claude
e7ac31b5c8
- waves: square (duty), saw, sine, triangle, pitched noise (seeded, deterministic) - envelope attack/sustain/decay, freq slide, vibrato, arpeggio jump, one-pole low/high-pass filters, clamped output - presets blip/coin/explosion/hurt/jump/laser/powerup with seeded variants; preset writes editable .sfx or renders .wav directly - go tests: parse/validate, determinism, per-preset RMS, WAV header roundtrip Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MmdG9GqfSWCzts7AkDwRDh
55 lines
1.8 KiB
Go
55 lines
1.8 KiB
Go
package sfx
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import (
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"encoding/binary"
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"fmt"
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"io"
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"math"
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)
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// WriteWAV encodes samples ([-1,1] floats) as a 16-bit mono PCM WAV.
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func WriteWAV(w io.Writer, samples []float64, sampleRate int) error {
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dataLen := len(samples) * 2
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var hdr [44]byte
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copy(hdr[0:4], "RIFF")
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binary.LittleEndian.PutUint32(hdr[4:8], uint32(36+dataLen))
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copy(hdr[8:12], "WAVE")
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copy(hdr[12:16], "fmt ")
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binary.LittleEndian.PutUint32(hdr[16:20], 16) // fmt chunk size
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binary.LittleEndian.PutUint16(hdr[20:22], 1) // PCM
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binary.LittleEndian.PutUint16(hdr[22:24], 1) // mono
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binary.LittleEndian.PutUint32(hdr[24:28], uint32(sampleRate)) // sample rate
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binary.LittleEndian.PutUint32(hdr[28:32], uint32(sampleRate*2)) // byte rate
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binary.LittleEndian.PutUint16(hdr[32:34], 2) // block align
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binary.LittleEndian.PutUint16(hdr[34:36], 16) // bits per sample
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copy(hdr[36:40], "data")
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binary.LittleEndian.PutUint32(hdr[40:44], uint32(dataLen))
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if _, err := w.Write(hdr[:]); err != nil {
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return err
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}
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buf := make([]byte, 2*len(samples))
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for i, s := range samples {
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v := int16(math.Round(s * 32767))
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binary.LittleEndian.PutUint16(buf[i*2:], uint16(v))
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}
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_, err := w.Write(buf)
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return err
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}
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// ReadWAVHeader sanity-parses a WAV header (used in tests and info).
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func ReadWAVHeader(r io.Reader) (sampleRate, bits, channels, dataBytes int, err error) {
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var hdr [44]byte
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if _, err = io.ReadFull(r, hdr[:]); err != nil {
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return
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}
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if string(hdr[0:4]) != "RIFF" || string(hdr[8:12]) != "WAVE" {
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err = fmt.Errorf("not a WAV file")
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return
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}
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channels = int(binary.LittleEndian.Uint16(hdr[22:24]))
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sampleRate = int(binary.LittleEndian.Uint32(hdr[24:28]))
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bits = int(binary.LittleEndian.Uint16(hdr[34:36]))
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dataBytes = int(binary.LittleEndian.Uint32(hdr[40:44]))
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return
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}
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