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• Bash : bash script to download trimmed mp3 from youtube url

  25 août 2017, par Bhishan Poudel

  I would like to download the initially x seconds trimmed mp3 from a video url of youtube.
  I found that youtube-dl can download the video from youtube to local machine. But, when I looked at the man pages of youtube-dl, I could not find any trim options.

  So I tried to use the ffmpeg to trim downloaded mp3 file.
  Instead of doing this is two steps, I like to write one bash script which does the same thing.
  My attempt is given below.

  However, I was stuck at one place :
  "HOW TO GET THE VARIABLE NAME OF OUTPUT MP3 FILE FROM YOUTUBE-DL ?"
  The script is given below :

  # trim initial x seconds of mp3 file
  
  # e.g. mytrim https://www.youtube.com/watch?v=dD5RgCf1hrI 30
  
  function mytrim() {
  
      youtube-dl --extract-audio --embed-thumbnail --audio-format mp3 -o "%(title)s.%(ext)s" $1
  
      ffmpeg -ss $2 -i $OUTPUT_MP3 -acodec copy -y temp.mp3
  
      mv temp.mp3 $OUTPUT_MP3
  
      }

  How to get the variable value $OUTPUT_MP3 ?
  echo "%(title)s.%(ext)s" gives the verbatim output, does not give the output filename.

  How could we make the script work ?

  The help will be appreciated.

• Generate individual HLS-compatible .ts segments on-demand by downloading as little bytes as possible from a remote input file

  28 juillet 2017, par Romain Cointepas

  I’m trying to generate individual HLS-compatible .ts segments on-demand by downloading/reading as little bytes as possible from a remote input file (hosted on a server supporting byte-ranges requests).

  One of the application for this would be to be able to transcode and play on Apple TV (via Airplay) a remote file that is not Airplay compatible, without having to download the entire file first.

  I am generating the playlist myself, and I have access to the ffprobe results for the remote file (that gives video duration, etc.).

  I have something working that plays via Airplay but with small video and audio glitches between each segments when I use the following command to generate each segment :

  ffmpeg -ss 60 -t 6 -i http://s3.amazonaws.com/misc-12345/avicii.vob -f mpegts -map 0:v:0 -map 0:a:0 -c:v libx264 -bsf:v h264_mp4toannexb -force_key_frames "expr:gte(t,n_forced*6)" -forced-idr 1 -pix_fmt yuv420p -colorspace bt709 -c:a aac -async 1 -preset ultrafast pipe:1

  Note : above command is for segment 11.ts, and in the m3u8 playlist I advertise each segment duration as 6 seconds.

  Here is a Youtube video showing the audio/video glitches between segments :
  https://www.youtube.com/watch?v=0vMwgbSfsu0

  The segment or hls modules of ffmpeg can’t be used because they both generate all the segments at once.

  I’ve been struggling on this for some days now and I would really appreciate some help !

• receive a ffmpeg live streaming with a golang server and echo to a websocket conn

  28 juillet 2017, par Lucas Carvalho

  I’m writing a server in go and need to get a cam video in a ffmpeg client and passes the streaming to websocket users.

  But in my code, the http body received from the ffmpeg client is loaded by a ioutil.ReadAll and cannot make a live broadcast because the body is receiving new values with the video capture.
  How i can take the last frame of the video, send to the websockets, clean the variable and receive the new frame correctly (or i’m doing in the wrong way) ?

  Here is my code to this function :

  //StartClientStream needs a email$clientName$streamName
  
  func StartClientStream(w http.ResponseWriter, r *http.Request) {
  
  
  
      values := strings.Split(string(mux.Vars(r)["rest"]), "$")
  
  
  
      if len(values) != 3 {
  
          w.Write([]byte(`{"err":"the passed value does not match with necessary fields"}`))
  
          return
  
      }
  
      //Get user ID
  
      id, _ := getID(values[0])
  
      //Take the streaming ClientName
  
      clientName := id + " - " + values[1]
  
      //Take the passed Body
  
      body, _ := ioutil.ReadAll(r.Body)
  
      //Watch for websockets requests for this video
  
      for user := range Streaming.User[clientName] {
  
          conexoes := strings.Split(Streaming.User[clientName][user], "-")
  
          for c := range conexoes {
  
              if strings.EqualFold(conexoes[c], values[2]) {
  
                  //Send the video
  
                  user.send <- body
  
              }
  
          }
  
      }
  
  
  
  }