用BASS库重采样音频

妖狐艹你老母 2022-06-05 05:56 414阅读 0赞

BASS库本身没有重采样的功能，不过BASSmix扩展有

首先要去[BASS官网][BASS]下载BASS和BASSmix

#include <Windows.h>
    
    #include <iostream>
    #include <fstream>
    #include <memory>
    #include <array>
    
    #include <bass.h>
    #include <bassmix.h>
    
    
    struct HSTREAMDeleter
    {
        typedef HSTREAM pointer;
    
        void operator()(pointer p)
        {
            BASS_StreamFree(p);
        }
    };
    
    struct WavHeader
    {
        BYTE riffMagicNumber[4] = { 'R', 'I', 'F', 'F' };
        DWORD restSize = 0;         // 文件剩下所有数据的长度
        BYTE waveMagicNumber[4] = { 'W', 'A', 'V', 'E' };
        BYTE fmtMagicNumber[4] = { 'f', 'm', 't', ' ' };
        DWORD wfSize = sizeof(wf);
        PCMWAVEFORMAT wf = {
            {
                WAVE_FORMAT_PCM,
                2,                  // 声道数
                44100,              // 采样率
                44100 * 2 * 2,      // 采样率 * 通道数 * 采样大小
                2 * 2               // 声道数 * 采样大小
            },
            2 * 8                   // 采样大小 * 8位
        };
        BYTE dataMagicNumber[4] = { 'd', 'a', 't', 'a' };
        DWORD dataSize = 0;         // 后面跟的PCM数据长度
    
    
        WavHeader(DWORD fileSize) :
            restSize(fileSize - sizeof(riffMagicNumber)),
            dataSize(fileSize - sizeof(WavHeader))
        {
        }
    };
    
    
    bool WritePcm(const std::string& audioPath, std::ostream& output, DWORD frequency = 44100, DWORD channels = 2)
    {
        // 重采样后的流
        std::unique_ptr<HSTREAM, HSTREAMDeleter> mixedStream(BASS_Mixer_StreamCreate(frequency, channels, BASS_STREAM_DECODE | BASS_MIXER_END));
        if (mixedStream.get() == NULL)
            return false;
        // 原音频流
        std::unique_ptr<HSTREAM, HSTREAMDeleter> srcStream(BASS_StreamCreateFile(FALSE, audioPath.c_str(), 0, 0, BASS_STREAM_DECODE));
        if (srcStream.get() == NULL)
            return false;
    
        // 重采样
        if (!BASS_Mixer_StreamAddChannel(mixedStream.get(), srcStream.get(), BASS_MIXER_BUFFER))
            return false;
    
        // 写到output流
        auto buffer = std::make_unique<std::array<BYTE, 10240> >();
        while (BASS_ChannelIsActive(mixedStream.get()) != BASS_ACTIVE_STOPPED)
        {
            DWORD size = BASS_ChannelGetData(mixedStream.get(), buffer.get(), buffer->size());
            if (size == -1)
                return false;
            output.write((char*)buffer.get(), size);
        }
    
        return true;
    }
    
    int _tmain(int argc, _TCHAR* argv[])
    {
        if (!BASS_Init(0, 44100, 0, NULL, NULL))
        {
            std::cout << "初始化BASS库失败" << std::endl;
            return 1;
        }
    
        std::ofstream f("D:\\output.wav", std::ios_base::binary);
        // 写PCM数据
        f.seekp(sizeof(WavHeader));
        if (!WritePcm(R"(E:\Music\Ken Arai - NEXT TO YOU.mp3)", f))
            return 1;
        // 写文件头
        WavHeader header((DWORD)f.tellp());
        f.seekp(0);
        f.write((char*)&header, sizeof(header));
    
        BASS_Free();
    
        return 0;
    }

[BASS]: http://www.un4seen.com/