. Edit->Change Length This is only available if you are editing a stand-alone sequence (ie, one without audio). In this case you can change the length (ie, running time) at will. Note that if you reduce the length, any data past the end will be lost. Playback->Set Playback Region If you select a time span and then use this command, the selection becomes the new playback region, which is shown in red. It is then independent of the selection. The “Play Region” command will then play that portion of the sequence. This is handy when you want to make a number of changes to a given section and play it back to check what you have done afterwards, without having to re-select the whole section each time. Lights->Cancel Light Actions All sequence commands in the selection are deleted. This means that during this period, the lights will remain in whatever state they were left just prior to it. To turn the lights off instead, use the “Lights Off” command. Lights->Set Light Brightness This option sets the brightness of the selected lights, in the selected time period, to be a constant, between 0% and 100% of full brightness. The actual brightness is set using the dropdown arrow adjacent to this command in the toolbar. LightsThis ramps the brightness of the selected lights smoothly from whatever brightness they are at the beginning >Interpolated Ramp of the selection to that at the end. Lights->Ramp Up/ Down These commands take the brightness of the selected lights at the beginning of the selection and either ramps them up to maximum brightness or down to minimum brightness (off) over the selected period. Lights->Custom Ramp/Cascade See the section on Dialogs. DSP->Beat Detection/Spectrum Analysis/Automatic Sequencing See the section on Dialogs. siliconchip.com.au December 2010  71 Table 6 – Automatic Sequencing options Number of light channels Defaults to the number of available channels. Use a lower number to leave some channels unaffected. Flash period Controls the flash duration Beat detection allocation The proportion of available channels to dedicate to the Beat Detection function. Pingpong Controls whether the Beat Detection uses “Low to high” or “Ping pong” order. Fade Controls whether the Beat Detection uses “Flash” or “Fade” mode. Beat detection sensitivity Allows the sensitivity to be adjusted over the most useful portion of the range. Spectrum analysis Stereo controls whether the Spectrum Analysis feature uses “Left to right” or “Mono” mode. Track selects either “Brightness tracks volume” or “Fade” mode. “Scale Duration” selects either “Scale Brightness” or “Scale Duration” mode. Spectrum analysis sensitivity Allows the sensitivity to be adjusted over the most useful portion of the range. If you adjust any of the dialog parameters, the preview will update to reflect the change. Because the operation could be slow if the selection is large (eg, Spectrum Analysis), it is a good idea to zoom into a portion of the selection while using Live Preview. In this case, only the visible portion will be updated, speeding up the preview. Once you click “OK” then the operation will be performed over the entire selection. Any operations which take more than about a quarter of a second will display a progress dialog. This is true whether it is a preview or the final operation which is being performed. When the progress dialog is open, it is possible to cancel the operation. Note that it is possible to go to the main window and scroll/zoom while a dialog is open. If Live Preview is active, the preview will automatically re-calculate when the view is changed (if necessary). You can also change the selection while a dialog is open. If Live Preview is active then the preview will be changed to apply to the new selection. Common options The other two common dialog options are “Merge” and “Mix”, which perform the same operations as described under the “Paste Special” command. When you click “OK” in a dialog, the options that you have selected are remembered for next time you perform that same operation. In addition, many of the dialogs are accessible via the toolbar as double-action buttons. Clicking the dropdown arrow alongside the button opens the dialog while pressing the button itself immediately applies the associated operation. This means that once you have the options set up the way you want and clicked “OK”, you can repeat the same 72  Silicon Chip operation on a different selection using the toolbar button, without having to go through the dialog. Alternatively, you can click the dropdown arrow and adjust the parameters again. Custom Ramp and Cascade The Custom Ramp dialog allows you to create a smoothly changing brightness level for one or more lights over a given time period. See Table 2 for the possible options. Note that as you change between the four different ramp types, the brightness values are shuffled around so that you don’t have to make as many adjustments. Cascade creates an effect where flashes occur across multiple light channels over time, with a constant period and duration for each flash. It is also possible to smooth the beginning and end of each flash with a brightness ramp. See Table 3 for the available options. It is possible to select a single light channel for a Cascade, in which case the Order option is disabled since it has no effect. Beat Detection Beat Detection provides a means to analyse the audio and attempt to discover the beat by looking for transients. Before searching for transients, a fourth-order notch filter is applied to the audio (400Hz-4kHz) in order to eliminate vocals and other instruments which might otherwise fool the algorithm. The sensitivity is critical and its operation is not always intuitive. It is a good idea to pick a small section of the audio file and try different sensitivity settings (using the Live Preview option) in order to detemine the setting which picks up the beats most reliably without much spurious triggering. The best settings are usually between mid-scale and halfway to maximum. Once the beats are detected, they are passed onto the Cascade routine, providing similar options for light triggering on each detected transient. The full set of options are explained in Table 4. Spectrum Analysis This is the most complicated of the sequencing dialogs. Spectrum Analysis is much like Beat Detection but rather than using a notch filter, instead the frequency spectrum is broken up into a series of bands and a bandpass filter (fourth order) is applied to isolate each set of frequencies. As with Beat Detection, transients in the result trigger flashing lights. Because each lighting channel operates on a separate band, that means that the lights respond to different frequencies, creating a more interesting effect. See Table 5 for a summary of the options. The final dialog, Automatic Sequencing, combines Beat Detection and Spectrum Analysis while presenting fewer options. This makes it easy to create a quick sequence for an audio file. Simply click the icon, adjust the settings (or leave them at the defaults) and then click “Go”. There is no preview in this mode but if you do not like the results you can undo the changes, adjust the parameters and try again. For a description of the Automatic Sequencing options, see Table 6. siliconchip.com.au Connecting multiple lights without spending big $$$! As you will recall from the first two parts, the Digital Lighting Controller has IEC mains output sockets, mainly because they will fit! However, practically all lights you can buy, especially Christmas lights, will be fitted with a standard 3-pin mains plug. We recommended buying an IEC-to-3-pinmains converter lead, such as that shown bottom left in the picture below. However, these are relatively expensive (~$10 each) so for eight channels it quickly adds up. And what happens when (as you almost certainly will with Christmas lights) you want to plug in multiple lights into the same channel? We have come up with a pretty cheap solution for both problems – and that is to use a standard 4-way mains power board (which you can buy anywhere these days for $3 or less!) and change the 230V mains lead over to one fitted with an IEC plug. Where do you get such a lead? Call us bower-birds if you like but every time we have thrown out an old CRT monitor, we have cut off the mains lead (back in the early days CRT monitors used to plug into the computer via an IEC socket). Ergo, our junk box had several lengths of mains leads fitted with IEC plugs one end. So for us, the only cost was buying some power boards (and we found a pack of four at Bunnings for $6.95!) Don’t have spare IEC cables on hand? If you don’t have the luxury of a well-stocked junk box, the alternative is to use a powerboard as is but change the mains plug over to an IEC type (as shown at right in the photo below). It’s not quite as cheap (these plugs usually sell for about $7 each) but at least you get multiple outlets via the powerboard. Opening up the powerboard Usually, powerboards are assembled with tamper-proof screws – so you’re going to need a tamper-proof screwdriver to remove them. (What self-respecting hobbyist wouldn’t have a set of tamper-proof bits in his/her toolbox?). Most we found simply use a slotted screw with centre raised section, which requires a slotted blade bit. However, we’ve also found them with star, Torx and other bits. Sometimes they are rivetted or welded together, in which case you can’t do this modification. Check your powerboard before buying! Remove the screws with whatever bit it takes and the two halves of the powerboard should separate. There will almost certainly be an overload circuit breaker built in – leave the brown wire connecting this to the Active bus bar but cut off the Earth wire where it connects to the Earth bus and similarly the Neutral (blue) wire where it connects to the Neutral bus. Remove the Active (brown) wire where it connects to the input of the circuit breaker. Invariably, the wires are all welded so they will have to be cut away. Replace the cable with your IEC-ended cable, cutting the brown, blue and green/yellow leads to the same length as those you removed. Make sure the individual wires are mechanically secured to the bus bars (ie, wrap them around tightly) and then solder them in place. Replace the cover and you’re done. SC Left: our modified powerboard, now fitted with an IEC mains plug and cable assembly “saved” from a junked monitor. Right: the alternative approach, fitting an IEC plug in place of the standard mains plug. Above: an IEC mains plug to 230V mains socket adaptor, as originally recommended. siliconchip.com.au December 2010  73