ffmpeg

calendar Jan 27, 2022 · 6 min read · audio video  ·
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Overview

ffmpeg is a complete, cross-platform solution to record, convert and stream audio and video.

ffmpeg Download

ffmpeg Documentation

Audio Processing

Convert to 8kHz, single-channel PCM

1ffmpeg -i "input.mp3" -ar 8000 -ac 1 output.wav

Convert to 16kHz, single-channel PCM

1ffmpeg -i "input.mp3" -ar 16000 -ac 1 output.wav

Convert to 48kHz, single-channel PCM

1ffmpeg -i input.mp3 -ar 48000 -ac 1 output.wav

Video Processing

Add Music to a Video

1ffmpeg -i video.mp4 -i music.mp3 -codec copy -shortest output.mp4
-i video.mp4
Select “video.mp4” as an input file from the same directory.
-i music.mp3
Select “music.mp4” as an input file from the same directory.
-codec copy
Specifies that we are not re-encoding anything.
-shortest
Use this flag if the video length is shorter than the audio length. Otherwise, use no flag at all here.

Assemble images into a video

1ffmpeg -framerate 60 -s 2560x1440 -i %04d.png output.mp4
-framerate 60
Set the frame rate to 60FPS.
-s 2560x1440
Set the video resolution to 2560x1440 pixels.
-i %04d.png
This flag assumes there is a folder of .png files in the same directory named in the format 0001.png, 0002.png, etc. It will load all images following this naming convention as inputs to be processed.
1>ffmpeg -start_number 0140 -i %04d.png interpolated-0.mp4

Re-encode Video For YouTube

1ffmpeg -i transition.mp4 -c:v libx264 -preset slow -crf 18 -c:a copy -pix_fmt yuv420p transition.mkv
-i transition.mp4
Select "transition.mp4" as the input file.
-c:v libx264
set the video codec to H.264
-preset slow
A preset is a collection of options that will provide a certain encoding speed to compression ratio. A slower preset will provide better compression (compression is quality per filesize). This means that, for example, if you target a certain file size or constant bit rate, you will achieve better quality with a slower preset. Similarly, for constant quality encoding, you will simply save bitrate by choosing a slower preset. Use the slowest preset that you have patience for. The available presets in descending order of speed are:
  • ultrafast
  • superfast
  • veryfast
  • faster
  • fast
  • medium (default preset)
  • slow
  • slower
  • veryslow
-crf 18
Constant Rate Factor (CRF). The range of the CRF scale is 0–51, where 0 is lossless, 23 is the default, and 51 is worst quality possible. A lower value generally leads to higher quality, and a subjectively sane range is 17–28. Consider 17 or 18 to be visually lossless or nearly so; it should look the same or nearly the same as the input but it isn't technically lossless.
-c:a copy
Copy the audio codec from that of the input file to the output file
-pix_fmt yuv420p
This flag is only needed for your output to work in QuickTime, Windows Media player and other offline media players. These players only support the YUV planar color space with 4:2:0 chroma subsampling for H.264 video. Otherwise, depending on your source, ffmpeg may output to a pixel format that may be incompatible with these players.

Video Filters

Stack two videos side-by-side

1ffmpeg -i "left.mp4" -i "right.mp4" -filter_complex hstack output.mp4

This command uses the ffmpeg software to combine two video files, "left.mp4" and "right.mp4", into a single output video file "output.mp4". The "-i" option specifies the input video files. The "-filter_complex" option applies the "hstack" filter, which horizontally stacks the two input videos side by side to form a single output video.

Vertical scroll and wrap

1ffmpeg -i input.mp4 -vf scroll=vertical=0.001,format=yuv420p output.mp4

This ffmpeg command takes an input video file named "input.mp4" and applies a video filter to it that creates a scrolling effect with a vertical scroll speed of 0.001 units per frame. The output video is then saved as "output.mp4" in the YUV420P format.

Remove black bars from top and bottom of video

1ffmpeg -i input.mp4 -vf "crop=iw:ih-40:0:20" -c:v libx264 -crf 18 -pix_fmt yuv420p output.mp4

Resize a video's height while maintaining aspect width aspect ratio

1ffmpeg -i input.mp4 -vf "scale=-1:1280" -c:v libx264 -crf 18 -pix_fmt yuv420p output.mp4

Crop a video down the center

1ffmpeg -i input.mp4 -vf "crop=720:ih:((iw-720)/2):0" -c:v libx264 -crf 18 -pix_fmt yuv420p output.mp4

Do the above three in one go

1ffmpeg -i input.mp4 -vf "crop=iw:ih-40:0:20,scale=-1:1280,crop=720:ih:((iw-720)/2):0" -c:v libx264 -crf 18 -pix_fmt yuv420p output.mp4

Screen recording

All screens

1ffmpeg -f gdigrab -framerate 30 -t 5 -i desktop -c:v libx264 -preset ultrafast -pix_fmt yuv420p -c:a aac -b:a 128k output.mp4

Just one screen

1ffmpeg -f gdigrab -framerate 30 -t 5 -offset_x 0 -offset_y 0 -video_size 1920x1080 -i desktop -c:v libx264 -preset ultrafast -pix_fmt yuv420p -c:a aac -b:a 128k output.mp4

Animated GIF

Create an animated GIF from a video

1ffmpeg -i input.mp4 output.gif

Assembled a folder of images into an animated GIF

Generate a palette

1ffmpeg -y -i %3d.png -vf palettegen palette.png

The command line above is using FFmpeg to process a sequence of PNG images, where each image is named with a number and a 3 digit format, such as "001.png", "002.png", etc. In summary, this command is generating a color palette from a sequence of PNG images and saving the palette to the file "palette.png". This palette can be used to create a GIF animation from the sequence of images. The resulting palette will have a smaller number of colors than the original images, allowing for a smaller file size for the final GIF.

The options used in the command are:

  • "-y" : Overwrite output files without asking.
  • "-i %3d.png" : The input file is a sequence of PNG images, where the file name format is "%3d" (3 digits) followed by ".png"
  • "-vf palettegen" : This is a video filter that generates a color palette from the input image sequence.
  • "palette.png" : This is the output file name for the generated color palette. In summary, this command is generating a color palette from a sequence of PNG images and saving the palette to the file "palette.png". This palette can be used to create a GIF animation from the sequence of images. The resulting palette will have a smaller number of colors than the original images, allowing for a smaller file size for the final GIF.

Create an animated GIF using the previously generated color palette

1ffmpeg -y -f image2 -framerate 60 -i %3d.png -i palette.png -filter_complex paletteuse file.gif

The command line above is using FFmpeg to create a GIF animation from a sequence of PNG images and a previously generated color palette.

The options used in the command are:

  • "-y" : Overwrite output files without asking.
  • "-f image2" : The input is a sequence of image files
  • "-framerate 60" : The frame rate for the output gif is set to 60 frames per second
  • "-i %3d.png" : The input file is a sequence of PNG images, where the file name format is "%3d" (3 digits) followed by ".png"
  • "-i palette.png" : The input file is the previously generated color palette
  • "-filter_complex paletteuse" : This is a filter that uses the previously generated palette to create the gif animation
  • "file.gif" : This is the output file name for the created gif animation In summary, this command is creating a gif animation from a sequence of PNG images using a previously generated color palette, and saving the animation to the file "file.gif". The resulting gif animation will have the same frame rate as the input images and a smaller file size due to the use of a limited color palette.