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• How to save python compatible audio file from JavaScript blob

  16 septembre 2020, par Talha Anwar

  I am trying to save an audio blob to the backend.
Here is an audio blob

  


   const blob = new Blob(chunks, { 'type' : 'audio/wav; codecs=0' });


  


  Here is the upload function

  


  function uploadAudio( blob ) {
  var reader = new FileReader();
  reader.onload = function(event){
    var fd = {};
    fd["data"] = event.target.result;
    $.ajax({
     // contentType:"application/x-www-form-urlencoded; charset=UTF-8",
      type: 'POST',
      url: 'testing/',
      data: fd,
      dataType: 'text'
    }).done(function(data) {
        console.log(data);
        document.getElementById("response").innerHTML=data;
       // alert(data);
    });
  };


  


  Here is the function to save the file.

  


  def upload_audio(request):
    print('upload_audio')
    if request.is_ajax():
        
        req=request.POST.get('data')
        d=req.split(",")[1]
        print("Yes, AJAX!")
        #print(request.body)
        f = open('./file.wav', 'wb')
        
        f.write(base64.b64decode(d))
        #f.write(request.body)
        f.close()
    return HttpResponse('audio received')


  


  When I try to read it in python for converting to text. I got following error

  


  ValueError: Audio file could not be read as PCM WAV, AIFF/AIFF-C, or Native FLAC; check if file is corrupted or in another format


  


  I tried to convert the file

  


  import ffmpeg
stream = ffmpeg.input('file.wav')
stream = ffmpeg.output(stream, 'filen.wav')
ffmpeg.run(stream)


  


  I got following error

  


  Traceback (most recent call last):&#xA;  File "script.py", line 8, in <module>&#xA;    ffmpeg.run(stream)&#xA;  File "C:\Anaconda3\envs\VA\lib\site-packages\ffmpeg\_run.py", line 320, in run&#xA;    overwrite_output=overwrite_output,&#xA;  File "C:\Anaconda3\envs\VA\lib\site-packages\ffmpeg\_run.py", line 285, in run_async&#xA;    args, stdin=stdin_stream, stdout=stdout_stream, stderr=stderr_stream&#xA;  File "C:\Anaconda3\envs\VA\lib\subprocess.py", line 729, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "C:\Anaconda3\envs\VA\lib\subprocess.py", line 1017, in _execute_child&#xA;    startupinfo)&#xA;FileNotFoundError: [WinError 2] The system cannot find the file specified&#xA;</module>

  


• Matplotlib use Ffmpeg to save plot to be mp4 not include full step

  21 décembre 2020, par 昌翰余

  I use ffmpeg to store the dynamic graph drawn on matplotlib, but the output file is only 2 seconds
but It should have been 30 seconds.
I set a graph to run three curves, a total of 30 seconds of data,
the graph that ran on the py file is normal,
but the output is only the first two seconds of the output.
May I ask if I missed something

  


  Below is my code

  


  import matplotlib.pyplot as plt
from matplotlib import animation
from numpy import random 
import pandas as pd
from matplotlib.animation import FFMpegWriter

FFwriter=animation.FFMpegWriter(fps=30, extra_args=['-vcodec', 'libx264'])
data = pd.read_csv('apple1.csv', delimiter = ',', dtype = None)
data = data.values
AccX1=[]
AccY1=[]
AccZ1=[]
AccX2=[]
AccY2=[]
AccZ2=[]

time = []

for i in range(600):
        AccX1.append(data[i][8])
        AccY1.append(data[i][9])
        AccZ1.append(data[i][10])
        AccX2.append(data[i][24])
        AccY2.append(data[i][25])
        AccZ2.append(data[i][26])
        
        time.append(data[i][0])
        
fig = plt.figure()
ax1 = plt.axes(xlim=(0,3000), ylim=(6,-6))
line, = ax1.plot([], [], lw=2)
plt.xlabel('ACC')
plt.ylabel('Time')

plotlays, plotcols = [3], ["r","g","b"]
lines = []
for index in range(3):
    lobj = ax1.plot([],[],lw=2,color=plotcols[index])[0]
    lines.append(lobj)


def init():
    for line in lines:
        line.set_data([],[])
    return lines

x1,y1 = [],[]
x2,y2 = [],[]
x3,y3 = [],[]



i=0

def animate(frame):
    global i
    
    i+=1
    x = i
    y = AccX1[i]

    x1.append(x)
    y1.append(y)

    x = i
    y = AccY1[i]
    x2.append(x)
    y2.append(y)

    x = i
    y = AccZ1[i]
    x3.append(x)
    y3.append(y)
    

    xlist = [x1, x2,x3]
    ylist = [y1, y2,y3]


    for lnum,line in enumerate(lines):
        line.set_data(xlist[lnum], ylist[lnum]) 


    return lines


anim = animation.FuncAnimation(fig, animate,
                    init_func=init, blit=True,interval=10)
anim.save('test.mp4',writer=FFwriter)
plt.show()


  


  The dynamic picture ran out using plt.show is correct.
And I don't think I have set the length of storage. Did I add something ?

  


• FFMPEG unable to take frame and save as image

  2 mai 2013, par alex

  I'm trying to save an image from a video frame and save it as a jpeg.
  This function works for smaller video files, but if the video is over 10 minutes it won't save the jpeg image. An error comes up as before trans.

  public function VideoToJpeg($localVideoPath, $localOutImgPath)
  
  {
  
      $Name = dirname(__FILE__) . "/ffmpeg";
  
      $Str = "$Name -i \"$localVideoPath\" -an -ss 00:00:03 -an -r 1 -vframes 1 -y \"$localOutImgPath\"";
  
  
  
      exec($Str);
  
  }

  Here is the error I got from ffmpeg

  [NULL @ 0370e760] Unable to find a suitable output format for 'path'
  
  : Invalid argument