请注意以下命令/事例均基于Mac环境

FFmpeg采集音频

• 通过命令方式

//采集
ffmpeg -f avfoundation -i :0 out.wav
//播放
ffplay out.wav

• 通过API方式

重要api讲解

av_read_frame //可以读取音频/视频数据

av_init_packet
av_packet_unref

av_packet_alloc //此方法先分配空间再调用av_init_packet
av_packet_free //此方法先调用av_packet_unref解引用再释放空间

事例
.h文件

#include <stdio.h>
#include "libavutil/avutil.h"
#include "libavdevice/avdevice.h"
#include "libavformat/avformat.h"
#include "libavcodec/avcodec.h"

void rec_audio(void);

.m文件

#include "testc.h"

void rec_audio() {

    int ret = 0;
    char errors[1024] = {0, };

    AVFormatContext *fmt_ctx = NULL;
    AVDictionary *options = NULL;
    
    int count = 0;
    AVPacket pkt;

    //[[video device]:[audio device]]
    char *devicename = ":0";
    
    av_log_set_level(AV_LOG_DEBUG);

    //注册设备
    avdevice_register_all();

    //设置采集方式
    AVInputFormat *iformat = av_find_input_format("avfoundation");

    //打开音频设备
    if ((ret = avformat_open_input(&fmt_ctx, devicename, iformat, &options)) < 0) {
        av_strerror(ret, errors, 1024);
        fprintf(stderr, "Failed to open audio device, [%d]%s\n", ret, errors);
        return;
    }
    
    //写入文件 w：写入 b：二进制 +：文件不存在就自动创建
    char *out = "/Users/mac/Downloads/my_av_base.pcm";
    FILE *outfile = fopen(out, "wb+");
    
    av_init_packet(&pkt);
    //读取音频数据
    while ((ret = av_read_frame(fmt_ctx, &pkt)) == 0  && count++ < 500) {
        
        //写入文件
        fwrite(pkt.data, pkt.size, 1, outfile);
        fflush(outfile);
        
        av_log(NULL, AV_LOG_INFO, "pkt size is %d(%p), count=%d \n",pkt.size, pkt.data, count);
        //释放资源
        av_packet_unref(&pkt);
    }
    
    //关闭文件
    fclose(outfile);
    
    //关闭设备
    avformat_close_input(&fmt_ctx);

    av_log(NULL, AV_LOG_DEBUG, "finish!\n");
}

ViewController.swift

import Cocoa

class ViewController: NSViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.setFrameSize(NSSize(width: 700, height: 300))
        
        let btn = NSButton.init(title: "button", target: self, action: #selector(myfunc))
        btn.frame = NSRect(x: 50, y: 60, width: 90, height: 30);
        self.view.addSubview(btn)
        
    }
    
    @objc func myfunc() {
        rec_audio()
    }

    override var representedObject: Any? {
        didSet {
        // Update the view, if already loaded.
        }
    }
    
}

播放

ffplay -ar 44100 -ac 2 -f f32le my_av_base.pcm