METHOD FOR NON-DESTRUCTIVE NORMALIZING LOUDNESS OF AUDIO SIGNALS WITHIN PORTABLE DEVICES, APPARATUS COMPRISING MEANS FOR IMPLEMENTATION OF THE METHOD, MEDIUM RECORDING A PROGRAM OF INSTRUCTIONS THAT IS EXECUTABLE BY A DEVICE TO PERFORM A METHOD

摘要

Many portable playback devices cannot decode and playback encoded audio content having wide bandwidth and wide dynamic range with consistent loudness and intelligibility unless the encoded audio content has been prepared specially for these devices. This problem can be overcome by including with the encoded content some metadata that specifies a suitable dynamic range compression profile by either absolute values or differential values relative to another known compression profile. A playback device may also adaptively apply gain and limiting to the playback audio. Implementations in encoders, in transcoders and in decoders are disclosed.