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MIDI Show Control and MIDI note – et cetera...

Written by Guest Blogger | Mar 28, 2017 5:00:00 AM
 This is the second article in a series about synchronization and timecode translated into English. You can read the first article here. This article describes MSC and MIDI note protocols and how they can be used for synchronization.

There are different event-synchronization methods used for show synchronization. Each event is associated with a definitive moment in time, and in terms of audio- or video-tracks, the time scale is the most important tool. The master device can generate the Time Code that will be transmitted to all controllers. It’s also possible to use a different type of synchronization where every device starts in unison, and sustained, constant synchronization is absent. That’s possible thanks to short commands sent from the master device to slave devices. MIDI protocol is ideal for this purpose.

Because the MIDI interface came from the music industry, everything that evolved from it was mostly intended for musical applications. It came out in October 1982. In the beginning, this interface was created in order to connect electronic musical instruments with equipment that sends information about musical notes back and forth.

MIDI language consists simply of control commands and their parameters. MIDI-language commands are called messages. Messages are divided into two basic types: ones that control sound generation, which dictate which notes to play and how loud they should be, and ones that carry out secondary functions, or in other words, ones that control setting adjustments for the tone generator and synchronization (MIDI Time Code or MTC is considered this type).

The first type of messages is called Channel Messages or MIDI note. The second kind are called System Messages. Channel Messages fall into two categories: Channel Voice Messages and Channel Mode Messages. System Messages can be System Real-Time Messages and System Exclusive Messages (SysEx). Only the first type of voice messages (MIDI note) and SysEx messages are used for show synchronization.

Now we’ll talk more about MIDI note and how it’s applied to synchronization. While MIDI note is made up of information about notes, the receiving device doesn’t need to generate sound for a selected note, but can perform other commands instead. Now there are many special programs and consoles in whose settings specific notes can be designated to carry out certain commands.

For example, in a lighting console or audio board, we can set it up that when the note “do” (C) from the first octave is received, a lighting program or video content starts up (each note has its own MIDI number, from 0 to 127). Now when these notes are received through MIDI, the audio and light desks start their programs simultaneously. Moreover, commands of this type are detected instantly and without any delay. Something to know about this method is that with a large number of different MIDI note commands, it can be difficult to keep track of which number corresponds with which action. At some point, MIDI note no longer met theatrical and concert needs, which introduced the desire to create a more specialized control protocol.

In 1989, Andy Meldrum of Vari-Lite suggested creating an open protocol that could connect show systems of different applications and by different manufacturers, and control them with the help of any MIDI controller. At the end of 1989, Charlie Richmond from Richmond Sound Design organized a working group that made up the MMA (MIDI Manufacturers Association) and opened a forum on an electronic message board. The resulting standards project was ratified by the MMA and JMSC (Japanese MIDI Standards Committee). On July 25th, it became “Recommended Practice RP-002,” otherwise known as MIDI Show Control v1.0.

MIDI Show Control messages are categorized as Real-Time Universal System Exclusive.

In MSC specifications, the terms Controller and Controlled Device are used. The device that generates MSC messages, called the Controller, is usually a computer with special software and a MIDI card. The receiving device, lighting desk, media server and other controllers are Controlled Devices.

What’s significant about MSC is that this type of message has certain categories, including a General Category and additional subcategories. There’s also a special ‘All-Types’ category for this type of message which transmits to all controller types. Lighting, sound, machinery, video, projection, special effects and pyrotechnics all have their own category.

Hex   command_format

 

———————————————–

00 reserved for extensions

 

 01 Lighting (General Category)

02 Moving Lights

03 Color Changers

04 Strobes

05 Lasers

06 Chasers

 

10 Sound (General Category)

11 Music

12 CD Players

13 EPROM Playback

14 Audio Tape Machines

15 Intercoms

16 Amplifiers

17 Audio Effects Devices

18 Equalizers

 

20 Machinery (General Category)

21 Rigging

22 Flying systems

23 Lifts

24 Turntables

25 Trusses

26 Robots

27 Animation

28 Floats

29 Breakaways

2A Barges

 30 Video (General Category)

 

31 Video Tape Machines

32 Video Cassette Machines

33 Video Disc Players

34 Video Switchers

35 Video Effects

36 Video Character Generators

37 Video Still Stores

38 Video Monitors

 

 40 Projection (General Category)

41 Film Projectors

42 Slide Projectors

43 Video Projectors

44 Dissolvers

45 Shutter Controls

 

50 Process Control (General Category)

51 Hydraulic Oil

52 H20

53 CO2

54 Compressed Air

55 Natural Gas

56 Fog

57 Smoke

58 Cracked Haze

 

60 Pyro (General Category)

61 Fireworks

62 Explosions

63 Flame

64 Smoke pots

 

7F All-types

 

Information about which device needs to receive a command is communicated in an MSC command. Each device in a category has its own unique ID that is configured manually in the receiving device’s settings. What does that give us? Now you can send definitive commands to each controlled device that are intended solely for it, and the messages for all remaining devices that have a different category of equipment and ID can just be ignored.

The advantage of MSC over MIDI note is that this protocol’s messages contain concrete action commands and not just a message code that needs an action assigned to it by the end device. There’s a basic group of MSC messages, General Commands, that are valid for all device types. Along with General Commands, there’s an additional Sound Commands group, which is specifically for sound-system synchronization. For general synchronization, we’re only interested in General Commands.

General Commands

 

Hex   command_format

———————————————

 

00 reserved for extensions

01 GO

02 STOP

03 RESUME

04 TIMED_GO

05 LOAD

06 SET

07 FIRE

08 ALL_OFF

09 RESTORE

0A RESET

0B GO_OFF

 

And so, we’ve figured out commands and where to send commands, so now it’s logical to discuss how to apply these commands. In MSC messages, there’s part of a code in which information about a controller’s object is encoded, and which needs to receive a command. A command can contain a cue number, cue list and cue path. The code <Q_number> 00 <Q_list> 00 <Q_path> consists of a scene number to apply the command (CueNumber), what list the scene is on (CueList) and the path where the cue list is (CuePath). There’s an additional option that can contain an always-empty value.

To summarize, you can say this about MSC: First, an MSC message contains information about which type of device a message is intended for, and under which number (Command Format, Device ID). Secondly, an MSC message has a command that needs to be carried out in the receiving device (Command). Thirdly, an MSC message contains information about which object accepts a command in a receiving device (CueNumber, CueList, CuePath).


In contrast, MIDI note has no clear association between commands and actions on a console. In addition, all clients receive MIDI note messages, even if they’re not meant for every client. And finally, with MIDI note messages, it’s not possible to know which object on the console the message is applicable to.

Based on what is outlined above, you could say that MSC is much more functional and has more capabilities than the simple MIDI note. MSC allows you to quickly program commands on the main controller for show synchronization. There’s no need for complicated settings on lighting consoles and other receiving devices. All necessary information is received from the control protocol.

Now you know the basic differences between MSC and MIDI note protocols, their advantages and disadvantages, and how you can use them for show synchronization.


For more information, you could read this article by ETC Technical Support Engineer Hans Hinrichsen, which explains how the Eos lighting-control family receives and transmits MSC commands. And this short article goes over the MSC messages supported by the Eos family.  

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Roman Vakulyuk

Award-winning lighting designer Roman Vakulyuk has always been interested in electronics, and he knew as a child what he wanted to do when he grew up. In school, he enjoyed programming and wrote several computer programs. Roman fell in love with music in college and moonlighted as a DJ in clubs. One of the clubs had a professional lighting system, and one night when there was no one at the lighting desk, he decided to give it a try. It was an important moment in his life, because he became infatuated with lighting and worked to become a lighting designer. After immersing himself in the profession, his skills advanced and Roman began to contemplate how to create more dramatic shows. He found out that there was such a thing as synchronization technology that could synchronize all show elements, and he began to research it. Over the years his light shows got better and better, and he began to use synchronization on his own projects. “Now I know so much more than the first time I sat behind a lighting console, but I haven’t stopped learning and progressing, because knowledge is the best path forward,” explains Roman. Currently he works with Global Show Trade (GST), a Moscow-based production company, education center and product showroom. Some of his recent projects include the Bilan 35 concert, the Counter-Strike: Global Offensive cyber tournament opening ceremonies, and the 2015 Circle of Light Festival.