FFMPEG image sequence to video with specific duration

Question

Let's say you have a folder with 40 .jpegs (frames captured from a webcam).

How to convert it to a video exactly 3 seconds long?

Using FFmpeg on Windows.

Solution

1. Rename images files sequentially:
   • a. Explorer (no 3rd party tools) method: Sort pictures by date (or filename) so oldest is at top. Select them all, right-click oldest one on top, rename, type img. They all are renamed in this format: img (1).jpg, img (2).jpg, img (11).jpg
   • b. I’m told this powershell command can do: dir *.jpg | %{$x=0} {Rename-Item $_ -NewName "Base$($x.tostring('000000')).jpg"; $x++ }
   • c. AntRename Portable can easily do this
2. Run this command: ffmpeg -i "img (%d).jpg" timelapse.mp4
   • a. -i says this is the input
   • b. %d is a sequence pattern (look for decimals/numbers) that’ll match filenames like this: img (1).jpg, img (2).jpg, img (11).jpg. Documentation mostly gives example %03d which will match zero-padded filenames: img001.jpg, img002.jpg
   • c. Additional options:
   • C1. -f image2 forces the image2 muxer/demuxer which it usually figures out on its own
   • C2. Framerate default is 25fps, customize it (-r 15). I set to 1fps with 21 pics to MP4 & it was a black video so mileage may vary, but I think MP4 format is to blame

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Useful links: • https://trac.ffmpeg.org/wiki/Slideshow • https://en.wikibooks.org/wiki/FFMPEG_An_Intermediate_Guide/image_sequence • https://ffmpeg.org/faq.html#How-do-I-encode-single-pictures-into-movies_003f • https://ffmpeg.org/ffmpeg-formats.html#image2-1 • https://photo.stackexchange.com/questions/1254/which-software-to-assemble-a-time-lapse-from-images

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Things that didn't work in Windows ffmpeg build (nothing is stopping you from doing it in Linux): https://trac.ffmpeg.org/wiki/Slideshow

• Wildcards *: Failed (err msg: globbing is not supported by this libavformat build): ffmpeg -pattern_type glob -i *.jpg timelapse.mp4
• concat demuxer with text file that mostly has file paths to all pictures. Failed (err msg: unsafe file name, operation not permitted): ffmpeg -f concat -i input.txt timelapse.mp4
• Piping (their example using cat linux command, I tried dir). Failed below commands give this error: pipe:: Invalid data found when processing input. dir *.jpg /s /b | ffmpeg -i - timelapse.mp4 & copy *.jpg | ffmpeg -i - timelapse.mp4
  • Failed below commands give this error: Could not find codec parameters for stream 0 (Video: none, none): unknown codec. copy *.jpg | ffmpeg -f image2pipe -i - timelapse.mp4 & dir *.jpg /s /b | ffmpeg -f image2pipe -i - timelapse.mp4

Comments

[gregg]

Which operating system? I assure you it matters since I did this recently. You didn't detail if you've researched other posts I am confident speak about this

[SharpAffair]

@gregg I've researched other posts, but haven't found any exact matches.

[gregg]

If you could I'd update your question with links to those & why they didn't work so people know not to suggest those & that you did some homework :)

[SharpAffair]

Is it possible to keep standard frame rate (25), but accomplish the desired duration of the video by adding/skipping frames?

[gregg]

You have 40 pictures. To get a 3sec video you'd have to do 13-14fps video (40/3). If you don't want certain pictures included delete/move those & then redo the math to get the new FPS with the sole purpose of controlling the length of the clip

[SharpAffair]

The number of pictures will vary. And I need to keep the framerate 25. To automatically match the length by inserting/removing frames, I can run an extra command: ffmpeg -i customframerate.avi -qscale 0 -r 25 -y standardframerate.avi, but any way to accomplish it from beginning?

[gregg]

No idea. This is literally my second project/time using ffmpeg. I just happened to have a lot of notes/trouble with it so I shared. Please upvote if you appreciate the input, you don't have to accept it as the answer if you don't want to