Question
How do I pipe an HTTP response like in NodeJS. Here is the snippet I am using in NodeJS:
request({
url: audio_file_url,
}).pipe(ffmpeg_process.stdin);
How can I achieve the same result in Go?
I am trying to pipe a audio stream from HTTP into an FFmpeg process so that it converts it on the fly and returns the converted file back to the client.
Just so its clear to everyone here is my source code so far:
func encodeAudio(w http.ResponseWriter, req *http.Request) {
path, err := exec.LookPath("youtube-dl")
if err != nil {
log.Fatal("LookPath: ", err)
}
path_ff, err_ff := exec.LookPath("ffmpeg")
if err != nil {
log.Fatal("LookPath: ", err_ff)
}
streamLink := exec.Command(path,"-f", "140", "-g", "https://www.youtube.com/watch?v=VIDEOID")
var out bytes.Buffer
streamLink.Stdout = &out
cmdFF := exec.Command(path_ff, "-i", "pipe:0", "-acodec", "libmp3lame", "-f", "mp3", "-")
resp, err := http.Get(out.String())
if err != nil {
log.Fatal(err)
}
// pr, pw := io.Pipe()
defer resp.Body.Close()
cmdFF.Stdin = resp.Body
cmdFF.Stdout = w
streamLink.Run()
//get ffmpeg running in another goroutine to receive data
errCh := make(chan error, 1)
go func() {
errCh <- cmdFF.Run()
}()
// close the pipeline to signal the end of the stream
// pw.Close()
// pr.Close()
// check for an error from ffmpeg
if err := <-errCh; err != nil {
// ff error
}
}
Error: 2014/07/29 23:04:02 Get : unsupported protocol scheme ""
Solution
Here's a possible answer using a standard http handler function. I don't have the programs to test this directly, but it does work with some simple shell commands standing in as a proxy.
func encodeAudio(w http.ResponseWriter, req *http.Request) {
streamLink := exec.Command("youtube-dl", "-f", "140", "-g", "https://www.youtube.com/watch?v=VIDEOID")
out, err := streamLink.Output()
if err != nil {
log.Fatal(err)
}
cmdFF := exec.Command("ffmpeg", "-i", "pipe:0", "-acodec", "libmp3lame", "-f", "mp3", "-")
resp, err := http.Get(string(out))
if err != nil {
log.Fatal(err)
}
defer resp.Body.Close()
cmdFF.Stdin = resp.Body
cmdFF.Stdout = w
if err := cmdFF.Run(); err != nil {
log.Fatal(err)
}
}
OTHER TIPS
http.Request.Body
is an io.ReadCloser
, so you could pipe it into exec.Cmd
.Stdin:
func Handler(rw http.ResponseWriter, req *http.Request) {
cmd := exec.Command("ffmpeg", other, args, ...)
cmd.Stdin = req.Body
go func() {
defer req.Body.Close()
if err := cmd.Run(); err != nil {
// do something
}
}()
//redirect the user and check for progress?
}
//edit I misunderstood the question, however the answer still stands, the http.Get
version:
http.Response.Body
is an io.ReadCloser
just like http.Request.Body
.
func EncodeUrl(url, fn string) error {
resp, err := http.Get(url)
if err != nil {
return err
}
defer resp.Body.Close()
cmd := exec.Command("ffmpeg", ......, fn)
cmd.Stdin = resp.Body
return cmd.Run()
}
//edit2:
this should work, according to the martini documentation, but again, I highly recommend learning to use ServeMux or at least use Gorilla.
m := martini.Classic()
m.Get("/stream/:ytid", func(params martini.Params, rw http.ResponseWriter,
req *http.Request) string {
ytid := params["ytid"]
stream_link := exec.Command("youtube-dl","-f", "140", "-g", "https://www.youtube.com/watch?v=" + ytid)
var out bytes.Buffer
stream_link.Stdout = &out
errr := stream_link.Run()
if err != nil {
log.Fatal(err)
}
log.Println("Link", out.String())
cmd_ff := exec.Command("ffmpeg", "-i", "pipe:0", "-acodec", "libmp3lame", "-f", "mp3", "-")
resp, err := http.Get(url)
if err != nil {
log.Fatal(err)
}
cmd_ff.Stdin = resp.Body
go func() {
defer resp.Body.Close()
if err := cmd_ff.Run(); err != nil {
log.Fatal(err)
}
}()
return "Youtube ID: " + ytid
})
m.Run()