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• ffmpeg perspective filter animation error

  17 mars 2021, par eeun

  I'm trying to create a pseudo-3d pan effect in ffmpeg using the perspective filter.

  


  Here is a sample for the starting point...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=x0=200:y0=200:x1=1600:y1=0:x2=200:y2=700:x3=1600:y3=900[skew]" -an -map [skew] "skew-start.mp4"


  


  And here is a sample for the end point...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=x0=0:y0=0:x1=1600:y1=0:x2=0:y2=900:x3=1600:y3=900[skew]" -an -map [skew] "skew-end.mp4"


  


  So far so good. Adding the animation would give this...

  


  ffmpeg -y -filter-complex "color=black:s=1600x900,trim=0:5,drawgrid=width=100:height=100:thickness=2:color=white,perspective=eval=frame:x0='200-(200*t/5)':y0='200-(200*t/5)':x1=1600:y1=0:x2='200-(200*t/5)':y2='700+(200*t/5)':x3=1600:y3=900[skew]" -an -map [skew] skew.mp4


  


  This is where the problem occurs. I get an error saying [Eval @ 000000f36ebfebf0] Undefined constant or missing '(' in 't/5)' Error while filtering: Invalid argument

  


  The perspective docs say it should work with an eval=frame option. Anyone got any ideas ? Does this look like a bug in ffmpeg ? I'm using the latest version, 4.3.2.

  


• ffmpeg : audio sync issue with video (too many approaches ?)

  31 mai 2019, par Serg

  I have input video which is out of sync. Either audio is ahead either video is ahead.

  How can I make them sync correctly and keeping the length of video(offset is known)

  There are so many ways in the internet with different approaches... so I’m confusing which one is better ?

  -ss time1 -i input.mp4 -t time2

  or

  -i input.mp4 -ss 2-t time2

  same with

  -ss -to
  
  
  
  -itsoffset 
  
  
  
  adelay

  should I also use -shortest ?

  Do I need to separate audio and video before sync ?

  ffmpeg -i input-video.mp4 -vn -acodec copy output-audio.aac
  
  ffmpeg -i input-video.mp4 -vcodec copy -an output-video.mp4

  are the above approaches faster then trim ?

  and the last question : is it possible to have them together - sync with above command and then trim ?

  Thanks in advance !

• Write EPIPE error when using ffmpeg with copy option with ytdl-core

  20 juillet 2022, par squeaky2137

  Using the following code i get a write EPIPE error. This is caused by the copy option as when i remove that option it works just takes forever. Any idea what would be the fix to this ?

  


  const audio = ytdl(videoURL, { quality: 'highestaudio', filter: 'audioonly', highWaterMark: 1 << 25 })
            .on('progress', (_, downloaded, total) => {
                tracker.audio = { downloaded, total };
            });
const video = ytdl(videoURL, { quality: 'highestvideo' })
  .on('progress', (_, downloaded, total) => {
      tracker.video = { downloaded, total };
   });

const ffmpegProcess = cp.spawn(ffmpeg, [
            '-loglevel', '8', '-hide_banner',
            '-progress', 'pipe:3',
            '-i', 'pipe:4',
            '-i', 'pipe:5',
            '-map', '0:a',
            '-map', '1:v',
            '-c:v', 'copy',
            'out.webm',
        ], {
            windowsHide: true,
            stdio: [
                'inherit', 'inherit', 'inherit',
                'pipe', 'pipe', 'pipe',
            ],
        });
        ffmpegProcess.on('close', () => {
            console.log('done');
        });

  
        ffmpegProcess.stdio[3].on('data', chunk => {
            if (!progressbarHandle) progressbarHandle = setInterval(showProgress, progressbarInterval);
            const lines = chunk.toString().trim().split('\n');
            const args = {};
            for (const l of lines) {
                const [key, value] = l.split('=');
                args[key.trim()] = value.trim();
            }
            tracker.merged = args;
        });
        audio.pipe(ffmpegProcess.stdio[4]);
        video.pipe(ffmpegProcess.stdio[5]);