Preparing the Performance, Rehearsals

Controlling Antescofo from AscoGraph

AscoGraph is very useful in a concert context, when you have to follow the follower to control the following part of Antescofo and to control what is launched in the Max patch.

The top of the Ascograph window has five buttons that correspond respectively to the Antescofo function previous event, stop, play, start and next event that you can launch also directly in your patch.

The play button simply sequences from the beginning of the score to the end, using given event timing and internal tempi, performing actions wherever available.

The Play string function (Menu/Transport/Play string) plays (evaluates) only the selected part of your score (restricted to a sequence of actions).

When Antescofo is in follower mode, and AscoGraph is up, the current position infered by the listening machine is outlined both in the piano roll and in the AscoGraph text editor.

Moving in the Augmented Score

They are several commands (Max/PD messages that can be sent to Antescofo) that are very useful in rehearsals. The idea is to be able to take over the score deterministically (with correct electronics) if you are rehearsing for example from "Measure10" (a label in score) onwards and assuring that things are prepared (or not) once you start from there as if you have performed everything before. Here is a list of these commands:

Methods with no argument

Methods with label/symbol control

NOTE: Most above commands would use "current position" and not "from the beginning". In order to reset, one would precede one of the above with the STOP method.

Methods with float/beat-position control

Same as above, but taking a float value corresponding to cumulative beat-position in score (useful for interaction via notation editors such as AscoGraph and NoteAbility PRO). Namely: startfrombeat, scrubtobeat, playfrombeat, playtobeat, and gotobeat

Non-standard use of score navigation command

Like the others commands understood by Antescofo, these navigation messages can be issued from the Antescofo score itself. They can be used to develop open pieces, or to alter the flow of the performance on purpose.

Tuning the Listening Machine

In the default audio observation mode, you need to define the analysis parameters which are window size, and hop size in sample numbers. Antescofo automatically buffers audio and does the required analysis. Your choice of window size and hopsize could alter the performance and computation of the system! Default value is [2048 1024]. For example, when following piano music, you might want to set window size to 4096 (for better spectral resolution). If you want more exact timing, reduce the hopsize (and pay more CPU).

In your max/PD Patch, you can access to advanced performance controls through the audio menu.

Calibration

The quality of audio input is of utmost importance for any recognition system and Antescofo is no exception! If the audio input is too low or corrupted, Antescofo can no longer correctly detect events.

Antescofo comes with a built-in Calibration mode to help make sure there is enough audio level for the recognition system to work. You can use it by sending the "calibrate 1" message to Antescofo, start sending audio to Antescofo (no need to "start") and watch the values sent from the left-most outlet with a prefix "calibration".

Antescofo calibration values are always between 0.0 and 1.0 and can be interpreted as follows: Whenever there are "events" present in audio, these values should be relatively high (>0.75) and in the contrary (non-events such as silence, hall noise etc.) it should be relatively low (<0.5). It is best practice to test these conditions before any use. If these conditions do not meet, you have to tweak the input level (in Max or audio console) to Antescofo.

It is highly preferable in practice to separate live processing input from that of Antescofo to keep separate level.

Tuning

For pitch and polyphonic detection, Antescofo is tuned by default to 440.Hz (on A4). This can be changed with the message tune $1, where $1 is the new tuning.

Harmonic Analysis Control

When run in polyphonic mode (default mode) Antescofo analyzes realtime audio and matches it to score pitches using a predefined number of harmonics. This can be controlled using the nofharm $1 message and is 10 by default. Use it if you are confident on what you're doing !

Some instruments have strange harmonic structures ! For example, clarinet usually has odd harmonics only. Or vibraphones (depending on the manufacturer) might produce only several non-arranged harmonics. If such cases are systematic (and you can observe it clearly on the instrument spectrum), you can tell Antescofo to systematically use a certain harmonic series (which also accepts floating points) with the message harmlist. We recommend you to be quite sure before changing this since it can severely affect behavior!

Dealing with Errors

Errors, either during parsing or during the execution of the Antescofo score, are signaled on the MAX console.

The reporting of syntax errors includes a localization. This is generally a line and column number in a file. If the error is raised during the expansion of a macro, the file given is the name of the macro and the line and column refers to the begining of the macro definition. Then the location of the call site of the macro is given.

Printing the Parsed File

Using Ascograph, one has a visual representation of the parsed Antescofo score along with the textual representation.

The result of the parsing of an Antescofo file can be listed using the printfwd message or the antescofo::printfwd internal command. This command opens a text editor. Following the verbosity, the listing includes more or less information.

Tracing

They are several alternative features that make it possible to trace a running program.

The Outlet

If an outlet named TRACE is present, the trace of all event and action are send on this outlet. The format of the trace is

      EVENT label ... 
      ACTION label ...
Verbosity

The verbosity can be adjusted to trace the events and the action. A verbosity of n includes all the messages triggered for a verbosity m < n. A verbosity of:

Tracing the Updates of a Variable

If one want to trace the updates of a variable $v, it is enough to add a corresponding whenever at the begining of the scope that defines $v:

      whenever ($v = $v) 
      {
              print Update "$v: " $v
      }

The condition may seems curious but is needed to avoid the case where the value of ::antescofo $v is interpreted as false (which will prohibit the triggering of the body).

Tracing the Evaluation of Functions

Function calls can be traced, see the description of the functions @Tracing and @UnTracing.