mirror of
https://github.com/cgzirim/seek-tune.git
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7104a1a7bc
- Scale and mask frequencies to 9 bits each - Mask time delta to 14 bits - Add sampleRate parameter to ExtractPeaks calls Prevents hash collisions from bit overflow in fingerprint addresses.
92 lines
2.8 KiB
Go
92 lines
2.8 KiB
Go
package shazam
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import (
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"fmt"
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"song-recognition/models"
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"song-recognition/utils"
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"song-recognition/wav"
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)
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const (
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maxFreqBits = 9
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maxDeltaBits = 14
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targetZoneSize = 5
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)
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// Fingerprint generates fingerprints from a list of peaks and stores them in an array.
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// Each fingerprint consists of an address and a couple.
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// The address is a hash. The couple contains the anchor time and the song ID.
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func Fingerprint(peaks []Peak, songID uint32) map[uint32]models.Couple {
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fingerprints := map[uint32]models.Couple{}
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for i, anchor := range peaks {
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for j := i + 1; j < len(peaks) && j <= i+targetZoneSize; j++ {
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target := peaks[j]
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address := createAddress(anchor, target)
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anchorTimeMs := uint32(anchor.Time * 1000)
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fingerprints[address] = models.Couple{
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AnchorTimeMs: anchorTimeMs,
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SongID: songID,
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}
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}
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}
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return fingerprints
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}
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// createAddress generates a unique address for a pair of anchor and target points.
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// The address is a 32-bit integer where certain bits represent the frequency of
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// the anchor and target points, and other bits represent the time difference (delta time)
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// between them. This function combines these components into a single address (a hash).
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func createAddress(anchor, target Peak) uint32 {
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anchorFreqBin := uint32(anchor.Freq / 10) // Scale down to fit in 9 bits
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targetFreqBin := uint32(target.Freq / 10)
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deltaMsRaw := uint32((target.Time - anchor.Time) * 1000)
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// Mask to fit within bit constraints
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anchorFreqBits := anchorFreqBin & ((1 << maxFreqBits) - 1) // 9 bits
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targetFreqBits := targetFreqBin & ((1 << maxFreqBits) - 1) // 9 bits
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deltaBits := deltaMsRaw & ((1 << maxDeltaBits) - 1) // 14 bits (max ~16 seconds)
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// Combine into 32-bit address
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address := (anchorFreqBits << 23) | (targetFreqBits << 14) | deltaBits
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return address
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}
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func FingerprintAudio(songFilePath string, songID uint32) (map[uint32]models.Couple, error) {
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wavFilePath, err := wav.ConvertToWAV(songFilePath)
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if err != nil {
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return nil, fmt.Errorf("error converting input file to WAV: %v", err)
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}
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wavInfo, err := wav.ReadWavInfo(wavFilePath)
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if err != nil {
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return nil, fmt.Errorf("error reading WAV info: %v", err)
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}
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fingerprint := make(map[uint32]models.Couple)
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spectro, err := Spectrogram(wavInfo.LeftChannelSamples, wavInfo.SampleRate)
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if err != nil {
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return nil, fmt.Errorf("error creating spectrogram: %v", err)
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}
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peaks := ExtractPeaks(spectro, wavInfo.Duration, wavInfo.SampleRate)
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utils.ExtendMap(fingerprint, Fingerprint(peaks, songID))
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if wavInfo.Channels == 2 {
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spectro, err = Spectrogram(wavInfo.RightChannelSamples, wavInfo.SampleRate)
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if err != nil {
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return nil, fmt.Errorf("error creating spectrogram for right channel: %v", err)
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}
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peaks = ExtractPeaks(spectro, wavInfo.Duration, wavInfo.SampleRate)
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utils.ExtendMap(fingerprint, Fingerprint(peaks, songID))
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}
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return fingerprint, nil
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}
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