go-whisper-api/whisper/whisper.go

package whisper

import (
    "fmt"
    "os"
    "path"
    "path/filepath"
    "strings"
    "time"

    "go-whisper-api/config"

    "github.com/ggerganov/whisper.cpp/bindings/go/pkg/whisper"
    "github.com/rs/zerolog/log"
)

type OutputFormat string

func (f OutputFormat) String() string {
    return string(f)
}

var (
    FormatTxt OutputFormat = "txt"
    FormatSrt OutputFormat = "srt"
    FormatCSV OutputFormat = "csv"
)

type Engine struct {
    cfg      *config.Whisper
    ctx      whisper.Context
    model    whisper.Model
    segments []whisper.Segment
    progress int
    runOpts  RunOptions
}

func (e *Engine) Transcript() error {
    return defaultPool.WithModel(e.cfg.Model, func(m whisper.Model) error {
        return e.transcribeWithModel(m)
    })
}

func (e *Engine) transcribeWithModel(model whisper.Model) error {
    data, cleanup, err := prepareAudioPCM(e.cfg.AudioPath)
    if err != nil {
        return err
    }
    defer cleanup()
    e.model = model
    e.ctx, err = e.model.NewContext()
    if err != nil {
        return err
    }
    e.ctx.SetThreads(e.cfg.Threads)
    if e.cfg.SpeedUp {
        e.ctx.SetAudioCtx(750)
    }
    e.ctx.SetTranslate(e.cfg.Translate)
    if e.cfg.Prompt != "" {
        e.ctx.SetInitialPrompt(e.cfg.Prompt)
    }
    e.ctx.SetMaxContext(int(e.cfg.MaxContext))
    if e.cfg.Debug {
        log.Info().Msgf("%s", e.ctx.SystemInfo())
    }
    if e.cfg.Language != "" {
        _ = e.ctx.SetLanguage(e.cfg.Language)
    }
    if e.cfg.BeamSize > 0 {
        e.ctx.SetBeamSize(int(e.cfg.BeamSize))
    }
    if e.cfg.EntropyThold > 0 {
        e.ctx.SetEntropyThold(float32(e.cfg.EntropyThold))
    }
    if err := prepareVAD(&e.cfg.VAD, ""); err != nil {
        return err
    }
    ApplyVAD(e.ctx, e.cfg.VAD)
    log.Debug().Msg("start transcribe process")
    e.ctx.ResetTimings()
    if err := e.ctx.Process(data, e.cbEncoderBegin(), e.cbSegment(), e.cbProgress()); err != nil {
        return err
    }
    if e.cfg.Debug {
        e.ctx.PrintTimings()
    }
    return nil
}

func (e *Engine) cbEncoderBegin() func() bool {
    return func() bool { return true }
}

func (e *Engine) cbSegment() func(segment whisper.Segment) {
    return func(segment whisper.Segment) {
        e.segments = append(e.segments, segment)
        if !e.cfg.PrintSegment {
            return
        }
        log.Info().Msgf(
            "[%6s -> %6s] %s",
            segment.Start.Truncate(time.Millisecond),
            segment.End.Truncate(time.Millisecond),
            segment.Text,
        )
    }
}

func (e *Engine) cbProgress() func(progress int) {
    return func(progress int) {
        if progress > 100 {
            progress = 100
        }
        if e.progress == progress {
            return
        }
        e.progress = progress
        if e.cfg.PrintProgress {
            log.Info().Msgf("current progress: %d%%", progress)
        }
    }
}

func (e *Engine) getOutputPath(format string) string {
    ext := filepath.Ext(e.cfg.AudioPath)
    filename := filepath.Base(e.cfg.AudioPath)
    if e.cfg.OutputFilename != "" {
        filename = e.cfg.OutputFilename
    }
    folder := filepath.Dir(e.cfg.AudioPath)
    if e.cfg.OutputFolder != "" {
        folder = e.cfg.OutputFolder
    }
    return path.Join(folder, strings.TrimSuffix(filename, ext)+"."+format)
}

func (e *Engine) Save(format string) error {
    outputPath := e.getOutputPath(format)
    log.Info().Str("output-path", outputPath).Str("output-format", format).Msg("save text to file")
    text := ""
    switch OutputFormat(format) {
    case FormatSrt:
        for i, segment := range e.segments {
            text += fmt.Sprintf("%d\n", i+1)
            text += fmt.Sprintf("%s --> %s\n", srtTimestamp(segment.Start), srtTimestamp(segment.End))
            text += segment.Text + "\n\n"

        }
    case FormatTxt:
        for _, segment := range e.segments {
            text += segment.Text
        }
    case FormatCSV:
        text = "start,end,text\n"
        for _, segment := range e.segments {
            text += fmt.Sprintf("%s,%s,\"%s\"\n", segment.Start, segment.End, segment.Text)
        }
    }
    if err := os.WriteFile(outputPath, []byte(text), 0o644); err != nil {
        return err
    }
    return nil
}

type Word struct {
    Word  string `json:"word"`
    Start int    `json:"start"`
    Stop  int    `json:"stop"`
}

type TranscriptResult struct {
    Text  string `json:"text"`
    Words []Word `json:"words,omitempty"`
}

func (e *Engine) SetTranscriptText(text string) {
    if len(e.segments) == 0 {
        e.segments = []whisper.Segment{{Text: text}}
        return
    }
    start := e.segments[0].Start
    end := e.segments[len(e.segments)-1].End
    e.segments = []whisper.Segment{{Text: text, Start: start, End: end}}
}

func (e *Engine) Result() TranscriptResult {
    segments := e.segments
    text := FormatSegments(segments, e.runOpts.Turns, e.runOpts.Format)
    if e.runOpts.PunctuateRestore != nil && text != "" {
        if updated, err := e.runOpts.PunctuateRestore(text); err == nil && strings.TrimSpace(updated) != "" {
            text = updated
        }
    }
    var words []Word
    for _, segment := range segments {
        words = append(words, segmentWords(segment)...)
    }
    return TranscriptResult{
        Text:  text,
        Words: words,
    }
}

func segmentWords(segment whisper.Segment) []Word {
    parts := strings.Fields(strings.TrimSpace(segment.Text))
    if len(parts) == 0 {
        return nil
    }
    startMs := int(segment.Start / time.Millisecond)
    endMs := int(segment.End / time.Millisecond)
    if endMs < startMs {
        endMs = startMs
    }
    span := endMs - startMs
    if span <= 0 {
        span = 1
    }
    step := span / len(parts)
    if step < 1 {
        step = 1
    }
    out := make([]Word, 0, len(parts))
    for i, part := range parts {
        wStart := startMs + i*step
        wStop := wStart + step
        if i == len(parts)-1 {
            wStop = endMs
        }
        out = append(out, Word{
            Word:  part,
            Start: wStart,
            Stop:  wStop,
        })
    }
    return out
}

func (e *Engine) Close() error {
    // Models are owned by ModelPool; do not close shared weights here.
    e.ctx = nil
    e.model = nil
    return nil
}