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• OpenCV 4.5.2 takes a long time (>100ms) to retrieve a single frame from a webcam, C++ on Windows 10

  9 juin 2021, par Mustard Tiger

  I've been having a tough time getting my webcam working quickly with opencv. Frames take a very long time to read, (a recorded average of 124ms across 500 frames) I've tried on three different computers (running Windows 10) with a logitech C922 webcam. The most recent machine I tested on has a Ryzen 9 3950X, with 32gbs of ram ; no lack of power.

  


  Here is the code :

  


  cv::VideoCapture cap = cv::VideoCapture(m_cameraNum);&#xA;&#xA;// Check if camera opened successfully&#xA;if (!cap.isOpened())&#xA;{&#xA;    m_logger->critical("Error opening video stream or file\n\r");&#xA;    return -1;&#xA;}&#xA;&#xA;bool result = true;&#xA;result &amp;= cap.set(cv::CAP_PROP_FRAME_WIDTH, 1280);&#xA;result &amp;= cap.set(cv::CAP_PROP_FRAME_HEIGHT, 720);&#xA;&#xA;bool ready = false;&#xA;std::vector<string> timeLog;&#xA;timeLog.reserve(50000);&#xA;int i = 0;&#xA;&#xA;while (i &lt; 500)&#xA;{&#xA;    auto start = std::chrono::system_clock::now();&#xA;    &#xA;    cv::Mat img;&#xA;    ready = cap.read(img);&#xA;&#xA;    // If the frame is empty, break immediately&#xA;    if (!ready)&#xA;    {&#xA;        timeLog.push_back("continue");&#xA;        continue;&#xA;    }&#xA;&#xA;    i&#x2B;&#x2B;;&#xA;    auto end = std::chrono::system_clock::now();&#xA;    timeLog.push_back(std::to_string(std::chrono::duration_cast(end - start).count()));&#xA;}&#xA;&#xA;for (auto&amp; entry : timeLog)&#xA;    m_logger->info(entry);&#xA;&#xA;cap.release();&#xA;return 0;&#xA;</string>

  


  Notice that I write the elapsed time to a log file at the end of execution. The average time is 124ms for debug and release, and not one instance of "continue" after half a dozen runs.

  


  It doesn't matter if I use USB 2 or USB 3 ports (the camera is USB2) or if I run a debug build or a release build, the log file will show anywhere from 110ms to 130ms of time for each frame. The camera works fine in other app, OBS can get a smooth 1080@30fps or 720@60fps.

  


  Stepping through the debugger and doing a lot of Googling, I've learned the following about my system :

  


  

  • The backend chosen by default is DSHOW. GStreamer and FFMPEG are also available.

  


  • DSHOW uses FFMPEG somehow (it needs the FFMPEG dll) but I cannot use FFMPEG directly through opencv. Attempting to use cv::VideoCapture(m_cameraNum, cv::CAP_FFMPEG) always fails. It seems like Opencv's interface to FFMPEG is only capable of opening video files.

  


  • Microsoft really screwed up camera devices in Windows a few years back, not sure if this is related to my problem.

  


  


  Here's a short list of the fixes I have tried, most taken from older SO posts :

  


  

  • result &= cap.set(cv::CAP_PROP_FRAME_COUNT, 30) ; // Returns false, does nothing

  


  • result &= cap.set(cv::CAP_PROP_CONVERT_RGB, 0) ; // Returns true, does nothing

  


  • result &= cap.set(cv::CAP_PROP_MODE, cv::VideoWriter::fourcc('M', 'J', 'P', 'G')) ; // Returns false, does nothing

  


  • Set registry key from http://alax.info/blog/1693 that should disable the new Windows camera server.

  


  • Updated from 4.5.0 to 4.5.2, no change.

  


  • Asked device manager to find a newer driver, no newer driver found.

  


  


  I'm out of ideas. Any help ?

  


• ffmpeg skips frames/packets while playing a file over http

  24 janvier 2020, par coban

  Microsoft Windows [Version 10.0.18362.592]  
  
  libavutil      56. 31.100 / 56. 31.100
  
  libavcodec     58. 54.100 / 58. 54.100
  
  libavformat    58. 29.100 / 58. 29.100
  
  libavdevice    58.  8.100 / 58.  8.100
  
  libavfilter     7. 57.100 /  7. 57.100
  
  libswscale      5.  5.100 /  5.  5.100
  
  libswresample   3.  5.100 /  3.  5.100
  
  libpostproc    55.  5.100 / 55.  5.100
  
  [hls @ 0600cac0] Skip ('#EXT-X-VERSION:3')    0KB sq=    0B f=0/0
  
  [hls @ 0600cac0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/chunklist_w1481451763.m3u8' for reading
  
  [hls @ 0600cac0] Skip ('#EXT-X-VERSION:3')    0KB sq=    0B f=0/0
  
  [hls @ 0600cac0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_0.ts' for reading
  
  [hls @ 0600cac0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_1.ts' for reading
  
  Input #0, hls, from 'http://ok2.se:8000/movie/xxxxxxxxxx/67933.m3u8':
  
  Duration: 02:02:22.46, start: 0.000000, bitrate: N/A
  
  Program 0
  
  Metadata: 0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0
  
    variant_bitrate : 2788912
  
  Stream #0:0: Data: timed_id3 (ID3  / 0x20334449)
  
  Metadata:
  
    variant_bitrate : 2788912
  
  Stream #0:1: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 720x304 [SAR 1:1 DAR 45:19], 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
  
  Metadata:
  
    variant_bitrate : 2788912
  
  Stream #0:2: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp
  
  Metadata:
  
    variant_bitrate : 2788912
  
  [http @ 060662c0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_2.ts' for reading
  
  [hls @ 0600cac0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_2.ts' for reading
  
  [http @ 0606fb40] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_3.ts' for reading
  
  [hls @ 0600cac0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_3.ts' for reading
  
  [http @ 0c2442c0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_4.ts' for reading
  
  [http @ 0606f8c0] Opening 'http://198.144.145.236:1935/ondemand-1/_definst_/mp4:path2/FRENCH.MOVIES/2017.JOHN.WICK.CHAPTER.2.FRN.mp4/media_w1481451763_5.ts' for reading

  I am trying to create an A/V player using ffmpeg library and Delphi. After puzzling and puzzling I found out how to read/decode/sync/display etc...

  I think this behaviour is in some specific situations, because I tested live streams and noticed no problems. In this case this is a video file, while playing my app and ffplay.exe (from ffmpeg not compiled by myself) behaving the same, and skipping packets "every time when the app has to wait while packetqueue is full ?" and loses about 10-30 seconds of audio and video.

  VLC doesn’t seem to have such a like behaviour, while as I understand from VLC credits, they are using ffmpeg or ffmpeg methods imported for decoding/encoding. inspecting vlc source doesn’t make much sense for me because I am a (noob) Delphi programmer. It’s like my main language is Dutch and try to translate form French to German language.

  Please any suggestions how to avoid this, because I think it has to do something with delivery of data from the server and/or read buffer of ffmpeg. If I increase the max size of packetqueue the skipping does happen later and if decrease the size, the skipping happens sooner.

  Including code from my app is not necessary because ffplay.exe has exact the same behavior. You can see debug from ffplay.exe.

• Pydub FFMPEG issue [closed]

  14 janvier, par Nikolai van den Hoven

  I am attempting to use FFMPEG with Pydub to create a program that chops .mp3 files into different words, each contained in their own .mp3 file, but when I run the script I am getting the following error :

  


  PS C:\Users\nik> & C:/Users/nik/AppData/Local/Microsoft/WindowsApps/python3.12.exe "d:/Python/Word Splitter.py"
C:\Users\nik\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.12_qbz5n2kfra8p0\LocalCache\local-packages\Python312\site-packages\pydub\utils.py:170: RuntimeWarning: Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work
  warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)


  


  This is the code I am using.

  


  import os
from pydub import AudioSegment
from pydub.silence import split_on_silence
import speech_recognition as sr
AudioSegment.ffmpeg = r"D:\Python\ffmpeg\bin\ffmpeg.exe"
def mp3_to_words(mp3_file, output_folder):
    # Ensure output folder exists
    os.makedirs(output_folder, exist_ok=True)

    # Load MP3 file
    print("Loading audio file...")
    audio = AudioSegment.from_mp3(mp3_file)

    # Split audio into chunks using silence detection
    print("Splitting audio into chunks...")
    chunks = split_on_silence(
        audio,
        min_silence_len=200,  # Minimum silence duration in ms to consider as a split point
        silence_thresh=audio.dBFS - 14,  # Silence threshold relative to average loudness
        keep_silence=100  # Retain some silence in chunks
    )

    recognizer = sr.Recognizer()

    for i, chunk in enumerate(chunks):
        print(f"Processing chunk {i + 1}/{len(chunks)}...")

        # Save the chunk temporarily
        temp_file = os.path.join(output_folder, f"chunk_{i}.wav")
        chunk.export(temp_file, format="wav")

        # Recognize words in the chunk
        with sr.AudioFile(temp_file) as source:
            audio_data = recognizer.record(source)
            try:
                text = recognizer.recognize_google(audio_data)
                words = text.split()

                # Export each word as its own MP3
                word_start = 0
                for j, word in enumerate(words):
                    word_duration = len(chunk) // len(words)  # Approximate duration per word
                    word_audio = chunk[word_start:word_start + word_duration]
                    word_file = os.path.join(output_folder, f"word_{i}_{j}.mp3")
                    word_audio.export(word_file, format="mp3")
                    word_start += word_duration

            except sr.UnknownValueError:
                print(f"Could not understand chunk {i + 1}.")
            except sr.RequestError as e:
                print(f"Could not request results; {e}")

        # Clean up temporary file
        os.remove(temp_file)

    print(f"Processed {len(chunks)} chunks. Word MP3s saved in {output_folder}.")

if __name__ == "__main__":
    input_file = input("Enter the path to the MP3 file: ").strip()
    output_dir = input("Enter the output folder path: ").strip()

    mp3_to_words(input_file, output_dir)


  


  I have added the Base FFMPEG folder and the bin folder within it to Windows PATH
My PATH variable on Windows 11,
But it does not show up in the variable when I typed PATH into cmd