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• opencv-python initial rtmp stream(cv2.VideoCapture(rtmp_url)), it takes a long time

  2 décembre 2022, par yang bai

  Question

  


  

  1. When read the stream from camera or video(with '-re' arg), the opencv initial will takes a long time about 10-30s.

  


  2. And the latency is about 2-3s, any optimzation suggestion ?

  


  


  Enviroment

  


  os : ubuntu 18.04

  


  rtmp serve : nginx + nginx-rtmp-module (default configuration)

  


  stream source : use camera

  


  Code

  


  push code :

  


  cap = cv2.VideoCapture(0)
fps = int(cap.get(cv2.CAP_PROP_FPS))
width = int(cap.get(cv2.CAP_PROP_WIDTH))
height = int(cap.get(cv2.CAP_PROP_HEIGHT))

rtmp_url = 'xxxx'

command = ['ffmpeg',
           '-re',
           '-y',
           '-flags', 'low_delay',
           '-f', 'rawvideo',
           '-vcodec', 'rawvideo',
           '-pix_fmt', 'bgr24',
           '-s', ''.format(width, height),
           '-r', str(fps),
           '-i', '-',
           '-c:v', 'libx264',
           '-pix_fmt', 'yuv420p',
           '-preset', 'ultrfast',
           '-f', 'flv',
           rtmp_url]

p = sp.Popen(command, stdin=sp.PIPE)
while cap.isOpened():
  ret, frame = cap.read()
  if ret:
    p.stdin.write(frame.tostring())
  else:
    break


  


  read code

  


  cap = cv2.VideoCapture(rtmp_url) # this code line will takes long time
...


  


  try to change the nginx conf 'chunk_size', but make no difference.

  


  and try to push in Windows : ffmpeg -f dshow -i video="Integrated Webcam" -s 640*480 -r 15 -vcodec libx264 -preset:v ultrafast -tune:v zerolatency -acodec libfaac -f flv rtmp://192.168.0.199:1935 rtmp_url again, no effect. only reduce a little latency.

  


• Gitlab CI - Combine two docker images into a single stage

  12 mars 2024, par seal.r00t

  I have this gitlab-ci.yaml file. Using this file I execute my k6.io load test from pipeline. Now I need to execute some FFmpeg commands during the run stage, and my question is how do I make the FFmpeg tool available to the run stage. Do I need to grab the image that has FFmpeg and add it next to grafa/k6 or something else ?

  


  default:
  tags:
    - default

workflow:
  name: "$PIPELINE_NAME"

stages:
  - lint
  - setup
  - run
  - teardown

lint:js:
  stage: lint
  image:
    name: tmknom/prettier
    entrypoint:
      - ""
  rules:
    - if: '$CI_PIPELINE_SOURCE == "push"'
      when: always
    - if: '$CI_PIPELINE_SOURCE == "schedule"'
      when: always
  script:
    - prettier --check '**/*.js'

setup:
  stage: setup
  image: alpine
  rules:
    - if: '$CI_PIPELINE_SOURCE == "web"'
      when: always
    - if: '$CI_PIPELINE_SOURCE == "schedule"'
      when: always
  script:
    - echo 'set up!'

run:
  stage: run
  environment:
    name: run
  image:
    name: grafana/k6:latest
    entrypoint: [ "" ]
  artifacts:
    when: always
    paths:
      - summaries/
  rules:
    - if: '$CI_PIPELINE_SOURCE == "web"'
      when: always  # Prevent pipeline run for push event
    - if: '$CI_PIPELINE_SOURCE == "schedule"'
      when: always
  script:
    - ./run.sh

teardown:
  stage: teardown
  image: alpine
  rules:
    - if: '$CI_PIPELINE_SOURCE == "web"'
      when: always
    - if: '$CI_PIPELINE_SOURCE == "schedule"'
      when: always
  script:
    - echo 'tear down!'


  


  I tried adding two name tags under the run stage for using two images but it didn't work and returned a syntax error.

  


  run:
  stage: run
  environment:
    name: run
  image:
    name: grafana/k6:latest
    name: linuxserver/ffmpeg


  


• Get middle line from the output of a command

  14 décembre 2022, par Kishore T

  The following command list the duration of I-frames present in a video file.

  


  ffprobe -i ./test.mp4 -v quiet -skip_frame nokey -select_streams v:0 -of flat -show_entries frame=pkt_pts_time | awk -F'=' '{gsub(/"/, "", $NF); print $NF}'


  


  I'm trying to get the duration of I-frame that is in middle. The output of the above command will be like

  


  0.066667
2.066667
4.066667
9.066667
14.066667
19.066667
24.066667


  


  How do I get the middle value ? Here, I would like to get 9.066667 as the result. If the number of lines is even (say I've 2 values), I need to get the 1st value.

  


  I tried using wc to get the number of lines and sed to print the middle line. But, this straightforward solution required me to run the command twice. I tried piping the command, but I didn't find any solution for storing the value in a variable (from the wc command) and using the same in another command (sed command) while retaining the piped output.