基于OHAudio的音频操作

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    1：场景描述

    场景：基于OHAudio模块实现音频录制和播放功能，带监听音频打断实现使用OH\_AudioCapturer接口录制音频生成PCM文件写入到文件保存到沙箱路径，再使用OH\_AudioRenderer接口播放音频文件，并监听音频打断

    使用的核心API：

    AudioCapturer：音频采集，用于录制PCM音频数据。

    AudioRenderer：音频渲染，用于播放PCM音频数据。

    OHAudio： 提供音频模块C接口定义。

    2：方案描述

    场景一：普通录制和播放实现

    Step1：导入audio模块, 引入OHAudio头文件， 提供播放和录制能力的API

    Step2：使用OH\_AudioCapturer接口录制功能实现

    Step3：使用OH\_AudioRenderer接口播放功能实现

    Step4：监听音频打断实现

    场景二：低时延模式录制和低时延播放实现

    可以将普通录制和播放切换为低时延录制和低时延播放

    效果如下：

    场景：普通录制和播放实现

    具体步骤如下：

    步骤一：导入audio模块, 引入OHAudio头文件， 提供播放和录制能力的API

    引入音频库和动态链接库

    import { BusinessError } from '@ohos.base';
import audioPlayer from 'libentry.so'

    动态链接库audioPlayer里面声明相关函数定义

    export const audioCapturerLowLatencyInit: () => void;
export const audioCapturerStart: () => void;
export const audioCapturerPause: () => void;
export const audioCapturerStop: () => void;
export const audioCapturerRelease: () => void;
export const audioRendererInit: () => void;
export const audioRendererLowLatencyInit: () => void;
export const audioRendererStart: () => void;
export const audioRendererPause: () => void;
export const audioRendererStop: () => void;
export const audioRendererRelease: () => void;
export const getRendererState: () => number;
export const getFileState: () => number;
export const getFramesWritten: () => number;
export const getFileSize: () => number;
export const closeFile: () => number;

    native侧接口映射，native侧和JS侧方法交互

    {
    napi_property_descriptor desc[] = {
        {"closeFile", nullptr, CloseFile, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioCapturerLowLatencyInit", nullptr, AudioCapturerLowLatencyInit, nullptr, nullptr, nullptr, napi_default,
         nullptr},
        {"audioCapturerInit", nullptr, AudioCapturerInit, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioCapturerStart", nullptr, AudioCapturerStart, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioCapturerPause", nullptr, AudioCapturerPause, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioCapturerRelease", nullptr, AudioCapturerRelease, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioCapturerStop", nullptr, AudioCapturerStop, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioRendererLowLatencyInit", nullptr, AudioRendererLowLatencyInit, nullptr, nullptr, nullptr, napi_default,
         nullptr},
        {"audioRendererInit", nullptr, AudioRendererInit, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioRendererStart", nullptr, AudioRendererStart, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioRendererPause", nullptr, AudioRendererPause, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioRendererRelease", nullptr, AudioRendererRelease, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"getRendererState", nullptr, GetRendererState, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"getFileSize", nullptr, GetFileSize, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"getFramesWritten", nullptr, GetFramesWritten, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"getFileState", nullptr, GetFileState, nullptr, nullptr, nullptr, napi_default, nullptr},
        {"audioRendererStop", nullptr, AudioRendererStop, nullptr, nullptr, nullptr, napi_default, nullptr}};
    napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
    return exports;
}
EXTERN_C_END

    步骤二：录制实现

    Step1：创建录制和播放构造器

    static OH_AudioRenderer *audioRenderer;
static OH_AudioStreamBuilder *builder;
static OH_AudioStreamBuilder *rendererBuilder;

    Step2：构造录制音频流，设置音频流参数和音频回调函数

    {
    if (audioCapturer) {
        OH_AudioCapturer_Release(audioCapturer);
        OH_AudioStreamBuilder_Destroy(builder);
        fclose(g_file);
        g_file = nullptr;
        audioCapturer = nullptr;
        builder = nullptr;
    }
    g_file = fopen(g_filePath.c_str(), "wb");
    // create builder
    OH_AudioStream_Type type = AUDIOSTREAM_TYPE_CAPTURER;
    OH_AudioStreamBuilder_Create(&builder, type);
    // set params and callbacks
    OH_AudioStreamBuilder_SetSamplingRate(builder, g_samplingRate);
    OH_AudioStreamBuilder_SetChannelCount(builder, g_channelCount);
    callbacks.OH_AudioCapturer_OnReadData = AudioCapturerOnReadData;
    OH_AudioStreamBuilder_SetCapturerCallback(builder, callbacks, nullptr);
    // create OH_AudioCapturer
    OH_AudioStreamBuilder_GenerateCapturer(builder, &audioCapturer);
    return nullptr;
}
// 低时延录制实现只需在普通录制的基础上切换成低时延模式
static napi_value AudioCapturerLowLatencyInit(napi_env env, napi_callback_info info)
{
 ...
    OH_AudioStreamBuilder_SetLatencyMode(builder, (OH_AudioStream_LatencyMode)g_latencyMode);
...
}

    Step3：开始录制，暂停录制，停止录制

    {
    // start
    OH_AudioCapturer_Start(audioCapturer);
    return nullptr;
}
static napi_value AudioCapturerPause(napi_env env, napi_callback_info info)
{
    OH_AudioCapturer_Pause(audioCapturer);
    return nullptr;
}
static napi_value AudioCapturerStop(napi_env env, napi_callback_info info)
{
    OH_AudioCapturer_Stop(audioCapturer);
    return nullptr;
}

    Step4：将采集到的音频数据写入文件中

    {
    size_t count = 1;
    if (fwrite(buffer, bufferLen, count, g_file) != count) {
        printf("buffer fwrite err");
    }
    return 0;
}
// 文件路径
static std::string g_filePath = "/data/storage/el2/base/haps/entry/files/oh_test_audio.pcm";

    Step5：释放构造器

    {
    if (audioCapturer) {
        OH_AudioCapturer_Release(audioCapturer);
        OH_AudioStreamBuilder_Destroy(builder);
        audioCapturer = nullptr;
        builder = nullptr;
    }
    return nullptr;
}

    步骤三：播放实现

    Step1：构造播放音频流，设置音频流参数和音频回调函数

    {
    if (audioRenderer) {
        OH_AudioRenderer_Release(audioRenderer);
        OH_AudioStreamBuilder_Destroy(rendererBuilder);
        fclose(g_file);
        g_file = nullptr;
        audioRenderer = nullptr;
        rendererBuilder = nullptr;
    }
    g_file = fopen(g_filePath.c_str(), "rb");
    if (g_file == nullptr) {
        return 0;
    }
    // create builder
    OH_AudioStream_Type type = AUDIOSTREAM_TYPE_RENDERER;
    OH_AudioStreamBuilder_Create(&rendererBuilder, type);
    // set params and callbacks
    OH_AudioStreamBuilder_SetSamplingRate(rendererBuilder, g_samplingRate);
    OH_AudioStreamBuilder_SetChannelCount(rendererBuilder, g_channelCount);
    rendererCallbacks.OH_AudioRenderer_OnWriteData = AudioRendererOnWriteData;
    OH_AudioStreamBuilder_SetRendererCallback(rendererBuilder, rendererCallbacks, nullptr);
    OH_AudioRenderer_Callbacks callbacks;
// 配置回调函数
    callbacks.OH_AudioRenderer_OnWriteData = MyOnWriteData;
    callbacks.OH_AudioRenderer_OnStreamEvent = MyOnStreamEvent;
    callbacks.OH_AudioRenderer_OnInterruptEvent = MyOnInterruptEvent;
    callbacks.OH_AudioRenderer_OnError = MyOnError;
    OH_AudioStreamBuilder_GenerateRenderer(rendererBuilder, &audioRenderer);
    g_readEnd = false;
    g_rendererLowLatency = false;
    return nullptr;
}
// 低时延播放实现只需在普通播放的基础上切换成低时延模式
static napi_value AudioRendererLowLatencyInit(napi_env env, napi_callback_info info)
{
 ...
    OH_AudioStreamBuilder_SetLatencyMode(rendererBuilder, (OH_AudioStream_LatencyMode)g_latencyMode);
...
}

    Step2：读取音频文件进行渲染

    {
    size_t readCount = fread(buffer, bufferLen, 1, g_file);
    if (!readCount) {
        if (ferror(g_file)) {
            printf("Error reading myfile");
        } else if (feof(g_file)) {
            OH_AudioRenderer_Stop(audioRenderer);
            OH_AudioRenderer_Release(audioRenderer);
            OH_AudioStreamBuilder_Destroy(rendererBuilder);
            fclose(g_file);
            g_file = fopen(g_filePath.c_str(), "rb");
            // 1. create builder

            OH_AudioStream_Type type = AUDIOSTREAM_TYPE_RENDERER;
            OH_AudioStreamBuilder_Create(&rendererBuilder, type);
            // 2. set params and callbacks

            OH_AudioStreamBuilder_SetSamplingRate(rendererBuilder, g_samplingRate);
            OH_AudioStreamBuilder_SetChannelCount(rendererBuilder, g_channelCount);
            if (g_rendererLowLatency) {
                OH_AudioStreamBuilder_SetLatencyMode(rendererBuilder, (OH_AudioStream_LatencyMode)g_latencyMode);
            }
            rendererCallbacks.OH_AudioRenderer_OnWriteData = AudioRendererOnWriteData;
            OH_AudioStreamBuilder_SetRendererCallback(rendererBuilder, rendererCallbacks, nullptr);
            // 3. create OH_AudioRenderer

            OH_AudioStreamBuilder_GenerateRenderer(rendererBuilder, &audioRenderer);
            g_readEnd = true;
        }
    }
    return 0;
}

    Step3：开始播放，暂停播放，停止播放

    {
    g_readEnd = false;
    // start

    OH_AudioRenderer_Start(audioRenderer);
    return nullptr;
}
static napi_value AudioRendererPause(napi_env env, napi_callback_info info)
{
    g_readEnd = false;
    OH_AudioRenderer_Pause(audioRenderer);
    return nullptr;
}
static napi_value AudioRendererStop(napi_env env, napi_callback_info info)
{
    g_readEnd = false;
    OH_AudioRenderer_Stop(audioRenderer);
    return nullptr;
}

    Step4：释放构造器

    {
    if (audioRenderer) {
        OH_AudioRenderer_Release(audioRenderer);
        OH_AudioStreamBuilder_Destroy(rendererBuilder);
        audioRenderer = nullptr;
        rendererBuilder = nullptr;
    }
    return nullptr;
}

    步骤四：OHAudio监听音频打断实现

    int32_t MyOnWriteData(OH_AudioRenderer *renderer, void *userData, void *buffer, int32_t length) {
// 将待播放的数据，按length长度写入buffer
if (g_file == nullptr) {
    LOGI("MyOnWriteData length fopen");
    g_file = fopen(g_filePath.c_str(), "r");
} else if (feof(g_file)) {
    LOGI("MyOnWriteData length fseek");
    fseek(g_file, 0, SEEK_SET);
}
LOGI("MyOnWriteData length %{public}d", length);
size_t readCount = fread(buffer, length, 1, g_file);
return 0;
}
// 自定义音频流事件函数
int32_t MyOnStreamEvent(OH_AudioRenderer *renderer, void *userData, OH_AudioStream_Event event) {
// 根据event表示的音频流事件信息，更新播放器状态和界面
LOGI("MyOnStreamEvent");
return 0;
}
// 自定义音频中断事件函数
int32_t MyOnInterruptEvent(OH_AudioRenderer *renderer, void *userData, OH_AudioInterrupt_ForceType type,
                           OH_AudioInterrupt_Hint hint) {
// 根据type和hint表示的音频中断信息，更新播放器状态和界面
LOGI("MyOnInterruptEvent ForceType: %{public}d, Hint: %{public}d", type, hint);
switch (hint) {
case AUDIOSTREAM_INTERRUPT_HINT_NONE:
    break;
case AUDIOSTREAM_INTERRUPT_HINT_RESUME:
    OH_AudioRenderer_Start(audioRenderer);
    break;
case AUDIOSTREAM_INTERRUPT_HINT_PAUSE:
    OH_AudioRenderer_Pause(audioRenderer);
    break;
case AUDIOSTREAM_INTERRUPT_HINT_STOP:
    OH_AudioRenderer_Stop(audioRenderer);
    break;
case AUDIOSTREAM_INTERRUPT_HINT_DUCK:
    break;
case AUDIOSTREAM_INTERRUPT_HINT_UNDUCK:
    break;
default:
    LOGI("无法识别中断事件");
}
return 0;
}
// 自定义异常回调函数
int32_t MyOnError(OH_AudioRenderer *renderer, void *userData, OH_AudioStream_Result error) {
// 根据error表示的音频异常信息，做出相应的处理
LOGI("MyOnError");
return 0;
}
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