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FFmpeg can capture images from videos that can be used as thumbnails to represent the video. Most common ways of doing that are captured in the FFmpeg Wiki.

But, I don't want to pick random frames at some intervals. I found some options using filters on FFmpeg to capture scene changes:

The filter thumbnail tries to find the most representative frames in the video:

ffmpeg -i input.mp4 -vf  "thumbnail,scale=640:360" -frames:v 1 thumb.png

and the following command selects only frames that have more than 40% of changes compared to previous (and so probably are scene changes) and generates a sequence of 5 PNGs.

ffmpeg -i input.mp4 -vf  "select=gt(scene\,0.4),scale=640:360" -frames:v 5 thumb%03d.png

Info credit for the above commands to Fabio Sonnati. The second one seemed better as I could get n images and pick the best. I tried it and it generated the same image 5 times.

Some more investigation led me to:

ffmpeg -i input.mp4 -vf "select=gt(scene\,0.5)" -frames:v 5 -vsync vfr  out%02d.png

-vsync vfr ensures that you get different images. This still always picks the first frame of the video, in most cases the first frame is credits/logo and not meaningful, so I added a -ss 3 to discard first 3 seconds of the video.

My final command looks like this:

ffmpeg -ss 3 -i input.mp4 -vf "select=gt(scene\,0.5)" -frames:v 5 -vsync vfr out%02d.jpg

This was the best I could do. I have noticed that since I pick only 5 videos , all of them are mostly from beginning of the video and may miss out on important scenes that occur later in the video

I would like to pick your brains for any other better options.

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Nice command examples. FWIW, I didn't run into any issues with FFmpeg-generated JPEG pictures on OS X (10.8, FFmpeg 1.1 and below). Your second to last command works fine for me—so does the last—and none of these results in blank JPG files. I did compile with libopenjpeg.. not sure if that makes a difference. – slhck Jan 18 '13 at 8:46
Thanks slhck. Edited the question with ffmpeg config/version details. I have not upgraded to 1.1 on this machine. I will do that and see if it changes any results. – d33pika Jan 18 '13 at 8:51
So you're on Ubuntu? Can you try the latest Git Master version from a static build or compiling yourself and running again? Or the latest stable. I just checked, it uses the mjpeg encoder for me as well, and I also checked jpegoptim and exiv2, both of which work fine for me with all the JPG results from your example commands. – slhck Jan 18 '13 at 8:59
I updated, and it works now! I guess the previous version had some bugs. – d33pika Jan 18 '13 at 9:37
Can you go ahead and post the solution- new version, preferably with link to changelog showing the bug you encountered and subsequently fixed with new version? – Lizz Mar 16 '13 at 7:15
up vote 14 down vote accepted

How about looking for, ideally, the first >40%-change frame within each of 5 time spans, where the time spans are the 1st, 2nd, 3rd, 4th, and 5th 20% of the video.

...and maybe you could split it into 6 time spans and disregard the 1st one to avoid credits.

In practice, this would probably mean setting the fps to a low number while also applying your scene change check and your argument to throw out the first bit of the video.

...something like:

ffmpeg -ss 3 -i input.mp4 -vf "select=gt(scene\,0.4)" -frames:v 5 -vsync vfr fps=fps=1/600 out%02d.jpg
share|improve this answer
Yes, this does help in picking thumbnails from different sections of the Video. thanks! – d33pika Jul 18 '13 at 5:56
Completely black or white images get picked up.How do I avoid those? – d33pika Jul 18 '13 at 5:57
As for white frames, well now it's getting complicated, but it still looks like there is a way: 1. strip out black frames 2. negate (white turns to black) 3. strip out white frames 4. negate again 5. extract thumbnails (If you do manage to strip out the black or white frames, especially on one line, can you post it back here? I can add it to the answer for future readers. ...or actually you could create a new question and answer it. I would definitely upvote it.) – A.M. Jul 18 '13 at 12:09
To avoid boring images such as plain black and white: generate more thumbnails than you need, compress them with jpeg, and choose the images with larger file size. This works surprisingly well by itself to get decent thumbnails. – Sam Watkins Aug 6 '15 at 12:28
This command didn't work, I got a the error Unable to find a suitable output format for 'fps=fps=1/600'. The solution is to add -vf before that argument (see – John Wiseman Apr 13 at 3:35

Defining meaningful is hard but if you want to make N thumbnails efficiently spanning whole video file this is what I use to generate thumbnails on production with user uploaded content.


for X in 1..N
  T = integer( (X - 0.5) * D / N )  
  run `ffmpeg -ss <T> -i <movie>
              -vf select="eq(pict_type\,I)" -vframes 1 image<X>.jpg`


  • D - video duration read from ffmpeg -i <movie> alone or ffprobe which has nice JSON output writer btw
  • N - total number of thumbnails you want
  • X - thumbnail number, from 1 to N
  • T - time point for tumbnail

Simply the above writes down center key-frame of each partition of the movie. E.g. if movie is 300s long and you want 3 thumbnails then it takes one key frame after 50s, 150s and 250s. For 5 thumbnails it would be 30s, 90s, 150s, 210s, 270s. You can adjust N depending on movie duration D, that e.g. 5 minute movie will have 3 thumbnails but over 1 hour will have 20 thumbnails.


Each invocation of above ffmpeg command takes a fraction of second (!) for ~1GB H.264. That is because it instantly jumps to <time> position (mind -ss before -i) and takes first key frame which is practically complete JPEG. There is no time wasted for rendering the movie to match exact time position.


You can mix above with scale or any other resize method. You can also remove solid color frames or try to mix it with other filters like thumbnail.

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wow moving -ss N to before -i is an amazing tip. thank you! – apinstein Mar 18 at 23:07

I once did something similar, but I exported all frames of the video (in 1 fps) and compared them with a perl utility I found which computes the difference between images. I compared each frame to previous thumbnails, and if it was different from all thumbnails, I added it to the thumbnails collection. The advantage here is that if your video moves from scene A to B and them returns to A, ffmpeg will export 2 frames of A.

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What factors did you use to compare 2 images? – d33pika Mar 18 '13 at 2:09
Unfortunately I don't remember, it was quite a long ago. You need to decide first which compare method to use, and then do some tests to find correct factor. This shouldn't take long. – Eran Ben-Natan Mar 18 '13 at 9:11
I'm just thinking out loud here but isn't this worse option? When you compare 2 exported images from video you've already lost some information from it. I mean, it is easier to calculate similarity from codec information than it is from 2 pictures, isn't it? Recently I've been looking into some algorithms / libraries to compare images and they don't work as well as one may require. – Samuel Oct 28 '13 at 10:03
Well, with ffmpeg you can extract frames without quality loss using the same_quality flag. If you use codec information you need to check that you don't just get the Iframes. Anyway that perl utility worked just fine for me, and is very configurable. Look here: – Eran Ben-Natan Oct 29 '13 at 11:24

Try this

 ffmpeg -i input.mp4 -vf fps= no_of_thumbs_req/total_video_time out%d.png

Using this command I am able to generate the required number of thumbnails which are representative of the entire video.

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Here's what I do to generate a periodic thumbnail for live m3u8 streams to use as a poster. I found running a continuous ffmpeg task just to generate thumbnails eats up all my CPU, so instead I run a cronjob every 60 seconds that generates all the thumbnails for my streams.

#!/usr/bin/env bash

## this is slow but gives better thumbnails (takes about 1+ minutes for 20 files)
#-vf thumbnail,scale=640:360 -frames:v 1 poster.png

## this is faster but thumbnails are random (takes about 8 seconds for 20 files)
#-vf scale=640:360 -frames:v 1 poster.png
cd ~/path/to/streams

find . -type f \
  -name "*.m3u8" \
  -execdir sh -c 'ffmpeg -y -i "$0" -vf scale=640:360 -frames:v 1 "poster.png"' \
  {} \;

If you need to do more frequently than 60 seconds (limitation of cronjob), then you can do a while loop in your script and it'll execute forever. Just add a sleep 30 to change the frequency to 30 seconds. I don't recommend doing this with large number of videos though, as the previous run may not complete before the next one starts.

Ideally with cronjob I just run it every 5 minutes.

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