Как проиграть ноту?

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This is a simple class that plays a formatted musical string. It is reminiscent of the old GWBASIC days whereby one could play a string of notes via the PC speaker. I know that WAV and MIDI files are available in todays technology, but sometimes one does not need all that overhead. The class is useful for certain types of alarms (specially if the user has his sound card volume muted) or simple "Cell Phone" like jingles. The trick of the matter in Delphi is that the standard DELPHI implementation of BEEP takes no arguments and has only one sound. However the WIN API BEEP() takes two arguments.

 

ie.

 

BOOL Beep(

         DWORD dwFreq,     // sound frequency, in hertz

         DWORD dwDuration  // sound duration, in milliseconds

        );

 

 

Parameters

 

dwFreq

 

  Windows NT:

  Specifies the frequency, in hertz, of the sound. This parameter   must be in the range 37 through 32,767 (0x25        through 0x7FFF).

 

  Windows 95:

  The parameter is ignored.

 

dwDuration

 

  Windows NT:

  Specifies the duration, in milliseconds, of the sound.

 

  Windows 95:

  The parameter is ignored.

 

As can be seen it appears that BEEP() is NOT supported on WIN95, but is OK from there upwards. (I have not tested it on WIN95, but assume you will just get a monotone ???? - anyone for comment)

 

It is easily called by prefixing the unit

ie. Windows.Beep(Freq,Duration)

 

The format of the "Music String" is a comma delimited (",<" terminated) string in the following formats. (The string is CASE-INSENSITIVE and [] means optional with defaults).

 

A..G[+ or -][0..5][/BEATS] and

 

@[/BEATS]

 

Where A..G   is the Note to be played.

     + or - is optional Sharp or Flat designator respectively. (default is normal NULL)

     0..5   is optional Octave range (default = 1)

     /BEATS is number of 100ms to hold the note (default = 1)

 

where @      is a musical pause

     /BEATS is the number of beats to pause for (default = 1)

 

where ,<     is the END OF STRING terminator.

 

Properties:

DefaultOctave                        : Used if no 0..5 designator specified in format. (System Default = 1)  

BetweenNotesPause        : Use to set number MS gap between notes (faster or slower default = 100ms)

 

Simple Example:

Code:

procedure TForm1.Button3Click(Sender: TObject);

var

Organ: TMusicPlayer;

begin

Organ := TMusicPlayer.Create;

Organ.Play('A,C,C+,D/3,C,A,C,A,@,F,D/4,<');

Organ.Play('A,A3/2,G4,G/3,@/2,D-0/4,<');

Organ.Free;

end;

 

 

 

Any enhancements or additional ideas welcome. Happy jingeling.

Code:

unit Music;

interface

 

uses Windows, SysUtils;

 

// ===========================================================================

// Mike Heydon May 2002

// Simple Music Player Class Win98/2000 (Win95 not supported)

// Implements Notes A,A#/Bb,C,C#/Db,D,D#,Eb,E,F,F#/Gb,G,G#/Ab

// Caters for Octaves 0..5

// In Between Note Pause setable.

// Defailt Octave setable.

//

// Based on Frequency Matrix

//

//         Octave0   Octave1   Octave2   Octave3   Octave4   Octave5

// A       55.000    110.000   220.000   440.000   880.000   1760.000

// A#/Bb   58.270    116.541   233.082   466.164   932.328   1864.655

// B       61.735    123.471   246.942   493.883   987.767   1975.533

// C       65.406    130.813   261.626   523.251   1046.502  2093.005

// C#/Db   69.296    138.591   277.183   554.365   1108.731  2217.461

// D       73.416    146.832   293.665   587.330   1174.659  2349.318

// D#/Eb   77.782    155.563   311.127   622.254   1244.508  2489.016

// E       82.407    164.814   329.628   659.255   1318.510  2637.020

// F       87.307    174.614   349.228   698.456   1396.913  2793.826

// F#/Gb   92.499    184.997   369.994   739.989   1479.978  2959.955

// G       97.999    195.998   391.995   783.991   1567.982  3135.963

// G#/Ab   103.826   207.652   415.305   830.609   1661.219  3322.438

//

// @ = Pause

// < = End of Music String Marker

//

// ===========================================================================

 

type

TOctaveNumber = 0..5;

TNoteNumber = -1..11;

 

TMusicPlayer = class(TObject)

private

   Octave,

     FDefaultOctave: TOctaveNumber;

   NoteIdx: TNoteNumber;

   FBetweenNotesPause,

     Duration: integer;

protected

   function ParseNextNote(var MS: string): boolean;

public

   constructor Create;

   procedure Play(const MusicString: string);

   property DefaultOctave: TOctaveNumber read FDefaultOctave

     write FDefaultOctave;

   property BetweenNotesPause: integer read FBetweenNotesPause

     write FBetweenNotesPause;

end;

 

// ---------------------------------------------------------------------------

implementation

 

const

MAXSTRING = 2048; // ASCIIZ String max length

 

MHERTZ: array[0..11, 0..5] of integer = // Array of Note MHertz

((55, 110, 220, 440, 880, 1760), // A

   (58, 117, 233, 466, 932, 1865), // A+ B-

   (62, 123, 247, 494, 988, 1976), // B

   (65, 131, 262, 523, 1047, 2093), // C

   (69, 139, 277, 554, 1109, 2217), // C+ D-

   (73, 147, 294, 587, 1175, 2349), // D

   (78, 156, 311, 622, 1245, 2489), // D+ E-

   (82, 165, 330, 659, 1319, 2637), // E

   (87, 1745, 349, 698, 1397, 2794), // F

   (92, 185, 370, 740, 1480, 2960), // F+ G-

   (98, 196, 392, 784, 1568, 3136), // G

   (105, 208, 415, 831, 1661, 3322) // G+ A-

   );

 

// =======================================

// Create the object and set defaults

// =======================================

 

constructor TMusicPlayer.Create;

begin

FDefaultOctave := 1;

FBetweenNotesPause := 100;

end;

 

// ===========================================================

// Parse the next note and set Octave,NoteIdx and Duration

// ===========================================================

 

function TMusicPlayer.ParseNextNote(var MS: string): boolean;

var

NS: string; // Note String

Beats,

   CommaPos: integer;

Retvar: boolean;

begin

Retvar := false; // Assume Error Condition

Beats := 1;

Duration := 0;

NoteIdx := 0;

Octave := FDefaultOctave;

CommaPos := pos(',', MS);

 

if (CommaPos > 0) then

begin

   NS := trim(copy(MS, 1, CommaPos - 1)); // Next Note info

   MS := copy(MS, CommaPos + 1, MAXSTRING); // Remove note from music string

 

   if (length(NS) >= 1) and (NS[1] in ['@'..'G']) then

   begin

     Retvar := true; // Valid Note - set return type true

 

     // Resolve NoteIdx

     NoteIdx := byte(NS[1]) - 65; // Map 'A'..'G' into 0..11 or -1

     NS := copy(NS, 2, MAXSTRING); // Remove the Main Note ID

 

     // Handle the @ Pause first

     if NoteIdx = -1 then

     begin

       if (length(NS) >= 1) and (NS[1] = '/') then

         Beats := StrToIntDef(copy(NS, 2, MAXSTRING), 1);

       Sleep(100 * Beats);

       Retvar := false; // Nothing to play

       NS := ''; // Stop further processing

     end;

 

     // Resolve Sharp or Flast

     if (length(NS) >= 1) and (NS[1] in ['+', '-']) then

     begin

       if NS[1] = '+' then // # Sharp

         inc(NoteIdx)

       else if NS[1] = '-' then // b Flat

         dec(NoteIdx);

 

       if NoteIdx = -1 then

         NoteIdx := 11; // Roll A Flat to G Sharp

       NS := copy(NS, 2, MAXSTRING); // Remove Flat/Sharp ID

     end;

 

     // Resolve Octave Number - Default := FDefaultOctave

     if (length(NS) >= 1) and (NS[1] in ['0'..'5']) then

     begin

       Octave := byte(NS[1]) - 48; // map '0'..'5' to 0..5 decimal

       NS := copy(NS, 2, MAXSTRING); // Remove Octave Number

     end;

 

     // Resolve Number of Beats - Default = 1

     if (length(NS) >= 1) and (NS[1] = '/') then

       Beats := StrToIntDef(copy(NS, 2, MAXSTRING), 1);

 

     Duration := 100 * Beats;

   end;

end

else

   MS := ''; // Signal end of music string

 

Result := Retvar;

end;

 

// ===================================

// Play the passed music string

// ===================================

 

procedure TMusicPlayer.Play(const MusicString: string);

var

MS: string; // Music String

begin

MS := trim(UpperCase(MusicString));

 

while (MS <> '') do

begin

   if ParseNextNote(MS) then

   begin

     Windows.Beep(MHERTZ[NoteIdx, Octave], Duration);

     Sleep(FBetweenNotesPause);

   end;

end;

end;

 

end.

 

 

©Drkb::03609

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