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• H.264 video file size from camera is much bigger than x264 output

  10 août 2020, par Lawrence song

  I have a UVC camera which supports h264 protocol. we can see the h264 listed below when we list all formats supported.

  


  msm8909:/data # ./ffmpeg -f v4l2 -list_formats all -i /dev/video1
ffmpeg version N-53546-g5eb4405fc5-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libxml2 --enable-libxvid --enable-libzimg
  libavutil      56. 56.100 / 56. 56.100
  libavcodec     58. 97.100 / 58. 97.100
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[video4linux2,v4l2 @ 0x4649140] Compressed:        h264 :                H.264 : 1920x1080 1280x720 640x480 320x240
[video4linux2,v4l2 @ 0x4649140] Compressed:       mjpeg :                MJPEG : 1920x1080 1280x720 640x480 320x240


  


  I am running the ffmpeg cmd to record UVC camera video to local device.

  


  ffmpeg -f v4l2 -input_format h264 -framerate 30 -video_size 1280*720 -i /dev/video1 -c copy /sdcard/Movies/output.mkv


  


  The video size is way bigger than running the command below :

  


  ffmpeg -f v4l2 -input_format mjpeg -framerate 30 -video_size 1280*720 -i /dev/video1 -c:v libx264 -vf format=yuv420p /sdcard/Movies/output.mp4


  


  I assume the camera already supports h264 protocol. Thus I don't need to re-encode to 264 formats. However, the video size does not look like an H264 encoded video.

  


• How can ffmpeg concat MP3s with full metadata incl. cover art ?

  13 décembre 2022, par TEN

  Audio books inconveniently split into dozens of MP3s (with spaces in their names) should be merged into one MP3 in a subdirectory (in which ffmpeg version 4.2.7-0ubuntu0.1 is invoked), without time-consuming and possibly degrading conversions, reliably preserving all metadata incl. cover art (present and similar in all MP3s of a title, their differences being significant only in lengths and track numbers).

  


  However, rather than picking the latter from the first input MP3, the https://trac.ffmpeg.org/wiki/Concatenate#protocol loses the cover art, the https://trac.ffmpeg.org/wiki/Concatenate#demuxer documented as more flexible even loses all metadata :

  


  ffmpeg -v verbose -f concat -safe 0 -i <(printf "file '$PWD/%s'\n" ../in\ track*.mp3) -c copy "out.mp3"
...
Input #0, concat, from '/dev/fd/63':
Duration: N/A, start: 0.000000, bitrate: 192 kb/s
Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
Stream #0:1: Video: png, 1 reference frame, rgba(pc), 300x300, 90k tbr, 90k tbn, 90k tbc
Metadata:
title           : 12ae3b8152eaf255ae0315c59400c540.png
comment         : Cover (front)
...
Output #0, mp3, to 'out.mp3':
Metadata:
TSSE            : Lavf58.29.100
Stream #0:0: Audio: mp3, 44100 Hz, stereo, fltp, 192 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (copy)
...
[AVIOContext @ 0x561459f3dac0] Statistics: 1958050 bytes read, 0 seeks
[mp3 @ 0x561459f3f900] Skipping 0 bytes of junk at 110334.
[mp3 @ 0x561459f3f900] Estimating duration from bitrate, this may be inaccurate
No more output streams to write to, finishing.
size=   75793kB time=00:53:03.12 bitrate= 195.1kbits/s speed= 636x
video:0kB audio:75793kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000865%
Input file #0 (/dev/fd/63):
Input stream #0:0 (audio): 121847 packets read (77611658 bytes);
Input stream #0:1 (video): 40 packets read (4358440 bytes);
Total: 121887 packets (81970098 bytes) demuxed
Output file #0 (out.mp3):
Output stream #0:0 (audio): 121847 packets muxed (77611658 bytes);
Total: 121847 packets (77611658 bytes) muxed
[AVIOContext @ 0x561459ef6700] Statistics: 2 seeks, 298 writeouts
[AVIOContext @ 0x561459f39e40] Statistics: 2006324 bytes read, 0 seeks
[AVIOContext @ 0x561459ee0300] Statistics: 5040 bytes read, 0 seek


  


  The metadata incl. cover PNG as detected (as single-frame "video") should end up in the output MP3, but doesn't (even when adding -movflags use_metadata_tags possibly intended for other formats).

  


  -metadata track="1/1" (or without the /1 ?) may be required as the first input MP3 sometimes wrongly starts at a higher number.

  


  How do I make sure no metadata (incl. image) other than track numbers is lost when concatenating MP3s (by protocol or demuxer, from a set of input files with spaces in their names and a wildcard to match across track numbers) ?

  


• OpenCV & RTSP - Python errors

  10 février, par Midhun M

  I’m working on a Python script that reads multiple RTSP streams using OpenCV, detects motion, and saves frames when motion is detected. Initially, I faced issues with ash-colored frames due to H.265 codec, which OpenCV doesn’t support by default. After switching the camera codecs to H.264, the ash-colored frames issue was resolved. However, I’m now encountering decoding errors and glitching frames.

  


  System Specifications :

  


  Processor : Intel Core i3-6100 CPU @ 3.70GHz
RAM:8GB
Resource Usage :
CPU : 35-45%
RAM : 1GB max
Network Speed : 7.4 Mb/s
Disk Usage : 2.3 MB/s

  


  Here’s the Python script I’m using :

  


  import cv2
import os
import datetime
import threading
import argparse
from cryptography.fernet import Fernet

def encrypt_text(text):
    return text

class MotionDetector:
    def __init__(self, base_dir="motion_frames"):
        self.base_dir = base_dir
        self.output_dirs = [os.path.join(self.base_dir, str(i)) for i in range(1, 4)]
        for dir_path in self.output_dirs:
            os.makedirs(dir_path, exist_ok=True)
        self.fgbg_dict = {}

    def initialize_fgbg(self, camera_name):
        if camera_name not in self.fgbg_dict:
            self.fgbg_dict[camera_name] = cv2.createBackgroundSubtractorMOG2(history=500, varThreshold=35, detectShadows=True)

    def detect_motion(self, frame, camera_name):
        self.initialize_fgbg(camera_name)
        fgmask = self.fgbg_dict[camera_name].apply(frame)
        thresh = cv2.threshold(fgmask, 200, 255, cv2.THRESH_BINARY)[1]
        thresh = cv2.dilate(thresh, None, iterations=2)
        contours, _ = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

        motion_detected = any(cv2.contourArea(contour) > 500 for contour in contours)
        return motion_detected

    def save_frame(self, frame, camera_name, count):
        folder_index = (count - 1) % 3  # This will rotate between 0, 1, and 2
        output_dir = self.output_dirs[folder_index]
        timestamp = datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
        filename = f"{camera_name}_Entireframe_object_{count}_{timestamp}.jpg"
        name = encrypt_text(filename)
        pathname = os.path.join(output_dir, f'{name}.jpg')
        cv2.imwrite(pathname, frame)
        # print(f"Motion detected: {pathname}")

def process_camera_stream(rtsp_url, camera_name, detector, stop_event):
    cap = cv2.VideoCapture(rtsp_url, cv2.CAP_FFMPEG)
    print("Started Camera : ",camera_name)
    count = 0

    while not stop_event.is_set():
        ret, frame = cap.read()
        if not ret:
            print(f"Connection lost: {camera_name}. Reconnecting...")
            cap.release()
            cap = cv2.VideoCapture(rtsp_url)
            continue

        if detector.detect_motion(frame, camera_name):
            count += 1
            detector.save_frame(frame, camera_name, count)

    cap.release()

def main():
    parser = argparse.ArgumentParser(description='RTSP Motion Detection')
    parser.add_argument('--output', type=str, default="motion_frames", help='Output directory')
    args = parser.parse_args()

    rtsp_urls = {
        "Camera1": "rtsp://admin:J**@884@192.168.1.103:554/cam/realmonitor?channel=1&subtype=1&protocol=TCP",
        "Camera2": "rtsp://admin:J***@884@192.168.1.105:554/cam/realmonitor?channel=1&subtype=1&protocol=TCP",
        "Camera3": "rtsp://admin:J***@884@192.168.1.104:554/cam/realmonitor?channel=1&subtype=1&protocol=TCP",
        "Camera4": "rtsp://admin:J@884@192.168.1.101:554/cam/realmonitor?channel=1&subtype=1&protocol=TCP",

        "Camera5": "rtsp://admin:admin123@192.168.1.33:554/Streaming/Channels/301&protocol=TCP",
        "Camera6": "rtsp://admin:admin123@192.168.1.33:554/Streaming/Channels/401&protocol=TCP",
        "Camera7": "rtsp://admin:admin123@192.168.1.33:554/Streaming/Channels/701&protocol=TCP",
    }

    detector = MotionDetector(base_dir=args.output)
    stop_event = threading.Event()
    threads = []

    try:
        for camera_name, url in rtsp_urls.items():
            thread = threading.Thread(target=process_camera_stream, args=(url, camera_name, detector, stop_event))
            thread.start()
            threads.append(thread)
        
        while True:
            pass
    except KeyboardInterrupt:
        print("Stopping...")
        stop_event.set()
        for thread in threads:
            thread.join()


if __name__ == "__main__":
    main()



  


  i am getting glitched some images are having glitches, i am attaching some image examples. When running the script, I’m getting the following decoding errors in the terminal :

  


  [h264 @ 00000185da541a80] error while decoding MB 26 1, bytestream -29
[h264 @ 00000185d8fefb00] error while decoding MB 23 31, bytestream -5
[h264 @ 00000185cedcc140] error while decoding MB 36 35, bytestream -7
[h264 @ 00000185d8ae73c0] cabac decode of qscale diff failed at 40 35
[h264 @ 00000185d8ae73c0] error while decoding MB 40 35, bytestream -5
[h264 @ 00000185da541a80] error while decoding MB 32 30, bytestream -11
[h264 @ 00000185e15f8500] error while decoding MB 16 34, bytestream -11
[h264 @ 00000185e15f9700] error while decoding MB 9 33, bytestream -9
[h264 @ 00000185e15fb680] error while decoding MB 6 32, bytestream -5
[h264 @ 00000185e15f8500] error while decoding MB 23 23, bytestream -7
[h264 @ 00000185e15fb680] error while decoding MB 28 23, bytestream -5
[h264 @ 00000185e15fa000] error while decoding MB 27 19, bytestream -37
[h264 @ 00000185e15fa900] error while decoding MB 6 27, bytestream -7
[h264 @ 00000185e15f8500] error while decoding MB 14 12, bytestream -5
[h264 @ 00000185e15f9280] error while decoding MB 22 35, bytestream -7
[h264 @ 00000185d8fefb00] error while decoding MB 31 32, bytestream -7
[h264 @ 00000185e15fb680] error while decoding MB 5 24, bytestream -5
[h264 @ 00000185d8ae7b00] error while decoding MB 29 26, bytestream -7


  


  i have ip cameras & analog cameras, the error from ip
camera are too frequent compared to analog camera.

  


  Questions :

  


  

  1. What could be causing these decoding errors and glitching frames ?

  


  2. Are there any specific settings or configurations I need to adjust in OpenCV or FFMPEG to handle H.264 streams more reliably ?

  


  3. Could this be related to network latency, hardware limitations, or OpenCV’s handling of RTSP streams ?

  


  4. Are there any alternative approaches or libraries I can use to improve the stability of RTSP stream processing ?

  


  


  the glitches are more on person or moving objects & i have no idea if the error and glitches are rtelated

  


  What I’ve Tried :

  


  

  1. Switched camera codecs from H.265 to H.264 (resolved the ash-colored frames issue).

  


  2. Tested the script with a single camera using a different object detection script, but the same errors occurred.

  


  


  I want the frames saved without the glitches