feat: 添加音频输入设备选择器与音频电平诊断

- audio_capture 启动时输出详细设备信息（名称、Host API、采样率）
- 录音停止时输出 RMS 电平和峰值，帮助诊断音频质量问题
- 设置页面新增音频输入设备下拉选择，支持从 PortAudio 设备列表中手动选择
- 语音输入服务使用配置的音频设备和采样率参数
- 检测 monitor/output 类型设备时发出警告，避免选错回环设备

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/audio/audio_capture.cpp

@@ -3,6 +3,7 @@
 
 #ifdef HAVE_PORTAUDIO
 #include <portaudio.h>
+#include <cmath>
 #endif
 
 static const char* const kTag = "AudioCapture";
@@ -41,6 +42,10 @@ struct CallbackContext {
     float buffer[kMaxBufferSize];
 #endif
     int sampleRate = 16000;
+    // 音频电平诊断
+    float peakLevel = 0.0f;
+    double sumSquares = 0.0;
+    int sampleCount = 0;
 };
 
 struct AudioCapture::Impl {
@@ -62,11 +67,22 @@ static int paCallback(const void* input, void* /*output*/,
     unsigned long count = frameCount;
     if (count > kMaxBufferSize) count = kMaxBufferSize;
 
-    // 拷贝到预分配缓冲区
+    // 拷贝到预分配缓冲区 + 计算音频电平
+    float peak = 0.0f;
+    double ss = 0.0;
     for (unsigned long i = 0; i < count; i++) {
-        ctx->buffer[i] = samples[i];
+        float s = samples[i];
+        ctx->buffer[i] = s;
+        float absS = std::fabs(s);
+        if (absS > peak) peak = absS;
+        ss += s * s;
     }
 
+    // 更新诊断数据
+    if (peak > ctx->peakLevel) ctx->peakLevel = peak;
+    ctx->sumSquares += ss;
+    ctx->sampleCount += count;
+
     // 发射信号（Qt 使用 QueuedConnection，线程安全）
     std::vector<float> data(ctx->buffer, ctx->buffer + count);
     emit ctx->owner->audioDataReady(data, ctx->sampleRate);
@@ -101,14 +117,26 @@ QStringList AudioCapture::getDeviceList() {
     for (int i = 0; i < count; ++i) {
         const PaDeviceInfo* info = Pa_GetDeviceInfo(i);
         if (info && info->maxInputChannels > 0) {
-            devices << QString("%1 (CH:%2, SR:%3)").arg(
-                info->name).arg(info->maxInputChannels).arg(info->defaultSampleRate);
+            const PaHostApiInfo* hostApi = Pa_GetHostApiInfo(info->hostApi);
+            QString hostApiName = hostApi ? hostApi->name : "未知";
+            devices << QString("[%1] %2 (CH:%3, SR:%4, %5)")
+                .arg(i).arg(info->name).arg(info->maxInputChannels)
+                .arg(info->defaultSampleRate).arg(hostApiName);
         }
     }
 #endif
     return devices;
 }
 
+int AudioCapture::getDefaultDeviceIndex() {
+#ifdef HAVE_PORTAUDIO
+    if (!ensurePaInitialized()) return -1;
+    return Pa_GetDefaultInputDevice();
+#else
+    return -1;
+#endif
+}
+
 bool AudioCapture::start(int deviceIndex, int sampleRate, int bufferSizeMs) {
     if (running_) {
         LOG_WARNING(kTag, "已在运行中");
@@ -121,9 +149,21 @@ bool AudioCapture::start(int deviceIndex, int sampleRate, int bufferSizeMs) {
         return false;
     }
 
+    // 枚举所有 Host API 用于诊断
+    LOG_DEBUG(kTag, QString("Host API 数量: %1").arg(Pa_GetHostApiCount()));
+    for (int i = 0; i < Pa_GetHostApiCount(); i++) {
+        const PaHostApiInfo* api = Pa_GetHostApiInfo(i);
+        if (api) {
+            LOG_DEBUG(kTag, QString("  Host API #%1: %2 (设备数: %3)")
+                .arg(i).arg(api->name).arg(api->deviceCount));
+        }
+    }
+
+    // 选择设备
     int devIdx = deviceIndex < 0 ? Pa_GetDefaultInputDevice() : deviceIndex;
     if (devIdx < 0 || devIdx >= Pa_GetDeviceCount()) {
-        LOG_ERROR(kTag, QString("无效的音频设备索引: %1 (默认设备: %2)").arg(deviceIndex).arg(Pa_GetDefaultInputDevice()));
+        LOG_ERROR(kTag, QString("无效的音频设备索引: %1 (默认设备: %2)")
+            .arg(deviceIndex).arg(Pa_GetDefaultInputDevice()));
         return false;
     }
 
@@ -133,6 +173,25 @@ bool AudioCapture::start(int deviceIndex, int sampleRate, int bufferSizeMs) {
         return false;
     }
 
+    const PaHostApiInfo* hostApi = Pa_GetHostApiInfo(devInfo->hostApi);
+    LOG_INFO(kTag, QString("=== 音频设备诊断 ==="));
+    LOG_INFO(kTag, QString("  设备 #%1: %2").arg(devIdx).arg(devInfo->name));
+    LOG_INFO(kTag, QString("  Host API: %1").arg(hostApi ? hostApi->name : "未知"));
+    LOG_INFO(kTag, QString("  最大输入通道: %1").arg(devInfo->maxInputChannels));
+    LOG_INFO(kTag, QString("  设备默认采样率: %1 Hz").arg(devInfo->defaultSampleRate, 0, 'f', 0));
+    LOG_INFO(kTag, QString("  请求采样率: %1 Hz").arg(sampleRate));
+    LOG_INFO(kTag, QString("  采样格式: paFloat32 | paNonInterleaved"));
+    LOG_INFO(kTag, QString("  请求通道数: 1 (mono)"));
+    LOG_INFO(kTag, QString("  缓冲区: %1ms (%2 帧)").arg(bufferSizeMs)
+        .arg(sampleRate * bufferSizeMs / 1000));
+
+    // 检查是否可能选错设备（名称包含 monitor 的通常是回环设备）
+    QString devName = QString(devInfo->name).toLower();
+    if (devName.contains("monitor") || devName.contains("output")) {
+        LOG_WARNING(kTag, "⚠️ 当前设备名称包含 'monitor' 或 'output'，"
+            "这可能是扬声器回环设备而非麦克风！如果录制的是噪音，请在设置中选择正确的麦克风设备。");
+    }
+
     PaStreamParameters inputParams{};
     inputParams.device = devIdx;
     inputParams.channelCount = 1;
@@ -161,6 +220,11 @@ bool AudioCapture::start(int deviceIndex, int sampleRate, int bufferSizeMs) {
         return false;
     }
 
+    // 重置诊断计数器
+    impl_->ctx.peakLevel = 0.0f;
+    impl_->ctx.sumSquares = 0.0;
+    impl_->ctx.sampleCount = 0;
+
     impl_->ctx.sampleRate = sampleRate;
     running_ = true;
     emit runningChanged(true);
@@ -178,6 +242,24 @@ void AudioCapture::stop() {
     if (!running_) return;
 
 #ifdef HAVE_PORTAUDIO
+    // 输出音频电平诊断信息
+    if (impl_->ctx.sampleCount > 0) {
+        double rms = std::sqrt(impl_->ctx.sumSquares / impl_->ctx.sampleCount);
+        LOG_INFO(kTag, QString("=== 音频电平诊断 ==="));
+        LOG_INFO(kTag, QString("  总样本数: %1").arg(impl_->ctx.sampleCount));
+        LOG_INFO(kTag, QString("  RMS 电平: %1").arg(rms, 0, 'f', 6));
+        LOG_INFO(kTag, QString("  峰值: %1").arg(impl_->ctx.peakLevel, 0, 'f', 4));
+        if (rms < 0.001) {
+            LOG_WARNING(kTag, "⚠️ 音频信号过弱，可能是静音或设备未正确采集");
+        } else if (rms > 0.5) {
+            LOG_WARNING(kTag, "⚠️ 音频信号过强，可能存在削波");
+        } else if (impl_->ctx.peakLevel > 0.9f) {
+            LOG_INFO(kTag, "  信号幅度正常");
+        } else {
+            LOG_WARNING(kTag, "⚠️ 信号幅度偏低，请检查设备选择");
+        }
+    }
+
     if (impl_->ctx.stream) {
         Pa_StopStream(impl_->ctx.stream);
         Pa_CloseStream(impl_->ctx.stream);

src/audio/audio_capture.h

@@ -23,6 +23,9 @@ public:
     /** @brief 获取可用输入设备列表 */
     static QStringList getDeviceList();
 
+    /** @brief 获取默认输入设备索引 (-1 表示无默认设备) */
+    static int getDefaultDeviceIndex();
+
     /** @brief 开始采集 */
     bool start(int deviceIndex = -1,
                int sampleRate = 16000,

src/core/voice_input_service.cpp

@@ -126,8 +126,10 @@ void VoiceInputService::onHotkeyActivated() {
     longPressTimer_->start(longPressThreshold_);
 
     // 开始音频采集（后台预采集）
-    int deviceIndex = -1; // 默认设备
-    impl_->audioCapture->start(deviceIndex, 16000, 20);
+    int deviceIndex = configManager_->get("audio.input_device").toInt();
+    int sampleRate = configManager_->get("stt.sample_rate").toInt();
+    int bufferSizeMs = configManager_->get("audio.buffer_size_ms").toInt();
+    impl_->audioCapture->start(deviceIndex, sampleRate, bufferSizeMs);
 
     emit statusChanged("等待长按确认...");
 }

src/ui/settings_page.cpp

@@ -1,5 +1,6 @@
 #include "settings_page.h"
 #include "app/config_manager.h"
+#include "audio/audio_capture.h"
 #include "widgets/hotkey_recorder.h"
 #include "utils/logger.h"
 
@@ -114,6 +115,11 @@ void SettingsPage::setupUI() {
     auto* audioGroup = new QGroupBox("音频设置", this);
     auto* audioLayout = new QFormLayout(audioGroup);
 
+    // 音频输入设备选择器
+    audioDeviceCombo_ = new QComboBox(this);
+    populateAudioDevices();
+    audioLayout->addRow("输入设备:", audioDeviceCombo_);
+
     bufferSizeSpin_ = new QSpinBox(this);
     bufferSizeSpin_->setRange(10, 100);
     bufferSizeSpin_->setValue(20);
@@ -197,6 +203,10 @@ void SettingsPage::loadFromConfig() {
     chunkDurationSpin_->setValue(configManager_->get("audio.chunk_duration_ms").toInt());
     paddingSpin_->setValue(configManager_->get("audio.padding_ms").toInt());
 
+    // 恢复音频设备选择
+    int savedDevice = configManager_->get("audio.input_device").toInt();
+    selectAudioDevice(savedDevice);
+
     themeCombo_->setCurrentText(configManager_->get("ui.theme").toString());
     fontSizeSpin_->setValue(configManager_->get("ui.font_size").toInt());
     showWaveformCheck_->setChecked(configManager_->get("ui.show_waveform").toBool());
@@ -218,6 +228,7 @@ void SettingsPage::saveToConfig() {
     batch["stt.beam_size"] = beamSizeSpin_->value();
     batch["stt.temperature"] = temperatureSpin_->value();
     batch["shortcuts.voice_hotkey"] = hotkeyRecorder_->hotkeyText();
+    batch["audio.input_device"] = getSelectedAudioDeviceIndex();
     batch["audio.buffer_size_ms"] = bufferSizeSpin_->value();
     batch["audio.chunk_duration_ms"] = chunkDurationSpin_->value();
     batch["audio.padding_ms"] = paddingSpin_->value();
@@ -237,6 +248,43 @@ void SettingsPage::onBrowseModelPath() {
     }
 }
 
+void SettingsPage::populateAudioDevices() {
+    audioDeviceCombo_->clear();
+    audioDeviceCombo_->addItem("默认设备", -1);
+
+#ifdef HAVE_PORTAUDIO
+    // 直接使用 PortAudio 枚举所有输入设备
+    QStringList devices = AudioCapture::getDeviceList();
+    // 跳过第一个 "默认设备"（已手动添加）
+    for (int i = 1; i < devices.size(); i++) {
+        audioDeviceCombo_->addItem(devices[i], i - 1); // display text, PortAudio index
+    }
+#else
+    audioDeviceCombo_->addItem("PortAudio 未启用", -1);
+#endif
+}
+
+void SettingsPage::selectAudioDevice(int deviceIndex) {
+    // deviceIndex == -1 表示默认设备，对应 combo 的第一项（index 0）
+    if (deviceIndex < 0) {
+        audioDeviceCombo_->setCurrentIndex(0);
+    } else {
+        // 在 combo 中查找 data == deviceIndex 的项
+        for (int i = 0; i < audioDeviceCombo_->count(); i++) {
+            if (audioDeviceCombo_->itemData(i).toInt() == deviceIndex) {
+                audioDeviceCombo_->setCurrentIndex(i);
+                return;
+            }
+        }
+        // 如果没找到，使用默认设备
+        audioDeviceCombo_->setCurrentIndex(0);
+    }
+}
+
+int SettingsPage::getSelectedAudioDeviceIndex() const {
+    return audioDeviceCombo_->currentData().toInt();
+}
+
 void SettingsPage::onBrowseTokensPath() {
     QString path = QFileDialog::getOpenFileName(this, "选择词表文件", "",
         "词表文件 (tokens.txt);;所有文件 (*.*)");

src/ui/settings_page.h

@@ -38,6 +38,9 @@ private:
     void setupUI();
     void loadFromConfig();
     void saveToConfig();
+    void populateAudioDevices();
+    void selectAudioDevice(int deviceIndex);
+    int getSelectedAudioDeviceIndex() const;
 
     ConfigManager* configManager_;
 
@@ -58,6 +61,7 @@ private:
     QDoubleSpinBox* temperatureSpin_;
 
     // 音频设置
+    QComboBox* audioDeviceCombo_;
     QSpinBox* bufferSizeSpin_;
     QSpinBox* chunkDurationSpin_;
     QSpinBox* paddingSpin_;