【OC】单音效处理器

1. 创建handle

创建handle，具体音效的Identify可以在单音效处理器介绍中查看

SAMICore_CreateParameter *create_param = [[SAMICore_CreateParameter alloc] init];
create_param.sampleRate = sample_rate;
create_param.maxBlockSize = pre_define_block_size;
create_param.modelBuffer = nullptr;
create_param.modelLen = 0;
create_param.numChannel = 2;
int result = 0;
SAMICore *sami_core_handle = [[SAMICore alloc] initWithIdentify:SAMICore_Identify_Processor_TimeDomainPitchShifter param:create_param result:&result];
if(result != SAMI_OK) {
    std::cerr << "create handler failed: " << result;
    exit(-1);
}

2. 设置参数

参数的设置可以分为两种情况：

1. 在主线程中创建了 handle，但音频线程还 未启动 音频处理时。这种情况下，调用 离线参数 设置接口。

2. 音频线程 已经启动 ，并正在进行音频处理时。这种情况下，调用 实时参数 设置接口

离线设置参数

SAMICore_Property* offline_property = [[SAMICore_Property alloc] init];
NSString* json_param = [[NSString alloc] initWithUTF8String:"{\"parameters\": {\"Pitch Ratio\": 2} }"];
offline_property.type = SAMICore_DataType_String;
offline_property.id = SAMICore_PropertyId_Processor_SetParametersOffline;
offline_property.data = json_param;
result = [sami_core_handle setProperty:offline_property withId:SAMICore_PropertyId_Processor_SetParametersOffline];
if(result != SAMI_OK) {
    std::cerr << "set property failed: " << result;
    exit(-1);
}

实时设置参数

SAMICore_ContextParameterEvent* param_event = [[SAMICore_ContextParameterEvent alloc] init];
param_event.parameterIndex = SAMICore_ProcessorTimeDomainPitchShifterParameter::SAMICore_TimeDomainPitchShifter_Pitch_Ratio;
param_event.plainValue = 2.0f;

SAMICore_Property* update_property = [[SAMICore_Property alloc] init];
update_property.data = param_event;
update_property.type = SAMICore_DataType_ParameterEvent;
result = [sami_core_handle setProperty:update_property withId:SAMICore_PropertyId_Processor_ContextEmplaceParameterEventNowWithPlainValue];
if(result != SAMI_OK) {
    std::cerr << "set property failed: " << result;
    exit(-1);
}

SAMICoreContextParameterEvent 描述了参数的位置和值 ,可以在SAMICoreEffectParam.h找到参数和范围，其中

• parameterIndex，参数下标，

• plainValue，参数值，有三种数据类型：float/bool/choice

以“TimeDomainPitchShifter”为例：

3.初始化buffer

SAMICore_AudioBuffer *in_audio_buffer
        = [[SAMICore_AudioBuffer alloc] initWithNumberSamples:pre_define_block_size
                                               numberChannels:num_channels
                                                 isInterleave:false];

SAMICore_AudioBuffer *out_audio_buffer
        = [[SAMICore_AudioBuffer alloc] initWithNumberSamples:pre_define_block_size
                                               numberChannels:num_channels
                                                 isInterleave:false];

SAMICore_AudioBlock *in_block = [[SAMICore_AudioBlock alloc] init];
in_block.dataType = SAMICore_DataType_AudioBuffer;
in_block.numberAudioData = 1;
in_block.audioData = in_audio_buffer;

SAMICore_AudioBlock *out_block = [[SAMICore_AudioBlock alloc] init];
out_block.dataType = SAMICore_DataType_AudioBuffer;
out_block.numberAudioData = 1;
out_block.audioData = out_audio_buffer;

4.处理数据

for(int inx = 0; inx + pre_define_block_size < (int)num_frames;) {
    // build in_block
    for(auto c = 0; c < num_channels; ++c) {
        std::copy_n(in_samples[c].data() + inx, pre_define_block_size, ((float**)in_audio_buffer.data)[c]);
    }

    result = [sami_core_handle processWithInBlock:in_block outBlock:out_block];

    if(result != SAMI_OK) {
        std::cerr << "process error: " << result;
        exit(-1);
    }

    // write output block to file
    audio_encoder->writePlanarData((float**)out_audio_buffer.data, num_channels, pre_define_block_size);
    inx += pre_define_block_size;
}

5.释放handle以及buffer

in_audio_buffer = nil;
out_audio_buffer = nil;
in_block = nil;
out_block = nil;

sami_core_handle = nil;