Windows mobile5.0上的mp3播放器只能播放wav格式的·

Windows mobile5.0下的mp3播放器只能播放wav格式的···
为什么我在Windows mobile 5.0下编写的MP3播放器只能播放wav格式的歌曲囧，怎么才能播放MP3文件呢？

"playControl.h"

#pragma once
#include <streams.h>
#pragma comment (lib,"Ole32.lib")
#pragma comment (lib,"Strmiids.lib")


#define HELPER_RELEASE(x) { if (x) x->Release(); x = NULL; }
#define WM_GRAPHNOTIFY  WM_USER+1

class CPlayControl
{
public:
	CPlayControl(void);
public:
	~CPlayControl(void);
public:
	IGraphBuilder *pGB;		//这是directshow的核心
	IMediaControl *pMC;		//帮我们连接filter(媒体文件,解码器等)          
	//简单的说,它帮我们简单地打开和播放文件.
	IMediaEventEx *pME;		//处理过滤器图表的事件
	IVideoWindow  *pVW;		//用这个来控制directshow的视频窗口
	IBasicAudio   *pBA;		//用于控制音频流的音量和平衡
	IBasicVideo   *pBV;     //用于设置视频特性，如视频显示的目的区域和源区域
	IMediaSeeking *pMS;		//提供搜索数据流位置和设置播放速率的方法,播放位置

	enum PLAYSTATE { RUNING, PAUSED, STOPPED, INIT };

public:

	PLAYSTATE playControlInfo;
	HWND      ghApp;

public:

	bool SetNotifyWindow(HWND inWindow);
	bool Create();
	bool RenderFile(WCHAR *szFile);
	bool buttonPlay();
	bool buttonPause();
	void buttonStop();
	void CloseInterfaces(void);
	bool ListPlay(WCHAR *szFile);
	float GetAlltime();
	float GetCurrentPosition();
	bool SetCurrentPosition(double inPosition) ;
	bool Running();
	void SetVol(int m_vol);

	IMediaEventEx * GetEventHandle();
};

"playControl.cpp"

#include "StdAfx.h"
#include "PlayControl.h"

CPlayControl::CPlayControl(void)
{
	IGraphBuilder *pGB = NULL;
	IMediaControl *pMC = NULL;
	IMediaEventEx *pME = NULL;
	IVideoWindow  *pVW = NULL;
	IBasicAudio   *pBA = NULL;
	IBasicVideo   *pBV = NULL;
	IMediaSeeking *pMS = NULL;
	playControlInfo = STOPPED;
	ghApp = 0;
}

CPlayControl::~CPlayControl(void)
{
	CoUninitialize();
}

void CPlayControl::CloseInterfaces(void)
{
	HELPER_RELEASE(pMC);
	HELPER_RELEASE(pME);
	HELPER_RELEASE(pMS);
	HELPER_RELEASE(pBV);
	HELPER_RELEASE(pBA);
	HELPER_RELEASE(pVW);
	HELPER_RELEASE(pGB);

	// No current media state
	playControlInfo = INIT;

}


bool CPlayControl::Create()
{
	if(FAILED(CoInitialize(NULL)))
		return false;

	// Get the interface for DirectShow's GraphBuilder
	if( SUCCEEDED( CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&pGB )))
	{
		HRESULT hr = NOERROR;
		// QueryInterface for DirectShow interfaces
		hr |= (pGB->QueryInterface(IID_IMediaControl, (void **)&pMC));
		hr |= (pGB->QueryInterface(IID_IMediaEventEx, (void **)&pME));
		hr |= (pGB->QueryInterface(IID_IMediaSeeking, (void **)&pMS));

		// Query for video interfaces, which may not be relevant for audio files