Method for Determining Volume Levels in Television Programs

Accordingly, Circular 34 has provided guidance on determining the volume level in television programs as follows:

- Measure "instantaneous" loudness according to the time frame "M" using a time-moving window with a length of 0.4s. The measurement method does not use gating.- Measure loudness over a short period of time according to the time frame "S" using a time-moving window with a length of 3s. The measurement method does not use gating. The update rate for the direct meter is at least 10 Hz;- Measure the loudness over the time of a program or a program segment according to the time frame "I" using the gating method as in ITU-R BS.1770-2. The update rate for the live TV program meter is at least 1 Hz; use the "silent" gating threshold at -70 LUFS to calculate the absolute gating loudness level; use the relative gating threshold -10 LU compared to the absolute gating loudness level; input is measured with the gating threshold being the 400 ms frames with a 75% overlap constant between successive windows.

Note, the last data section of the integrated loudness measurement process, if incomplete, will be discarded.

The loudness measurement diagram is illustrated in Circular 34 as follows:

In which:

- Measurement signal: If measuring mono sound, only 1 audio input channel is required.- Stereo sound measurement: Measured on 2 channels L and R and calculates loudness.- 5.1 audio/signal measurement: Only the loudness of 5 channels L/R/C/Ls/RS is measured. The LFE channel is ignored (see diagram in ITU-R BS.1770-2).

See details in Circular 34/2017/TT-BTTTT effective from July 1, 2018.

-Thao Uyen-

>> CLICK HERE TO READ THIS ARTICLE IN VIETNAMESE