91 lines
3.3 KiB
Go
91 lines
3.3 KiB
Go
package wav
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"rtp-app/pkg/riff"
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)
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func DecodeSamplerChunk(d *Decoder, ch *riff.Chunk) error {
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if ch == nil {
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return fmt.Errorf("can't decode a nil chunk")
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}
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if d == nil {
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return fmt.Errorf("nil decoder")
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}
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if ch.ID == CIDSmpl {
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buf := make([]byte, ch.Size)
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var err error
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if _, err = ch.Read(buf); err != nil {
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return fmt.Errorf("failed to read the smpl chunk - %v", err)
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}
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if d.Metadata == nil {
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d.Metadata = &Metadata{}
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}
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d.Metadata.SamplerInfo = &SamplerInfo{}
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r := bytes.NewReader(buf)
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scratch := make([]byte, 4)
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if _, err = r.Read(scratch); err != nil {
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return fmt.Errorf("failed to read the smpl Manufacturer")
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}
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copy(d.Metadata.SamplerInfo.Manufacturer[:], scratch[:4])
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if _, err = r.Read(scratch); err != nil {
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return fmt.Errorf("failed to read the smpl Product")
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}
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copy(d.Metadata.SamplerInfo.Product[:], scratch[:4])
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SamplePeriod); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.MIDIUnityNote); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.MIDIPitchFraction); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SMPTEFormat); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.SMPTEOffset); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &d.Metadata.SamplerInfo.NumSampleLoops); err != nil {
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return err
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}
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var remaining uint32
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if err := binary.Read(r, binary.BigEndian, &remaining); err != nil {
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return err
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}
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if d.Metadata.SamplerInfo.NumSampleLoops > 0 {
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d.Metadata.SamplerInfo.Loops = []*SampleLoop{}
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for i := uint32(0); i < d.Metadata.SamplerInfo.NumSampleLoops; i++ {
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sl := &SampleLoop{}
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if _, err = r.Read(scratch); err != nil {
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return fmt.Errorf("failed to read the sample loop cue point id")
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}
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copy(sl.CuePointID[:], scratch[:4])
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if err := binary.Read(r, binary.LittleEndian, &sl.Type); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &sl.Start); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &sl.End); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &sl.Fraction); err != nil {
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return err
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}
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if err := binary.Read(r, binary.LittleEndian, &sl.PlayCount); err != nil {
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return err
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}
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d.Metadata.SamplerInfo.Loops = append(d.Metadata.SamplerInfo.Loops, sl)
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}
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}
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}
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ch.Drain()
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return nil
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}
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