Introducing the Ventriloquist: A DMX-512 Triggered Audio Player
Is your theatre going through budget cuts? Replace your audio guy* with a simple, sanitary, hassle-free playback solution. Does your haunted house need automated audio playback, precisely sync'd with lighting cues? The applications are endless.
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The Ventriloquist is a standalone DMX-512 triggered audio playback engine.
It currently supports MP3 files at any resolution and bitrate, as well as regular .wma files.
These files are stored on a bog-standard USB memory stick of any size. Simply create a directory in the top level of the USB drive with the title 'mp3', then fill the directory with audio tracks.
The Ventriloquist determines its start address by reading a text file (located in the same mp3 directory) called 'config.txt.' The system also contains a USB port for easy firmware updates. Future versions of the software may allow for more advanced settings via the config.txt file.
It's important to note that config.txt needs to be created with a simple text editor, such as Notepad (Windows) or TextEdit (Mac). Other word processing programs, such as Word, will insert extra garbage characters in the file, which won't be recognized by the Ventriloquist. Be sure the file has the extension .txt.
Obviously, this pictures shows that DMX address 13 has been chosen for for the start address.
The system then listens to DMX channel values on 7 consecutive DMX channels. DMX channel values are used to send basic transport control commands and/or access arbitrary audio tracks at any time. The vertical character after '013' was the computer's cursor, and was present during the screen capture.
This .zip file [4.33MB] contains 51 computer-generated MP3 files and a sample config.txt file.
Setting up the USB Memory Stick
At power up, The Ventriloqist looks for a directory called 'MP3' in the memory stick's top level. On many computers, this directory would be designated
F:\MP3\
Inside this directory should be two things: a text file called 'config.txt' and an array of MP3 / WAV files. For example:
F:\MP3\config.txt
F:\MP3\001.mp3
F:\MP3\002.mp3
F:\MP3\003.mp3
F:\MP3\hello.mp3
F:\MP3\thunder.mp3
System Operation
Follow these steps to ensure stable system operation:
- Insert the USB stick
- Attach a 'live' DMX data cable
- Apply power, which is provided by a switching power supply, 5.0V @ 1.0A DC, center positive. Do not use any other power supply, specifically any type of 'non-switching' design. Note also that the Ventriloquist ships with a properly designated power adapter.
- Attach the line-level audio output (1/8" stereo jack) to an amplifier, set of powered speakers, etc.
On power up, the system waits approximately 8 seconds to initialize the internal settings, USB filesystem, and so forth. During this time, only the power LED is illuminated.
Once this boot process has been completed, the system first attempts to determine its DMX start address by reading the file 'config.txt.' If this file exists and is properly formatted,the system's DMX and Serial Data LEDs will flash 2 times:
1 second on - 1 second off - 1 second on - 1 second off
If the file cannot be found or is improperly created, the system will assume a DMX start address of '1' and flash two times at a shorter rate:
.5 second on - 1 second off - .5 second on - 1 second off
If valid DMX is detected, the system's DMX LED will pulse briskly.
Controlling MP3 Playback
The system utilizes 7 consecutive DMX channels. For the purposes of these instructions, a system start address of '1' is assumed. Therefore, channel 2 would be 'start address + 1,' channel 4 would be 'start address + 3,' etc.
The Ventriloquist responds to the following DMX channels and levels:
DMX Channel Values & Transport Control Functions
- 100% (255) Play all tracks in order
- 100% (255) Stop
- 100% (255) Pause / Resume
- 100% (255) Skip track backward (+)
- 100% (255) Skip track forward
- 2% - 100% Discrete track access 1-51 *see below
- 2% - 100% Discrete track access 52-102 *see below
(+) If a track is currently playing, the skip backward command should be sent twice in fairly quick succession. The first command will restart the currently playing track. The second command will skip backwards one track. Just like on a CD player.
There are two ways to trigger playback of various MP3 files. The first is direct/sequential access. The second is random/arbitrary track access.
Notes on Direct track access:
- DMX channels 1,2,3,4 & 5 may be used
- Unused channels should be set to zero
- To determine the track playing order, simply display the contents of the USB drive on a computer screen, then click on the file name to sort in numeric / alphabetical order.
- In Direct track mode, playback continues from one track to the next, unless a 'stop' or 'pause' command has been received.
Notes on arbitrary track access
- DMX channels 6, 7 and (optionally) 2 are used
- Unused channels should be set to zero
- In arbitrary track mode, only the selected track is triggered. At the end of the track, playback stops and the 'transport' returns to the top of the list.
- Arbitrary tracks must be named in the format 'XXX.mp3' where XXX is a three digit decimal number, often with leading zeros. Examples of proper file names are:
001.mp3DMX Input Track Playback
010.mp3
101.mp3
087.mp3
etc.
0 N/A
[1 5] play 001.mp3
[6-10] play 002.mp3
[11-15] play 003.mp3
... ...
[250-255] play 051.mp3
Specs:
- Power Supply 5V @ 1.5A, 2.1mm x 5.5mm barrel, center positive
- DMX IN & Through Jacks on Neutrik XLR-5 connectors, optically and galvanically isolated from the rest of the circuitry.
- Internal USB port for easy fimrware upgrades
The Fine Print
As with everything we sell, the Ventriloquist comes with a 30-day no-questions-asked money back guarantee. If you're not thrilled with your new gear, we'll make it right or promptly refund the purchase price. The system is also warranted against failure for one year.
* Just kidding. We love audio guys. Even the hygenically impaired ones.
Seriously, though... There's a ton of applications where a self contained, easily controlled audio playback engine would be really, really convenient.