go语言调用上下文拉起ffmpeg，并引入livego做的简单流媒体服务器

package ffmpeg

import (
    "bytes"
    "context"
    "os"
    "os/exec"
    "syscall"
    "time"
)

type C struct {
    Name   string
    ctx    context.Context
    cancel context.CancelFunc
    cmd    *exec.Cmd
}

func New(name string, args []string) C {
    var c C
    c.Name = name
    c.ctx, c.cancel = context.WithCancel(context.Background())
    c.cmd = exec.CommandContext(c.ctx, "ffmpeg", args...)
    c.cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
    c.cmd.Stdout = os.Stdout
    return c
}

func (c *C) Run() error {
    return c.cmd.Start()
}

func (c *C) RunThenClose(ch chan int) error {
    err := c.cmd.Start()
    c.cancel()
    //tell go i take it
    return err
}

func (c *C) Close() {
    c.cancel()
}

//run and wait for back
func RunAndClose(args []string, callback func(c, t time.Duration)) error {
    cmd := exec.Command("ffmpeg", args...)

    if callback == nil {
        var cmdErr bytes.Buffer
        cmd.Stderr = &cmdErr

        if err := cmd.Run(); err != nil {
            return extractError(err, cmdErr.String())
        }

        return nil
    }

    // ffmpeg stdout is stderr
    stderr, err := cmd.StderrPipe()
    if err != nil {
        return err
    }

    w, err := newWatcher(stderr, callback)
    if err != nil {
        return err
    }

    defer w.Close()
    defer cmd.Process.Wait()

    if err := cmd.Run(); err != nil {
        return err
    }

    return nil
}