Solved

MidiStreams - how to use?

Posted on 1997-03-12
2
958 Views
Last Modified: 2012-05-04
OK, here's the question:

How can I get a MidiStream running?  More specifically, what's wrong with my call to midiStreamOut in the following program, and how can I fix it?

I'll gladly give 100 points for a solution.

Thanks,

Alex Fanti
University of Massachusetts


Source code follows:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

uses
  MMsystem;

var
  MidiStream_handle: HMIDISTRM;
  errorstr : array[1..254] of char;

procedure TForm1.Button1Click(Sender: TObject);
var
  MMResult : longint;
  pMidiStream_handle: PHMIDISTRM;
  DeviceID : UINT;
  pDeviceID : PUINT;
begin
  DeviceID := -1;  // midimapper
  pDeviceID := @DeviceID;
  pMidiStream_handle := @MidiStream_handle;
  MMResult := midiStreamOpen(pMidiStream_handle, pDeviceID, 1, 0, 0, 0);
  MMResult := midiOutGetErrorText(MMResult, @errorstr, Length(errorstr));
  label1.caption := errorstr; //inttostr(DeviceID);
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  MMResult : longint;
begin
  MMResult := midiStreamStop(MidiStream_handle);
  MMResult := midiOutGetErrorText(MMResult, @errorstr, Length(errorstr));
  label1.caption := errorstr; //inttostr(DeviceID);
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  MMResult : longint;
begin
  MMResult := midiStreamClose(MidiStream_handle);
  MMResult := midiOutGetErrorText(MMResult, @errorstr, Length(errorstr));
  label1.caption := errorstr; //inttostr(DeviceID);
end;

procedure TForm1.Button4Click(Sender: TObject);
var
  MMResult : longint;
  AnEvent : TMidiEvent;
  pAnEvent : PMidiEvent;
  MidiHeader : TMidiHdr;
  pMidiHeader : PMidiHdr;
begin

  AnEvent.dwDeltaTime := 30; // start at 30 milliseconds
  AnEvent.dwStreamID := 0;  // must be 0
  AnEvent.dwEvent := $3C90;  // play middle C on channel 1 of the midi device
  AnEvent.dwParms[0] := 0;
  pAnEvent := @AnEvent;

  MidiHeader.lpData:= @AnEvent;               { pointer to locked data block }
  MidiHeader.dwBufferLength:= SizeOf(AnEvent);       { length of data in data block }
  MidiHeader.dwFlags:= 0;                 { assorted flags (see defines) }

  pMidiHeader := @MidiHeader;
  MMResult := midiOutPrepareHeader(MidiStream_handle, pMidiHeader, SizeOf(MidiHeader));

//  Finally, here's the problem...
// The next call fails.  There's something wrong with the
//  MidiHdr, MidiEvent the  pointers, or something.
//    What do you think?

  MMResult := midiStreamOut(MidiStream_handle, pMidiHeader, SizeOf(MidiHeader));

  MMResult := midiOutGetErrorText(MMResult, @errorstr, Length(errorstr));
  label1.caption := errorstr; //inttostr(DeviceID);
end;

end.
0
Comment
Question by:afanti
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 3

Accepted Solution

by:
sperling earned 50 total points
ID: 1334754
Can you use midiStreamOut when you're trying to send a shortmsg?

I'd suggest you created a real midi stream, and attempted to play it. This error might occur because midiStreamOut expects a stream of data, not just a single event.

To play 3C90, use midiOutShortMsg

Erik.
0
 

Expert Comment

by:Ben_iti
ID: 3173952
Hello there

So does that mean in order to send a stream of data through the midistreamout , you must first declare the values in MEVT_EVENTTYPE
then MEVT_EVENTPARM then continue with declaring the other values needed to create the MIDIEVENT structure
then from there I can use
the MidiStreamOut

MMResult := midiStreamOut(MidiStream_handle, pMidiHeader, SizeOf(MidiHeader));


then i should be able to stream midi data then if I want to have a continous buffer, I would then have to make my own circular buffer??

Am I right?
Please let me know

Ben
0

Featured Post

Enroll in June's Course of the Month

June’s Course of the Month is now available! Experts Exchange’s Premium Members, Team Accounts, and Qualified Experts have access to a complimentary course each month as part of their membership—an extra way to sharpen your skills and increase training.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Hello everybody This Article will show you how to validate number with TEdit control, What's the TEdit control? TEdit is a standard Windows edit control on a form, it allows to user to write, read and copy/paste single line of text. Usua…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…

729 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question