Audio signal processing method and apparatus for controlling loudness level and dynamic range

A method of operating an audio signal processing apparatus playing content including an audio signal, the method comprising:

• receiving the audio signal;
• receiving metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information, for each of a plurality of steps separated according to a loudness magnitude, indicating a ratio between an amount of an audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal;
• and
• adjusting the loudness of the audio signal based on the metadata,
• wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
• wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.

A method of generating metadata for content including an audio signal, the method comprising:

• obtaining loudness distribution information of the audio signal, the loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of the audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal;
• and
• inserting the loudness distribution information in the metadata,
• wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
• wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.

An audio signal processing apparatus playing content including an audio signal, the audio signal processing apparatus comprising:

• a receiver receiving the audio signal;
• and
• a processor controlling the audio signal processing apparatus, wherein the processor is configured to:
• receive metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of an audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal;
• and
• adjust the loudness of the audio signal based on the metadata, ,
• wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
• wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.