ffmpeg - ghdrako/doc_snipets GitHub Wiki

FFmpeg

Conversion

ffmpeg -i some-video.mov same-video.mp4
ffmpeg -i song-video.mp4 song-audio.mp3

Extract subtitle

ffmpeg -i Movie.mkv -map 0:s:0 subs.srt
  • -i: Input file URL/path.
  • -map: Designate one or more input streams as a source for the output file.
  • s:0: Select the subtitle stream.

use 0:s:1 to download the second one, 0:s:2 to download the third one, and so on.

To extract more subtitles at once you have to duplicate the -map parameters for each file. Also include -c copy so that it just extracts the file without trying to process it:

ffmpeg -i Movie.mkv -c copy -map 0:s:0 subs.01.srt -c copy -map 0:s:1 subs.02.srt

The Windows/DOS counterpart for the Linux null device (/dev/ null) is NUL. This means that you should replace all instances of 2> / dev/null in this book with 2> NUL. This construct is used to prevent the commands from displaying text messages on the screen. ffmpeg outputs all its messages to standard error, which happens to be the screen. In case it outputs something to standard output, which also happens to be screen, and has to be blocked, the Linux remedy is to use > /dev/null. To do the same on your Windows computer, you will have to use > NUL instead.

. Cut video file into a smaller clip

You can use the time offset parameter -ss to specify the start time stamp in HH:MM:SS.ms format while the -t parameter is for specifying the actual duration of the clip in seconds.

ffmpeg -i input.mp4 -ss 00:00:50.0 -codec copy -t 20 output.mp4
  1. Split a video into multiple parts

If you want to split a large video into multiple smaller clips without re-encoding, FFmpeg can help. This command will split the source video into 2 parts - one ending at 50s from the start and the other beginning at 50s and ending at the end of the input video.

ffmpeg -i video.mp4 -t 00:00:50 -c copy small-1.mp4 -ss 00:00:50 -codec copy small-2.mp4
  1. Convert video from one format to another

You can use the -vcodec parameter to specify the encoding format to be used for the output video. Encoding a video takes time but you can speed up the process by forcing a preset though it would degrade the quality of the output video.

ffmpeg -i youtube.flv -c:v libx264 filename.mp4

ffmpeg -i video.wmv -c:v libx264 -preset ultrafast video.mp4
  1. Join (concatenate) video files

If you have multiple audio or video files encoded with the same codecs, you can join them into a single file using FFmpeg. Create an input file with a list of all source files that you wish to concatenate and then run this command.

ffmpeg -f concat -i file-list.txt -c copy output.mp4
  1. Mute a video (Remove the audio component)

Use the -an parameter to disable the audio portion of a video stream.

ffmpeg -i video.mp4 -an mute-video.mp4
  1. Extract the audio from video

The -vn switch extracts the audio portion from a video and we are using the -ab switch to save the audio as a 256kbps MP3 audio file.

ffmpeg -i video.mp4 -vn -ab 256 audio.mp3
  1. Convert a video into an animated GIF

FFmpeg is an excellent tool for converting videos into animated GIFs and the quality isn’t bad either. Use the scale filter to specify the width of the GIF, the -t parameter specific the duration while -r specifies the frame rate (fps).

ffmpeg -i video.mp4 -vf scale=500:-1 -t 10 -r 10 image.gif
  1. Extract image frames from a video

This command will extract the video frame at the 15s mark and saves it as a 800px wide JPEG image. You can also use the -s switch (like -s 400x300) to specify the exact dimensions of the image file though it will probably create a stretched image if the image size doesn’t follow the aspect ratio of the original video file.

ffmpeg -ss 00:00:15 -i video.mp4 -vf scale=800:-1 -vframes 1 image.jpg
  1. Convert Video into Images

You can use FFmpeg to automatically extract image frames from a video every ‘n’ seconds and the images are saved in a sequence. This command saves image frames from the video after every 4 seconds.

ffmpeg -i movie.mp4 -r 0.25 frames_%04d.png
  1. Merge an audio and video file

You can also specify the -shortest switch to finish the encoding when the shortest clip ends.

ffmpeg -i video.mp4 -i audio.mp3 -c:v copy -c:a aac -strict experimental output.mp4

ffmpeg -i video.mp4 -i audio.mp3 -c:v copy -c:a aac -strict experimental -shortest output.mp4
  1. Resize a video

Use the size (-s) switch with FFmpeg to resize a video while maintaining the aspect ratio.

ffmpeg -i input.mp4 -s 480x320 -c:a copy output.mp4
  1. Create video slideshow from images

This command creates a video slideshow using a series of images that are named as img001.png, img002.png, etc. Each image will have a duration of 5 seconds (-r 1/5).

ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p slideshow.mp4
  1. Add a poster image to audio

You can add a cover image to an audio file and the length of the output video will be the same as that of the input audio stream. This may come handy for uploading MP3s to YouTube.

ffmpeg -loop 1 -i image.jpg -i audio.mp3 -c:v libx264 -c:a aac -strict experimental -b:a 192k -shortest output.mp4
  1. Convert a single image into a video

Use the -t parameter to specify the duration of the video.

ffmpeg -loop 1 -i image.png -c:v libx264 -t 30 -pix_fmt yuv420p video.mp4
  1. Add subtitles to a movie

This will take the subtitles from the .srt file. FFmpeg can decode all the common subtitle formats.

ffmpeg -i movie.mp4 -i subtitles.srt -map 0 -map 1 -c copy -c:v libx264 -crf 23 -preset veryfast output.mkv
  1. Crop an audio file

This will create a 30 second audio file starting at 90 seconds from the original audio file without transcoding.

ffmpeg -ss 00:01:30 -t 30 -acodec copy -i inputfile.mp3 outputfile.mp3
  1. Change the audio volume

You can use the volume filter to alter the volume of a media file using FFmpeg. This command will half the volume of the audio file.

ffmpeg -i input.wav -af 'volume=0.5' output.wav
  1. Rotate a video

This command will rotate a video clip 90° clockwise. You can set transpose to 2 to rotate the video 90° anti-clockwise.

ffmpeg -i input.mp4 -filter:v 'transpose=1' rotated-video.mp4

This will rotate the video 180° counter-clockwise.

ffmpeg -i input.mp4 -filter:v 'transpose=2,transpose=2' rotated-video.mp4
  1. Speed up or Slow down the video

You can change the speed of your video using the setpts (set presentation time stamp) filter of FFmpeg. This command will make the video 8x (1/8) faster or use setpts=4*PTS to make the video 4x slower.

ffmpeg -i input.mp4 -filter:v "setpts=0.125*PTS" output.mp4
  1. Speed up or Slow down the audio

For changing the speed of audio, use the atempo audio filter. This command will double the speed of audio. You can use any value between 0.5 and 2.0 for audio.

ffmpeg -i input.mkv -filter:a "atempo=2.0" -vn output.mkv

Stack Exchange has a good overview to get you started with FFmpeg. You should also check out the official documentation at ffmpeg.org or the wiki at trac.ffmpeg.org to know about all the possible things you can do with FFmpeg.