what is libgsm?

1. libgsm: libgsm is a software library that provides encoding and decoding functionality for the GSM audio codec. GSM (Global System for Mobile Communications) is a popular audio codec used in telecommunications and mobile networks, primarily for voice compression. The libgsm library enables developers to encode and decode audio in the GSM format, which is commonly used in applications like voice-over-IP (VoIP) systems and telecommunications software.
2. libfdk-aac: As mentioned in the previous response, libfdk-aac is a library developed by Fraunhofer IIS that provides encoding and decoding capabilities for the Advanced Audio Coding (AAC) format. AAC is a widely used audio codec known for its high audio quality and efficient compression. libfdk-aac is renowned for its excellent audio encoding performance and is often used in applications that require AAC audio encoding and decoding.

To summarize, libgsm and libfdk-aac are two separate libraries: libgsm for the GSM audio codec and libfdk-aac for the Advanced Audio Coding (AAC) format.