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• Gnuplot how to set a variable to standard-input if not passed

  27 août 2020, par DDS

  I have a gnuplot script (plot.script) that is invoked like

  


  C:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data - | gnuplot -e "fileout='plot';fileformat='png';wid=500;" .\plot.script        


  


  Now I'd want to default filein variable to stdin if it is not passed as argument. This because I want to be able to call this script as a 1-liner command with ffmpeg data generation and also as step-by-step procedure

  


  My idea was to use

  


  if(!exists('filein')){
filein = '-';
}


  


  but this throws warning: Skipping data file with no valid points

  


  if i print the variable datafile I got - (I expected something like stdin).

  


  this is the plot.script script :

  


  
if(!exists('filein')){
    filein = '-';
    }

if (!exists("hei")){
    hei = 4444;
    }
if (!exists("wid")){
    wid = 5555;
    }
if(!exists("fileformat")){
     fileformat = 'png';
     }
if(!exists("fileout")){
     fileout = 'risultato';
   }
   
fileout = fileout . '.' . fileformat;
   
if(!exists("dataformat")){
    dataformat = '%int16';
    }
if(fileformat eq 'png'){
  set terminal png transparent size larghezza,altezza;
  
  }else{
  set terminal fileformat size wid,hei;
  }
  set output fileout;
  unset key;
  unset tics;
  unset border;
  set lmargin 0;
  set rmargin 0;
  set tmargin 0;
  set bmargin 0;


print filein;
plot filein binary filetype=bin format=dataformat endian=little array=1:0 with lines linecolor "0x009900";


  


  But I also want to call this command-by-command :
generate the data-file :

  


  c:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data audio.dat


  


  plot the data :

  


  c:> gnuplot -e "filein='audio.dat';fileout='plot';fileformat='png';wid=500;" .\plot.script


  


• Why is my FastAPI process being suspended, and how can I avoid this ?

  19 janvier, par blermen

  I'm working on a web app using FastAPI that uses ffmpeg to overlay audio onto video for the user. I'm running into an issue where, when I use subprocess.run(cmd), it automatically suspends the process running my FastAPI app. I can't figure out how to get the error logs to help deduce why this is, and I haven't found anything online talking about this.

  


  @app.get("/overlay-audio/")
async def get_video(audio_file: str, forged_name: Annotated[str, Query()] = "default"):
    video_path = os.path.join(output_path, "sample.mp4")
    audio_path = os.path.join(output_path, audio_file)
    forged_path = os.path.join(output_path, forged_name + ".mp4")
    print("Video path: " + video_path)
    print("Audio path: " + audio_path)
    print("Output path: " + forged_path)

    # command to recreate
    # ffmpeg -i input.mp4 -i input.wav -c:v copy -map 0:v:0 -map 1:a:0 -c:a aac -b:a 192k output.mp4

    cmd = ["/opt/homebrew/bin/ffmpeg", 
           "-i", video_path,
           "-i", audio_path,
           "-c:v", "copy",
           "-map", "0:v:0",
           "-map", "1:a:0",
           "-c:a", "aac",
           "-b:a", "192k",
           forged_path]
    
    subprocess.run(cmd)
           
    return {"forged_vid": f"forged_{forged_name}"}


if __name__ == "__main__":
    uvicorn.run("main:app", host="127.0.0.1", port=8000, reload=True)


  


  I've tried not writing output to the terminal, as I've read that could be a reason why it suspends using result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE), and I've also tried running it asynchronously to avoid blocking the event loop using

  


  result = await asyncio.create_subprocess_exec(
        *cmd,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE
    )


  


  but nothing works. Any help or possible other ways to go about this would be greatly appreciated. Terminal output about the suspension : [1] + 12526 suspended (tty output) "/Users//Tech Projects/project/tts/videnv/bin/python"

  


• ffmpeg append video with different dimensions

  21 avril 2020, par friendlygiraffe

  I am cropping and adding subtitles to a video using the following :

  



  ffmpeg -i inputfile.mov -lavfi "crop=720:720:280:360,subtitles=subs.srt:force_style='OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,MarginV=20,Fontsize=18'" -crf 1 -c:a copy output.mov

  



  I have another video called credits.mp4 which has the same dimensions as the output.mov (after cropping). Can I do this during the above process, or would I have to use something like concat afterwards ?

  



  Using bash in Terminal on a Mac