CODEWITHSUNDEEP
node.jsffmpegraspberry-pichild-process
Kenny Lim
Kenny Lim

Reputation: 1214

execSync and ffmpeg execution gap

I am not sure if this is a new question but search for 5 minutes doesn't yield any result. I want to use ffmpeg to capture 10 seconds mp4 blocks into files for my other program to post-analysis. Right now, in the code below. I will see 1-1.5 seconds gap between between the generated mp4. Only one process can poke with the /dev/video0 device. I know there's overhead in executing a process, open/close device and file i/o. How can I minimize the gap? Thanks.

const { execSync, exec } = require("child_process");

capture()

function capture() {
while(true) {
  let fileName = getNewFileName();
  let captureCmd = `ffmpeg -hide_banner -loglevel error -t 10 -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 ${fileName}.mp4 -r 1 ${fileName}-%03d.jpg`
  execSync(captureCmd)
}

}

function getNewFileName() {
let date = new Date()

let month = ("0" + date.getMonth()).slice(-2);
let day = ("0" + date.getDay()).slice(-2);
let hour = ("0" + date.getHours()).slice(-2);
let min = ("0" + date.getMinutes()).slice(-2);
let sec = ("0" + date.getSeconds()).slice(-2);

return "output/" + date.getFullYear() + month + day + hour + min + sec;

}

~

Upvotes: 0

Views: 113

Answers (1)

Gyan
Gyan

Reputation: 93008

This is what the segment muxer is meant for

ffmpeg -hide_banner -loglevel error -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 -f segment -segment_time 10 -g 250 ${fileName}-%03d.mp4 -r 1 ${fileName}-%03d.jpg

Upvotes: 1

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