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• PiCamera stream to youtube with ffmpeg and capture image every second

  9 octobre 2020, par MisterGray

  I'm sending a livestream with a Python script on a Raspberry Pi 4 to Youtube with ffmpeg.

  


  Additionally I want to check the stream for movements. Therefore I want to compare two frames with each other. Since this is relatively computationally intensive, I wanted to limit myself to "only" compare single frames every second.

  


  The camera.capture() command, however, seems to take very long, so the stream hangs again and again.

  


  What is the best way to get a raw frame during the stream ?

  


  Is there a better alternative to detect movements while creating a stream with ffmpeg ?

  


  #!/usr/bin/env python3
import subprocess
from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2
import numpy as np

YOUTUBE = 'rtmp://a.rtmp.youtube.com/live2/'
KEY = 'MyYoutubeKey'
stream_cmd = 'ffmpeg -re -ar 44100 -ac 2 -acodec pcm_s16le -f s16le -ac 2 -i /dev/zero -f h264 -i - -vcodec copy -acodec aac -ab 128k -g 50 -strict experimental -f flv ' + YOUTUBE + KEY

avg = None
stream_pipe = subprocess.Popen(stream_cmd, shell=True, stdin=subprocess.PIPE)
resolution = (1280,720)
with PiCamera(resolution = resolution) as camera:

    rawCapture = PiRGBArray(camera, size = resolution)

    camera.framerate = 25
    camera.vflip = True
    camera.hflip = True
    camera.start_recording(stream_pipe.stdin, format='h264', bitrate = 6000000)
    while True:
        camera.wait_recording(1)

        # this command takes a long time to finish
        frame = camera.capture(stream_pipe.stdin, 'rgb')

        """
        further calculations
        """

        rawCapture.truncate(0)

    camera.stop_recording()
    stream_pipe.stdin.close()
    stream_pipe.wait()


  


• Handling "NullReferenceException" when executing "ffmpeg.exe" process in C# [duplicate]

  1er juillet 2023, par FrostDream

  I'm trying to execute the "ffmpeg.exe" process in my C# application to process media files. However, I'm encountering a "NullReferenceException" when running the code. I've tried various approaches, including using a try-catch block, but the exception still persists. Here's the relevant code snippet :

  


  bool isValidMedia = true;

try
{
    Process process = new Process();
    process.StartInfo.FileName = "ffmpeg.exe";
    process.StartInfo.Arguments = $"-i \"{file}\" -f null -";
    process.StartInfo.UseShellExecute = false;
    process.StartInfo.RedirectStandardOutput = true;
    process.StartInfo.CreateNoWindow = true;
    process.OutputDataReceived += (sender, e) =>
    {
        if (!string.IsNullOrEmpty(e.Data))
        {
            int startIndex = e.Data.IndexOf("samples=") + 8;
            button.Width = int.Parse(e.Data.Substring(startIndex, e.Data.IndexOf(" ") - startIndex)) / zoom * 100;
        }
        else
        {
            isValidMedia = false;
        }
    };

    process.Start();
    process.BeginOutputReadLine();
    process.WaitForExit();
}
catch
{
    isValidMedia = false;
}

if (!isValidMedia)
{
    MessageBox.Show("Not a valid media.");
    return;
}



  


  I suspect that the issue may be related to the asynchronous execution of the event handler or the initialization of the ProcessStartInfo object. Can anyone please help me identify the cause of the "NullReferenceException" and provide guidance on how to resolve it ? Thank you in advance for your assistance.

  


• Why do I get UnknownValueError when trying to run .recognize_google ?

  21 juillet 2022, par John Smith

  Following code is meant to transcribe a long audio file to text. It is to do this piece by piece. trimmed.wav holds a 15-second-long piece of a longer audio file (whose path is stored in fname) :

  


  #!/usr/bin/env python3

from subprocess import run
from sys import exit

italic = '\33[3m'
end = '\33[m'

try:
    from speech_recognition import AudioFile, Recognizer
except:
    run("pip3 install SpeechRecognition", shell=True)
    from speech_recognition import AudioFile, Recognizer

def transcribe_piece(fname, lang, stime):
    extension = fname[-3:]
    etime = stime + 15
    cmd = f"ffmpeg -ss {stime} -to {etime} -i {fname} -c copy trimmed.{extension} >/dev/null 2>&1"
    run(cmd, shell=True)
    cmd = f"ffmpeg -i trimmed.{extension} -f wav trimmed.wav >/dev/null 2>&1"
    run(cmd, shell=True)
    r = Recognizer()    
    af = AudioFile("trimmed.wav")
    with af as source:
        r.adjust_for_ambient_noise(source)
        audio = r.record(source)
        t = r.recognize_google(audio, language=lang)#UnknownValueError() speech_recognition.UnknownValueError
        print(f"{italic}{t}{end}")
        with open("of", "w") as f:
            f.write(f"{t}\n")
    run(f"rm trimmed.{extension}", shell=True) 
    run(f"rm trimmed.wav", shell=True)
    
    

fname = input("File name? Skip the path if the file is in CWD. The usage of ~ is allowed.\n")

lang = input("""Specify one of the following languages:
fr-BE, fr-CA, fr-FR, fr-CH

en-AU, en-CA, en-GH, en-HK, en-IN, en-IE, en-KE, en-NZ, en-PK, en-PH, en-SG, en-ZA, en-TZ, en-GB, en-US

es-AR, es-BO, es-BO, es-CL, es-CO, es-CR, es-DO, es-EC, es-SV, es-SV, es-GT, es-HN, es-MX, es-NI, es-PA, es-PY, es-PE, es-PR, es-ES, es-US, es-UY, es-VE\n""")


#for stime in range(0, 10000, 15):
#    try:
#        transcribe_piece(fname, lang, stime)
#    except:
#        run("shred -u trimmed.wav" , shell=True) 
        #run("shred -u trimmed.wav >/dev/null 2>&1" , shell=True) 
#        exit(0)
        
for stime in range(0, 10000, 15):#this loop is only for the sake of debugging, use try/except above
    transcribe_piece(fname, lang, stime)



  


  It gives me the following error :

  


  Traceback (most recent call last):&#xA;  File "/home/jim/CS/SoftwareDevelopment/MySoftware/Python/speech-to-text/long-audio-to-text.py", line 61, in <module>&#xA;    transcribe_piece(fname, lang, stime)&#xA;  File "/home/jim/CS/SoftwareDevelopment/MySoftware/Python/speech-to-text/long-audio-to-text.py", line 31, in transcribe_piece&#xA;    t = r.recognize_google(audio, language=lang)&#xA;  File "/home/jim/.local/lib/python3.10/site-packages/speech_recognition/__init__.py", line 858, in recognize_google&#xA;    if not isinstance(actual_result, dict) or len(actual_result.get("alternative", [])) == 0: raise UnknownValueError()&#xA;speech_recognition.UnknownValueError&#xA;&#xA;</module>

  


  The said error refers to line 31, that is t = r.recognize_google(audio, language=lang).
Why do I get this error ? How might I rewrite this code so that such error does not appear ?