ISO/IEC 23003-4:2020/Amd 1:2022

INTERNATIONAL ISO/IEC
STANDARD 23003-4
Second edition
2020-06
AMENDMENT 1
2022-07
Information technology — MPEG
audio technologies —
Part 4:
Dynamic range control
AMENDMENT 1: Side chain
normalization
Partie 4: Contrôle de gamme dynamique
AMENDEMENT 1: Normalisation de l’entrée latérale
Reference number
ISO/IEC 23003-4:2020/Amd. 1:2022(E)
© ISO/IEC 2022

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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
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© ISO/IEC 2022
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
Foreword
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This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information Technology,
Subcommittee SC 29, Coding of audio, picture, multimedia, and hypermedia.
A list of all parts in the ISO/IEC 23003 series can be found on the ISO and IEC websites.
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
Information technology — MPEG audio technologies —
Part 4:
Dynamic range control
AMENDMENT 1: Side chain normalization

6.1.1
In the second last paragraph replace "UNIDRCCONFEXT_V1" with "UNIDRCCONFEXT_V1 or
UNIDRCCONFEXT_V2".

6.1.2.3
Add, after the fourth paragraph, the following new paragraph:
The drcCoefficientsUniDrc() payload for ISO/IEC 14496-12 (see Table 69) for version=2 and
characteristicV1Override=1 carries essentially the same information as the extension UNIDRCCONFEXT_
V2. The corresponding bitstream fields are coded the same way as specified in Table A.10.

6.4.6
Add, after the fourth paragraph, the following new paragraph:
If the encoder-side characteristic is provided in the bitstream, it is recommended to use linear gain
interpolation. ISO/IEC 23091-3 (CICP) encoder characteristics in the range of 65 to 70 are only supported
by drcCoefficientsUniDrcV1() as part of a UNIDRCCONFEXT_V2 extension. These characteristics shall
not be used otherwise. When a CICP characteristic in this range is inverted in the decoder, loudness
normalization shall be applied after the inversion based on the available loudness metadata and encoder
normalization gain, if applicable. This is shown in the pseudo code of Table E.3, where the output of
the inverse characteristic is computed with an offset depending on the value of sourceLoudness and
encDrcNormGainDb. sourceLoudness is the integrated DRC input loudness at the encoder before any
normalization. The value of sourceLoudness is obtained from the loudness metadata for the DRC.
encDrcNormGainDb is the signal gain in dB applied at the encoder DRC input. This gain value is available
in a UNIDRCCONFEXT_V2 extension payload to support legacy devices when characteristicV1Override==1
(see also E.4). The value of drcInputLoudnessTarget is the target input loudness of the DRC characteristic
applied to generate the DRC gains in the decoder. The drcCoefficientsUniDrc() payload of the Base
Media File Format ISO/IEC 14496-12 supports CICP characteristics 65 to 70 only if version>=2 (see also
Table 69).

6.4.6
Replace Table 17 with the following table:
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
Table 17 — Conversion of a DRC gain sample and associated slope from dB to linear domain
(slopeIsNegative==1 if the source DRC characteristic has a negative slope)
toLinear (gainDb, slopeDb) {
 SLOPE_FACTOR_DB_TO_LINEAR = 0.1151f;   /* ln(10) / 20 */
  EFFECT_BIT_CLIPPING = 0x0100;       /* drcSetEffect 9 (Clip.Prev.) */
  EFFECT_BIT_FADE  = 0x0200;        /* drcSetEffect 10 (Fade) */
  EFFECT_BITS_DUCKING = 0x0400 | 0x0800;   /* drcSetEffect 11 or 12 (Ducking) */
  gainRatio = 1.0;
  gainDbMod = gainDb;
  if (((drcSetEffect & EFFECT_BITS_DUCKING) == 0) &&
          (drcSetEffect != EFFECT_BIT_FADE) &&
         (drcSetEffect != EFFECT_BIT_CLIPPING)) {
    if (drcCharacteristicTarget > 0) {
       gainDbMod = mapGain(gainDb); /* target characteristic from host */
    }
    else if (drcCoefficientsUniDrcV1Present == 1) {
      if (((gainDb >= 0.0) && (slopeIsNegative == 1)) || ((gainDb <= 0.0) && (slopeIsNegative == 0))) {
        if (targetCharacteristicLeftPresent == 1) {
          gainDbMod = mapGain(gainDb); /* target characteristic in payload */
        }
      }
      else if (((gainDb <= 0.0) && (slopeIsNegative == 1)) || ((gainDb >= 0.0) && (slopeIsNegative == 0))) {
        if (targetCharacteristicRightPresent == 1) {
           gainDbMod = mapGain(gainDb); /* target characteristic in payload */
        }
      }
    }
    if (gainDbMod < 0.0) {
      gainRatio *= compress;
    }
    else {
      gainRatio *= boost;
    }
  }
  if (gainScalingPresent) {
    if (gainDbMod < 0.0) {
      gainRatio *= attenuationScaling;
    }
    else {
      gainRatio *= amplificationScaling;
    }
  }
  if (duckingScalingPresent && (drcSetEffect & EFFECT_BITS_DUCKING)) {
    gainRatio *= duckingScaling;
  }
  gainLin = pow(2.0, gainRatio * gainDbMod / 6.0);
  slopeLin = SLOPE_FACTOR_DB_TO_LINEAR * gainRatio * gainLin * slopeDb;
  if (gainOffsetPresent) {
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
    gainLin *= pow(2, gainOffset/6.0);
  }
  /* The only drcSetEffect is "clipping prevention" */
  if (limiterPeakTargetPresent && (drcSetEffect == EFFECT_BIT_CLIPPING)) {
    gainLin *= pow(2, max(0.0, -limiterPeakTarget-loudnessNormalizationGainDb
         -loudnessNormalizationGainModificationDb)/6.0);
    if (gainLin >= 1.0) {
      gainLin = 1.0;
      slopeLin = 0.0;
    }
  }
  return (gainLin, slopeLin);
}
7.3
Replace Table 69 with the following table:
Table 69 — Syntax of drcCoefficientsUniDrc() payload for ISO/IEC 14496-12
aligned(8) class DRCCoefficientsUniDrc extends FullBox(‘udc2’, version, flags=0) {
  // N copies of this box, one of these per DRC_location, plus boxes with characteristicV1Override ==
1
  characteristicV1Override = 0;
  if (version >= 2) {
   bit(1) characteristicV1Override;
   if (characteristicV1Override == 1) {
     bit(4) reserved = 0;
     signed int(5)  DRC_location;
     unsigned int(6) gainSetCount;
     for (j=1; j<=gainSetCount; j++) {
       bit(3) reserved = 0;
       bit(1) characteristicOverridePresent;
       unsigned int(4) bandCount;
       if (characteristicOverridePresent == 1) {
           for (k=1; k<=bandCount; k++) {
              bit(3) reserved = 0;
              unsigned int(7) overrideCicpCharacteristic;
              unsigned int(6) bsEncDrcNormGain;
             }
          }
        }
      }
  }
  if (characteristicV1Override == 0) {
      if (version < 2) {
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
        bit(1) reserved = 0;
      }
      bit(1)     reserved = 0;
      signed int(5)  DRC_location;
      bit(1)     drc_frame_size_present;
      if (drc_frame_size_present == 1) {
        bit(1)      reserved = 0;
        unsigned int(15)  bs_drc_frame_size;
      }
      if (version >= 1) {
        bit(5) reserved = 0;
        bit(1) drc_characteristic_left_present;
        bit(1) drc_characteristic_right_present;
        bit(1) shape_filters_present;
        if (drc_characteristic_left_present == 1) {
           bit(4)      reserved = 0;
           unsigned int(4) characteristic_left_count;
           for (k=1; k<=characteristic_left_count; k++) {
              bit(7)      reserved = 0;
              unsigned int(1) characteristic_format;
              if (characteristic_format==0) {
                 bit(1)      reserved = 0;
                 unsigned int(6) bs_gain_left;
                 unsigned int(4) bs_io_ratio_left;
                 unsigned int(4) bs_exp_left;
                 bit(1)     flip_sign_left;
             } else {
                 bit(6)      reserved = 0;
                 unsigned int(2)  bs_char_node_count;
                 for (n=1; n<=bs_char_node_count+1; n++) {
                 bit(3)      reserved = 0;
                 unsigned int(5)  bs_node_level_delta;
                 unsigned int(8)  bs_node_gain;
               }
            }
          }
       }
       if (drc_characteristic_right_present == 1) {
          bit(4)      reserved = 0;
          unsigned int(4) characteristic_right_count;
          for (k=1; k<=characteristic_right_count; k++) {
              bit(7)      reserved = 0;
              unsigned int(1)  characteristic_format;
              if (characteristic_format==0) {
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
                   bit(1)     reserved = 0;
                unsigned int(6) bs_gain_right;
                unsigned int(4) bs_io_ratio_right;
                unsigned int(4) bs_exp_right;
                bit(1)     flip_sign_right;
              } else {
                bit(6)     reserved = 0;
                unsigned int(2) bs_char_node_count;
                for (n=1; n<=bs_char_node_count+1; n++) {
                    bit(3)     reserved = 0;
                    unsigned int(5) bs_node_level_delta;
                    unsigned int(8) bs_node_gain;
                  }
               }
             }
         }
         if (shape_filters_present==1) {
            bit(4) reserved = 0;
            unsigned int(4) shape_filter_count;
            for (k=1; k<=shape_filter_count; k++) {
                bit(4) reserved = 0;
                bit(1) LF_cut_filter_present;
                bit(1) LF_boost_filter_present;
                bit(1) HF_cut_filter_present;
                bit(1) HF_boost_filter_present;
            if (LF_cut_filter_present) {
                bit(3)     reserved = 0;
                unsigned int(3) LF_corner_freq_index;
                unsigned int(2) LF_filter_strength_index;
             }
             if (LF_boost_filter_present) {
                bit(3)     reserved = 0;
                unsigned int(3) LF_corner_freq_index;
                unsigned int(2) LF_filter_strength_index;
             }
             if (HF_cut_filter_present) {
                bit(3)     reserved = 0;
                unsigned int(3) HF_corner_freq_index;
                unsigned int(2) HF_filter_strength_index;
             }
             if (HF_boost_filter_present) {
                bit(3)     reserved = 0;
                unsigned int(3) HF_corner_freq_index;
                unsigned int(2) HF_filter_strength_index;
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
             }
          }
       }
   }
   bit(1)     reserved = 0;
   unsigned int(1) delayMode;
   if (version >= 1} {
       bit(2)     reserved = 0;
       unsigned int(6) gain_sequence_count;
   }
   unsigned int(6) gain_set_count;
   for (i=1; i<=gain_set_count; i++) {
       bit(2)     reserved = 0;
       unsigned int(2) gain_coding_profile;
       unsigned int(1) gain_interpolation_type;
       unsigned int(1) full_frame;
       unsigned int(1) time_alignment;
       bit(1)     time_delta_min_present;
       if (time_delta_min_present == 1) {
          bit(5)      reserved = 0;
          unsigned int(11) bs_time_delta_min;
      }
      if (gain_coding_profile!=3) {
          bit(3)     reserved = 0;
          unsigned int(4) band_count;    // shall be >= 1
          unsigned int(1) drc_band_type;
          for (j = 1; j <= band_count; j++) {
             if (version>=1) {
                 unsigned int(6) bs_index;
                 bit(1)     drc_characteristic_present
                 bit(1)     drc_characteristic_format_is_CICP
                 if (drc_characteristic_present==1) {
                    if (drc_characteristic_format_is_CICP==1) {
                       bit(1)     reserved;
                       unsigned int(7) drc_characteristic;
                    } else {
                       unsigned int(4) drc_characteristic_left_index;
                       unsigned int(4) drc_characteristic_right_index;
                    }
                 }
             } else {
                 bit(1)     reserved = 0;
                 unsigned int(7) drc_characteristic;
             }
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
          }
          for (j = 2; j <= band_count; j++){
             if (drc_band_type == 1) {
             bit(4)     reserved = 0;
             unsigned int(4) crossover_freq_index;
             } else {
             bit(6)      reserved = 0;
             unsigned int(10) start_sub_band_index;
             }
           }
        }
     }
  }
}
7.3
Replace Table 75 with the following table:
Table 75 — Syntax of uniDrcConfigExtension() payload
Syntax No. of bits Mnemonic

uniDrcConfigExtension()

{
   while (uniDrcConfigExtType != UNIDRCCONFEXT_TERM) { 4 uimsbf
       extSizeBits = bitSizeLen + 4; 4 uimsbf
       extBitSize = bitSize + 1; extSizeBits uimsbf

       switch (uniDrcConfigExtType) {

         case UNIDRCCONFEXT_PARAM_DRC:

            drcCoefficientsParametricDrc();
            parametricDrcInstructionsCount; 4 uimsbf

            for (i=0; i
               parametricDrcInstructions ();

            }

            break;

         case UNIDRCCONFEXT_V2:
            if (characteristicV1Override==1) { 1 bslbf
                              drcCoefficientsOverrideCount; 3 uimsbf

               for (i=0; i                   drcLocation; 4 uimsbf
                  gainSetCount; 6 uimsbf

                  for (j=0; j                       if (characteristicOverridePresent==1) { 1 bslbf
                         bandCount; 4 uimsbf

                         for (k=0; k                             overrideCicpCharacteristic; 7 uimsbf
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ISO/IEC 23003-4:2020/Amd. 1:2022(E)
Table 75 (continued)
Syntax No. of bits Mnemonic
                            bsEncDrcNormGain; 6 uimsbf


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