Convert M4B to AMR

M4B, which stands for MPEG-4 Audiobook, is a file extension specifically used for audiobooks. It falls under the MPEG-4 Part 14 container format, derived from Apple's implementation of MPEG-4 multimedia. M4B files typically support metadata and chapters, enabling users to bookmark their place in an audiobook and resume listening later. Unlike standard MP3 files, M4B files can incorporate Digital Rights Management (DRM) for copyright protection. Originating from the early 2000s, the M4B format gained popularity with the rise of Apple's iTunes Store and its focus on digital audiobook distribution. Today, M4B remains a standard for digital audiobooks, known for its advanced features and compatibility with various devices.

Adaptive Multi-Rate Codec (AMR) is a file extension used primarily in voice applications, including VoIP, audio messaging, and mobile phone telephony. Originating from the European Telecommunications Standards Institute (ETSI) in 1999, AMR files enable efficient compression and transmission of speech audio. The codec dynamically adjusts bit rates during transmission to optimize audio quality and network capacity. Its efficient bandwidth utilization and compatibility with various communication standards have made AMR a preferred choice for many modern communication systems.