Using android FFMPEG library for limited video frames [duplicate] - android-studio

Question

I need to create multiple thumbnails (ex. 12) from a video at equal times using ffmpeg.
So for example if the video is 60 seconds - I need to extract a screenshot every 5 seconds.
Im using the following command to get the frame in the 5ths second.
ffmpeg -ss 5 -i video.webm -frames:v 1 -s 120x90 thumbnail.jpeg
Is there a way to get multiple thumbnails with one command?

Answer 1

Get duration (optional)
Get duration using ffprobe. This is an optional step but is helpful if you will be scripting or automating the next commands.
ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 input.mp4
Example result:
60.000000
Output one frame every 5 seconds
Using the select filter:
ffmpeg -i input.mp4 -vf "select='not(mod(t,5))',setpts=N/FRAME_RATE/TB" output_%04d.jpg
or
ffmpeg -i input.mp4 -vf "select='not(mod(t,5))'" -vsync vfr output_%04d.jpg
Files will be named output_0001.jpg, output_0002.jpg, output_0003.jpg, etc. See image muxer documentation for more info and options.
To adjust JPEG quality see How can I extract a good quality JPEG image from a video with ffmpeg?
Output specific number of equally spaced frames
This will output 12 frames from a 60 second duration input:
ffmpeg -i input.mp4 -vf "select='not(mod(t,60/12))'" -vsync vfr output_%04d.jpg
You must manually enter the duration of the input (shown as 60 in the example above). See an automatic method immediately below.
Using ffprobe to automatically provide duration value
Bash example:
input=input.mp4; ffmpeg -i "$input" -vf "select='not(mod(t,$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 $input)/12))'" -vsync vfr output_%04d.jpg
With scale filter
Example using the scale filter:
ffmpeg -i input.mp4 -vf "select='not(mod(t,60/12))',scale=120:-1" -vsync vfr output_%04d.jpg

Answer 2

$ffmpegPath = exec('which ffmpeg'); $ffprobePath = exec('which ffprobe');
$command = "$ffprobePath -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 $input_video"; $video_duration = shell_exec($command);
$thumbnails_output = 'output%02d.png'; $command = "$ffmpegPath -i $input_video -vf fps=3/$video_duration $thumbnails_output";
shell_exec($command);