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Playing Midi Files with DirectMusic

, 30 Dec 2010
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A DirectX 8 class to perform Midi music playback

Introduction

This article focuses on the use of CMidiMusic which allows an easy access to DirectX DirectMusic API. This class allows loading and playing general midi sequence files(.mid). The class is designed to perform midi playback in one segment and offers additional features like using any midi port installed in your system, 3D sound environment, sound effects, etc.

Direct Audio Specifications

The DirectX 8.0 Audio part offers improved integration between DirectSound and DirectMusic, including a great set of new features. Some of these are listed hereafter:

  • The last version of Direct Audio allows using hardware acceleration for sound synthesis.
  • With the new AudioPath model, the sound of a port does not go directly to a directsound buffer, instead, it goes to an audiopath which controls data flow from a performance to the final output. The audiopath allows controlling the 3D position of each sound and adding other effects.
  • The segments are modified independently and you can apply effects like pan, volume, individually.
  • It allows using DLS2 (Downloadable sound level 2 standard) which provides a great sound quality and unlimited use of instruments with the software synthesizer.
  • FX (Reverb, Chorus...) if it is available in the software synthesizer.
  • It overcomes the 16 midi channels limit, allowing the use of as many midi channels as the software is able to handle.
  • The playback can be controlled accurately in run time by selecting different sets of musical variations and changes in the chords progress.
  • 3D Positioning.

Main Interfaces of DirectMusic

  • IDirectMusic8: This interface allows managing buffers and ports. There should only exist one instance of this interface per application.
  • IDirectMusicPerformance8: This is the most important interface in playback management. It is used to add and remove ports, play segments, notify event reception, control music parameters and obtain timing information.
  • IDirectMusicPort8: This interface provides access to DirectMusicPorts objects like MPU-401 or the software synthesizer.
  • IDirectMusicSegment8: This interface represents a segment, musical piece made up of multiple tracks. It can contain a midi file, a wave, a segment.
  • IDirectMusicLoader8: Its main function is to find and load the different objects. These objects are to be stored in a segment.
  • IDirectMusicSegmentState8: The (playback) engine creates a SegmentState object which allows analyzing the state of the segment currently playing.
  • IDirectMusicAudioPath8: The IDirectMusicAudioPath8 interface represents the stages of data flow from the data file to the primary buffer.

DirectMusic Architecture

Once a resource has been loaded in a segment, the performance dispatches the messages defined by a tool of an application, such tools are grouped in toolgraphs which process specific segment messages. A tool can modify a message and pass it on, delete it, or send a new message.

Finally, the messages are delivered to the output tool, which converts the data to MIDI format before passing it to the synthesizer. Channel-specific MIDI messages are directed to the appropriate channel group on the synthesizer. The synthesizer creates sound waves and streams them to a device called a sink, which manages the distribution of data through buses to DirectSound buffers.

There are three kinds of buffers:

  • Sink-in buffers are DirectSound secondary buffers into which the sink streams data. Here are applied many effects like 3D, pan, volume, etc...The resulting waveform is passed either directly to the primary buffer or to one or more mix-in buffers.
  • Mix-in buffers receive data from other buffers, apply effects, and mix the resulting wave forms. These buffers can be used to apply global effects.
  • The primary buffer performs the final mixing on all data and passes it to the rendering device.

The following diagram shows the flow of data from files to the speakers:

Using CMidiMusic

In first sight, it is necessary to add in Visual C++ IDE this library: Go to Project -> Settings -> Object Library Modules and add dxguid.lib of DirectX8 SDK.

After this, it will be necessary to include in the project the header "dmusic.h" and "dmusic.cpp" file and finally instance an object of CMidiMusic class type as shown below:

void CPlayerDlg::OnButton_Start()     
{
    DWORD dwcount; // Counter variable to enumerate the midi ports 
    INFOPORT Info; // INFOPORT structure to store port information 
    BOOL bSelected;

    CMidiMusic *pMidi;     // Pointer to CMidiMusic object type
    pMidi=new CMidiMusic;     // Allocate it      
    pMidi->Initialize(FALSE);// Initialize without 3D positioning
    
    dwcount=0;
    bSelected=FALSE;
    
     // Port enumeration  phase 
     // It is necessary to supply a port counter 
    while (pMidi->PortEnumeration(dwcount,&Info)==S_OK)
    {
        // Ensure it is an output hardware device
        if (Info.dwClass==DMUS_PC_OUTPUTCLASS) 
        {
            if (!((Info.dwFlags & DMUS_PC_SOFTWARESYNTH) || bSelected))
            {
                // Select the enumerated port 
                pMidi->SelectPort(&Info);
                bSelected=TRUE;
            }
        }
    
    dwcount++;      
   }

     // Read the MIDI file 
    pMidi->LoadMidiFromFile("c:\\music\\song_004.mid");
     // Play the file
    pMidi->Play();
    AfxMessageBox("Playing...");
     // Stop it
    pMidi->Stop();

    //Important!: Delete the pointer to the object in order to call the 
    //destructor 
    //which call the DirectMusic releases interfaces
    delete pMidi;
}

CMidiMusic Capabilities

Synthesizer 3D Effects (Reverb,Chorus)
Microsoft Software Yes Only in not 3D mode
Hardware No No
External No No

More Information

For more information about the CMidiMusic class, read the attached file readme.txt included in the sources. You will be able to find more information in the online help of http://www.microsoft.com/directx and DirectX 8 SDK technical documentation.

Overview of the Demo Project

As you can see, this is not WinAmp, wish it was. Wink | ;) Nevertheless, all of CMidiMusic class features are made available.

History

  • 31 Jan 2002 - Updated source files
  • 12 May 2003 - Updated source files
  • 28 Dec 2010 - Updated article and source files

License

This article, along with any associated source code and files, is licensed under The GNU Lesser General Public License (LGPLv3)

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About the Author

Carlos Jiménez de Parga
Software Developer
Spain Spain
No Biography provided

Comments and Discussions

 
GeneralRe: getting the length in (milli)seconds PinmemberCarlos Jiménez de Parga30-Aug-04 0:18 
GeneralRe: getting the length in (milli)seconds Pinmembersolace12126-Nov-06 3:29 
GeneralRe: getting the length in (milli)seconds [modified] PinmemberCarlos Jiménez de Parga26-Nov-06 4:13 
Personally, I've never tried to call GetParam thousands of times to get tempo changes, it would be a madness, besides it's against the system performance. If I were you, I would read part of the MIDI file to obtain the tempo track and finally read the tempo marks inside it to use them for your time seeking calculation.
 
This URL may help you:
 
http://www.borg.com/~jglatt/tech/midifile.htm[^]
 

-- modified at 10:20 Sunday 26th November, 2006
GeneralRe: getting the length in (milli)seconds Pinmembersolace1213-Dec-06 15:56 
GeneralRe: getting the length in (milli)seconds PinmemberCarlos Jiménez de Parga4-Dec-06 0:04 
GeneralHelp me to show the lyrics Pinsussgenievn27-Jun-04 10:30 
GeneralRe: Help me to show the lyrics PinmemberCarlos Jiménez de Parga27-Jun-04 20:37 
GeneralRe: Help me to show the lyrics Pinmembergenievn27-Jun-04 22:46 
GeneralRe: Help me to show the lyrics PinmemberCarlos Jiménez de Parga29-Jun-04 0:25 
GeneralRetrieve sound samples from synthesizer PinsussAbhijit Patait17-Jun-04 13:12 
GeneralRe: Retrieve sound samples from synthesizer PinmemberCarlos Jiménez de Parga17-Jun-04 22:36 
GeneralPlaying a midi file PinmemberQuais_10016-Jun-04 7:53 
GeneralRe: Playing a midi file PinmemberCarlos Jiménez de Parga16-Jun-04 9:26 
GeneralRe: Playing a midi file PinmemberQuais_10015-Jul-04 9:18 
QuestionHow to get total play time of midi file with DirectMusic? Pinmembervachel24-Feb-04 14:35 
AnswerRe: How to get total play time of midi file with DirectMusic? PinmemberCarlos Jiménez de Parga24-Feb-04 20:31 
GeneralRe: How to get total play time of midi file with DirectMusic? Pinmembermmsguru31-May-04 13:54 
QuestionHow to save part of midi data into new midi file? Pinmembervachel18-Feb-04 18:54 
AnswerRe: How to save part of midi data into new midi file? PinmemberCarlos Jiménez de Parga18-Feb-04 20:08 
GeneralRe: How to save part of midi data into new midi file? Pinmembervachel18-Feb-04 21:57 
GeneralRe: How to save part of midi data into new midi file? Pinmemberglushkin3-Mar-12 1:34 
QuestionWhy not have sound after pressing Play? Pinmembervachel11-Feb-04 22:23 
AnswerRe: Why not have sound after pressing Play? PinmemberCarlos Jiménez de Parga12-Feb-04 4:10 
GeneralRe: Why not have sound after pressing Play? PinsussAnonymous18-Feb-04 17:26 
GeneralRe: Why not have sound after pressing Play? Pinmembervachel18-Feb-04 17:29 

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