ffmpeg-koraktor

An occasionally-growing selection of FFmpeg invocations that have proven handy in various situations.

I'm calling it "Koraktor" for reasons.

Some of these have been grabbed straight from history | grep ffmpeg during the initial writeup of this list – I haven't tested everything for working-tude in current versions of FFmpeg.

There's more in this Hacker News thread (some of which I found interesting enough to include here for future reference).

Related: Fred's ImageMagick Scripts, ffmprovisr.

Cropping a letterboxed originally-vertical 1080p video

ffmpeg -i input.mp4  -vf "crop=606:1080:657:0" -crf 24 result.mp4

Numbers (format w:h:x:y, where x:y is counted from the top left corner) might differ depending on interpolation. And -crf 24 is a quality setting – lower is better, 18 is basically lossless.

Straightening (rotating and cropping) a video

For example:

ffmpeg -i DSCF3983.MOV  -vf "rotate=-PI/90:ow='iw*0.92':oh='ih*0.92'" out.mp4

This rotates a video by -π/90, i.e. one degree counterclockwise (you'll have to convert your degrees to radians). The resulting video would end up with black triangles in the corners, so we crop in by 5% via ow='iw*0.95':oh='ih*0.95'. This'll depend on the angle (you could use trigonometry to figure this out, alas, trial & error requires less thought).

Speeding up a video (+ audio) by 400% while setting a different framerate

ffmpeg -i video.mov -filter:v "setpts=0.25*PTS,fps=60" -filter:a "atempo=4.0" output.mp4

Explanation: setpts=0.25*PTS speeds up the video (to 0.25 of its original duration, i.e., a 400% speedup), fps=60 sets the target framerate, and the audio filter atempo=4.0 speeds up the audio by 400%.

Making a video black and white

Via Alastair Tse:

ffmpeg -i "${x}" -vf hue=s=0,eq=brightness=0.1 "${OUTPUT_DIR}/${x}"

Turning a series of images into a GIF (or GIF, depending on your pronunciation preferences)

This is taken from a BIT-101 post where things in explained in more detail and with more background information. Assuming you've got a series of images frames/frame_%04d.png, there's a two-step process:

1. Have FFmpeg analyze your images to generate the ideal palette (since GIFs are limited to 256 colors):

   ffmpeg -i frames/frame_%04d.png -vf palettegen palette.png

2. Assemble the GIF:

   ffmpeg -framerate 30 -i frames/frame_%04d.png -i palette.png -filter_complex paletteuse out.gif

Turning a video into a faux slomo video (while also fiddling with the colors and setting a certain output quality)

I've deployed a variant of this to generate the video in this tweet. Note that anything more than a slowdown factor of 2 (I've used 8 for the video in the tweet) is invariably going to lead to significant artifacts which make the whole thing basically unusable.

ffmpeg -i in.mov -vf "eq=contrast=1.1:brightness=0.08:saturation=1.08,minterpolate='fps=60',setpts=2*PTS" -c:v libx264 -preset fast -crf 20 -c:a aac -b:a 192k out-slow.mp4

(The minterpolate='fps=60',setpts=2*PTS part's the important part. This whole thing doesn't do anything to the audio, so it's best to also strip it off using ffmpeg -i out-slow.mp4 -c copy -an out-slow-silent.mp4, which doesn't reencode the video.)

(Note that while experimenting, you can use the -y flag to keep FFmpeg from asking whether to override files.)

Scaling a video down to 50% of its original size and halving the frame rate

This is handy for screen recordings (and accordingly assumes the input fps was 60):

ffmpeg -i in.mov -vf "scale=iw*.5:ih*.5,fps=30" -crf 18 out.mp4

Saving all keyframes to images

This is a good way of getting some high-quality wallpapers from a Ghibli movie, I suppose (via Hacker News).

ffmpeg -i video.mp4 -vf "select=eq(pict_type\,I)" -vsync vfr video-%03d.png

It's pretty quick, too (the fps count in FFmpeg's output refers to the image files written, not the progress in the video file).

Extracting 1 second of video every 90 seconds

This one can come in handy to condense a very long video that doesn't look good as a timelapse – think bird nest building, dashcam footage, or reminding yourself what happened in a movie you've seen a while ago (via Hacker News).

ffmpeg -i video.mp4 -vf "select='lt(mod(t,90),1)',setpts=N/FRAME_RATE/TB" -af "aselect='lt(mod(t,90),1)',asetpts=N/SR/TB" out.mp4

The lt(mod(t,90),1) bit (repeated twice!) steers the length 1 and interval 90.

Cutting out a corner

Everybody's done it: Having recorded a neat little video, you realize that a corner of the frame is obscured by your finger or part of whatever you've mounted or perched your camera on.

Assuming the blemish is in the bottom right corner and covers a 250×50 pixel area, the following invocation will crop the video to avoid it, then resize it back to 1920×1080 pixels. (Note that 1030 = 1080 - 50 and 1831 = 1920 * (1030 / 1080).)

ffmpeg -i video.mov -vf "crop=1831:1030:0:0,scale=1920:-2" -crf 18 result.mp4

As usual, you can employ ffplay to check whether the crop is correct:

ffplay -i video.mov -vf "crop=1831:1030:0:0,scale=1920:-2"

I required this after recording a 30-minute timelapse of some clouds passing by where I failed to notice that part of my little phone tripod thingy was in frame.

Almost losslessly converting a video from mjpeg/pcm_s16le to h264/aac

When recording video, my aging camera, a Pentax K-7, produces AVI files that each contain an MJPEG-encoded video stream and whatever audio format that in the headline is. The following command compresses those videos to roughly half their size with zero perceptible quality loss.

ffmpeg -i raw.AVI -c:v libx264 -preset fast -crf 18 -c:a aac -b:a 192k compressed.mp4

• -c:v libx264 selects the new video codec.
• -preset fast does the work faster than the default at the expense of file size. I think this steers how many frames are looked at for diffing and stuff.
• -crf 18 sets the compression quality – values range from 0 (lossless but uselessly massive) to 51 (just no), with 18 being visually lossless while still cutting filesizes in half or so.
• -c:a aac selects the new audio codec.
• -b:a 192k sets the bitrate to 192k – this is roughly equivalent to a 256k MP3, i.e., lossless unless you're in a soundproof room with very expensive speakers and your ears are made of literal magic.

Vertically and horizontally stacking videos

I used this while prototyping earthacrosstime.

ffmpeg -i topleft.mp4 -i bottomleft.mp4 -filter_complex vstack=inputs=2 left.mp4
ffmpeg -i topright.mp4 -i bottomright.mp4 -filter_complex vstack=inputs=2 right.mp4
ffmpeg -i left.mp4 -i right.mp4 -filter_complex hstack=inputs=2 whole.mp4

The first line takes topleft.mp4 and bottomleft.mp4 and stacks them vertically, i.e., on top of each other, yielding a video with the same width but twice the height. The last line does the same, but horizontally. Taken together, the three lines montage four videos into a 2×2 grid.

Trimming, colorgrading, adding an end card to a video, and fading it in and out

Used to turn a raw video into this YouTube upload.

ffmpeg -i raw.mov -loop 1 -i endcard.png -ss 00:01:30 -t 00:00:59 -filter_complex "[0:v]eq=contrast=1.1:brightness=0.01 [corr]; [1:v]fade=in:st=140:d=2:alpha=1 [end]; [corr][end] overlay=0:0:enable='between(t,140,149)' [final]; [final]fade=in:st=90:d=1,fade=out:st=148:d=1" out.mp4

The bits do:

• -i raw.mov loads in the video.
• -loop 1 -i endcard.png loads in the end card (-loop 1 is required, I think to turn it into an "infinite" video instead of just a single frame, which is needed for fading it in).
• -ss 00:01:30 -t 00:00:59 trims the video to only include the interesting bit. Despite this, all future time references are with regard to the original.
• [0:v]eq=contrast=1.1:brightness=0.01 [corr] makes the video prettier and stores in in "corr".
• [1:v]fade=in:st=140:d=2:alpha=1 [end] fades in the end card at 140s (i.e. 50s into the trimmed span) for 2s and stores in "end".
• [corr][end] overlay=0:0:enable='between(t,140,149)' [final] overlays the two, showing the end card starting at 140s (note that this is also where the fade starts) until 149s (end of video).
• [final]fade=in:st=90:d=1,fade=out:st=148:d=1 fades the whole video in and out from black.

Note that endcard.png must be the same resolution as the video.

When you run this command, it will look like it's doing nothing for a minute or so – I think it spends that time "scanning" to the start timestamp in a really inefficient way (it probably runs through the filters here already).

Note that this will preserve the original audio, as well as the frame rate etc. (The latter of which was the whole reason for doing this – iMovie emits 30 fps, which I felt was unacceptable given that my iPhone records at 60fps. That's every other frame lost! Gasp!)

I'm sure there's a way more elegant way of doing all this.

Similar, for another video:

ffplay -i raw.AVI -vf "eq=contrast=1.3:brightness=0.3"  # preview

ffmpeg -i raw.AVI -loop 1 -i endcard.png -t 00:00:59 -filter_complex "[0:v]crop=in_h:in_h,eq=contrast=1.3:brightness=0.3 [corr]; [1:v]fade=in:st=50:d=2:alpha=1 [end]; [corr][end] overlay=0:0:enable='between(t,50,59)' [final]; [final]fade=in:st=0:d=1,fade=out:st=58:d=1" out.mp4

The ffplay bit allows for preview of the "colorgrading".

The main bits are very similar to the previous command. crop=in_h:in_h makes the video square, and there was no need for trimming off the start here, which made things more straightforward. Note that here, endcard.png must be the same resolution as the output video.

Converting all images in a directory into a video

ffmpeg -framerate 24 -pattern_type glob -i '*.jpg' -pix_fmt yuv420p out.mp4

Or, as an alias in your .bashrc (mind the quotes!):

alias jpg2mp4='ffmpeg -framerate 24 -pattern_type glob -i '"'"'*.jpg'"'"' -pix_fmt yuv420p out.mp4'

There's also this:

ffmpeg -framerate 30 -i %05d.jpg -c:v libx264 -r 30 -pix_fmt yuv420p barge.mp4

Stabilizing a video

Assuming the filename lives in $VID:

ffmpeg -i $VID -vf vidstabdetect=shakiness=9:show=1 dummy.mp4
ffmpeg -i $VID -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 dummy2.mp4

The result will be dummy2.mp4. Feel free to give it a better name.

This particular invocation works well for very shaky video, i.e., kestrels filmed with a 800 mm equivalent lens and basically non-existent in-camera stabilization. Play with the parameters, perhaps look them up in the documentation.

Concatenating a list of videos

Write a newline-separated list of video paths to mylist.txt, then:

ffmpeg -f concat -i mylist.txt -c copy output.ts

This is handy for video from streaming services. I think I used this to rip a personal copy of the Harmontown movie from whatever now-defunct streaming service it had been released on (or, rather, merge the ripped .ts files into a usable video).

Similarly, if it's only a few videos:

ffmpeg -i "concat:heatvisionandjack_1.mpg|heatvisionandjack_2.mpg|heatvisionandjack_3.mpg" -c copy heatvisionandjack.mpg

Scaling (and padding, if required) all videos in the current directory to a fixed size

for i in $(ls -1); do ffmpeg -i $i -vf 'scale=1080:720,pad=1280:720:(ow-iw)/2:(oh-ih)/2' scaled_$i; done

Slowing a video down to 50% of the original speed

Handy for making raw slow-motion footage actually look slo-mo.

ffmpeg -i 2015-01-03.mp4 -filter:v "setpts=2.0*PTS" output.mp4

See also.

Extracting frames from a 60 fps video

This starts at 65 seconds:

ffmpeg -ss 00:01:05 -i video.mp4 -filter:v fps=fps=60/1 frames/ffmpeg_%3d.png

Making the audio twice as loud

ffmpeg -i video.mp4 -filter:a "volume=2" video-loud.mp4

Removing audio

ffmpeg -i video.mov -c copy -an video_wosound.mov

Extracting audio

ffmpeg -i Desktop/video.mp4 Desktop/audio.mp3

Adding WAV audio to a video as MP3

ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a mp3 -strict experimental -map 0:v:0 -map 1:a:0 video_with_audio.mp4

Transcoding M4A to MP3

ffmpeg -i music.m4a -acodec libmp3lame -ab 256k music.mp3

Trimming a video

ffmpeg -i in.mp4 -ss 01:01:00 -t 00:00:10 out.mp4

Note that -t isn't the end, it's the duration.

Converting a video to a more digestible codec

ffmpeg -i video.mov -vcodec h264 -acodec mp2 video2.mp4

Test patters

More of a curiosity, really (via Hacker News).

ffmpeg -f lavfi -i testsrc=d=60:s=1920x1080:r=24,format=yuv420p -f lavfi -i sine=f=440:b=4 -b:v 1M -b:a 192k -shortest output-testsrc.mp4
ffmpeg -f lavfi -i testsrc2=d=60:s=1920x1080:r=24,format=yuv420p -f lavfi -i sine=f=440:b=4 -b:v 1M -b:a 192k -shortest output-testsrc.mp4
ffmpeg -f lavfi -i smptebars=d=60:s=1920x1080:r=24,format=yuv420p -f lavfi -i sine=f=440:b=4 -b:v 1M -b:a 192k -shortest output-smptebars.mp4

Bonus: Averaging a series of images with ImageMagick

convert image1.jpg ... imageN.jpg -evaluate-sequence Mean average.jpg

Also possible: Pixel-wise min/max/median.

convert image1.jpg ... imageN.jpg -evaluate-sequence Min minimum.jpg
convert image1.jpg ... imageN.jpg -evaluate-sequence Max maximum.jpg
convert image1.jpg ... imageN.jpg -evaluate-sequence Median median.jpg

More possible modes of the -evaluate-sequence tool can be found out by running convert -list evaluate.

Bounus: Making a GIF with ImageMagick

convert -delay 15 -loop 0 -dispose previous * -resize 1000x1000\> animated.gif

The delay between successive frames must be given in hundreths of a second, -loop should be zero for a proper GIF, and -resize isn't required but it's usually sensible.