MPEG-4 SLS is an extension to the MPEG-4 Part 3 standard that allows lossless audio compression. The compression is scalable to lossy MPEG-4 General audio coding methods. Developed by the Institute for Infocomm Research and Fraunhofer, it has been published by ISO/IEC.
The codec allows for having both a lossy and a lossless correction layer like Wavpack Hybrid or OptimFROG DualStream. This also confers backwards compatibility to MPEG AAC-compliant bitstreams. The codec can work without a lossy layer but in that case, it won’t be backwards compatible. For files that need to be played in devices with limited storage or streamed to the internet require lossy compression.
DRM disables the ripping of lossless data or playback on non DRM-enabled devices. The combination data compression technology provides a coding solution for production environments that require transmission of results to many recipients through channels of differing bandwidth.
The codec also enables storage of original music data and transfer of compressed copies, for private and professional use in music archives, without transcoding. Audio compression technologies are used to reduce the data size using a variety of digital signal processing technologies without any loss of sound quality. The reduction is achieved by not recording the sounds that are difficult for humans to hear.