These technologies are based on G723, G728, MPEG-1 and MPEG-2. Then use video transform coding technology. (CELP, CodeExcitedLinearPredictive) coding technology and code rate above 16kbit/s. For example, 2~4kbit/s speech coding of 8kHz sampling frequency and 4~16kbit/s speech coding of 8kHz or 16kHz sampling frequency generally adopt parametric coding and 6~24kbit/s speech coding generally adopts code excitation linear prediction. The MPEG-4 study compares various existing audio coding algorithms and supports natural sound coding from 2 to 64 kbit/s. The MPEG-4 audio portion combines the synthesized encoding of audio with the encoding of natural sound and supports object features of audio. Compared to MPEG-1 and MPEG-2, MPEG-4 supports not only natural sounds (such as voice and music) but also synthetic sounds (such as MIDI). MPEG-4 includes the vast majority of MPEG-1 and MPEG-2 features and the strengths of other formats, and adds and extends support for Virtual Reality Modeling Language (VRML), object-oriented composite files (including Sound effects, video and VRML objects), as well as digital rights management (DRM) and other interactive features. MP4 is a set of compression coding standards for audio and video information. Part 2: How to Convert MP4 Video to Any Format on a Mac What IS MP4? Part 1: How to Convert Video to MP4 on a Mac
