DIY WinAMP plug-in

 

 

I want to answer: "What player are you using ?"MP3 ", 90% of people will answer Winamp! So you must have used the Winamp plug-in function. It is a variety of plug-ins that make this "old" Player continuously become youthful. No matter what audio format (MP4, VQF, RM...) is introduced, the plug-in can be played once it is installed. There are also a variety of visual plug-ins, such as Giess, to fully express the rhythm of music!

 

Since the plug-in is written in a program, why don't we give it a try ?! UsedWinamp everyone knows that the Winamp plug-in is a DLL (Dynamic Link Library) file in the Pulgin folder, so writing the Winamp plug-in is actually a dynamic link library for writing Windows. Of course, certain standards must be followed when writing (relevant documents can be downloaded from www.winamp.com). In this regard, the example of a visual plug-in written by Winamp author Justin Frankel can be used as our reference. Next we will take this example (of course also a compilation Specification) as a reference to understand the compiling method of the Winamp visual plug-in.

 

　　(The following program can be downloaded from the Winamp official website. The file name is vis_minisdk.zip)

 

First, let's take a look at the data structure used by the visual plug-in.(In File Vis. h)

 

// Note:

// Any plug-in window that stays at the front end should send the key to its parent window (WinAMP) to ensure

// You can still control WinAMP (unless you press the ESC key or the key specified by the plug-in ).

// The configuration data should be stored in plugin. ini.

// Consider this plug-in routine as a framework.

 

Typedef struct winampVisModule {

　Char * description; // module description (displayed in the drop-down list box under the plug-in selection list box)

　HWND hwndParent; // parent window ------------- (filled by the main application)

　HINSTANCE hDllInstance; // instance handle of this DLL-(filled by the main application)

　Int sRate; // sampling rate ---------- (filled by the main application)

　Int nCh; // number of audio channels ---------- (filled by the main application)

　Int latencyMs; // The latent time (in milliseconds) from calling RenderFrame to actually drawing)

　// (The main application will view this value when obtaining data)

　Int delayMs; // interval between each call (MS)

 

　// Data is filled according to their Nch (number of channels) Entries

　Int spectrumNch;

　Int waveformNch;

　Unsigned char spectrumData [2] [576]; // spectrum data

　Unsigned char waveformData [2] [576]; // waveform data

 

　Void (* Config) (struct winampVisModule * this_mod); // module configuration function

　Int (* Init) (struct winampVisModule * this_mod );

　// Initialize the function (create a window, and so on ). 0 is returned successfully.

　Int (* Render) (struct winampVisModule * this_mod );

　// "Performance" function. 0 is returned. If 1 is returned, the plug-in should be terminated.

　Void (* Quit) (struct winampVisModule * this_mod );

　// Exit the function. Call

 

　Void * userData; // user data (optional)

} WinampVisModule;

 

Typedef struct {

　Int version; // VID_HDRVER (current module version)

　Char * description; // plug-in description (displayed in the plug-in list box in the select plug-in dialog box)

　WinampVisModule * (* getModule) (int); // used to obtain the module structure

} WinampVisHeader;

 

// Define the export ID

Typedef winampVisHeader * (* winampVisGetHeaderType )();

 

// Version of the current module (0x101 = 1.01)

# Define VIS_HDRVER 0x101

 

 

The above list is a header file that must be included in the preparation of the visual plug-in, which lists the data structures used by the visual plug-in. Before discussing specific plug-in programs, you must understand some concepts: a visual plug-in can contain several modules.(Each module is a demo. You can select which module to use in the plug-in selection dialog box.) These modules are obtained by Winamp in some way (which will be seen later, in this way, you can get a chance to perform the show.

 

In short,Winamp uses a uniform name function exported from all plug-in DLL to obtain a plug-in header data structure, then, use a function in the data structure to obtain information about each module (this process is somewhat similar to the usage of the QueryInterface () of COM. It seems that a good design idea is the same ), then, the visual plug-in is displayed using multiple threads (observed by DLL View. The following is the source program of the visual plug-in:

 

// Visual plug-in v1.0 for Winamp Testing

// Copyright (C) 1997-1998, Justin Frankel/Nullsoft

// Based on this framework, You can freely compile any visual plug-in...

 

# Include

 

# Include "vis. h"

 

Char szAppName [] = "SimpleVis"; // window class name

 

// Configuration Declaration

Int config_x = 50, config_y = 50; // the horizontal and vertical coordinates of the window on the screen

Void config_read (struct winampVisModule * this_mod); // read the configuration