audio - 如何使用soundio一次播放多个流？

Question

我是Soundio的新手。我想知道如何一次播放多个音频源。
我想了解是否应该创建多个流(似乎是错误的)并让操作系统进行混合，还是应该实现软件混合？
如果我的输入源以不同的频率运行，软件混合似乎也很困难。
我基本上是在问“如何混合音频”吗？
我需要一点指导。
这是我的用例:
我有5个不同的MP3文件。一种是背景音乐，另一种是声音效果。我想启动背景音乐，然后在用户执行某些操作(例如单击图形按钮)时播放声音效果。 (这是一个游戏)

Answer 1

您可以创建多个流并同时播放它们。您无需自己进行混合。无论如何，它需要大量的工作。
定义WAVE_INFO和PLAYBACK_INFO:

struct WAVE_INFO
{
    SoundIoFormat format;
    std::vector<unsigned char*> data;
    int frames; // number of frames in this clip
}

struct PLAYBACK_INFO
{
    const WAVE_INFO* wave_info; // information of sound clip
    int progress; // number of frames already played
}

从声音片段中提取WAVE信息，并将其存储在WAVE_INFO:std::vector<WAVE_INFO> waves_;数组中。初始化后，此 vector 将不会更改。

当您想播放waves_[index]时:

SoundIoOutStream* outstream = soundio_outstream_create(sound_device_);
outstream->write_callback = write_callback;
PlayBackInfo* playback_info = new PlayBackInfo({&waves_[index], 0});
outstream->format = playback_info->wave_info->format;
outstream->userdata = playback_info;
soundio_outstream_open(outstream);
soundio_outstream_start(outstream);
std::thread stopper([this, outstream]()
{
    PlayBackInfo* playback_info = (PlayBackInfo*)outstream->userdata;
    while (playback_info->progress != playback_info->wave_info->frames)
    {
        soundio_wait_events(soundio_);
    }
    soundio_outstream_destroy(outstream);
    delete playback_info;
});
stopper.detach();

在write_callback函数中:

PlayBackInfo* playback_info = (PlayBackInfo*)outstream->userdata;
int frames_left = playback_info->audio_info->frames - playback_info->progress;
if (frames_left == 0)
{
    soundio_wakeup(Window::window_->soundio_);
    return;
}
if (frames_left > frame_count_max)
{
    frames_left = frame_count_max;
}
// fill the buffer using
// soundio_outstream_begin_write and
// soundio_outstream_end_write by
// data in playback_info->wave_info.data
// considering playback_info->progress.

// update playback_info->progress based on
// number of frames are written to buffer

// for background music:
if (playback_info->audio_info->frames == playback_info->progress)
{
    // if application has not exited:
    playback_info->progress = 0;
}

此解决方案也有效，需要大量改进。请仅将其视为POC。