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• Not able to display first frame of mp4 file with opencv and python

  22 juin 2024, par Jatin Parmar

  I am learning opencv from the youtube and I just created the very basic program in python

  


  import cv2 as cv

sources = cv.VideoCapture("test.mp4");

if not sources.isOpened():
    print("Failed to open video file");
else:
    print("video file opened successfully");

win_name = "test"
cv.namedWindow(win_name)

(has_input, frame) = sources.read()
if has_input:
    cv.imshow(win_name, frame[...,::-1])
    cv.waitKey(0)

sources.release()


  


  But when i run the programm i have following errors, i have tried googling it but i didn't find any working solution

  


  [av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
video file opened successfully
[av1 @ 0x55e6dc97a7c0] Your platform doesn't suppport hardware accelerated AV1 decoding.
[av1 @ 0x55e6dc97a7c0] Failed to get pixel format.


  


  I have no i idea how to fix this ?

  


• How to use temporary files and replace the input when using ffmpeg in batch ?

  18 juin 2020, par Fabio Freitas

  What I did so far :

  



  I learned with this answer that I can use negative mapping to remove unwanted streams (extra audio, subtitles) from my video files.

  



  I them proceeded to apply it to a few dozen files in a folder using a simple for /r loop on Windows' cmd. Since I thought this process as some kind of trim, I didn't care about my original files and wanted ffmpeg to replace them, which of course it cannot.

  



  I tried to search a bit further and find ways to work around this issue without simply using a new destination an manually replacing files afterwards, but had no luck.

  



  However a lot of my findings seemed to indicate that ffmpeg has capabilities to use external temporary files for some of it's functions, even though I couldn't really find more onto it.

  



  What I want to do :

  



  So is there any way that I can make ffmpeg remove those extra streams and them replace the original file somehow. I'll also be needing to use this to multiple file, by I don't think this would be a big issue...

  



  I really need this to be done with ffmpeg, as learning the tool to it's full extent is a long-therm goal of mine and I want to keep working on that curve, but as for batch/cmd, I prefer it because I haven't properly learned a programming language yet (even if I often meddle with a few), but I would be happy to use suggestions of any kind for handling ffmpeg !

  



  Thank you !

  


• FFMPEG command works in shell ! but not in my node.js

  29 juillet 2021, par Kuno Kim

  When my ffmpeg command is built by my node.js application it does not run.

  



  error

  



  Unrecognized option 'ss 3.2 -t 1.9 -i videoplayback.mp4 -vf  fps=15,scale=240:-1:flags=lanczos,palettegen palette.png'.


  



  command

  



  ffmpeg -ss 3.2 -t 1.9 -i videoplayback.mp4 -vf \ fps=15,scale=240:-1:flags=lanczos,palettegen palette.png


  



  this is my code

  



  var child_process = require('child_process')

function recordVideo() {

var spawn = child_process.spawn;

var args = [
    '-y', 
    '-ss', '3.2',
    '-t', '1.9', 
    '-i', '../getback/bin/videos/videoplayback.mp4', 
    '-vf', ' \\ ', 
    'fps=', '15', 
    'scale=', '320:-1', 
    'flags=','lanczos,palettegen palette.png', 
];



var ffmpeg = spawn('ffmpeg', args);

ffmpeg.stdout.on('data', function (data) {
    console.log(data);
});

ffmpeg.stderr.on('data', function (data) {
    console.log('grep stderr: ' + data);
});

ffmpeg.on('close', (code) => {
    console.log('child process exited with code ' + code);
}); 
};
recordVideo();


  



  what is this error ?
I think.. 'fps=', '15', In the following code 
 '=' options a problem.

  



  I am still learning English.
I'm sorry if it was hard to understand.