跨平台实时音频驱动:libsoundio

jopen 6年前

libsoundio 是轻量级抽象的声音驱动程序,是一个跨平台实时音频输入和输出的 C99 库。libsoundio 提供文档完善的 API,适用于实时软件,比如游戏,数字音频工作站,音乐播放器等等实用工具。

libsoundio 非常健壮,可以正确处理内存不足的状态

特性&限制

  • 支持的后端

    • JACK

    • PulseAudio

    • ALSA

    • CoreAudio

    • WASAPI

    • Dummy (silence)

  • 支持原始设备和共享设备

  • 支持设备 ID 和友好的名字

  • 支持优化每个后端的使用

  • C 语言库,仅仅依赖于后端 API 库和 libc


  • 支持频道布局

基础正弦波示例

#include <soundio/soundio.h>  #include <stdio.h>  #include <stdlib.h>  #include <string.h>  #include <math.h>  static const float PI = 3.1415926535f;  static float seconds_offset = 0.0f;  static void write_callback(struct SoundIoOutStream *outstream,          int frame_count_min, int frame_count_max)  {      const struct SoundIoChannelLayout *layout = &outstream->layout;      float float_sample_rate = outstream->sample_rate;      float seconds_per_frame = 1.0f / float_sample_rate;      struct SoundIoChannelArea *areas;      int frames_left = frame_count_max;      int err;      while (frames_left > 0) {          int frame_count = frames_left;          if ((err = soundio_outstream_begin_write(outstream, &areas, &frame_count))) {              fprintf(stderr, "%s\n", soundio_strerror(err));              exit(1);          }          if (!frame_count)              break;          float pitch = 440.0f;          float radians_per_second = pitch * 2.0f * PI;          for (int frame = 0; frame < frame_count; frame += 1) {              float sample = sinf((seconds_offset + frame * seconds_per_frame) * radians_per_second);              for (int channel = 0; channel < layout->channel_count; channel += 1) {                  float *ptr = (float*)(areas[channel].ptr + areas[channel].step * frame);                  *ptr = sample;              }          }          seconds_offset += seconds_per_frame * frame_count;          if ((err = soundio_outstream_end_write(outstream))) {              fprintf(stderr, "%s\n", soundio_strerror(err));              exit(1);          }          frames_left -= frame_count;      }  }  int main(int argc, char **argv) {      int err;      struct SoundIo *soundio = soundio_create();      if (!soundio) {          fprintf(stderr, "out of memory\n");          return 1;      }      if ((err = soundio_connect(soundio))) {          fprintf(stderr, "error connecting: %s", soundio_strerror(err));          return 1;      }      soundio_flush_events(soundio);      int default_out_device_index = soundio_default_output_device_index(soundio);      if (default_out_device_index < 0) {          fprintf(stderr, "no output device found");          return 1;      }      struct SoundIoDevice *device = soundio_get_output_device(soundio, default_out_device_index);      if (!device) {          fprintf(stderr, "out of memory");          return 1;      }      fprintf(stderr, "Output device: %s\n", device->name);      struct SoundIoOutStream *outstream = soundio_outstream_create(device);      outstream->format = SoundIoFormatFloat32NE;      outstream->write_callback = write_callback;      if ((err = soundio_outstream_open(outstream))) {          fprintf(stderr, "unable to open device: %s", soundio_strerror(err));          return 1;      }      if (outstream->layout_error)          fprintf(stderr, "unable to set channel layout: %s\n", soundio_strerror(outstream->layout_error));      if ((err = soundio_outstream_start(outstream))) {          fprintf(stderr, "unable to start device: %s", soundio_strerror(err));          return 1;      }      for (;;)          soundio_wait_events(soundio);      soundio_outstream_destroy(outstream);      soundio_device_unref(device);      soundio_destroy(soundio);      return 0;  }

项目主页:http://www.open-open.com/lib/view/home/1441673873336