Method Transcode

api/service/recording_transcoder.go:120–178

(ctx context.Context, segments [][]byte, targetFormat string)

)

func (t *ffmpegRecordingTranscoder) Transcode(ctx context.Context, segments [][]byte, targetFormat string) ([]byte, error) {
	if len(segments) == 0 {
		return nil, errors.New("录音分段为空")
	}
	if len(segments) != 1 {
		return nil, fmt.Errorf("录音转码仅支持单个分段: %d", len(segments))
	}

	var totalSize int64
	for _, seg := range segments {
		totalSize += int64(len(seg))
	}
	if totalSize > maxTotalSegmentsSize {
		return nil, fmt.Errorf("录音总大小超限: %d > %d bytes", totalSize, maxTotalSegmentsSize)
	}

	normalizedFormat := normalizeRecordingTargetFormat(targetFormat)
	encoder, err := encoderForRecordingTargetFormat(normalizedFormat)
	if err != nil {
		return nil, err
	}
	ffmpegPath, err := ResolveFFmpegToolchainPath()
	if err != nil {
		return nil, err
	}

	workDir, err := os.MkdirTemp("", "recording-transcode-*")
	if err != nil {
		return nil, fmt.Errorf("创建临时目录失败: %w", err)
	}
	defer os.RemoveAll(workDir)

	inputPath := filepath.Join(workDir, "input.webm")
	if err := writeSegmentsToFile(inputPath, segments); err != nil {
		return nil, err
	}
	outputPath := filepath.Join(workDir, "output."+normalizedFormat)
	if err := ensureRecordingWritableFile(outputPath, recordingLocalArtifactMode); err != nil {
		return nil, err
	}
	args := []string{
		"-y",
		"-i", inputPath,
		"-vn",
		"-c:a", encoder,
		outputPath,
	}
	if err := t.runner.Run(ctx, ffmpegPath, args...); err != nil {
		return nil, fmt.Errorf("转码录音失败: %w", err)
	}
	if err := ensureRecordingFileMode(outputPath, recordingLocalArtifactMode); err != nil {
		return nil, err
	}
	result, err := os.ReadFile(outputPath)
	if err != nil {
		return nil, fmt.Errorf("读取最终输出失败: %w", err)
	}
	return result, nil