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• Download a part of youtube video using a powershell script

  26 octobre 2024, par Nguyễn Đức Minh

  I'm writing this Powershell script :

  


  $URL = "https://www.youtube.com/watch?v=KbuwueqEJL0"
$from = 00:06:15
$to = 00:09:17

$cmdOutput = (youtube-dl --get-url $URL) 

ffmpeg -ss $from -to $to -i  -ss $from -to $to -i  output.mkv


  


  This script's purpose is to download a part of a Youtube video. I've set the variable $URL to specify the Youtube URL, while $from and $to is the start and end time of the part I want to download.

  


  $cmdOutput is used to output the stream URL. The output would have two lines : the first one is the URL for the video stream, while the second one is the audio stream URL.

  


  Currently, I don't know how to use the output as a variable and specify the line number of $cmdOutput to put it into the correct stream. I guess and would be replaced by something like $cmdOutput[line 1], and $cmdOutput[line 2], though I know that those are incorrect.

  


  I've consulted this answer, and it is handy for me to write this script. I've also read Boris Lipschitz's answer on how to do the same thing with Python, but his answer does not work.

  


  In that script, the -ss flag inputs the seeking point, and the -t <duration></duration> flag tells FFmpeg to stop encoding after the specified duration. For example, if the start time is 00:02:00 and the duration is 00:03:00, FFmpeg would download from 00:02:00 to 00:05:00, which is not the expected outcome. For some reason, his Python script skips the first 5 seconds of output, even if I replace the -t flag with -to . I've tried to edit his script, but it does not work unless you explicitly specify the time for both video and audio stream, as well as their respective stream URL.

  


• FFmpeg restream RTSP with 3 sub-channels

  6 mars 2024, par KyO Hoai Bac

  I want to reproduce the RTSP stream by a video file, the stream will have 3 sub-channels like this via Ffmpeg, not need exactly the encoding and resolution :

  


  - Stream #0:0: Video: h264 (Main)
- Stream #0:1: Audio: pcm_mulaw
- Stream #0:2: Data: none


  


  I asked chat GPT and here is it suggestion :

  


  ffmpeg -i input_video.mp4 -i input_audio.wav -f lavfi -t 1 -i anullsrc=r=44100:cl=stereo -filter_complex "[0:v][1:a][2:a]concat=n=3:v=1:a=1[v][a]" -map "[v]" -map "[a]" -rtsp_transport tcp -threads 0 -muxdelay 0.1 rtsp://localhost:8554/stream

  


  I tried but it fail :

  


  Stream specifier ':a' in filtergraph description [0:v][1:a][2:a]concat=n=3:v=1:a=1[v][a] matches no streams.

  


• Can you stream multiple video clips to youtube or twitch with a separate audio track with a different length than the video clips with FFMPEG ?

  8 juin 2020, par Fight Fire With Fire

  What I'd like to do is stream a set of video clips to youtube or twitch using FFMPEG. Right now i loop thru the videos file names in a list called DIRECTORY. video[0] is the file name and send to stream_url with the audio for the video attached.

  



  What i would love to figure out, is there a way I could mux in a single audio track streaming to youtube/twitch but switch the video clips out live. Here is the code I am working with right now :

  



  
     for video in directory:
            command = [
            "ffmpeg" , "-re" , "-i" , video[0] ,
            "-vcodec" , "libx264", "-pix_fmt", "yuv420p",
            "-preset" , "medium" , "-r" , "30" , "-g" , "48" , "-b:v" , "2500k" ,
            "-acodec" , "libmp3lame" , "-ar" , "44100", "-threads" , "6" ,
            "-q:a" , "3" , "-b:a" , "712000" ,"-bufsize", "512k" , "-f" ,
            "flv" , STREAM_URL,
        ]
             subprocess.run(command)