Delphi with Multimedia library Bass.dll play MP3 [10]

This example effect chart:

Code files:

Unit Unit1;
Interface
Uses
Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms,
Dialogs, Stdctrls, Extctrls, Comctrls;
Type
TForm1 = Class (Tform)
Opendialog1:topendialog;
Trackbar1:ttrackbar;
Timer1:ttimer;
Button1:tbutton;
Button2:tbutton;
Button3:tbutton;
Procedure Formcreate (Sender:tobject);
Procedure Button1Click (Sender:tobject);
Procedure Button2click (Sender:tobject);
Procedure Button3click (Sender:tobject);
Procedure Formdestroy (Sender:tobject);
Procedure Timer1timer (Sender:tobject);
End
Var
Form1:tform1;
Implementation
{$R *.DFM}
Uses Bass;
Var
Hs:hstream; {Stream Handle}
{callback function: MYSYNC1; Although no parameters are used, it is written in the specified parameter format}
Procedure MySync1 (Handle:hsync; channel, data, User:dword); stdcall;
Begin
Form1.text: = ' start playing ';
End
{callback function: MySync2}
{Parameter 1: is a callback handle that can have Bass_channelsetsync returned and can be removed with Bass_channelremovesync}
{parameter 2: Stream handle}
{Parameter 3: not known}
{Parameter 4: is the user data specified by Bass_channelsetsync}
Procedure MySync2 (Handle:hsync; channel, data, User:dword); stdcall;
Begin
Form1.text: = ' past midpoint ';
{If you play to this (middle point) from the beginning again, you can do this:}
Bass_channelplay (channel, True);
End
{callback function: MySync3; Although no parameters are used, it must be specified as required}
Procedure MySync3 (Handle:hsync; channel, data, User:dword); stdcall;
Begin
Form1.text: = ' play finished ';
End
{Initialize}
Procedure Tform1.formcreate (Sender:tobject);
Begin
Trackbar1.height: = 23;
timer1.enabled: = False;
Timer1.interval: = 100;
If HiWord (bass_getversion) <> Bassversion Then
MessageBox (0, "Bass.dll" file version is not suitable!) ', nil, mb_iconerror);
If not Bass_init ( -1, 44100, 0, 0, nil) then ShowMessage (' initialization error ');
End
Open
Procedure Tform1.button1click (Sender:tobject);
Var
mp3path:ansistring;
mp3len:cardinal;
Begin
Bass_streamfree (HS);
timer1.enabled: = False;
Opendialog1.filter: = ' Mp3 file (*.mp3) |*.mp3| Wav file (*.wav) |*wav ';
If Opendialog1.execute Then
Mp3path: = ansistring (Opendialog1.filename);
HS: = Bass_streamcreatefile (False, Pansichar (Mp3path), 0, 0, 0);
If HS < bass_error_ended Then
Text: = ' Open failed '
ELSE begin
Text: = string (Mp3path);
{Get the total byte length of the stream first, useful below}
Mp3len: = Bass_channelgetlength (HS, Bass_pos_byte);
Trackbar1.max: = Mp3len;
{Start playback is callback MySync1}
{parameter 1: stream handle; parameter 2: parameter type; parameter 3: parameter value; parameter 4: to callback function pointer; parameter 5: User Data}
Bass_channelsetsync (HS, Bass_sync_pos, 0, @MySync1, nil);
{Callback MySync2} when playing to middle
Bass_channelsetsync (HS, Bass_sync_pos, Mp3len Div 2, @MySync2, nil);
{Callback MySync3} at end of playback
Bass_channelsetsync (HS, Bass_sync_end, 0, @MySync3, nil);
{Of course you can also write:}
Bass_channelsetsync (HS, Bass_sync_pos, Mp3len, @MySync3, nil);
{If the second parameter specifies Bass_sync_onetime, the callback function will execute only once}
Bass_channelsetsync (HS, bass_sync_end or bass_sync_onetime, 0, @MySync3, nil);
End
End
Play
Procedure Tform1.button2click (Sender:tobject);
Begin
Bass_channelplay (HS, False);
timer1.enabled: = True;
End
Suspended
Procedure Tform1.button3click (Sender:tobject);
Begin
Bass_channelpause (HS);
timer1.enabled: = False;
End
Procedure Tform1.formdestroy (Sender:tobject);
Begin
Bass_free;
End
Procedure Tform1.timer1timer (Sender:tobject);
Begin
If Bass_channelisactive (HS) = Bass_active_playing Then
Trackbar1.position: = Bass_channelgetposition (HS, Bass_pos_byte);
End
End.