Loudness Control

Loudness control parameters.

When utilizing the Dolby encoding engines, it's possible to provide values for dialog normalization, and what loudness modes should be utilized to comply with the supported standards in Dolby's engines.

ParameterDescriptionAllowed ValuesDefault Value
loudness_modeSpecify the content loudness calculation mode for Dolby Media Generator.1770-1-di – Dolby Dialogue Intelligence™ with ungated loudness measurement with optional speech gating
1770-2 – level gated loudness measurement
1770-2-di – Dolby Dialogue Intelligence™ will level gated loudness measurement with optional speech gating
input_speechForce enable/disable speech detection for Dolby Media Generator.yes, nonone
audio_normalizationSpecify the target loudness for Dolby Media Generator and Dolby Encoding Engine.-31–0 or 1–100%none
dialnorm_thresholdSpecify the dialnorm threshold for Dolby Media Generator.One or two comma separated positive float numbers less than 99.9none
adjust_gain_for_dialnormApply gain or attenuation to the audio signal, so that the loudness of the output audio signal is corrected to be equal to the value specified by input metadata.yes, nonone
clipmodeSpecify the clipmode for Dolby Media Generator.scale, prolimit, hardnone
prolimiter_max_peakSet the maximum peak sample value allowed by the limiter output. Allowed only for prolimiter clipmode.-20.0–-0.1none
input_dialnormSpecify the dialnorm value for Dolby Media Generator. Set it to copy to preserve dialnorm value from source file. Should be used when the input dialnorm is already measured.
Can’t be used with audio_normalization option.
• float number between -31 and -1
• copy
speech_thresholdSpeech threshold percentageInteger number between 0 and 100none
peak_referencePeak reference modetrue_peak, sample_peaknone
loudnorm_presetLoudness measurement and correction according to one of the preset standardsmanual, atsc_a85, atsc_a85_agile, ebu_r128, freetv_op59, arib_b32none
correction_modeLoudness correction modepcm_scale, md_updatenone
peak_limit_dbMaximum Audio Output LevelFloat number with one digit between -12 and -0.1-0.1
dynrange_lineLine dynamic range control profilefilm_standard, film_light, music_standard, music_light, speechnone
dynrange_rfRF dynamic range control profilefilm_standard, film_light, music_standard, music_light, speechnone
ddp_bitstream_modeAudio bitstream modemusic_and_effects, visually_impaired, hearing_impaired, dialogue, commentary, emergency, voice_overnone


For audio_normalization parameter

If a negative integer is provided to the audio_normalization parameter, the number will be interpreted as an absolute value in dB. Percentage values (or positive integers) will be interpreted as relative value where 100% is equal to -31db.