Sur d’autres sites (8015)

• Shows improper/corrupted TS segments from Opencv webcam and FFmpeg

  30 juin 2020, par playmaker420

  Im experimenting with opencv and ffmpeg to create a live hls stream from the webcam using some scripts

  


  The ffmpeg version i use is 3.4

  


  frame-detection.py

  


  import numpy as np
import cv2
import sys


cap = cv2.VideoCapture(0)

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()
    framestring = frame.tostring()
    sys.stdout.write(str(framestring))

    # Display the resulting frame
    cv2.imshow('frame', frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()


  


  hlslive_generator.sh

  


  #!/bin/bash

# Create folder from args
mkdir -p $1

# Get into the folder
cd $1

# Start running FFmpeg HLS Live streaming
python frame-detection.py | ffmpeg  \
  -f rawvideo \
  -framerate 10 \
  -video_size 640x480 \
  -i - foo.mp4  \
  -vcodec libx264 \
  -acodec copy \
  -pix_fmt yuv420p \
  -color_range 2 \
  -hls_time 1 \
  -hls_list_size 5 \
  -hls_flags delete_segments \
  -use_localtime 1 \
  -hls_segment_filename '%Y%m%d-%s.ts' \
  ./playlist.m3u8


  


  I used the following commands to run the scripts and it creates a folder and generate ts segments in it

  


  ./hlslive_generator.sh hlssegments


  


  The issue i face here is with the created ts files, on playing these segments with the video player it shows improper/corrupted segments.

  


  Can someone help me to identify the issue ? Thanks in advance

  


• Play just audio (without launching a window)

  6 août 2017, par Paradise on E

  Is there a way to hide ffplay window on Windows ? I want to play audio files (some of them have video streem as well), but I don’t want a window to appear. Is there any way to hide window completelly ?

  I took a look at their documentationa and I didn’t find a way to do it. I also searched on the internet and didn’t find anything useful. Everyone are asking "Why in the world do you want to hide window..." and similar questions instead of actually posting an answer on how to do it.

  I believe ffplay doesn’t have native way to hide window. So, what are the most easiest alternative ? One of the alternatives would be to download ffplay source code, modify it and recompile it, but it is definitelly not an easy and quick way.

  Is there any way I can launch a process without showing window. It would be great if there is some way to achieve it when ffplay is launched from Node.js (becuase I am using Node.js’s module child_process to play audio files). So, how can I hide ffplay’s window ?

  My current code is following :

  var cp = require('child_process');
  
  var proc = cp.spawn('ffplay', [
  
    '-no_banner',
  
    '-loglevel', 'panic',
  
    playlist.splice(Math.random() * playlist.length | 0, 1)[0]
  
  ]);

  Question

  How to hide ffplay’s window ? If it is possible using ffplay native arguemnts (which I didn’t find in ther documentation) then what arguments to use ? If there is no native way, then is it possible to do it using Node.js’s module child_process ? If not, is there any other way I can hide ffplay’s window ? Again, I must note that some of files I play have video stream as well. So, is there any way to hide ffplay’s window ?

  Thanks in advance.

• Playback : audio-video synchronization algorithm

  7 août 2016, par Rick77

  I’m in the process of creating a very basic video player with the ffmpeg libraries and I have all the decoding and re-encoding in place, but I’m stuck on audio video synchronization.

  My problem is, movies have audio and video streams muxed (intertwined) in a way that audio and video comes in "bursts" (a number of audio packets, followed by juxtaposed video frames), like this, where each packet has its own timestamp :

  A A A A A A A A V V V V A A A A A A A V V V V ...
  
  
  
  A: decoded and re-encoded audio data chunk
  
  V: decoded and re-encoded video frame

  supposedly in a way to prevent too much audio to be processed without video, and the other way around.

  Now I have to decode the "bursts" and send them to the audio/video playing components in a timely fashion, and I am a bit lost in the details.

  1. is there a "standard" strategy/paradigm/pattern to face this kind of problems ?
  2. are there tutorials/documentation/books around explaining the techniques to use ?
  3. how far can the muxing go in a well coded movie ?

  Because I don’t expect anything like this :

  AAAAAAAAAAA .... AAAAAAAAAAAAA x10000 VVVVVVVVVVVVVV x1000
  
  audio for the whole clip followed by video

  or this :

  VVVVVVVVVVVV x1000 AAAAAAAAAAA...AAAAAAAAA x1000    
  
  all video frames followed by the audio

  to happen in a well encoded video (after all, preventing such extremes is what muxing is all about...)

  Thanks !

  UPDATE : since my description might have been unclear, the issue is not with how the streams are, or about how to decode them : the whole audio/video demuxing, decoding, rescaling and re-encoding is set and sound, and each chunk of data has its own timestamp.

  My problem is what to do with the decoded data without incurring in buffer overrun and underrun and, generally, clogging my pipeline, so I guess it might be considered a "scheduling" problem.