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• How to read realtime microphone audio volume in python and ffmpeg or similar

  1er septembre 2023, par Ryan Martin

  I'm trying to read, in near-realtime, the volume coming from the audio of a USB microphone in Python.

  


  I have the pieces, but can't figure out how to put it together.

  


  If I already have a .wav file, I can pretty simply read it using wavefile :

  


  from wavefile import WaveReader

with WaveReader("/Users/rmartin/audio.wav") as r:
    for data in r.read_iter(size=512):
        left_channel = data[0]
        volume = np.linalg.norm(left_channel)
        print(volume)


  


  This works great, but I want to process the audio from the microphone in real-time, not from a file.

  


  So my thought was to use something like ffmpeg to PIPE the real-time output into WaveReader, but my Byte knowledge is somewhat lacking.

  


  import subprocess
import numpy as np

command = ["/usr/local/bin/ffmpeg",
            '-f', 'avfoundation',
            '-i', ':2',
            '-t', '5',
            '-ar', '11025',
            '-ac', '1',
            '-acodec','aac', '-']

pipe = subprocess.Popen(command, stdout=subprocess.PIPE, bufsize=10**8)
stdout_data = pipe.stdout.read()
audio_array = np.fromstring(stdout_data, dtype="int16")

print audio_array


  


  That looks pretty, but it doesn't do much. It fails with a [NULL @ 0x7ff640016600] Unable to find a suitable output format for 'pipe:' error.

  


  I assume this is a fairly simple thing to do given that I only need to check the audio for volume levels.

  


  Anyone know how to accomplish this simply ? FFMPEG isn't a requirement, but it does need to work on OSX & Linux.

  


• Inputting Audio Stream to FFMPEG

  5 avril 2018, par Wijaya

  I’m building a real time chat application with C# and ffmpeg.exe. My requirement is to get a memory stream from Microsoft Speech API and feed it to ffmpeg process in real time. I can take a memory stream from Microsoft Speech API. I’m using following code to create the memory stream.

          using (MemoryStream stream = new MemoryStream())
  
          {
  
              MemoryStream streamAudio = new MemoryStream();
  
              System.Media.SoundPlayer m_SoundPlayer = new System.Media.SoundPlayer();
  
              _speechSynthesizerVisemesSender.SetOutputToWaveStream(streamAudio);
  
              _speechSynthesizerVisemesSender.SetOutputToNull();
  
              stream.WriteTo(proc.StandardInput.BaseStream);
  
          }   

  I’m already using another datapipe with another command to feed video content to ffmpeg. But I couldn’t find a stable solution to feed audio through a datapipe. This article briefly explains about audio datapipe. I’m using following command to stream audio.

  "ffmpeg -re -f s16le -i pipe:wav -f mpegts udp://127.0.0.1:1234"

  But it is not working with the datapipe. If I try the command with mp3 or wav file, it works.

• Send RTSP + Audio to RTMP server with ffmpeg

  7 février 2018, par Emiliano Spada

  I successfully sent an rtsp video stream to rtmp server (facebook) but have not been able to use audio using ffmpeg.

  If I play RTSP from camera locally audio works fine.

  This is the command I use (ubuntu server 16.0.4 LTS - ffmpeg 2.8.11) :

  sudo ffmpeg -f lavfi -i anullsrc -rtsp_transport tcp -i "rtsp://admin:admin@192.168.1.2/mode=real&idc=1&ids=1" -tune zerolatency -vcodec libx264 -g 60 -keyint_min 60 -r 30 -pix_fmt + -b:v 4000k -acodec copy -ar 44100 -b:a 128k -strict experimental -f flv  "rtmp://live-api.facebook.com:80/rtmp/STREAM-KEY"

  Here the full log :
  https://www.dropbox.com/s/vo05n0kehs75iba/ffmpeg-20180207-100549.log?dl=0