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312 lines
7.7 KiB
Go
312 lines
7.7 KiB
Go
package mpeg
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// one AAC frame or "raw data block"
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// ISO/IEC 13818-7 Part 7: Advanced Audio Coding (AAC)
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// ISO/IEC 14496-3
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import (
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"github.com/wader/fq/format"
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"github.com/wader/fq/format/registry"
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"github.com/wader/fq/pkg/decode"
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)
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func init() {
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registry.MustRegister(decode.Format{
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Name: format.AAC_FRAME,
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Description: "Advanced Audio Coding frame",
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DecodeFn: aacDecode,
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RootArray: true,
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RootName: "elements",
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})
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}
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const (
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SCE = 0b000
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CPE = 0b001
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CCE = 0b010
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LFE = 0b011
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DSE = 0b100
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PCE = 0b101
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FIL = 0b110
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TERM = 0b111
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)
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var syntaxElementNames = decode.UToStr{
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SCE: "SCE",
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CPE: "CPE",
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CCE: "CCE",
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LFE: "LFE",
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DSE: "DSE",
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PCE: "PCE",
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FIL: "FIL",
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TERM: "TERM",
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}
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//nolint:revive
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const (
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EXT_FILL = 0x0
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EXT_FILL_DATA = 0x1
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EXT_DATA_ELEMENT = 0x2
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EXT_DYNAMIC_RANGE = 0xb
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EXT_SBR_DATA = 0xd
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EXT_SBR_DATA_CRC = 0xe
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)
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var extensionPayloadIDNames = decode.UToStr{
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EXT_FILL: "EXT_FILL",
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EXT_FILL_DATA: "EXT_FILL_DATA",
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EXT_DATA_ELEMENT: "EXT_DATA_ELEMENT",
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EXT_DYNAMIC_RANGE: "EXT_DYNAMIC_RANGE",
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EXT_SBR_DATA: "EXT_SBR_DATA",
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EXT_SBR_DATA_CRC: "EXT_SBR_DATA_CRC",
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}
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//nolint:revive
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const (
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ONLY_LONG_SEQUENCE = 0x0
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LONG_START_SEQUENCE = 0x1
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EIGHT_SHORT_SEQUENCE = 0x2
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LONG_STOP_SEQUENCE = 0x3
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)
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var windowSequenceNames = decode.UToStr{
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ONLY_LONG_SEQUENCE: "ONLY_LONG_SEQUENCE",
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LONG_START_SEQUENCE: "LONG_START_SEQUENCE",
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EIGHT_SHORT_SEQUENCE: "EIGHT_SHORT_SEQUENCE",
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LONG_STOP_SEQUENCE: "LONG_STOP_SEQUENCE",
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}
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var windowSequenceNumWindows = map[int]int{
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ONLY_LONG_SEQUENCE: 1,
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LONG_START_SEQUENCE: 1,
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EIGHT_SHORT_SEQUENCE: 8,
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LONG_STOP_SEQUENCE: 1,
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}
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func aacLTPData(d *decode.D, objectType int, windowSequence int) {
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switch objectType {
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case format.MPEGAudioObjectTypeER_AAC_LD:
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// TODO:
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default:
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d.FieldU11("ltp_lag")
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d.FieldU3("ltp_coef")
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_ = windowSequenceNumWindows[windowSequence]
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}
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}
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func aacICSInfo(d *decode.D, objectType int) {
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d.FieldU1("ics_reserved_bit")
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windowSequence := d.FieldU2("window_sequence", d.MapUToStrSym(windowSequenceNames))
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d.FieldU1("window_shape")
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switch windowSequence {
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case EIGHT_SHORT_SEQUENCE:
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d.FieldU4("max_sfb")
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d.FieldU7("scale_factor_grouping")
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default:
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maxSFB := d.FieldU6("max_sfb")
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predictorDataPresent := d.FieldBool("predictor_data_present")
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if predictorDataPresent {
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switch objectType {
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case format.MPEGAudioObjectTypeMain: // 1
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predictorReset := d.FieldBool("predictor_reset")
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if predictorReset {
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d.FieldU5("predictor_reset_group_number")
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}
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d.FieldU5("predictor_reset_group_number")
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// TODO: min(max_sfb, PRED_SFB_MAX)
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// TODO: array?
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d.FieldRawLen("prediction_used", int64(maxSFB))
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default:
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ltpDataPresent := d.FieldBool("ltp_data_present")
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if ltpDataPresent {
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aacLTPData(d, objectType, int(windowSequence))
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}
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}
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}
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}
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// ;
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// if (window_sequence == EIGHT_SHORT_SEQUENCE) {
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// max_sfb; scale_factor_grouping;
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// } }
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// else {
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// ltp_data_present;
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// if (ltp_data_present) {
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// ltp_data(); }
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// if (common_window) {
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// ltp_data_present;
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// LICENSED TO MECON Limited. - RANCHI/BANGALORE,
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// FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
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// if (ltp_data_present) {
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// ltp_data(); }
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// } }
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// } }
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// }
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}
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func aacIndividualChannelStream(d *decode.D, objectType int, commonWindow bool, scaleFlag bool) {
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d.FieldU8("global_gain")
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if !commonWindow && !scaleFlag {
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d.FieldStruct("ics_info", func(d *decode.D) {
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aacICSInfo(d, objectType)
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})
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}
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}
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func aacSingleChannelElement(d *decode.D, objectType int) {
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d.FieldU4("element_instance_tag")
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aacIndividualChannelStream(d, objectType, false, false)
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}
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func aacProgramConfigElement(d *decode.D, ascStartPos int64) {
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d.FieldU4("element_instance_tag")
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d.FieldU2("object_type")
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d.FieldU4("sampling_frequency_index")
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numFrontChannelElements := d.FieldU4("num_front_channel_elements")
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numSideChannelElements := d.FieldU4("num_side_channel_elements")
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numBackChannelElements := d.FieldU4("num_back_channel_elements")
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numLfeChannelElements := d.FieldU2("num_lfe_channel_elements")
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numAssocDataElements := d.FieldU3("num_assoc_data_elements")
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numValidCcElements := d.FieldU4("num_valid_cc_elements")
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monoMixdownPresent := d.FieldBool("mono_mixdown_present")
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if monoMixdownPresent {
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d.FieldU4("mono_mixdown_element_number")
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}
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stereoMixdownPresent := d.FieldBool("stereo_mixdown_present")
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if stereoMixdownPresent {
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d.FieldU4("stereo_mixdown_element_number")
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}
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matrixMixdownIdxPresent := d.FieldBool("matrix_mixdown_idx_present")
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if matrixMixdownIdxPresent {
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d.FieldU2("matrix_mixdown_idx")
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d.FieldBool("pseudo_surround_enable")
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}
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d.FieldArray("front_channel_elements", func(d *decode.D) {
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for i := uint64(0); i < numFrontChannelElements; i++ {
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d.FieldStruct("front_channel_element", func(d *decode.D) {
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d.FieldBool("is_cpe")
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d.FieldU4("tag_select")
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})
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}
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})
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d.FieldArray("side_channel_elements", func(d *decode.D) {
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for i := uint64(0); i < numSideChannelElements; i++ {
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d.FieldStruct("side_channel_element", func(d *decode.D) {
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d.FieldBool("is_cpe")
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d.FieldU4("tag_select")
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})
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}
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})
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d.FieldArray("back_channel_elements", func(d *decode.D) {
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for i := uint64(0); i < numBackChannelElements; i++ {
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d.FieldStruct("back_channel_element", func(d *decode.D) {
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d.FieldBool("is_cpe")
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d.FieldU4("tag_select")
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})
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}
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})
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d.FieldArray("lfe_channel_elements", func(d *decode.D) {
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for i := uint64(0); i < numLfeChannelElements; i++ {
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d.FieldStruct("lfe_channel_element", func(d *decode.D) {
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d.FieldU4("tag_select")
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})
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}
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})
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d.FieldArray("assoc_data_elements", func(d *decode.D) {
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for i := uint64(0); i < numAssocDataElements; i++ {
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d.FieldStruct("assoc_data_element", func(d *decode.D) {
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d.FieldU4("tag_select")
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})
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}
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})
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d.FieldArray("valid_cc_elements", func(d *decode.D) {
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for i := uint64(0); i < numValidCcElements; i++ {
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d.FieldStruct("valid_cc_element", func(d *decode.D) {
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d.FieldU1("cc_element_is_ind_sw")
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d.FieldU4("valid_cc_element_tag_select")
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})
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}
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})
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byteAlignBits := (8 - ((d.Pos() + ascStartPos) & 0x7)) & 0x7
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d.FieldRawLen("byte_alignment", byteAlignBits)
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commentFieldBytes := d.FieldU8("comment_field_bytes")
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d.FieldUTF8("comment_field", int(commentFieldBytes))
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}
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func aacFillElement(d *decode.D) {
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var cnt uint64
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d.FieldStruct("cnt", func(d *decode.D) {
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count := d.FieldU4("count")
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cnt = count
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if cnt == 15 {
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escCount := d.FieldU8("esc_count")
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cnt += escCount - 1
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}
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})
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d.FieldValueU("payload_length", cnt)
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d.FieldStruct("extension_payload", func(d *decode.D) {
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d.LenFn(int64(cnt)*8, func(d *decode.D) {
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extensionType := d.FieldU4("extension_type", d.MapUToStrSym(extensionPayloadIDNames))
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// d.FieldU("align4", 2)
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switch extensionType {
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case EXT_FILL:
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d.FieldU4("fill_nibble")
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d.FieldRawLen("fill_byte", 8*(int64(cnt)-1))
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}
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})
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})
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}
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func aacDecode(d *decode.D, in interface{}) interface{} {
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var objectType int
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if afi, ok := in.(format.AACFrameIn); ok {
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objectType = afi.ObjectType
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}
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// objectType = 2
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// TODO: seems tricky to know length of blocks
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// TODO: currently break when length is unknown
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seenTerm := false
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for !seenTerm {
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d.FieldStruct("element", func(d *decode.D) {
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se := d.FieldU3("syntax_element", d.MapUToStrSym(syntaxElementNames))
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switch se {
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case FIL:
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aacFillElement(d)
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case SCE:
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aacSingleChannelElement(d, objectType)
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seenTerm = true
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case PCE:
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aacProgramConfigElement(d, 0)
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seenTerm = true
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default:
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fallthrough
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case TERM:
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seenTerm = true
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}
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})
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}
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if d.ByteAlignBits() > 0 {
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d.FieldRawLen("byte_align", int64(d.ByteAlignBits()))
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}
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d.FieldRawLen("data", d.BitsLeft())
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return nil
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}
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