113 lines
3.2 KiB
Go
113 lines
3.2 KiB
Go
package transcode
|
|
|
|
import (
|
|
"bufio"
|
|
"fmt"
|
|
"os/exec"
|
|
"regexp"
|
|
"strconv"
|
|
)
|
|
|
|
// ──────────────────────────────────────────────────────────────────────────────
|
|
// Silence detection
|
|
// ──────────────────────────────────────────────────────────────────────────────
|
|
|
|
// DetectSpeechSegments runs ffmpeg's silencedetect filter and returns the
|
|
// non-silent (speech) segments. A "segments" WebSocket message is broadcast
|
|
// when detection finishes.
|
|
func DetectSpeechSegments(inputPath string, noiseDb, minDuration, padding float64, broadcast func([]byte)) ([]Segment, error) {
|
|
filter := fmt.Sprintf("silencedetect=noise=%.0fdB:d=%.2f", noiseDb, minDuration)
|
|
|
|
cmd := exec.Command("ffmpeg",
|
|
"-i", inputPath,
|
|
"-af", filter,
|
|
"-f", "null", "-",
|
|
)
|
|
|
|
// ffmpeg writes silencedetect output to stderr
|
|
stderr, err := cmd.StderrPipe()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := cmd.Start(); err != nil {
|
|
return nil, fmt.Errorf("ffmpeg start: %w", err)
|
|
}
|
|
|
|
var (
|
|
silences []silenceInterval
|
|
pendingStart float64
|
|
totalDuration float64
|
|
|
|
durationRe = regexp.MustCompile(`Duration:\s+(\d+):(\d+):([0-9.]+)`)
|
|
startRe = regexp.MustCompile(`silence_start:\s*([0-9.e+\-]+)`)
|
|
endRe = regexp.MustCompile(`silence_end:\s*([0-9.e+\-]+)`)
|
|
)
|
|
|
|
scanner := bufio.NewScanner(stderr)
|
|
for scanner.Scan() {
|
|
line := scanner.Text()
|
|
|
|
if m := durationRe.FindStringSubmatch(line); m != nil {
|
|
h, _ := strconv.ParseFloat(m[1], 64)
|
|
min, _ := strconv.ParseFloat(m[2], 64)
|
|
s, _ := strconv.ParseFloat(m[3], 64)
|
|
totalDuration = h*3600 + min*60 + s
|
|
}
|
|
if m := startRe.FindStringSubmatch(line); m != nil {
|
|
pendingStart, _ = strconv.ParseFloat(m[1], 64)
|
|
}
|
|
if m := endRe.FindStringSubmatch(line); m != nil {
|
|
end, _ := strconv.ParseFloat(m[1], 64)
|
|
silences = append(silences, silenceInterval{start: pendingStart, end: end})
|
|
}
|
|
}
|
|
|
|
if err := cmd.Wait(); err != nil {
|
|
return nil, fmt.Errorf("ffmpeg: %w", err)
|
|
}
|
|
|
|
segments := removeSilence(silences, totalDuration, padding)
|
|
|
|
send(&wsMsg{
|
|
Type: "segments",
|
|
Segments: segments,
|
|
Duration: totalDuration,
|
|
}, broadcast)
|
|
|
|
return segments, nil
|
|
}
|
|
|
|
type silenceInterval struct{ start, end float64 }
|
|
|
|
// removeSilence turns silence regions into speech regions, with a small
|
|
// padding buffer so words at the edges don't get clipped.
|
|
func removeSilence(silences []silenceInterval, totalDuration, padding float64) []Segment {
|
|
if len(silences) == 0 {
|
|
return []Segment{{Start: 0, End: totalDuration}}
|
|
}
|
|
|
|
var segments []Segment
|
|
cursor := 0.0
|
|
|
|
for _, s := range silences {
|
|
segEnd := s.start + padding
|
|
if segEnd > totalDuration {
|
|
segEnd = totalDuration
|
|
}
|
|
if segEnd-cursor > 0.05 {
|
|
segments = append(segments, Segment{Start: cursor, End: segEnd})
|
|
}
|
|
next := s.end - padding
|
|
if next < segEnd {
|
|
next = segEnd
|
|
}
|
|
cursor = next
|
|
}
|
|
|
|
if cursor < totalDuration-0.01 {
|
|
segments = append(segments, Segment{Start: cursor, End: totalDuration})
|
|
}
|
|
|
|
return segments
|
|
}
|