Structure of an Antescofo Program

An Antescofo program, or augmented score, is a sequence of:

written in a file. This file can include other files (inclusions can be nested arbitrarily) using the @insert and @insert_once commands, see section file structure. File inclusion does not alter the organization of an augmented score: the interpreter sees one single flat file resulting from the textual inclusion of all included files before any evaluation.

     Augmented Score:

Events are recognized by the listening machine (described in detail in chapter Event Specification). Actions, outlined in chapter Actions and detailed in Atomic Actions and Compound Actions, are computations triggered upon the occurrence of an event or of another action. Actions can be dynamically parametrised by Expressions and data structures, evaluated in real-time and described in detail in the sections Scalar Values and Data Structures.

Comments may appear anywhere and are simply ignored by the interpreter.

Definitions

Definitions may appear anywhere between events and actions. This is only for the programmer convenience: they are handled when the score is loaded and their appearance do not alter the sequence of events, the sequence of actions or the interleaving of events and actions. When the sequencing of actions and events must be considered, definitions are simply abstracted away.

     Definitions:

There are nine kinds of entities that can be defined (see the above diagram). An entity (function, process, etc.) must be defined before being used. So we suggest gathering all definitions at the begining of the program, even if they can appear anywhere in the file. That said, the position of a process definition in the file has an impact on its priority. See section Action Priority.

When definitions are abstracted away, the structure of an augmented score is better viewed as a first sequence of actions followed by reactions made of an event followed by a sequence of actions :

     Augmented score = a First Secquence of Actions followed by   Reactions

     Reaction = Event followed by   sequence of actions

The First Sequence of Actions

Abstracting the definitions away, an augmented score starts by an optional sequence of actions. Actions in this section are evaluated at the begining of the performance, as soon as the program is launched with a start or a play command and before the recognition of the first musical event.

An augmented score can consists of only this first sequence of actions. In this case, there is no musical event to recognize at all, and the actions correspond to a synchronous and temporized program (like a sophisticated cue list). This program is launched by the command start or play, may wait the elapsing of delays and can react to changes in the external environments through

Reactions: Events Triggering a Sequence of Actions

A reaction is the specification of a musical event followed optionally by a sequence of actions. This sequence of actions is triggered by the recognition of the musical evant in the input stream (audio or midi).

Some elements categorized here as events do not act as true musical event to recognize in the input stream but as modifiers that affect the state of the listening machine for the recognition of the following 'real' musical events:

See also the section Elements in the user guide.

These elements can be abstracted away when considering the sequence of actions linked to an event.

Events are further described in the chapter Event Specification. Actions are further described in the chapter Actions Specification.

The Sequence of Reactions

Reactions appear in an augmented score in a sequence. The order in this sequence is fixed by the order of textual apparition in the file.

The score followed by the listening machine corresponds to the sequence of musical events extracted from the sequence of reactions. However, the @jump attribute can be used on musical events to evade the strict linear ordering of events and to specify arbitrary graph between events. In this graph a branching between events corresponds to an open score given the choice between several possible futures. See section open scores.

An Example

Consider the following score (excerpt of an actual piece):

        BPM 65

        // some definition
        @proc_def ::CS_solo_points($x, $y, $z, $u, $v)  { /* ... */ }

        @global $tSolo, $tabFreq

        let $tSolo := 65
        let $tabFreq := [ /* ... */ ]

        // start of score 
        NOTE D1 1/8 
        NOTE C2 1/8
        NOTE Db2 1/8
        NOTE Ab1 1/8
        NOTE A2 1/2
             Curve tSolo @grain := 0.05s
             {   $tSolo
                 {          {  $RT_TEMPO     } @type "exp"
                        1/2 { ($RT_TEMPO+30) } @type "cubic_out"
                        2/4 { ($RT_TEMPO-20) }
                 }
             }
        BPM 68
             GROUP Solo @tempo := $tSolo
             {
                            ::CS_solo_points("i3",1/2,0.08,0.5,81)
                        1/8 ::CS_solo_points("i1",1/2,0.09,0.5,91)
             }

        NOTE 0 5/2
        NOTE G1 0
        NOTE B1 0
        NOTE D2 0
        NOTE C1 1/2
        NOTE 0 1/2
        NOTE C1 1/2 
        NOTE G2 1

        @fun_def @midi2hz($x)  {$diapason * @exp(($x-69.0) * @log(2.0)/12)}

             GROUP Solo2
             {
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[0]))
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[2]))
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[4]))
             }

        NOTE 0 1/2
        NOTE G1 0 
        NOTE B1 0
        NOTE D2 0

With respect to the structure of the performance, the definition of process ::CS_solo_points and of function @midi2hz can be abstracted away. The definitions are mandatory but they are processed when the file is loaded, not during the performance.

The @global clause is also a definition introducing global variables. Global variables are implicitly defined, so here this definition is used only for documentation purposes, to outline that two global variables will be used in this score.

The two BPM specifications are not real sonic events: they alter the recognition of the following musical events.

When we abstract these definitions and event modifiers away, the resulting score is:

        let $tSolo := 65
        let $tabFreq := [ /* ... */ ]

        NOTE D1 1/8 
        NOTE C2 1/8
        NOTE Db2 1/8
        NOTE Ab1 1/8
        NOTE A2 1/2
             Curve tSolo @grain := 0.05s
             {   $tSolo
                 {          {  $RT_TEMPO     } @type "exp"
                        1/2 { ($RT_TEMPO+30) } @type "cubic_out"
                        2/4 { ($RT_TEMPO-20) }
                 }
             }
             GROUP Solo @tempo := $tSolo
             {
                            ::CS_solo_points("i3",1/2,0.08,0.5,81)
                        1/8 ::CS_solo_points("i1",1/2,0.09,0.5,91)
             }

        NOTE 0 5/2
        NOTE G1 0
        NOTE B1 0
        NOTE D2 0
        NOTE C1 1/2
        NOTE 0 1/2
        NOTE C1 1/2 
        NOTE G2 1
             GROUP Solo2
             {
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[0]))
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[2]))
                            ASCOtoCS_SYNTH4 c (@midi2hz($tabFreq[4]))
             }

        NOTE 0 1/2
        NOTE G1 0 
        NOTE B1 0
        NOTE D2 0

which is composed of a first sequence of actions

        let $tSolo := 65
        let $tabFreq := [ /* ... */ ]         

followed by 17 reactions. These reactions corresponds to the following sequence of musical events looked in the audio stream by the listening machine

        NOTE D1 1/8 
        NOTE C2 1/8
        NOTE Db2 1/8
        NOTE Ab1 1/8
        NOTE A2 1/2
        NOTE 0 5/2
        NOTE G1 0
        NOTE B1 0
        NOTE D2 0
        NOTE C1 1/2
        NOTE 0 1/2
        NOTE C1 1/2 
        NOTE G2 1
        NOTE 0 1/2
        NOTE G1 0 
        NOTE B1 0
        NOTE D2 0

Only two reactions have actions associated to it: NOTE A21/2 and NOTE G2. A sequence of two actions (the curve tSolo and the group Solo) is associated to NOTE A2 1/2. Only one action, the group Solo2 is associated to NOTE G2 1. The groups are compound actions that gather together several others actions. Here they call processes or send MAX/PD messages.