ffmpeg将多个flv文件合成为mp4（golang版）

之前拿python写了个合并flv文件为mp4的脚本，运行感觉有点慢，用go重写下

-loglevel quiet

package main

import (
    "bytes"
    "flag"
    "fmt"
    "io/ioutil"
    "os"
    "os/exec"
    "path/filepath"
    "strings"
    "sync"
    "time"
)

var (
    wg     sync.WaitGroup
)

// 判断文件或目录是否存在
func pathExists(path string) (bool, error) {
    _, err := os.Stat(path)
    if err == nil {
        return true, nil
    }
    if os.IsNotExist(err) {
        return false, nil
    }
    return false, err
}

// 命令行调用
func Cmd(commandName string, params []string) (string, error) {
    cmd := exec.Command(commandName, params...)
    //fmt.Println("Cmd", cmd.Args)
    var out bytes.Buffer
    cmd.Stdout = &out
    cmd.Stderr = os.Stderr
    err := cmd.Start()
    if err != nil {
        return "", err
    }
    err = cmd.Wait()
    return out.String(), err
}

// 视频格式转换
func videoConvert(in string, out string) {
    defer wg.Done()
    //fmt.Println(in, out)
    cmdStr := fmt.Sprintf("ffmpeg -i %s -loglevel quiet -c copy -bsf:v h264_mp4toannexb -f mpegts %s", in, out)
    args := strings.Split(cmdStr, " ")
    msg, err := Cmd(args[0], args[1:])
    if err != nil {
        fmt.Printf("videoConvert failed, %v, output: %v\n", err, msg)
        return
    }
}

// 视频合成
func videoMerge(in []string, out string) {
    //fmt.Println(in, out)
    cmdStr := fmt.Sprintf("ffmpeg -i concat:%s -loglevel quiet -c copy -absf aac_adtstoasc -movflags faststart %s",
        strings.Join(in, "|"), out)
    args := strings.Split(cmdStr, " ")
    msg, err := Cmd(args[0], args[1:])
    if err != nil {
        fmt.Printf("videoMerge failed, %v, output: %v\n", err, msg)
        return
    }
}

func flvs2mp4(inDir string, outFile string)(err error) {
    tsFileDir := filepath.Join(inDir, "tsfile")
    if err = os.RemoveAll(tsFileDir); err != nil {
        return
    }
    if err = os.RemoveAll(outFile); err != nil {
        return
    }
    if err = os.Mkdir(tsFileDir,0666); err!=nil {
        return
    }

    infiles, _ := ioutil.ReadDir(inDir)
    for _, f := range infiles {
        if filepath.Ext(f.Name()) == ".flv" {
            tsfileName := filepath.Join(tsFileDir, strings.TrimSuffix(f.Name(), ".flv") + ".ts")
            wg.Add(1)
            go videoConvert(filepath.Join(inDir, f.Name()), tsfileName)
        }
    }
    wg.Wait()

    tsfiles, _ := ioutil.ReadDir(tsFileDir)
    tsfileNames := make([]string, 0, len(tsfiles))
    for _, f := range tsfiles {
        if filepath.Ext(f.Name()) == ".ts" {
            tsfileNames = append(tsfileNames, filepath.Join(tsFileDir, f.Name()))
        }
    }
    videoMerge(tsfileNames, outFile)

    return
}

func main() {
    start := time.Now()
    var inputDir string
    var outputName string
    flag.StringVar(&inputDir, "i", "./dvr-file/flv", "input file dir")
    flag.StringVar(&outputName, "o", "out.mp4", "output file name")
    //解析命令行参数
    flag.Parse()

    exist, err := pathExists(inputDir)
    if err != nil {
        fmt.Printf("get dir error!: %v", err)
        return
    }
    if !exist {
        inputDir = os.Args[0]
    }
    inputDir, _  = filepath.Abs(inputDir)
    fmt.Println("argv: ", inputDir, outputName)
    if err = flvs2mp4(inputDir, outputName); err != nil {
        fmt.Printf("flv to mp4 error!: %v", err)
    }

    elapsed := time.Since(start)
    fmt.Println("Running time:", elapsed)
}

11个30s左右的flv合成mp4不用groutine需要时间5.74秒，开启groutine只要3.2秒，确实快了不少