male voice to female voice in real time

I am just thinking how to convert a male voice to female voice in real time voice signal from any source, say Mp3 player audio out.

If i convert the voice signal to DPCM then i got a streaming digital signal..right..,
Now i am interested to modify that DPCM using a PIC microcontroller.
But what should i do to convert it to a female voice? I know frequency of female voice is higher than male voice. But i couldnt time scale the realtime streaming to increase the frequency...and more over, i think time scaling is not the procedure for voice conversion because the total time of converted voice should be equal to the input voice.
So what exactly i should do to convert the male voice to female voice in realtime?

Pitch shifting without changing the time scale has been used as a musical effect since long. The basic principle is to cut the audio signal into short segments and resample them at a different speed. Depending on the direction of pitch change, either a segment has to be replayed multiple times (increment) or parts have to be skipped (decrement).

The first technical solution has been a tape recorder with rotating heads, posssible adopted from an early professionial video recording machine. In the 70th, the Harmonizer implemented pitch variation as a digital studio effect. As the name suggests, it has been used first to add harmonies to a single voice.

At these days, digital pitch variation should be available as a software effect for PC audio systems.

Sir you can test what is happening in changing the female to male .or viscera. in audio editing software with seeing frequency range of each sound
there is also features like converting voice that you want .please check and measure what is happening after converting
software is Adobe Audition ,FL Studio ,Audacity Etc.