CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0125086 filed in the Korean Intellectual Property Office on Oct. 10, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method and a device for effectively generating audio loudness metadata and, more particularly, to a method and a device for easily generating loudness information from audio in broadcasting, streaming, and the like.

BACKGROUND ART

As mainstream audio technology changes from analog technology to digital technology, it is possible to provide a wider loudness, and the loudness of content also differs depending on the case. International standards organizations such as ITU (International Telecommunication Union), EBU (European Broadcasting Union), and the like have released standards, but the standards are not being implemented well in practice because the target volume may differ in the content production process. In addition, methods and standards for measuring loudness may differ between countries, which makes it difficult to directly use corresponding loudness information.

Relying on the psychoacoustic characteristic by which perceived sound quality is improved as the volume increases, content creators provide content mixed with louder sounds to users, and a competitive phenomenon known as the “Loudness War” is taking place according thereto. Accordingly, the user has to frequently adjust the volume due to the difference in loudness between pieces of content or even within a single piece of content. Therefore, for the convenience of the end user, loudness normalization has been introduced as a solution to unify the target volume of content of which the target volume is irregular.

Accordingly, loudness normalization is being performed in various ways. In the case where a plurality of clips is made from one piece of content, the loudness between the clips may be corrected, but the context of the content in its entirety may be damaged. For example, a classical symphony composed of a total of 4 movements may be managed for the respective movements using separate clips, thereby configuring a total of 4 clips. Here, the 3rdmovement of the classical symphony may have a quiet section and the 4thmovement thereof may have a majestic section. In this case, if loudness correction is performed independently for each of the movements, the volume of the 3rdmovement is increased and the volume of the 4thmovement is decreased, thereby resulting in distortion of the artistic intent of the composer and the performers for each movement. In order to avoid the phenomenon of distorting the artistic intent, loudness normalization is required to be performed for one piece of content encompassing all of the 1stto 4thmovements. As another example, a video of about 2 hours may include 10 clips each having a duration of 12 minutes, and the video also requires loudness normalization for the entire section thereof. This loudness normalization may be referred to as an “album mode” or a “group mode”. Therefore, it is necessary to extract group integrated loudness information on a complete piece of content together with integrated loudness of individual clips. That is, when one clip is finally reproduced, metadata is required to be provided so as to reproduce the same according to the loudness appropriate for the context thereof, among the integrated loudness of the one clip and the group integrated loudness of the entire content.

DISCLOSURE

Technical Problem

An objective of the present disclosure is to provide a method of predicting the loudness of the entire content by utilizing loudness information on each of tracks constituting the content.

Technical Solution

This specification provides a method of generating audio loudness.

Specifically, a method of generating audio loudness performed by an audio loudness generation device may include: receiving loudness information on each of a plurality of audio tracks included in one group; predicting an intermediate loudness distribution, which is a loudness distribution for the one group, on the basis of the loudness information on each of the plurality of audio tracks; and generating an integrated loudness for the one group on the basis of the intermediate loudness distribution, wherein the loudness information on each of the plurality of audio tracks may include at least one of an integrated loudness, a loudness range, and a duration for each of the plurality of audio tracks.

In addition, in the specification, the method may further include performing loudness normalization for the one group on the basis of the integrated loudness for the one group.

In addition, in the specification, an audio loudness generation device for performing a method of generating audio loudness may include: an input terminal configured to receive loudness information on each of a plurality of audio tracks included in one group; and a processor, wherein the processor may be configured to predict an intermediate loudness distribution, which is a loudness distribution for the one group, on the basis of the loudness information on each of the plurality of audio tracks and generate an integrated loudness for the one group on the basis of the intermediate loudness distribution, and wherein the loudness information for each of the plurality of audio tracks may include at least one of an integrated loudness, a loudness range, and a duration for each of the plurality of audio tracks.

In addition, in the specification, the processor may be configured to perform loudness normalization for the one group on the basis of the integrated loudness for the one group.

In addition, in the specification, the intermediate loudness distribution may be predicted based on the loudness distribution for each of the plurality of audio tracks, and the loudness distribution for each of the plurality of audio tracks may be generated based on the loudness information on each of the plurality of audio tracks.

In addition, in the specification, the loudness distribution for each of the plurality of audio tracks may be a histogram.

In addition, in the specification, the intermediate loudness distribution may be a histogram.

In addition, in the specification, the duration of each of the plurality of audio tracks may be a relative duration.

In addition, in the specification, the intermediate loudness distribution may be predicted by summing all of the loudness distributions for the respective audio tracks.

In addition, in the specification, the loudness distribution for each of the plurality of audio tracks may be generated through the following equation,
dist_n[k]=D_n/LRA_n/res
for (L_n−LRA_n/2)/res<k<(L_n+LRA_n/2)/res
dist_n[k]=0  [Equation]

otherwise

where, “D_n” is the duration of the nthtrack among the plurality of audio tracks, “LRA_n” is the loudness range of the nthtrack among the plurality of audio tracks, “L_n” is the integrated loudness of the nthtrack among the plurality of audio tracks, “res” is the momentary loudness resolution of the nthtrack among the plurality of audio tracks, “dist_n[k]” is the intermediate loudness distribution of the nthtrack among the plurality of audio tracks, and “k” is the loudness index according to a res interval.

In addition, in the specification, the loudness distribution for each of the plurality of audio tracks may be a loudness distribution measured in a predetermined time period.

Advantageous Effects

The present disclosure has the effect of rapidly and efficiently predicting the loudness of the entire content through loudness information on each of tracks constituting the content, thereby performing loudness normalization.

The present disclosure has the effect of reproducing the original author's intent when reproducing final content using the loudness of the entire content for loudness normalization and maintaining a change in loudness between tracks constituting the content.

