c - 如何使用 libsoundios sio_sine 示例分离音频通道以从不同来源输出?
问题描述
我正在尝试运行 libsoundio 库中的 sio_sine 示例代码的变体。该示例所做的只是输出指定频率的音调。我想改变这一点,以便能够在每个输出通道(左右扬声器)中产生不同频率的音调。我对 C 和整体编程非常陌生,并且尝试过环顾四周,但我似乎无法弄清楚。如果有帮助,我正在使用的后端是 PulseAudio。
我正在使用 Ubuntu 18.04
图书馆: https ://github.com/andrewrk/libsoundio.git
下面的代码:
#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 = fmodf(seconds_offset +
seconds_per_frame * frame_count, 1.0f);
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;
}
Thanks!
解决方案
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