webrtc之音频设备采集及封装

音频设备同样抽象出音频设备对象：

class AudioDevice {
public:
    AudioDevice(const std::string& id, const std::string& name) :device_id(id), device_name(name) {
    }
    virtual ~AudioDevice() {
    }

public:
    std::string device_id;
    std::string device_name;
};

设备集合：

class AudioDeviceCollection
{
public:
    AudioDeviceCollection();
    virtual ~AudioDeviceCollection();

private:
    void addAudioDevice(std::shared_ptr device);

    std::vector> audio_devices_;
public:
    int getCount();
    std::shared_ptr getDevice(int index);
    int getDevice(int index, std::string &deviceName, std::string &deviceId);
    int searchDevice(const std::string &deviceId);

    friend class XXX::AudioDeviceManager;
};

音频设备枚举，因为需要使用到webrtc内部的音频设备管理器，而其使用只能在webrtc的几个固定线程中，否则抛异常，故首先需要创建adm对象，并且需要做一个统一的webrtc线程管理对象，需要使用的线程都丢到那里面：

AudioDeviceManager::AudioDeviceManager():/*audio_sink_(nullptr), */recording_devices_enumerated_(false), playout_devices_enumerated_(false)
{
    audio_recording_collection_ = std::make_shared();
    audio_playout_collection_ = std::make_shared();

    XXXThreadManager::getInstance()->worker_thread_->Invoke(RTC_FROM_HERE, [&]() {
        adm_ = webrtc::AudioDeviceModule::Create(webrtc::AudioDeviceModule::kPlatformDefaultAudio);
        adm_->Init();
    });
    EnableBuiltInAEC(false);
}

void AudioDeviceManager::init()
{
    XXXThreadManager::getInstance()->worker_thread_->Invoke(RTC_FROM_HERE, [&]() {
        if (adm_) {
            adm_->Init();
        }
    });
}

枚举音频采集设备：

std::shared_ptr AudioDeviceManager::enumerateRecordingDevices()
{
    if (recording_devices_enumerated_) {
        return audio_recording_collection_;
    }

    XXXThreadManager::getInstance()->worker_thread_->Invoke(RTC_FROM_HERE, [&]() {
        int num_devices = adm_->RecordingDevices();
        for (int i = 0; i < num_devices; i++)
        {
            char name[webrtc::kAdmMaxDeviceNameSize];
            char id[webrtc::kAdmMaxGuidSize];
            if (adm_->RecordingDeviceName(i, name, id) != -1)
            {
                std::shared_ptr device = std::make_shared(id, name);
                audio_recording_collection_->addAudioDevice(device);
            }
        }
    });
    recording_devices_enumerated_ = true;

    return audio_recording_collection_;
}

枚举音频播放设备：

std::shared_ptr AudioDeviceManager::enumeratePlayoutDevices()
{
    if (playout_devices_enumerated_) {
        return audio_playout_collection_;
    }

    XXXThreadManager::getInstance()->worker_thread_->Invoke(RTC_FROM_HERE, [&]() {
        int num_devices = adm_->PlayoutDevices();
        for (int i = 0; i < num_devices; i++)
        {
            char name[webrtc::kAdmMaxDeviceNameSize];
            char id[webrtc::kAdmMaxGuidSize];
            if (adm_->PlayoutDeviceName(i, name, id) != -1)
            {
                std::shared_ptr device = std::make_shared(id, name);
                audio_playout_collection_->addAudioDevice(device);
            }
        }
    });
    playout_devices_enumerated_ = true;
    return audio_playout_collection_;
}

设置音频数据回调：

int AudioDeviceManager::RegisterAudioSink(webrtc::AudioTransport *audio_sink)
{
    int iRet = XXXThreadManager::getInstance()->worker_thread_->Invoke(RTC_FROM_HERE, [=]() {
        return adm_->RegisterAudioCallback(audio_sink);
    });
    return iRet;
}

管理对象总体接口（当然我们还需要在外部封装一层，屏蔽webrtc的头文件）：

class AudioDeviceManager : public webrtc::AudioTransport
{
    public:
        static AudioDeviceManager *getInstance();
        virtual ~AudioDeviceManager();
    private:
        AudioDeviceManager();
    public:
        std::shared_ptr enumerateRecordingDevices();
        std::shared_ptr enumeratePlayoutDevices();

        int setRecordingDevice(const std::string& deviceId);
        int setRecordingDevice(std::shared_ptr audio_device);
        int setRecordingDeviceVolume(uint32_t volume);
        int getRecordingDeviceVolume();
        int setRecordingDeviceMute(bool mute);
        int getRecordingDeviceMute(bool* mute);
        int EnableBuiltInAEC(bool enable);
        int RegisterAudioSink(webrtc::AudioTransport *audio_sink);
        int initRecording();
        int startRecording();

        int setPlayoutDevice(const std::string& deviceId);
        int setPlayoutDevice(std::shared_ptr audio_device);
        int setPlayuotDeviceVolume(uint32_t volume);
        int setPlayoutDeviceMute(bool mute);
        int getPlayoutDeviceMute(bool* mute);
        int getPlayoutDeviceVolume();
        int startPlayout();

        void init();

    public:
        rtc::scoped_refptr adm_;
        rtc::scoped_refptr getADM();
    private:
        static AudioDeviceManager *instance_;
        std::shared_ptr audio_recording_collection_;
        std::shared_ptr audio_playout_collection_;

        std::shared_ptr curr_recording_device_;
        std::shared_ptr curr_playout_device_;

        bool playout_devices_enumerated_;
        bool recording_devices_enumerated_;
    private:
        int32_t RecordedDataIsAvailable(const void* audioSamples,
            const size_t nSamples,
            const size_t nBytesPerSample,
            const size_t nChannels,
            const uint32_t samplesPerSec,
            const uint32_t totalDelayMS,
            const int32_t clockDrift,
            const uint32_t currentMicLevel,
            const bool keyPressed,
            uint32_t& newMicLevel) {
            return 0;
        }

        // Implementation has to setup safe values for all specified out parameters.
        int32_t NeedMorePlayData(const size_t nSamples,
            const size_t nBytesPerSample,
            const size_t nChannels,
            const uint32_t samplesPerSec,
            void* audioSamples,
            size_t& nSamplesOut,  // NOLINT
            int64_t* elapsed_time_ms,
            int64_t* ntp_time_ms) {
            return 0;
        };

        // Method to pull mixed render audio data from all active VoE channels.
        // The data will not be passed as reference for audio processing internally.
        void PullRenderData(int bits_per_sample,
            int sample_rate,
            size_t number_of_channels,
            size_t number_of_frames,
            void* audio_data,
            int64_t* elapsed_time_ms,
            int64_t* ntp_time_ms) {};
};