Linux上使用FFmpeg进行录音功能

➜  ~ lsb_release -a
No LSB modules are available.
Distributor ID:	Linuxmint
Description:	Linux Mint 22
Release:	22
Codename:	wilma

# 设置变量
set(ffmpeg444 "../ffmpeg444")

# 引入头文件目录
include_directories(${ffmpeg444}/include/)
# 引入库文件目录,注意link_directories要放在add_executable之前
link_directories(${ffmpeg444}/lib/)

# 链接库中添加avdevice avutil avformat
target_link_libraries(audio PRIVATE Qt${QT_VERSION_MAJOR}::Widgets avdevice avutil avformat)

#include "mainwindow.h"

#include <QApplication>
extern "C" {
// 设备相关
#include <libavdevice/avdevice.h>

}
int main(int argc, char *argv[])
{
    // 注册设备,程序整个运行过程只需要注册一次
    avdevice_register_all();
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

➜  ~ ffmpeg -hide_banner -devices
Devices:
 D. = Demuxing supported
 .E = Muxing supported
 --
 DE fbdev           Linux framebuffer
 D  kmsgrab         KMS screen capture
 D  lavfi           Libavfilter virtual input device
 DE oss             OSS (Open Sound System) playback
 DE pulse           Pulse audio output
  E sdl,sdl2        SDL2 output device
 DE video4linux2,v4l2 Video4Linux2 output device
 D  x11grab         X11 screen capture, using XCB

➜  arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: K66 [K66], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Device [USB Audio Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 0: ALC897 Analog [ALC897 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: PCH [HDA Intel PCH], device 2: ALC897 Alt Analog [ALC897 Alt Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 4: Camera [USB 2.0 Camera], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

#include "mainwindow.h"
#include "./ui_mainwindow.h"
#include <QDebug>
#include <QFile>

extern "C" {
#include <libavdevice/avdevice.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
}

#define BUF_SIZE 1024

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_audioButton_clicked()
{
    const char* fmtName = "pulse"; //设置输入设备格式名称
    // 获取输入格式对象
    AVInputFormat *fmt = av_find_input_format(fmtName);

    if (!fmt) {
        qDebug() << "获取输入格式对象失败" << fmtName;
        return;
    }

    AVFormatContext *ctx = nullptr;  // 打开的设备上下文对象，可以利用这个上下文对象来操作设备

    // 设备名称，可以使用 arecord -l查看设备
    const char* deviceName = "hw:0";  // 使用card 0, arecord -l命令列出的第一个设备

    AVDictionary* options = nullptr;  // 选项

    // 利用输入格式对象打开设备
    int ret = avformat_open_input(&ctx, deviceName, fmt, &options);

    if (ret < 0) {
        char errbuf[BUF_SIZE] = {0};
        // av_strerror获取错误原因
        av_strerror(ret, errbuf, BUF_SIZE);
        qDebug() << "打开设备失败：" << errbuf;
        return;

    }


    // 录音保存的文件
    const char* fileName = "out.pcm";  // 采集的数据是原始pcm数据
    QFile file(fileName);

    // 打开文件
    // WriteOnly: 只写模式，如果文件不存在，则创建文件。如果文件存在，则清空文件内容
    if (!file.open(QIODevice::WriteOnly)) {
        qDebug() << "文件打开失败" << fileName;
        avformat_close_input(&ctx);  // 关闭设备
        return;
    }

    // 开始采集数据
    int count = 50; // 采集数据的次数
    AVPacket pkt;  // 数据包
    while(count-- > 0 && av_read_frame(ctx, &pkt) == 0) {  // 一直采集数据，当为0时说明数据采集成功了
        // 将数据写入文件
        file.write((const char *)pkt.data, pkt.size);
    }

    // 释放资源
    file.close();  // 关闭文件
    avformat_close_input(&ctx); // 关闭设备

}

#ifdef Q_OS_LINUX
    const char* fmtName = "pulse"; //设置输入设备格式名称
#elif Q_OS_WIN
    const char* fmtName = "dshow"; //设置输入设备格式名称
#endif



#ifdef Q_OS_LINUX
    // 设备名称，可以使用 arecord -l查看设备
    const char* deviceName = "hw:0";
#elif Q_OS_WIN
    const char* deviceName = "audio=麦克风 (K66)";
#endif

➜  ~ ffmpeg -hide_banner -formats | grep PCM
 DE alaw            PCM A-law
 DE f32be           PCM 32-bit floating-point big-endian
 DE f32le           PCM 32-bit floating-point little-endian
 DE f64be           PCM 64-bit floating-point big-endian
 DE f64le           PCM 64-bit floating-point little-endian
 DE mulaw           PCM mu-law
 DE s16be           PCM signed 16-bit big-endian
 DE s16le           PCM signed 16-bit little-endian
 DE s24be           PCM signed 24-bit big-endian
 DE s24le           PCM signed 24-bit little-endian
 DE s32be           PCM signed 32-bit big-endian
 DE s32le           PCM signed 32-bit little-endian
 DE s8              PCM signed 8-bit
 DE u16be           PCM unsigned 16-bit big-endian
 DE u16le           PCM unsigned 16-bit little-endian
 DE u24be           PCM unsigned 24-bit big-endian
 DE u24le           PCM unsigned 24-bit little-endian
 DE u32be           PCM unsigned 32-bit big-endian
 DE u32le           PCM unsigned 32-bit little-endian
 DE u8              PCM unsigned 8-bit
 DE vidc            PCM Archimedes VIDC

ffplay -ar 44100 -ac 2 -f s16le out.pcm