C语言使用ffmpeg和sdl实现多路音频播放

static std::map<void*, std::function<void(void* userdata, Uint8* stream, int len)>> _audioCallbacks;//记录每一路音频的回调方法
//总的回调方法
static void _audio_callback_sum(void* userdata, uint8_t* stream, int len)
{
    memset(stream, 0, len);
    std::unique_lock< std::mutex >lck(_mtx);
    //调用每一路的回调方法
    for (auto i : _audioCallbacks)
    {
        i.second(userdata, stream, len);
    }
}

static SDL_AudioSpec _wanted_spec, _spec;
_wanted_spec.channels = 2;
_wanted_spec.freq = 44100;
_wanted_spec.format = AUDIO_F32SYS;
_wanted_spec.silence = 0;
_wanted_spec.samples = 1024;
_wanted_spec.callback = _audio_callback_sum;
 SDL_OpenAudio(&_wanted_spec, &_spec) == 0;

_audioCallbacks[pFrame] = [&](void* userdata, Uint8* stream, int len) {
    //此处实现单独一路的播放逻辑
};

if (av_audio_fifo_space(fifo) >= samples)
{
    av_audio_fifo_write(fifo, (void**)&data, (int)samples);
    break;
}

//读取音频队列数据 
int read = av_audio_fifo_read(fifo, (void**)&data, _spec.samples);
//开始混合
SDL_MixAudioFormat(stream, data, _spec.format, newLen, SDL_MIX_MAXVOLUME);

#pragma once
/// <summary>
/// 播放音频
/// 此方法同步阻塞，播放完成后返回
/// 支持多路播放，可放在线程中播放，线程安全。
/// </summary>
/// <param name="input">输入url</param>
/// <param name="exitFlag">中断标记</param>
/// <returns></returns>
int simple_audio_play(const char* input, int* exitFlag)

int exitflag= false;    
simple_audio_play("D:\\test_music.wav", &exitflag);

#include"simple_audio_play.h"
void main() {
    int exitflag = false;
    auto t1 = new std::thread([&]() {
        while (!exitflag) {
            simple_audio_play("D:\\test_music.wav", &exitflag);
        }
        });
    auto t2 = new std::thread([&]() {
        while (!exitflag) {
            simple_audio_play("D:\\test.mp4", &exitflag);
        }
        });
    system("pause");
    exitflag = true;
    t1->join();
    t2->join();
}