This paper is going to present recent advances in MPEG-2/-4 audio and video (AV) codec implementations for broadband and mobile applications. Several design approaches based on special purpose hardwired LSIs, programmable DSPs, media processors, embedded MPUs, and MPUs for personal computes(PCs), which are used to implement MPEG engines are introduced. Then, design approaches for low power and low cost AV codec LSIs for broadband and mobile applications are discussed, by introducing recent implementation examples. Finally, future trends and challenges are discussed.