Directly on the player:
Players require the use of similar TTPlayer fade function, the sound fades, is the beginning of the sound gradually increases, it will not suddenly be great. At the end of the sound gradually release small, will not suddenly disappear. Especially particularly useful for certain special occasions, such as ballroom dancing, songs and other audio sound stage where a lot of switching, with the fade will not be very smooth unexpected! Closer to home, in fact, achieve program principle is very simple, linear control music playback volume. At first, for example within 3 seconds, the volume gradually increases from 0 to 100. 3 seconds before the end, when the volume gradually reduced from 100 to 0. drag the progress, and start playing the same approach. OK, directly on the core code:
void CMP3FenGe::SetFadeIn( LONG nFadeIn, LONG nFadeInStartTime, LONG nFadeInTime)
{
m_nFadeIn=nFadeIn;
m_nFadeInStartTime=nFadeInStartTime;
m_nFadeInTime=nFadeInTime;
}
void CMP3FenGe::SetFadeOut( LONG nFadeOut, LONG nFadeOutStartTime, LONG nFadeOutTime)
{
m_nFadeOut=nFadeOut;
m_nFadeOutStartTime=nFadeOutStartTime;
m_nFadeOutTime=nFadeOutTime;
}
声音回调函数调用插入：
FadeIn((BYTE*)BufLeft,dwRetBytesL);
FadeOut((BYTE*)BufLeft,dwRetBytesL);
具体实现：
//淡入淡出 0无效果 1淡入
void CMP3FenGe::FadeIn(BYTE *pData,int nLen)
{
if(m_nFadeIn==0)
return;
if(m_nFadeInTime<=100)
return;
__int64 nCurTime=this->GetCurMSec();
if(nCurTime>=m_nFadeInStartTime&&nCurTime<=m_nFadeInStartTime+m_nFadeInTime)
{
double dbGain=(double)(nCurTime-m_nFadeInStartTime)/(double)(m_nFadeInTime);
WaveGain(pData,nLen,dbGain);
TRACE("fadein gain:%0.2f\n",dbGain);
}
}
//淡入淡出 0无效果 1淡入 2淡出
void CMP3FenGe::FadeOut(BYTE *pData,int nLen)
{
if(m_nFadeOut==0)
return;
if(m_nFadeOutTime<=100)
return;
__int64 nCurTime=this->GetCurMSec();
if(nCurTime>=m_nFadeOutStartTime&&nCurTime<=m_nFadeOutStartTime+m_nFadeOutTime)
{
double dbGain=1-(double)(nCurTime-m_nFadeOutStartTime)/(double)(m_nFadeOutTime);
WaveGain(pData,nLen,dbGain);
TRACE("fadeout gain:%0.2f\n",dbGain);
}
}
声音增益调整函数：
//调整增益
static void WaveGain(BYTE *pBuf,int nLen,float fGain=3.0f)//16位单声道
{
short w;
for(int i=0;i<nLen;i+=2)
{
w=MAKEWORD(pBuf[i],pBuf[i+1]);
int iw=(float)w*fGain;
if(iw>32767)
iw=32767;
if(iw<-32767)
iw=-32767;
w = iw;
(pBuf)[i]=LOBYTE(w);
(pBuf)[i+1]=HIBYTE(w);
}
}
Well, this document mainly speak at the sound fade algorithm, next time to continue speaking tone processing algorithms speed of sound at the same harmonic sounds. Stay tuned!
May be one day, probably in January, it may be one year. . . . . .
When uploading the code to find time to go, and finally make ads:
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