ue4 将音频从 48 立体声转换为 16 单声道

Posted 2023-02-25

【中文标题】ue4 将音频从 48 立体声转换为 16 单声道

【英文标题】：ue4 Convert audio from 48 stereo to 16 mono

【发布时间】：2021-09-07 09:45:21

【问题描述】：

如何在 ue4 的 wav 录音中将采样率从 48000（ue4 默认）更改为 16000 个样本，并将立体声更改为单声道？我在BP中搜索过，但并不缺乏。下图显示了我对 BP 所做的事情。为了使它工作，我必须在 WindowsEngine.ini 中将音频设置更改为 XAudio（参见：https://www.youtube.com/watch?v=BpP1SxxwYIE）

因此，我认为这应该只适用于 C++。

【参考方案1】：

我是用 C++ 做的

文件 -> 新 C++ 类 -> VoiceCharacter -> 公共

更改您的角色以将“VoiceCharacter”作为父级。可以在角色 BP 的职业设置中找到。

将此方法添加到 VoiceCharacter C++ 类并构建和播放。

void AVoiceCharacter::StereoToMono(TArray<uint8> stereoWavBytes, TArray<uint8>& monoWavBytes)


    if(stereoWavBytes.Num() == 0)
    
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, "Stereo Bytes is empty");
        return;
    
    
    //Change wav headers
    for (int i = 0; i < 44; i++)
    
        //NumChannels starts from 22 to 24
        if (i == 22)
        
            short originalChannels = (*(short*)&stereoWavBytes[i]);
            short NumChannels = originalChannels / 2;

            FString message = FString::FromInt(originalChannels);   
            
            GEngine->AddOnScreenDebugMessage(-1, 25.f, FColor::Red, message);
            
            monoWavBytes.Append((uint8*)&NumChannels, sizeof(NumChannels));
            i++;
        //SamplingRate starts from 24 to 27
        else if (i == 24)
        
            int OriginalSamplingRate = (*(int*)&stereoWavBytes[i]); 
            int SamplingRate = OriginalSamplingRate / 3 ;

            GEngine->AddOnScreenDebugMessage(-1, 25.f, FColor::Yellow, FString::FromInt(OriginalSamplingRate));
            
            monoWavBytes.Append((uint8*)&SamplingRate, sizeof(SamplingRate));
            i += 3;
         //ByteRate starts from 28 to 32
        else if (i == 28)
        

            int OriginalByteRate = (*(int*)&stereoWavBytes[i]); 
            int ByteRate = OriginalByteRate / 6 ;

            GEngine->AddOnScreenDebugMessage(-1, 25.f, FColor::Yellow, FString::FromInt(OriginalByteRate));
            
            monoWavBytes.Append((uint8*)&ByteRate, sizeof(ByteRate));
            i += 3;
        
        //BlockAlign starts from 32 to 34
        else if (i == 32)
        
            short BlockAlign = (*(short*)&stereoWavBytes[i]) / 2;

            GEngine->AddOnScreenDebugMessage(-1, 25.f, FColor::White, FString::FromInt(BlockAlign));
            
            monoWavBytes.Append((uint8*)&BlockAlign, sizeof(BlockAlign));
            i++;
        
        //SubChunkSize starts from 40 to 44
        else if (i == 40)
        
            int SubChunkSize = (*(int*)&stereoWavBytes[i]) / 2;

            GEngine->AddOnScreenDebugMessage(-1, 25.f, FColor::Green, FString::FromInt(SubChunkSize));
            
            monoWavBytes.Append((uint8*)&SubChunkSize, sizeof(SubChunkSize));
            i += 3;
        
        else
        
            monoWavBytes.Add(stereoWavBytes[i]);
        
    
 
    //Copies only the left channel and ignores the right channel
    // for (int i = 44; i < stereoWavBytes.Num(); i += 4)
    // 
    //  monoWavBytes.Add(stereoWavBytes[i]);
    //  monoWavBytes.Add(stereoWavBytes[i+1]);
    // 

    //Copies only the left channel and ignores the right channel. Also downsamples by 3,
    // i.e. converts Windows 48000 sampling rate of ue4 to 16000
    for (int i = 44; i < stereoWavBytes.Num(); i += 12)
    
        monoWavBytes.Add(stereoWavBytes[i]);
        monoWavBytes.Add(stereoWavBytes[i+1]);
    
    

不要忘记在 VoiceCharacter.h 中添加它，以便您可以使用它的 BP。

UFUNCTION(BlueprintCallable, Category="Audio")
static void StereoToMono(TArray<uint8> stereoWavBytes, TArray<uint8>& monoWavBytes); 

这里是如何在 BPs 中使用它

一些有用的插件（CUFile） https://github.com/getnamo/nodejs-ue4 https://github.com/getnamo/socketio-client-ue4