MP4 Definition: MP4 stands for MPEG-4 file extension, a type of video container.

Audio/Video To Wav Converter is also a MP4 converter which can extract audio from MP4 files to WAV format. 

1. To convert mp4 to wav: please install the mp4 decoder based on DirectShow on your Windows system like Haali Media Splitter and FFDSHOW, or MainConcept mpeg4 codec.

2 Run Audio/Video to Wav Converter, click the Open Media File button, select an mp4 file for mp4 to wav.

3. To convert the whole mp4 file to wav, set the Output File name if necessary, then click the Convert button.

To convert a part of the mp4 file, drag the slide bar directly, or click the Play button to preview the mp4 file, then set the Start Time and the End Time. Finally, click the Convert button to convert mp4 to wav.

2. PSP is PlayStation Portable developed by SONY company. It is a small device to play game, multimedia, still image, video and audio. PSP supports jpg, gif, bmp, png, tif, MP3, MP4, AAC, ATRAC, WAV, MPEG4.

Converting PSP to avi means convert mpeg4 AVC video files to avi normally. Please install PSP filters such as mp4 splitter, HDX4 player.