feat:최고 품질 음성 녹음 시스템 구축 (STT V2 + Chirp 2 + Web Audio)

- 프론트엔드: Web Audio API 전처리 파이프라인 (GainNode + DynamicsCompressor + AnalyserNode) - 프론트엔드: VU 미터 실시간 레벨 표시 + 마이크 감도 슬라이더 (0.5x~3.0x) - 프론트엔드: getUserMedia constraints 강화 + MediaRecorder 128kbps Opus - 백엔드: Google STT V2 API + Chirp 2 모델 batchRecognize 메서드 추가 - 백엔드: V2→V1 자동 폴백 래퍼 (speechToTextWithDiarizationAuto) - 백엔드: Speech Adaptation 도메인 용어 힌트 (블라인드/스크린 등 22개) - 백엔드: V2 SentencePiece 토큰 자동 감지 분기 처리 - 설정: config/services.php에 google.location 추가 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-11 21:01:37 +09:00
parent 55b5ab6d1d
commit 7f1f7165a5
4 changed files with 543 additions and 9 deletions
--- a/app/Services/GoogleCloudService.php
+++ b/app/Services/GoogleCloudService.php
@@ -545,6 +545,364 @@ private function cleanSttText(string $text): string
        return trim(preg_replace('/\s{2,}/', ' ', $cleaned));
    }

+    /**
+     * Speech-to-Text V2 API + Chirp 2 모델
+     *
+     * @return array|null ['segments' => [...], 'full_transcript' => '...', 'speaker_count' => int]
+     */
+    public function speechToTextV2(
+        string $gcsUri,
+        string $languageCode = 'ko-KR',
+        int $minSpeakers = 2,
+        int $maxSpeakers = 6,
+        array $phraseHints = []
+    ): ?array {
+        $token = $this->getAccessToken();
+        if (! $token) {
+            return null;
+        }
+
+        $projectId = $this->serviceAccount['project_id'] ?? null;
+        if (! $projectId) {
+            Log::warning('Google Cloud: STT V2 - project_id 없음, V1 폴백 필요');
+
+            return null;
+        }
+
+        $location = config('services.google.location', 'us-central1');
+
+        try {
+            $requestBody = [
+                'config' => [
+                    'configMask' => 'auto_decoding_config,model,language_codes,features',
+                    'auto_decoding_config' => (object) [],
+                    'model' => 'chirp_2',
+                    'language_codes' => [$languageCode],
+                    'features' => [
+                        'enableAutomaticPunctuation' => true,
+                        'enableWordTimeOffsets' => true,
+                        'diarizationConfig' => [
+                            'minSpeakerCount' => $minSpeakers,
+                            'maxSpeakerCount' => $maxSpeakers,
+                        ],
+                    ],
+                ],
+                'files' => [
+                    ['uri' => $gcsUri],
+                ],
+                'recognitionOutputConfig' => [
+                    'inlineResponseConfig' => (object) [],
+                ],
+            ];
+
+            // Speech Adaptation: phrase hints
+            if (! empty($phraseHints)) {
+                $phrases = array_map(fn ($p) => ['value' => $p, 'boost' => 10.0], $phraseHints);
+                $requestBody['config']['adaptation'] = [
+                    'phraseSets' => [
+                        [
+                            'inlinePhraseSet' => [
+                                'phrases' => $phrases,
+                            ],
+                        ],
+                    ],
+                ];
+                $requestBody['config']['configMask'] .= ',adaptation';
+            }
+
+            $url = "https://speech.googleapis.com/v2/projects/{$projectId}/locations/{$location}/recognizers/_:batchRecognize";
+
+            Log::info('Google Cloud: STT V2 (Chirp 2) 요청 시작', [
+                'gcsUri' => $gcsUri,
+                'model' => 'chirp_2',
+                'language' => $languageCode,
+                'phraseHints' => count($phraseHints),
+            ]);
+
+            $response = Http::withToken($token)
+                ->timeout(30)
+                ->post($url, $requestBody);
+
+            if (! $response->successful()) {
+                Log::error('Google Cloud: STT V2 요청 실패', [
+                    'status' => $response->status(),
+                    'response' => $response->body(),
+                ]);
+
+                return null;
+            }
+
+            $operation = $response->json();
+            $operationName = $operation['name'] ?? null;
+
+            if (! $operationName) {
+                Log::error('Google Cloud: STT V2 작업 이름 없음');
+
+                return null;
+            }
+
+            Log::info('Google Cloud: STT V2 작업 시작됨', ['operationName' => $operationName]);
+
+            $operationResult = $this->waitForV2Operation($operationName);
+
+            if (! $operationResult) {
+                return null;
+            }
+
+            return $this->parseV2Result($operationResult, $gcsUri);
+        } catch (\Exception $e) {
+            Log::error('Google Cloud: STT V2 예외', ['error' => $e->getMessage()]);
+
+            return null;
+        }
+    }
+
+    /**
+     * V2 Operation 폴링
+     */
+    private function waitForV2Operation(string $operationName, int $maxAttempts = 60): ?array
+    {
+        $token = $this->getAccessToken();
+        if (! $token) {
+            return null;
+        }
+
+        for ($i = 0; $i < $maxAttempts; $i++) {
+            sleep(5);
+
+            $response = Http::withToken($token)
+                ->get("https://speech.googleapis.com/v2/{$operationName}");
+
+            if (! $response->successful()) {
+                continue;
+            }
+
+            $result = $response->json();
+
+            if (isset($result['done']) && $result['done']) {
+                if (isset($result['error'])) {
+                    Log::error('Google Cloud: STT V2 작업 실패', ['error' => $result['error']]);
+
+                    return null;
+                }
+
+                Log::info('Google Cloud: STT V2 작업 완료');
+
+                return $result;
+            }
+        }
+
+        Log::error('Google Cloud: STT V2 작업 타임아웃');
+
+        return null;
+    }
+
+    /**
+     * V2 batchRecognize 결과 파싱
+     */
+    private function parseV2Result(array $operationResult, string $gcsUri): ?array
+    {
+        // V2 응답 구조: response.results[uri].transcript.results[].alternatives[].words[]
+        $batchResults = $operationResult['response']['results'] ?? [];
+
+        // URI 키로 결과 찾기
+        $transcriptData = $batchResults[$gcsUri] ?? null;
+
+        // URI가 정확히 매치하지 않으면 첫 번째 결과 사용
+        if (! $transcriptData && ! empty($batchResults)) {
+            $transcriptData = reset($batchResults);
+        }
+
+        if (! $transcriptData) {
+            Log::warning('Google Cloud: STT V2 결과 없음');
+
+            return null;
+        }
+
+        $results = $transcriptData['transcript']['results'] ?? [];
+
+        if (empty($results)) {
+            Log::warning('Google Cloud: STT V2 transcript 결과 없음');
+
+            return null;
+        }
+
+        // 마지막 result에 전체 word-level diarization 정보가 있음
+        $lastResult = end($results);
+        $words = $lastResult['alternatives'][0]['words'] ?? [];
+
+        if (empty($words)) {
+            // word-level 결과 없으면 일반 transcript 사용
+            $transcript = '';
+            foreach ($results as $res) {
+                $transcript .= ($res['alternatives'][0]['transcript'] ?? '') . ' ';
+            }
+            $transcript = trim($transcript);
+
+            return [
+                'segments' => [[
+                    'speaker_name' => '화자 1',
+                    'speaker_label' => '1',
+                    'text' => $transcript,
+                    'start_time_ms' => 0,
+                    'end_time_ms' => null,
+                    'is_manual_speaker' => false,
+                ]],
+                'full_transcript' => '[화자 1] ' . $transcript,
+                'speaker_count' => 1,
+            ];
+        }
+
+        // SentencePiece 토큰 여부 감지 (▁ 문자 포함 시)
+        $hasSentencePiece = false;
+        foreach ($words as $w) {
+            if (preg_match('/[\x{2581}_]/u', $w['word'] ?? '')) {
+                $hasSentencePiece = true;
+                break;
+            }
+        }
+
+        // word-level 화자 정보를 세그먼트로 그룹핑
+        $segments = [];
+        $currentSpeaker = null;
+        $currentTokens = [];
+        $currentWords = [];
+        $segmentStartMs = 0;
+
+        foreach ($words as $word) {
+            $speakerTag = $word['speakerTag'] ?? 0;
+            $wordText = $word['word'] ?? '';
+            $startMs = $this->parseGoogleTimeToMs($word['startOffset'] ?? $word['startTime'] ?? '0s');
+            $endMs = $this->parseGoogleTimeToMs($word['endOffset'] ?? $word['endTime'] ?? '0s');
+
+            if ($hasSentencePiece) {
+                // SentencePiece 방식 처리
+                $isNewWord = preg_match('/^[\x{2581}_]/u', $wordText);
+                $cleanToken = preg_replace('/[\x{2581}_]/u', '', $wordText);
+                if (trim($cleanToken) === '') {
+                    continue;
+                }
+
+                if ($speakerTag !== $currentSpeaker && $currentSpeaker !== null && ! empty($currentTokens)) {
+                    $segments[] = [
+                        'speaker_name' => '화자 ' . $currentSpeaker,
+                        'speaker_label' => (string) $currentSpeaker,
+                        'text' => $this->joinSentencePieceTokens($currentTokens),
+                        'start_time_ms' => $segmentStartMs,
+                        'end_time_ms' => $startMs,
+                        'is_manual_speaker' => false,
+                    ];
+                    $currentTokens = [];
+                    $segmentStartMs = $startMs;
+                }
+
+                $currentSpeaker = $speakerTag;
+                $currentTokens[] = ['text' => $cleanToken, 'new_word' => (bool) $isNewWord];
+            } else {
+                // 일반 단어 방식 처리 (Chirp 2)
+                if ($speakerTag !== $currentSpeaker && $currentSpeaker !== null && ! empty($currentWords)) {
+                    $segments[] = [
+                        'speaker_name' => '화자 ' . $currentSpeaker,
+                        'speaker_label' => (string) $currentSpeaker,
+                        'text' => implode(' ', $currentWords),
+                        'start_time_ms' => $segmentStartMs,
+                        'end_time_ms' => $startMs,
+                        'is_manual_speaker' => false,
+                    ];
+                    $currentWords = [];
+                    $segmentStartMs = $startMs;
+                }
+
+                $currentSpeaker = $speakerTag;
+                $currentWords[] = trim($wordText);
+            }
+        }
+
+        // 마지막 세그먼트
+        if ($hasSentencePiece && ! empty($currentTokens)) {
+            $lastWord = end($words);
+            $segments[] = [
+                'speaker_name' => '화자 ' . $currentSpeaker,
+                'speaker_label' => (string) $currentSpeaker,
+                'text' => $this->joinSentencePieceTokens($currentTokens),
+                'start_time_ms' => $segmentStartMs,
+                'end_time_ms' => $this->parseGoogleTimeToMs($lastWord['endOffset'] ?? $lastWord['endTime'] ?? '0s'),
+                'is_manual_speaker' => false,
+            ];
+        } elseif (! $hasSentencePiece && ! empty($currentWords)) {
+            $lastWord = end($words);
+            $segments[] = [
+                'speaker_name' => '화자 ' . $currentSpeaker,
+                'speaker_label' => (string) $currentSpeaker,
+                'text' => implode(' ', $currentWords),
+                'start_time_ms' => $segmentStartMs,
+                'end_time_ms' => $this->parseGoogleTimeToMs($lastWord['endOffset'] ?? $lastWord['endTime'] ?? '0s'),
+                'is_manual_speaker' => false,
+            ];
+        }
+
+        // full_transcript 생성
+        $fullTranscript = '';
+        foreach ($segments as $seg) {
+            $fullTranscript .= "[{$seg['speaker_name']}] {$seg['text']}\n";
+        }
+
+        $speakerCount = count(array_unique(array_column($segments, 'speaker_label')));
+
+        Log::info('Google Cloud: STT V2 파싱 완료', [
+            'segments' => count($segments),
+            'speakers' => $speakerCount,
+            'sentencePiece' => $hasSentencePiece,
+        ]);
+
+        return [
+            'segments' => $segments,
+            'full_transcript' => trim($fullTranscript),
+            'speaker_count' => $speakerCount,
+        ];
+    }
+
+    /**
+     * V2 + Chirp 2 시도 → 실패 시 V1 + latest_long 자동 폴백
+     *
+     * @return array|null ['segments' => [...], 'full_transcript' => '...', 'speaker_count' => int, 'engine' => 'v2'|'v1']
+     */
+    public function speechToTextWithDiarizationAuto(
+        string $gcsUri,
+        string $languageCode = 'ko-KR',
+        int $minSpeakers = 2,
+        int $maxSpeakers = 6,
+        array $phraseHints = []
+    ): ?array {
+        $projectId = $this->serviceAccount['project_id'] ?? null;
+
+        // V2 + Chirp 2 시도
+        if ($projectId) {
+            Log::info('Google Cloud: STT V2 (Chirp 2) 시도');
+
+            $v2Result = $this->speechToTextV2($gcsUri, $languageCode, $minSpeakers, $maxSpeakers, $phraseHints);
+
+            if ($v2Result && ! empty($v2Result['segments'])) {
+                $v2Result['engine'] = 'v2';
+
+                return $v2Result;
+            }
+
+            Log::warning('Google Cloud: STT V2 실패, V1 폴백');
+        }
+
+        // V1 + latest_long 폴백
+        Log::info('Google Cloud: STT V1 (latest_long) 폴백 실행');
+
+        $v1Result = $this->speechToTextWithDiarization($gcsUri, $languageCode, $minSpeakers, $maxSpeakers);
+
+        if ($v1Result) {
+            $v1Result['engine'] = 'v1';
+        }
+
+        return $v1Result;
+    }
+
    /**
     * GCS 파일 삭제
     */
--- a/app/Services/MeetingMinuteService.php
+++ b/app/Services/MeetingMinuteService.php
@@ -208,6 +208,7 @@ public function logSttUsage(int $durationSeconds): void

    /**
     * 업로드된 오디오에 대해 자동 화자 분리(Speaker Diarization) 실행
+     * V2 + Chirp 2 우선 시도, 실패 시 V1 + latest_long 자동 폴백
     */
    public function processDiarization(MeetingMinute $meeting, int $minSpeakers = 2, int $maxSpeakers = 6): ?array
    {
@@ -218,11 +219,12 @@ public function processDiarization(MeetingMinute $meeting, int $minSpeakers = 2,
        $meeting->update(['status' => MeetingMinute::STATUS_PROCESSING]);

        try {
-            $result = $this->googleCloudService->speechToTextWithDiarization(
+            $result = $this->googleCloudService->speechToTextWithDiarizationAuto(
                $meeting->audio_gcs_uri,
                $meeting->stt_language ?? 'ko-KR',
                $minSpeakers,
-                $maxSpeakers
+                $maxSpeakers,
+                $this->getDefaultPhraseHints()
            );

            if (! $result || empty($result['segments'])) {
@@ -232,6 +234,13 @@ public function processDiarization(MeetingMinute $meeting, int $minSpeakers = 2,
                return null;
            }

+            $engine = $result['engine'] ?? 'v1';
+            Log::info('MeetingMinute: 화자 분리 완료', [
+                'meeting_id' => $meeting->id,
+                'engine' => $engine,
+                'segments' => count($result['segments']),
+            ]);
+
            // 기존 세그먼트 교체
            $meeting->segments()->delete();
            $fullTranscript = '';
@@ -258,9 +267,10 @@ public function processDiarization(MeetingMinute $meeting, int $minSpeakers = 2,
                'status' => MeetingMinute::STATUS_DRAFT,
            ]);

-            // STT 사용량 기록
+            // STT 사용량 기록 (엔진 구분)
            if ($meeting->duration_seconds > 0) {
-                AiTokenHelper::saveSttUsage('회의록-화자분리', $meeting->duration_seconds);
+                $usageLabel = $engine === 'v2' ? '회의록-화자분리(Chirp2)' : '회의록-화자분리';
+                AiTokenHelper::saveSttUsage($usageLabel, $meeting->duration_seconds);
            }

            return [
@@ -279,6 +289,20 @@ public function processDiarization(MeetingMinute $meeting, int $minSpeakers = 2,
        }
    }

+    /**
+     * Speech Adaptation 도메인 용어 힌트
+     */
+    private function getDefaultPhraseHints(): array
+    {
+        return [
+            '블라인드', '스크린', '롤스크린', '허니콤', '버티컬',
+            '원단', '바텀레일', '헤드레일', '브라켓',
+            '주일', '경동', '주일블라인드', '경동블라인드',
+            '수주', '발주', '납기', '출하', '재고', '원가', '단가',
+            'SAM', 'ERP', 'MES',
+        ];
+    }
+
    private function buildSummaryPrompt(string $transcript): string
    {
        return <<<PROMPT
--- a/config/services.php
+++ b/config/services.php
@@ -47,6 +47,7 @@
    'google' => [
        'credentials_path' => env('GOOGLE_APPLICATION_CREDENTIALS'),
        'storage_bucket' => env('GOOGLE_STORAGE_BUCKET'),
+        'location' => env('GOOGLE_STT_LOCATION', 'us-central1'),
    ],

    /*
--- a/resources/views/juil/meeting-minutes.blade.php
+++ b/resources/views/juil/meeting-minutes.blade.php
@@ -269,6 +269,9 @@ function MeetingDetail({ meetingId, onBack, showToast }) {
    const [diarizing, setDiarizing] = useState(false);
    const [alertModal, setAlertModal] = useState(null);

+    // 마이크 감도
+    const [micGain, setMicGain] = useState(1.5);
+
    // 세그먼트 편집 상태
    const [editingSegments, setEditingSegments] = useState(false);
    const [editBackup, setEditBackup] = useState([]);
@@ -281,6 +284,9 @@ function MeetingDetail({ meetingId, onBack, showToast }) {
    const timerRef = useRef(null);
    const transcriptRef = useRef(null);
    const startTimeRef = useRef(null);
+    const audioContextRef = useRef(null);
+    const analyserRef = useRef(null);
+    const gainNodeRef = useRef(null);

    const loadMeeting = useCallback(async () => {
        try {
@@ -340,11 +346,56 @@ function MeetingDetail({ meetingId, onBack, showToast }) {
    // ===== 녹음 시작 =====
    const startRecording = async () => {
        try {
-            const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
+            const stream = await navigator.mediaDevices.getUserMedia({
+                audio: {
+                    echoCancellation: true,
+                    noiseSuppression: true,
+                    autoGainControl: true,
+                    channelCount: 1,
+                    sampleRate: 48000,
+                }
+            });
            streamRef.current = stream;

-            // MediaRecorder
-            const recorder = new MediaRecorder(stream);
+            // Web Audio API 전처리 체인
+            const audioCtx = new (window.AudioContext || window.webkitAudioContext)({ sampleRate: 48000 });
+            audioContextRef.current = audioCtx;
+
+            const source = audioCtx.createMediaStreamSource(stream);
+
+            // GainNode: 감도 조절 (기본 1.5x)
+            const gainNode = audioCtx.createGain();
+            gainNode.gain.value = micGain;
+            gainNodeRef.current = gainNode;
+
+            // DynamicsCompressor: 작은 소리 증폭 + 큰 소리 억제
+            const compressor = audioCtx.createDynamicsCompressor();
+            compressor.threshold.value = -50;
+            compressor.knee.value = 40;
+            compressor.ratio.value = 12;
+            compressor.attack.value = 0;
+            compressor.release.value = 0.25;
+
+            // AnalyserNode: VU 미터용
+            const analyser = audioCtx.createAnalyser();
+            analyser.fftSize = 2048;
+            analyserRef.current = analyser;
+
+            // MediaStreamDestination: 처리된 스트림
+            const destination = audioCtx.createMediaStreamDestination();
+
+            // 체인 연결: source → gain → compressor → analyser → destination
+            source.connect(gainNode);
+            gainNode.connect(compressor);
+            compressor.connect(analyser);
+            analyser.connect(destination);
+
+            const processedStream = destination.stream;
+
+            // MediaRecorder (처리된 스트림 사용)
+            const mimeType = MediaRecorder.isTypeSupported('audio/webm;codecs=opus')
+                ? 'audio/webm;codecs=opus' : 'audio/webm';
+            const recorder = new MediaRecorder(processedStream, { mimeType, audioBitsPerSecond: 128000 });
            audioChunksRef.current = [];
            recorder.ondataavailable = (e) => { if (e.data.size > 0) audioChunksRef.current.push(e.data); };
            recorder.start();
@@ -423,6 +474,14 @@ function MeetingDetail({ meetingId, onBack, showToast }) {
            streamRef.current = null;
        }

+        // AudioContext 정리
+        if (audioContextRef.current) {
+            audioContextRef.current.close().catch(() => {});
+            audioContextRef.current = null;
+            analyserRef.current = null;
+            gainNodeRef.current = null;
+        }
+
        // MediaRecorder 중지 → blob 생성
        const recorder = mediaRecorderRef.current;
        if (recorder && recorder.state !== 'inactive') {
@@ -831,6 +890,10 @@ function MeetingDetail({ meetingId, onBack, showToast }) {
                diarizing={diarizing}
                hasSegments={segments.length > 0}
                hasAudio={!!meeting?.audio_gcs_uri}
+                analyserRef={analyserRef}
+                micGain={micGain}
+                onMicGainChange={setMicGain}
+                gainNodeRef={gainNodeRef}
            />
        </div>
    );
@@ -1056,8 +1119,73 @@ function SummaryPanel({ meeting, onSummarize, summarizing }) {
    );
 }

+// ========== AudioLevelMeter ==========
+function AudioLevelMeter({ analyserRef, isRecording }) {
+    const canvasRef = useRef(null);
+    const animFrameRef = useRef(null);
+
+    useEffect(() => {
+        if (!isRecording || !analyserRef?.current) {
+            if (animFrameRef.current) cancelAnimationFrame(animFrameRef.current);
+            // 녹음 중지 시 캔버스 클리어
+            const canvas = canvasRef.current;
+            if (canvas) {
+                const ctx = canvas.getContext('2d');
+                ctx.clearRect(0, 0, canvas.width, canvas.height);
+            }
+            return;
+        }
+
+        const analyser = analyserRef.current;
+        const dataArray = new Uint8Array(analyser.fftSize);
+
+        const draw = () => {
+            analyser.getByteTimeDomainData(dataArray);
+
+            // RMS 계산
+            let sum = 0;
+            for (let i = 0; i < dataArray.length; i++) {
+                const v = (dataArray[i] - 128) / 128;
+                sum += v * v;
+            }
+            const rms = Math.sqrt(sum / dataArray.length);
+            const level = Math.min(1, rms * 3); // 0~1 정규화
+
+            const canvas = canvasRef.current;
+            if (!canvas) return;
+            const ctx = canvas.getContext('2d');
+            const w = canvas.width;
+            const h = canvas.height;
+            ctx.clearRect(0, 0, w, h);
+
+            // 바 그리기
+            const barWidth = Math.round(w * level);
+            const gradient = ctx.createLinearGradient(0, 0, w, 0);
+            gradient.addColorStop(0, '#22c55e');
+            gradient.addColorStop(0.6, '#eab308');
+            gradient.addColorStop(1, '#ef4444');
+            ctx.fillStyle = gradient;
+            ctx.fillRect(0, 0, barWidth, h);
+
+            // 배경 바
+            ctx.fillStyle = 'rgba(0,0,0,0.06)';
+            ctx.fillRect(barWidth, 0, w - barWidth, h);
+
+            animFrameRef.current = requestAnimationFrame(draw);
+        };
+
+        draw();
+
+        return () => {
+            if (animFrameRef.current) cancelAnimationFrame(animFrameRef.current);
+        };
+    }, [isRecording, analyserRef?.current]);
+
+    return <canvas ref={canvasRef} width={120} height={12} className="rounded-full" style={{ display: 'block' }} />;
+}
+
 // ========== RecordingControlBar ==========
-function RecordingControlBar({ isRecording, recordingTime, currentSpeakerIdx, speakers, sttLanguage, onStart, onStop, onSwitchSpeaker, onAddSpeaker, onLanguageChange, onSummarize, onDiarize, saving, summarizing, diarizing, hasSegments, hasAudio }) {
+function RecordingControlBar({ isRecording, recordingTime, currentSpeakerIdx, speakers, sttLanguage, onStart, onStop, onSwitchSpeaker, onAddSpeaker, onLanguageChange, onSummarize, onDiarize, saving, summarizing, diarizing, hasSegments, hasAudio, analyserRef, micGain, onMicGainChange, gainNodeRef }) {
    return (
        <div className="bg-white border-t shadow-lg px-4 py-3 flex-shrink-0">
            <div className="flex items-center justify-between gap-3">
@@ -1083,7 +1211,29 @@ function RecordingControlBar({ isRecording, recordingTime, currentSpeakerIdx, sp
                    )}
                </div>

-                {/* Record Button */}
+                {/* Mic Gain Slider */}
+                {isRecording && (
+                    <div className="flex items-center gap-1.5">
+                        <svg className="w-4 h-4 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 11a7 7 0 01-7 7m0 0a7 7 0 01-7-7m7 7v4m0 0H8m4 0h4m-4-8a3 3 0 01-3-3V5a3 3 0 116 0v6a3 3 0 01-3 3z" /></svg>
+                        <input
+                            type="range"
+                            min="0.5"
+                            max="3.0"
+                            step="0.1"
+                            value={micGain}
+                            onChange={(e) => {
+                                const val = parseFloat(e.target.value);
+                                onMicGainChange(val);
+                                if (gainNodeRef?.current) gainNodeRef.current.gain.value = val;
+                            }}
+                            className="w-16 h-1 accent-blue-500"
+                            title={`감도 ${micGain.toFixed(1)}x`}
+                        />
+                        <span className="text-xs text-gray-400 min-w-[28px]">{micGain.toFixed(1)}x</span>
+                    </div>
+                )}
+
+                {/* Record Button + VU Meter */}
                <div className="flex items-center gap-3">
                    {isRecording ? (
                        <button onClick={onStop} disabled={saving} className="bg-red-600 text-white px-5 py-2 rounded-full hover:bg-red-700 transition flex items-center gap-2 text-sm font-medium shadow-lg disabled:opacity-50">
@@ -1096,6 +1246,7 @@ function RecordingControlBar({ isRecording, recordingTime, currentSpeakerIdx, sp
                            녹음
                        </button>
                    )}
+                    {isRecording && <AudioLevelMeter analyserRef={analyserRef} isRecording={isRecording} />}
                    <span className="text-sm font-mono text-gray-600 min-w-[60px]">{formatDuration(recordingTime)}</span>
                    {isRecording && <span className="flex items-center gap-1 text-xs text-red-500"><span className="w-2 h-2 bg-red-500 rounded-full animate-pulse"></span>REC</span>}
                </div>