ETSI TS 103 190-1 V1.3.1 (2018-02)

TECHNICAL SPECIFICATION
Digital Audio Compression (AC-4) Standard;
Part 1: Channel based coding
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2 ETSI TS 103 190-1 V1.3.1 (2018-02)

Reference
RTS/JTC-043-1
Keywords
audio, broadcasting, codec, content, digital,
distribution
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ETSI
3 ETSI TS 103 190-1 V1.3.1 (2018-02)
Contents
Intellectual Property Rights . 17
Foreword . 17
Modal verbs terminology . 17
Introduction . 18
1 Scope . 20
2 References . 20
2.1 Normative references . 20
2.2 Informative references . 20
3 Definitions, symbols, abbreviations and conventions . 21
3.1 Definitions . 21
3.2 Symbols . 23
3.3 Abbreviations . 24
3.4 Conventions . 25
4 Bitstream syntax . 26
4.1 Semantics of syntax specification. 26
4.2 Syntax specification . 26
4.2.1 raw_ac4_frame - Raw AC-4 frame . 26
4.2.2 variable_bits - Variable bits . 26
4.2.3 AC-4 frame information . 27
4.2.3.1 ac4_toc - AC-4 table of contents . 27
4.2.3.2 ac4_presentation_info - AC-4 presentation information . 27
4.2.3.3 presentation_version - Presentation version information . 29
4.2.3.4 frame_rate_multiply_info - Frame rate multiplier information . 29
4.2.3.5 emdf_info - EMDF information . 29
4.2.3.6 ac4_substream_info - AC-4 substream information . 30
4.2.3.7 content_type - Content type . 30
4.2.3.8 presentation_config_ext_info - Presentation configuration extended information . 30
4.2.3.9 ac4_hsf_ext_substream_info - AC-4 HSF extension substream information . 31
4.2.3.10 emdf_payloads_substream_info - EMDF payloads substream information . 31
4.2.3.11 substream_index_table - Substream index table . 31
4.2.4 AC-4 substreams . 32
4.2.4.1 AC-4 substreams . 32
4.2.4.2 ac4_substream - AC-4 substream . 32
4.2.4.3 ac4_hsf_ext_substream - AC-4 high sampling frequency extension substream . 32
4.2.4.4 emdf_payloads_substream - EMDF payloads substream . 33
4.2.5 audio_data - Audio data . 33
4.2.6 Channel elements . 33
4.2.6.1 single_channel_element - Single channel element . 33
4.2.6.2 mono_data - Mono data . 34
4.2.6.3 channel_pair_element - Channel pair element . 34
4.2.6.4 stereo_data - Stereo data . 35
4.2.6.5 3_0_channel_element - 3.0 channel element. 35
4.2.6.6 5_X_channel_element - 5.X channel element . 36
4.2.6.7 two_channel_data - Two channel data . 37
4.2.6.8 three_channel_data - Three channel data . 37
4.2.6.9 four_channel_data - Four channel data . 38
4.2.6.10 five_channel_data - Five channel data . 38
4.2.6.11 three_channel_info - Three channel info. 38
4.2.6.12 four_channel_info - Four channel info . 38
4.2.6.13 five_channel_info - Five channel info. 39
4.2.6.14 7_X_channel_element - 7.X channel element . 39
4.2.7 Spectral frontend . 40
4.2.7.1 sf_info - Spectral frontend info . 40
4.2.7.2 sf_info_lfe - Spectral frontend info for LFE . 40
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4 ETSI TS 103 190-1 V1.3.1 (2018-02)
4.2.7.3 sf_data - Spectral frontend data . 41
4.2.7.4 sf_hsf_data - Spectral frontend HSF extension data . 41
4.2.8 Audio spectral frontend . 41
4.2.8.1 asf_transform_info - ASF transform info . 41
4.2.8.2 asf_psy_info - ASF scale factor band info . 41
4.2.8.3 asf_section_data - ASF section data . 42
4.2.8.4 asf_spectral_data - ASF spectral data . 43
4.2.8.5 asf_scalefac_data - ASF scale factor data . 44
4.2.8.6 asf_snf_data - ASF spectral noise fill data . 44
4.2.8.7 asf_hsf_spectral_data - ASF spectral data for HSF extension . 44
4.2.8.8 asf_hsf_scalefac_data - ASF scale factor data for HSF extension . 45
4.2.8.9 asf_hsf_snf_data - ASF spectral noise fill data for HSF extension . 45
4.2.9 Speech spectral frontend . 46
4.2.9.1 ssf_data - Speech spectral frontend data . 46
4.2.9.2 ssf_granule - Speech spectral frontend granule . 46
4.2.9.3 ssf_st_data - Speech spectral frontend static data . 47
4.2.9.4 ssf_ac_data - Speech spectral frontend arithmetic coded data . 47
4.2.10 Stereo audio processing . 48
4.2.10.1 chparam_info -Stereo information . 48
4.2.10.2 sap_data - Stereo audio processing data . 48
4.2.11 Companding control . 49
4.2.12 Advanced spectral extension - A-SPX . 49
4.2.12.1 aspx_config - A-SPX configuration . 49
4.2.12.2 aspx_data_1ch - A-SPX 1-channel data . 49
4.2.12.3 aspx_data_2ch - A-SPX 2-channel data . 50
4.2.12.4 aspx_framing - A-SPX framing . 50
4.2.12.5 aspx_delta_dir - A-SPX direction of envelope delta coding . 51
4.2.12.6 aspx_hfgen_iwc_1ch - A-SPX 1-channel HF generation and interleaved waveform coding . 52
4.2.12.7 aspx_hfgen_iwc_2ch - A-SPX 2-channel HF generation and interleaved waveform coding . 52
4.2.12.8 aspx_ec_data - A-SPX entropy coded data . 53
4.2.12.9 aspx_huff_data - A-SPX Huffman data . 54
4.2.13 Advanced coupling - A-CPL . 54
4.2.13.1 acpl_config_1ch - A-CPL 1-channel configuration . 54
4.2.13.2 acpl_config_2ch - A-CPL 2-channel configuration . 54
4.2.13.3 acpl_data_1ch - A-CPL 1-channel data . 55
4.2.13.4 acpl_data_2ch - A-CPL 2-channel data . 55
4.2.13.5 acpl_framing_data - A-CPL framing data . 55
4.2.13.6 acpl_ec_data - A-CPL entropy coded data . 56
4.2.13.7 acpl_huff_data - A-CPL Huffman data . 56
4.2.14 Metadata . 56
4.2.14.1 metadata() - Metadata . 56
4.2.14.2 basic_metadata - Basic metadata . 57
4.2.14.3 further_loudness_info - Additional loudness information . 58
4.2.14.4 extended_metadata - Extended metadata . 59
4.2.14.5 drc_frame - DRC frame . 60
4.2.14.6 drc_config - DRC configuration . 60
4.2.14.7 drc_decoder_mode_config - DRC decoder mode configuration . 60
4.2.14.8 drc_compression_curve - Compression curve parameters . 61
4.2.14.9 drc_data -DRC frame-based data . 61
4.2.14.10 drc_gains - DRC gains . 62
4.2.14.11 dialog_enhancement - Dialog enhancement metadata . 62
4.2.14.12 de_config - Dialog enhancement configuration . 62
4.2.14.13 de_data - Dialog enhancement data . 63
4.2.14.14 emdf_payload_config - EMDF payload configuration . 64
4.2.14.15 emdf_protection - EMDF protection data . 64
4.3 Description of bitstream elements . 64
4.3.0 Introduction. 64
4.3.1 raw_ac4_frame - raw AC-4 frame . 65
4.3.1.1 fill_area - fill area . 65
4.3.1.2 fill_bits - byte alignment bits . 65
4.3.1.3 byte_align - byte alignment bits . 65
4.3.2 variable_bits - Variable bits . 65
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4.3.2.0 Encoding . 65
4.3.2.1 read - read bits . 65
4.3.2.2 b_read_more - read more flag . 65
4.3.3 AC-4 frame information . 66
4.3.3.1 Purpose . 66
4.3.3.2 ac4_toc - AC-4 table of contents . 66
4.3.3.2.1 bitstream_version - bitstream version . 66
4.3.3.2.2 sequence_counter - sequence counter . 66
4.3.3.2.3 b_wait_frames . 66
4.3.3.2.4 wait_frames . 66
4.3.3.2.5 fs_index - Sampling frequency index . 67
4.3.3.2.6 frame_rate_index - frame rate . 67
4.3.3.2.7 b_iframe_global - global I-frame flag . 68
4.3.3.2.8 b_single_presentation - single presentation flag . 68
4.3.3.2.9 b_more_presentations - more presentations flag . 68
4.3.3.2.10 b_payload_base - payload base flag . 68
4.3.3.2.11 payload_base_minus1 - payload base offset minus 1 . 69
4.3.3.2.12 byte_align - byte alignment bits . 69
4.3.3.3 ac4_presentation_info - AC-4 presentation information . 69
4.3.3.3.1 b_single_substream - single substream flag . 69
4.3.3.3.2 b_belongs_to_presentation_id - Presentation identifier assignment flag. 69
4.3.3.3.3 b_hsf_ext - high sampling frequency extension flag . 69
4.3.3.3.4 presentation_config - presentation configuration - . 69
4.3.3.3.5 b_pre_virtualized - pre-virtualized flag . 69
4.3.3.3.6 b_add_emdf_substreams - additional EMDF substreams flag . 69
4.3.3.3.7 n_add_emdf_substreams - number of additional EMDF substreams . 69
4.3.3.3.8 mdcompat - compatibility indication . 70
4.3.3.4 presentation_version - presentation version information . 70
4.3.3.4.1 b_tmp - temporary flag . 70
4.3.3.5 frame_rate_multiply_info - frame rate multiplier information . 70
4.3.3.5.1 b_multiplier - multiplier flag . 70
4.3.3.5.2 multiplier_bit - multiplier bit . 70
4.3.3.5.3 frame_rate_factor - frame rate factor . 70
4.3.3.6 emdf_info - EMDF information . 71
4.3.3.6.1 emdf_version - EMDF syntax version . 71
4.3.3.6.2 key_id - authentication ID . 71
4.3.3.6.3 b_emdf_payloads_substream_info - EMDF payloads substream information flag . 71
4.3.3.7 ac4_substream_info - AC-4 substream information . 71
4.3.3.7.1 channel_mode - channel mode . 71
4.3.3.7.2 b_sf_multiplier - sampling frequency multiplier flag . 71
4.3.3.7.3 sf_multiplier - sampling frequency multiplier bit . 72
4.3.3.7.4 b_bitrate_info - bit-rate presence flag . 72
4.3.3.7.5 bitrate_indicator - bit-rate indicator . 72
4.3.3.7.6 add_ch_base - additional channels coupling base . 72
4.3.3.7.7 b_content_type - content type presence flag. 72
4.3.3.7.8 b_iframe - I-frame flag . 72
4.3.3.7.9 substream_index - substream index . 72
4.3.3.8 content_type - content type . 73
4.3.3.8.1 content_classifier - content classifier . 73
4.3.3.8.2 b_language_indicator - programme language indicator flag . 73
4.3.3.8.3 b_serialized_language_tag - serialized language tag flag . 73
4.3.3.8.4 b_start_tag - language tag start flag . 73
4.3.3.8.5 language_tag_chunk - language tag chunk . 73
4.3.3.8.6 n_language_tag_bytes - number of language tag bytes . 74
4.3.3.8.7 language_tag_bytes - language tag bytes. 74
4.3.3.9 presentation_config_ext_info - presentation configuration extended information . 74
4.3.3.9.1 n_skip_bytes - number of bytes to skip . 74
4.3.3.9.2 b_more_skip_bytes - more bytes to skip flag . 74
4.3.3.9.3 reserved - Reserved . 74
4.3.3.10 ac4_hsf_ext_substream_info - AC-4 HSF extension substream information . 74
4.3.3.10.1 substream_index - substream index . 74
4.3.3.11 emdf_payloads_substream_info - EMDF payloads substream information . 74
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4.3.3.11.1 substream_index - substream index . 74
4.3.3.12 substream_index_table - substream index table . 74
4.3.3.12.1 n_substreams - number of substreams . 74
4.3.3.12.2 b_size_present - size present flag . 74
4.3.3.12.3 b_more_bits - more bits flag . 75
4.3.3.12.4 substream_size - substream size . 75
4.3.4 ac4_substream - AC-4 substream . 75
4.3.4.1 audio_size_value - audio size value . 75
4.3.4.2 b_more_bits - more bits flag . 75
4.3.4.3 byte_align - byte alignment bits . 75
4.3.5 Channel elements . 75
4.3.5.0 Introduction . 75
4.3.5.1 mono_codec_mode - mono codec mode . 75
4.3.5.2 spec_frontend - spectral frontend selection . 76
4.3.5.3 stereo_codec_mode - stereo codec mode . 76
4.3.5.4 3_0_codec_mode - 3.0 codec mode . 76
4.3.5.5 3_0_coding_config - 3.0 coding configuration . 76
4.3.5.6 5_X_codec_mode - 5.X codec mode . 76
4.3.5.7 7_X_codec_mode - 7.X codec mode . 77
4.3.5.8 coding_config - coding configuration . 77
4.3.5.9 2ch_mode - channel coupling mode . 77
4.3.5.10 b_enable_mdct_stereo_proc - enable MDCT stereo processing flag . 77
4.3.5.11 chel_matsel - matrix selection code . 77
4.3.5.12 b_use_sap_add_ch - use SAP for additional channels flag . 77
4.3.5.13 max_sfb_master - max_sfb indication for related channels . 77
4.3.6 audio spectral front end . 77
4.3.6.1 asf_transform_info - ASF transform information . 77
4.3.6.1.1 b_long_frame - long frame flag . 77
4.3.6.1.2 transf_length[i] - transform length index i . 78
4.3.6.1.3 transf_length - transform length . 78
4.3.6.1.4 get_transf_length(g) – get transform length for group g . 79
4.3.6.2 asf_psy_info - ASF psy information . 80
4.3.6.2.1 n_msfb_bits - number of maxsfb bits . 80
4.3.6.2.2 max_sfb[i] - number of transmitted scale factor bands for index i . 81
4.3.6.2.3 max_sfb_side[i] - number of transmitted scale factor bands for side channel and index i . 81
4.3.6.2.4 n_grp_bits - number of grouping bits . 81
4.3.6.2.5 scale_factor_grouping_bit - scale factor grouping bit . 82
4.3.6.2.6 asf_psy_info helper elements . 82
4.3.6.2.7 get_max_sfb(g) – get max_sfb for group g . 83
4.3.6.3 asf_section_data - ASF section data . 83
4.3.6.3.1 sect_cb[g][i] - section codebook . 83
4.3.6.3.2 sect_len_incr - section length increment . 84
4.3.6.4 asf_spectral_data - ASF spectral data . 84
4.3.6.4.1 asf_qspec_hcw - Huffman coded quantized spectral lines . 84
4.3.6.4.2 huff_decode(hcb, hcw) - Huffman decoding . 84
4.3.6.4.3 quad_sign_bits - quad sign bits . 84
4.3.6.4.4 pair_sign_bits - pair sign bits . 84
4.3.6.4.5 ext_code - extension code. 84
4.3.6.5 asf_scalefac_data - ASF scale factor data . 84
4.3.6.5.1 reference_scale_factor - reference scale factor . 84
4.3.6.5.2 asf_sf_hcw - Huffman coded scale factor delta . 84
4.3.6.6 asf_snf_data - ASF spectral noise fill data . 84
4.3.6.6.1 b_snf_data_exists - spectral noise fill data exists flag . 84
4.3.6.6.2 asf_snf_hcw - Huffman code spectral noise fill delta . 85
4.3.7 Speech spectral frontend . 85
4.3.7.1 ssf_data - Speech spectral frontend data . 85
4.3.7.1.1 b_ssf_iframe - SSF I-frame flag . 85
4.3.7.2 ssf_granule - speech spectral frontend granule . 85
4.3.7.2.1 stride_flag - stride flag . 85
4.3.7.2.2 SSF configuration . 85
4.3.7.2.3 num_bands_minus12 - number of SSF coded bands minus 12 . 86
4.3.7.2.4 predictor_presence_flag[b] - predictor presence flag for block b . 86
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4.3.7.2.5 delta_flag[b] - delta coding flag for block b . 86
4.3.7.3 ssf_st_data - speech spectral frontend static data . 86
4.3.7.3.1 env_curr_band0_bits - signal envelope index for band 0 . 86
4.3.7.3.2 env_startup_band0_bits - startup envelope index for band 0 . 86
4.3.7.3.3 gain_bits[b] - envelope gain bits for block b . 86
4.3.7.3.4 predictor_lag_delta_bits[b] - predictor lag delta for block b . 86
4.3.7.3.5 predictor_lag_bits[b] - predictor lag index for block b . 86
4.3.7.3.6 variance_preserving_flag[b] - variance preserving flag for block b . 86
4.3.7.3.7 alloc_offset_bits[block] - allocation offset bits for block b . 86
4.3.7.4 ssf_ac_data - speech spectral frontend arithmetic coded data . 87
4.3.7.4.1 env_curr_ac_bits - arithmetic coded signal envelope indices . 87
4.3.7.4.2 env_startup_ac_bits - arithmetic coded startup envelope indices . 87
4.3.7.4.3 predictor_gain_ac_bits[b] - arithmetic coded predictor gain index for block b . 87
4.3.7.4.4 q_mdct_coefficients_ac_bits[b] - arithmetic coded quantized MDCT coefficients for block b . 87
4.3.7.5 SSF helper elements . 87
4.3.8 Stereo audio processing . 87
4.3.8.1 chparam_info - stereo information . 87
4.3.8.1.1 sap_mode - stereo audio processing mode . 87
4.3.8.1.2 ms_used - M/S coding used . 88
4.3.8.2 sap_data - stereo audio processing data . 88
4.3.8.2.1 sap_coeff_all - SAP coding all scale factor bands flag . 88
4.3.8.2.2 sap_coeff_used - SAP coding used in scale factor band sfb . 88
4.3.8.2.3 delta_code_time - delta coding in time . 88
4.3.8.2.4 sap_hcw - Huffman coded alpha_q delta . 88
4.3.9 Companding control . 88
4.3.9.1 sync_flag . 88
4.3.9.2 b_compand_on . 88
4.3.9.3 b_compand_avg . 89
4.3.10 Advanced spectral extension - A-SPX . 89
4.3.10.1 aspx_config - A-SPX configuration . 89
4.3.10.1.1 aspx_quant_mode_env . 89
4.3.10.1.2 aspx_start_freq - A-SPX start QMF subband . 89
4.3.10.1.3 aspx_stop_freq - A-SPX stop QMF subband . 89
4.3.10.1.4 aspx_master_freq_scale - A-SPX master frequency table scale . 89
4.3.10.1.5 aspx_interpolation - A-SPX interpolation used . 90
4.3.10.1.6 aspx_preflat - A-SPX pre-flattening used . 90
4.3.10.1.7 aspx_limiter - A-SPX limiter used . 90
4.3.10.1.8 aspx_noise_sbg - A-SPX number of noise subband groups . 90
4.3.10.1.9 aspx_num_env_bits_fixfix - A-SPX frame class FIXFIX bit count . 90
4.3.10.1.10 aspx_freq_res_mode - A-SPX frequency resolution transmission mode . 91
4.3.10.2 aspx_data_1ch - A-SPX 1-channel data . 91
4.3.10.2.1 aspx_xover_subband_offset - A-SPX crossover subband offset . 91
4.3.10.3 aspx_data_2ch - A-SPX 2-channel data . 91
4.3.10.3.1 aspx_xover_subband_offset - A-SPX crossover subband offset . 91
4.3.10.3.2 aspx_balance - A-SPX balance setting . 91
4.3.10.4 aspx_framing - A-SPX framing . 91
4.3.10.4.1 aspx_int_class - A-SPX interval class . 91
4.3.10.4.2 tmp_num_env - temporary variable.
...