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84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
package mp3
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// https://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header
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import (
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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)
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.XING,
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Description: "Xing header",
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DecodeFn: xingDecode,
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})
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}
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func xingDecode(d *decode.D, _ any) any {
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// TODO: info has lame extension?
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hasLameExtension := false
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switch d.FieldUTF8("header", 4) {
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case "Xing":
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case "Info":
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hasLameExtension = true
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default:
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d.Errorf("no xing header found")
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}
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qualityPresent := false
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tocPresent := false
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bytesPresent := false
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framesPresent := false
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d.FieldStruct("present_flags", func(d *decode.D) {
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d.FieldU("unused", 28)
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qualityPresent = d.FieldBool("quality")
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tocPresent = d.FieldBool("toc")
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bytesPresent = d.FieldBool("bytes")
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framesPresent = d.FieldBool("frames")
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})
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if framesPresent {
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d.FieldU32BE("frames")
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}
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if bytesPresent {
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d.FieldU32BE("bytes")
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}
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if tocPresent {
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d.FieldArray("toc", func(d *decode.D) {
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for i := 0; i < 100; i++ {
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d.FieldU8("entry")
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}
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})
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}
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if qualityPresent {
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d.FieldU32BE("quality")
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}
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if hasLameExtension {
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d.FieldStruct("lame_extension", func(d *decode.D) {
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d.FieldUTF8("encoder", 9)
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d.FieldU4("tag_revision")
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d.FieldU4("vbr_method")
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d.FieldU8("lowpass_filter") // TODO: /100
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d.FieldU32("replay_gain_peak")
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d.FieldU16("radio_replay_gain")
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d.FieldU16("audiophile_replay_gain")
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d.FieldU4("lame_flags")
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d.FieldU4("lame_ath_type")
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d.FieldU8("abr_vbr") // TODO:
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d.FieldU12("encoder_delay") // TODO:
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d.FieldU12("encoder_padding") // TODO:
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d.FieldU8("misc") // TODO:
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d.FieldU8("mp3_gain") // TODO:
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d.FieldU16("preset") // TODO:
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d.FieldU32("length")
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d.FieldU16("music_crc") // TODO:
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d.FieldU16("tag_crc") // TODO:
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})
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}
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return nil
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}
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