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9b81d4d3ab
Preparation to make decoder use less memory and API more type safe. Now each scalar type has it's own struct type so it can store different things and enables to have a scalar interface. Also own types will enable experimenting with decode DLS designs like using chained methods that are type aware.
125 lines
3.3 KiB
Go
125 lines
3.3 KiB
Go
package opus
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// https://tools.ietf.org/html/rfc7845
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import (
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"bytes"
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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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var vorbisComment decode.Group
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.OPUS_PACKET,
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Description: "Opus packet",
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DecodeFn: opusDecode,
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Dependencies: []decode.Dependency{
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{Names: []string{format.VORBIS_COMMENT}, Group: &vorbisComment},
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},
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})
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}
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func opusDecode(d *decode.D, _ any) any {
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d.Endian = decode.LittleEndian
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var prefix []byte
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if d.BitsLeft() >= 8*8 {
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prefix = d.PeekBytes(8)
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}
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switch {
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case bytes.Equal(prefix, []byte("OpusHead")):
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d.FieldValueStr("type", "head")
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d.FieldUTF8("prefix", 8)
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d.FieldU8("version")
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channelCount := d.FieldU8("channel_count")
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d.FieldU16("pre_skip")
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d.FieldU32("sample_rate")
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d.FieldU16("output_gain")
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mapFamily := d.FieldU8("map_family")
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if mapFamily != 0 {
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d.FieldU8("stream_count")
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d.FieldU8("coupled_count")
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i := uint64(0)
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d.FieldArrayLoop("channel_mappings", func() bool { return i < channelCount }, func(d *decode.D) {
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d.FieldU8("channel_mapping")
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})
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}
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case bytes.Equal(prefix, []byte("OpusTags")):
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d.FieldValueStr("type", "tags")
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d.FieldUTF8("prefix", 8)
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d.FieldFormat("comment", vorbisComment, nil)
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default:
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d.FieldValueStr("type", "audio")
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d.FieldStruct("toc", func(d *decode.D) {
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d.FieldStruct("config", func(d *decode.D) {
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configurations := map[uint64]struct {
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mode string
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bandwidth string
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frameSize float64
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}{
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0: {"SILK-only", "NB", 10},
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1: {"SILK-only", "NB", 20},
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2: {"SILK-only", "NB", 40},
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3: {"SILK-only", "NB", 60},
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4: {"SILK-only", "MB", 10},
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5: {"SILK-only", "MB", 20},
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6: {"SILK-only", "MB", 40},
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7: {"SILK-only", "MB", 60},
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8: {"SILK-only", "WB", 10},
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9: {"SILK-only", "WB", 20},
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10: {"SILK-only", "WB", 40},
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11: {"SILK-only", "WB", 60},
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12: {"Hybrid", "SWB", 10},
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13: {"Hybrid", "SWB", 20},
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14: {"Hybrid", "FB", 10},
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15: {"Hybrid", "FB", 20},
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16: {"CELT-only", "NB", 2.5},
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17: {"CELT-only", "NB", 5},
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18: {"CELT-only", "NB", 10},
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19: {"CELT-only", "NB", 20},
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20: {"CELT-only", "WB", 2.5},
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21: {"CELT-only", "WB", 5},
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22: {"CELT-only", "WB", 10},
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23: {"CELT-only", "WB", 20},
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24: {"CELT-only", "SWB", 2.5},
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25: {"CELT-only", "SWB", 5},
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26: {"CELT-only", "SWB", 10},
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27: {"CELT-only", "SWB", 20},
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28: {"CELT-only", "FB", 2.5},
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29: {"CELT-only", "FB", 5},
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30: {"CELT-only", "FB", 10},
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31: {"CELT-only", "FB", 20},
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}
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n := d.FieldU5("config")
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config := configurations[n]
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d.FieldValueStr("mode", config.mode)
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d.FieldValueStr("bandwidth", config.bandwidth)
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d.FieldValueFlt("frame_size", config.frameSize)
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})
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d.FieldBool("stereo")
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d.FieldStruct("frames_per_packet", func(d *decode.D) {
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framesPerPacketConfigs := map[uint64]struct {
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frames uint64
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mode string
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}{
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0: {1, "1 frame"},
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1: {2, "2 frames, equal size"},
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2: {2, "2 frames, different size"},
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3: {0, "arbitrary number of frames"},
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}
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n := d.FieldU2("config")
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config := framesPerPacketConfigs[n]
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d.FieldValueUint("frames", config.frames)
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d.FieldValueStr("mode", config.mode)
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})
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d.FieldRawLen("data", d.BitsLeft())
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})
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}
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return nil
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}
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