Как проиграть ноту?

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:
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.
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.
Source: http://www.baltsoft.com/
ID: 03609
Category:Звук