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• Should H.264 bit rate be multiples of 8 ?

  31 août 2016, par Dan Sharp

  I’m working on a video platform receiving H.264 video and building an HLS stream (transmuxing the H.264 to Mpeg2 TS segments via calls to ffmpeg).

  I wanted to set the bit rate to be about 2000 kbps, but I’m wondering : does it matter if it’s 2000 or 2048 ?

  In other words, do things calculate better if the bit rate is multiples of 8, like 512 or 2024 or 2048 ?

  I don’t know enough about how the bit rate is used, either on the sending side (camera) or on the processing side (ffmpeg).

  From tests... I can’t see any noticeable difference between 2000 and 2048, but maybe one is slightly better than another for the transmuxing and segmenting ?

  I welcome any thoughts/advice.

• Scrolling Effect of an Image using FFmpeg [closed]

  5 juin, par neeebzz

  I want to create an mp4 video of 40 seconds where an image just floats from top to bottom and vice versa.

  


  I am using the following ffmpeg command :

  


  ffmpeg 
    -loop 1 
    -t 40 
    -i ./input.jpg 
    -filter_complex [0]scale=800:-1[s0];[s0]crop=h=450:w=800:x=0:y=(ih-450)*(3*pow(t/40.241\,2) - 2*pow(t/40\,3))[s1];[s1]scale=800:400[s2] 
    -map [s2] 
    -pix_fmt yuv420p 
    -preset medium 
    -r 30 
    -vcodec libx264 
    ./output.mp4 -y


  


  The animation is working as expected however the motion is very jerky. How can I smooth it out ?

  


  Ffmpeg version :

  


  ffmpeg version 5.1.6-0+deb12u1 Copyright (c) 2000-2024 the FFmpeg developers


  


• How to send a camera capture frame to YouTube streaming using ffmpeg

  2 mars 2024, par 유혜진

  import subprocess 
import cv2

# YouTube streaming settings
YOUTUBE_URL = "rtmp://a.rtmp.youtube.com/live2/"
KEY = "..."

# OpenCV camera setup
cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

# FFmpeg command for streaming
command = [r"C:\utility\ffmpeg\ffmpeg-2024-02-22-git-76b2bb96b4-full_build\ffmpeg-2024-02-22-git-76b2bb96b4-full_build\bin\ffmpeg.exe",
            '-f', 'rawvideo',
            '-pix_fmt', 'bgr24',
            '-s', '640x480',
            '-i', '-',
            '-ar', '44100',
            '-ac', '2',
            '-acodec', 'pcm_s16le',
            '-f', 's16le',
            '-ac', '2',
            '-i', 'NUL',   
            '-acodec', 'aac',
            '-ab', '128k',
            '-strict', 'experimental',
            '-vcodec', 'h264',
            '-pix_fmt', 'yuv420p',
            '-g', '50',
            '-vb', '1000k',
            '-profile:v', 'baseline',
            '-preset', 'ultrafast',
            '-r', '30',
            '-f', 'flv', 
            f"{YOUTUBE_URL}/{KEY}",]

# Open a subprocess with FFmpeg
pipe = subprocess.Popen(command, stdin=subprocess.PIPE)

while True:
    # Read a frame from the camera
    ret, frame = cap.read()
    if not ret:
        break

    # Display the frame
    cv2.imshow('Frame', frame)
    cv2.waitKey(1)  # Wait for 1ms

    # Send the frame through the pipe for streaming
    pipe.stdin.write(frame.tobytes())

    # Check for 'q' key press to stop streaming
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# Release resources
cap.release()
cv2.destroyAllWindows()


  


  I'm trying to implement capturing the camera screen using opencv and transmitting this frame to the YouTube streaming broadcast via ffmpeg. YouTube streaming does start when I run this code. However, it appears to be a black screen, not a camera screen. I don't see what the problem is.

  


  I didn't even start streaming at first, but I changed the command option to various things, and when I ran the code, I succeeded in starting streaming. There are many references to transmitting mp4, but there are not many references to transmitting real-time capture. I'm going to process the camera screen using opencv and then send it to streaming. I don't know what the problem is. Please help me.