Meridian Lossless Packing

Meridian Lossless Packing, also known as Packed PCM (PPCM),[citation needed] is a lossless compression technique for PCM audio data developed by Meridian Audio, Ltd. MLP is the standard lossless compression method for DVD-Audio content[1] (often advertised with the Advanced Resolution logo) and typically provides about 1.5:1 compression on most music material.

All DVD-Audio players are equipped with MLP decoding,[2] while its use on the discs themselves is at their producers' discretion.

Dolby TrueHD, used in Archival Disc Blu-ray and HD DVD, employs the MLP codec, but compared with DVD-Audio, adds higher bit rates, 32 full-range channels, extensive metadata, and custom speaker placements (as specified by SMPTE).

Should MLP not be able to compress the stream below the maximum transfer rate – or in case there is a need to reduce the size to fit overall disc capacity – it can exploit (lossy) pre-quantification zeroing out least significant bits when necessary.

[4][5][6] The MLP stream can also contain "substreams", like surround and stereo downmix, which need not be of the same bit depth or sampling frequency – this further enables (lossy) pre-processing to save space.