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• Increase processing speed FFmpeg

  12 juillet 2018, par Yarik Denisyk

  I try to scale video from a gallery using FFmpeg library on android.
  I am using the following command :

  val command = arrayOf("-i", background, "-vf", "scale=$width :$height", out)

  But for it`s very slow. For the video 10 sec, I need to wait around one minute.
  My video resolution 2160x3840
  As I understand now FFmpeg uses CPU for processing. Do have some way to use GPU or make it process faster ?

• How to slow down the ouput speed of ffmpeg while streaming to a RTMP server ?

  25 avril 2023, par Loc Bui Nhien

  I'm currently trying to process multipul short videos (each is about 0.5s long) to be stream on a RTMP server. However, the output/fps/speed when sending is too high (results printed here), making the server crashed very often.

  


  Here is the the code and settings that I'm using :

  


  import cv2
import ffmpeg
import av
import numpy as np
import os
import subprocess

url = "rtmp://..."
key = "..."
rtmp_url = url + "/" + key

cap = cv2.VideoCapture('traffic.mp4')

# gather video info to ffmpeg
fps = int(cap.get(cv2.CAP_PROP_FPS))
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

# command and params for ffmpeg
command = ['ffmpeg',
           '-y',
           '-f', 'rawvideo',
           '-vcodec', 'rawvideo',
           '-pix_fmt', 'bgr24',
           '-s', "{}x{}".format(width, height),
           '-i', '-',
           '-r', '20',
           '-c:v', 'libx264',
           '-pix_fmt', 'yuv420p',
           '-preset', 'slow',
           '-f', 'flv',
           rtmp_url]

# using subprocess and pipe to fetch frame data
p = subprocess.Popen(command, stdin=subprocess.PIPE, shell=True)

received_video_path = 'ReceivedRecording'
while True:
    video_files = [filenames for filenames in sorted(os.listdir(received_video_path), reverse=True)]
    # Loop through the videos and concatenate them
    for filename in video_files[:len(video_files)-3]:
        video = cv2.VideoCapture(os.path.join(received_video_path,filename))

        # Loop through the frames of each video
        while True:
            ret, frame = video.read()
            if not ret:
                # End of video, move to next video
                video.release()
                break
            
            p.stdin.write(frame.tobytes())

        os.remove(os.path.join(received_video_path, filename))


  


  The same settings work fine with the webcam, but I can not control the speed and fps of it sending to the server. The stream on the server seems to work fine with a steady 20fps as intended.

  


• avfilter/f_realtime : add option to scale speed

  1er mai 2019, par Moritz Barsnick

  avfilter/f_realtime : add option to scale speed
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/f_realtime.c