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• How to create side by side horizontally stacked video with delay in video and audio using ffmpeg-python ?

  29 juillet 2021, par kup

  I am trying to create a video from two videos that will be stacked horizontally but the resulting video is not what i expected. The same video is appearing on both side (left & right). So wondering how that can be achieved ?

  


  The ffmpeg command i tried, which kinda worked :

  


  ffmpeg -i left.mp4 -i right.mp4 -filter_complex "
[0:v]setpts=PTS-STARTPTS[l]; 
[1:v]setpts=PTS-STARTPTS,tpad=start_duration=14:start_mode=add:color=black[r]; 
[l][r]hstack=inputs=2[stacked]; [0:a][1:a]amix=inputs=2[a]
" -map "[stacked]" -map "[a]" -c:a aac -preset superfast result.mp4


  


  ffmpeg-python script that's not working :

  


  in0 = ffmpeg.input('0.mp4')
in1 = ffmpeg.input('right.mkv')
aout = ffmpeg.filter([in0.audio, in1.audio.filter('adelay', "5000|5000")],'amix')
vout = ffmpeg.filter([inv0.video, inv1.video.filter('tpad', start_duration=5, start_mode='add', color='black')], 'hstack')

(
    ffmpeg
    .concat(vout, aout, v=1, a=1)
    .output("out.mkv")
    .run()
)


  


  This script not resulting in the expected output which two videos side-by-side horizontally stacked.

  


• How to add overlay video with opacity and run in loop using ffmpeg-python ?

  30 juillet 2021, par kup

  I am trying the below code :

  


  in0 = ffmpeg.input('left.mkv')
in1 = ffmpeg.input('right.mkv')
aout = ffmpeg.filter([in0.audio, in1.audio.filter('adelay', "5000|5000")],'amix')
vout = ffmpeg.filter([inv0.video, inv1.video.filter('tpad', start_duration=5, start_mode='add', color='black')], 'hstack')

overlay_file = ffmpeg.input(overlay).filter('scale', 1280, 720, force_original_aspect_ratio='decrease')
vout = vout.overlay(overlay_file, x=0, y=0)


(
    ffmpeg
    .concat(vout, aout, v=1, a=1)
    .output("out.mkv")
    .run()
)


  


  But the overlay does not appear to be at top left (0,0) instead it is at top left of the stacked video which is somewhat at (0, 260). Is it possible to make the overlay video to cover full screen and with opacity to run in loop.

  


• How to stream a video from localhost to web browser using video tag ?

  31 juillet 2021, par kup

  Basically what i want to stream a video to my browser both on localhost, using flask and opencv or ffmpeg.

  


  But not sure how to do it.

  


  i tried this :

  


  #!/usr/bin/env python
from flask import Flask, render_template, Response
import cv2
import sys
import numpy

app = Flask(__name__)

def get_frame():
    c=cv2.VideoCapture("output.mkv") 

    while True:
        retval, im = c.read()
        imgencode=cv2.imencode('.jpg',im)[1]
        stringData=imgencode.tostring()
        yield (b'--frame\r\n'
            b'Content-Type: text/plain\r\n\r\n'+stringData+b'\r\n')

    del(c)

@app.route('/vid')
def vid():
     return Response(get_frame(),mimetype='multipart/x-mixed-replace; boundary=frame')


if __name__ == '__main__':
    app.run(host='localhost',port=5000, debug=True, threaded=True)


  


  but its not working may be because it is sending images, how can i stream video ?