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• FFmpeg cannot extract correct first frame - always extract the second frame [closed]

  21 octobre 2024, par Cai Yu

  I am on macos Ventura 13.2.1, on Macbook Pro M1Max.

  


  The video is number counting animation video. From 2 to 125. The number on first frame is 2. The number on last frame is 125. The number plus one on each frame. You can download the video here.

  


  NOTE that :
First, you hit space bar to play it in Finder, you can see the first frame of the video is number 2.

  


  Second, in professional Video editing software - davinci resolve, on the timeline, you can see the first frame is number 2.

  


  Now I try to use FFmpeg to extract the first frame of the video.
First Try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -vframes 1 /Users/chris/Downloads/1.png


  


  The output png image is number 3. So it's actually the second frame.

  


  Second try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -frames:v 1 /Users/chris/Downloads/1.png


  


  The output png image is still the second frame - the number 3.

  


  Third try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -vf "select=eq(n\,0)" -q:v 3 /Users/chris/Downloads/1.png


  


  The output image is sitll the wrong second frame.

  


  NOTE that :

  


  first : all these three method are from internet. And a lot of people voted correct answer for this question.

  


  second : all their output on my system is the incorrect second frame, not the first frame.

  


  I cannot find what's wrong. Hope friend here help me.

  


• Converting an audio file from .oga format to .mp3 using ffmpeg package on nodeJs produces a max of 3 seconds output file no matter the input duration

  15 janvier 2024, par JnrLouis

  I am downloading an audio file in .oga format and saving it. Then I am trying to convert the file to .mp3 format, but the issue is the output file is always truncated and a maximum of 3 seconds. I have gone through the fluent-ffmpeg library and I can't seem to find what I'm doing wrong.

  


  I have ffmpeg installed and I'm using the fluent-ffmpeg library. The downloaded .oga file doesn't seem to have any issues, the issue is after it gets converted to .mp3.

  


  I also tried converting to .wav, and I faced the same issue.

  


  Below is my current code :

  


  const fs = require("fs");
const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path;
const ffmpeg = require('fluent-ffmpeg');
ffmpeg.setFfmpegPath(ffmpegPath);
const axios = require("axios");

const inputPath = __dirname + '/audio/input.oga';
const outputPath = __dirname + '/audio/output.mp3';

const saveVoiceMessage = async (url) => {
    try {
        const response = await axios({
            method: 'GET',
            url: url,
            responseType: 'stream'
        });
        const inStream = fs.createWriteStream(inputPath);
        await response.data.pipe(inStream);
    } catch (error) {
        console.error(error);
    }
}

const convertToMp3 = async () => {
    try {
        const outStream = fs.createWriteStream(outputPath);
        const inStream = fs.createReadStream(inputPath);
        // I also tried using the inputPath directly, still didn't work
        ffmpeg(inStream)
            .toFormat("mp3")
            .on('error', error => console.log(`Encoding Error: ${error.message}`))
            .on('exit', () => console.log('Audio recorder exited'))
            .on('close', () => console.log('Audio recorder closed'))
            .on('end', () => console.log('Audio Transcoding succeeded !'))
            .pipe(outStream, { end: true })
    } catch (error) {
        console.error(error);
    }
}

const saveAndConvertToMp3 = async (url) => {
    try {
        await saveVoiceMessage(url);
        await convertToMp3();
        }

    } catch (error) {
        console.error(error);
    }
}


  


• Why videos generated using FFMPEG in android doesn't play on all video players ?

  9 juillet 2014, par Divya Motiwala

  I am trimming a video using FFMPEG command mentioned below in android. It only plays with MX Player and not the default or any other player.

    String trimVideoUrl = mFfmpegInstallPath + " -y -i " +
  
              videoPath + " -ss " +
  
               hms + " -t "+ duration + 
  
               "  -async 1 -preset ultrafast -strict -2 "+ OUTPUT_FILENAME;

  Please let me know what other paramaters will help to make it run on other players. I did try -c:v libx264 but didn’t help.