HN FFMPEG oneliners

https://news.ycombinator.com/item?id=26746537

	
godmode2019 3 hours ago [–]

I think everyone was a txt file on their computer filled with FFmpeg commands.
Care to share yours?
	
stevens37 0 minutes ago [–]

# slow down by 10x (gopro 240fps to 24fps)
ffmpeg -i ${1} -sn -an -c:v libx264 -r 24 -filter:v "setpts=10PTS" -crf 19 ${1}-10x.mkv

# reverse video

ffmpeg -i $IFILE -s 3840x2160 -f image2 -q:v 1 -vf format=yuvj420p $tmpdir/p%8d.jpg cat $(ls -t $tmpdir/p.jpg) | ffmpeg -f image2pipe -c:v mjpeg -r 30 -i - -c:v libx264 -crf 18 -vf format=yuv420p -preset slow -f mp4 $OFILE

#loop a video: loopcount=$1

ffmpeg -stream_loop $1 -i $2 -c copy $3.mkv

eXpl0it3r 1 hour ago [–]

Video to GIF
  SET filters="fps=%4,scale=%3:-1:flags=lanczos"
  ffmpeg -v warning -i %1 -vf "%filters%,palettegen" -y palette.png
  ffmpeg -v warning -i %1 -i palette.png -lavfi "%filters% \[x\]; \[x\]\[1:v\] paletteuse" -y %2
  DEL palette.png

  togif.bat <input.mp4> <output.gif> <width> <fps>
Extract audio from a video
  ffmpeg -i "path\to\my_input_video_file.mp4" "path\to\my_output_audio_only.wav"
Extract specific video and audio stream
  ffmpeg -i "path\to\my_input_video_file.mp4" -map 0:0 -c copy video.mp4 -map 0:1 -c copy audio0.m4a -map 0:2 -c copy audio1.m4a
Concatenate two or more video clips
  (echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
  ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
Convert 10-bit H.265 to 10-bit H.264
  ffmpeg -i input -c:v libx264 -crf 18 -c:a copy output.mkv
Convert 10-bit H.265 to 8-bit H.265
  ffmpeg -i input -c:v libx265 -vf format=yuv420p -c:a copy output.mkv
Convert 10-bit H.265 to 8-bit H.264
  ffmpeg -i input -c:v libx264 -crf 18 -vf format=yuv420p -c:a copy output.mkv
	
Ndymium 2 hours ago [–]

Here's one I wrote a blog post[0] about on how to merge two audio tracks of a video into one track without re-encoding the video:
    ffmpeg -i 'input.mkv' -filter_complex '[0:a:1]volume=0.1[l];[0:a:0][l]amerge=inputs=2[a]' -map '0:v:0' -map '[a]' -c:v copy -c:a libmp3lame -q:a 3 -ac 2 'output.mp4'
[0] https://blog.nytsoi.net/2017/12/31/ffmpeg-combining-audio-tr...
	
cm2187 2 hours ago [–]

mine:
  h264:
  -c:v libx264 -preset medium -crf 22

  h265:
  -c:v libx265 -preset medium -crf 26

  no recompress:
  -c copy

  presets:
  ultrafast,superfast, faster, fast, medium, slow, slower, veryslow

  desinterlace:
  -vf yadif

  target size:
  -s 1920x1080

  aspect ratio without recompressing:
  -aspect 16:9

  rotate video:
  -vf "transpose=1"
  0 = 90CounterCLockwise and Vertical Flip (default)
  1 = 90Clockwise
  2 = 90CounterClockwise
  3 = 90Clockwise and Vertical Flip

  rotate without recompressing:
  -metadata:s:v rotate="90"

  audio aac two channels:
  -c:a aac -b:a 160k -ac 2

  web fast start:
  -movflags +faststart

  autoscale to WxH with black bands:
  -vf "scale=W:H:force_original_aspect_ratio=decrease,pad=W:H:(ow-iw)/2:(oh-ih)/2"

  get jpeg snapshot:
  -vframes 1 -q:v 2 dest.jpg

  concatenate mp4 without recompressing:
  -f concat -safe 0 -i "files.txt" -c copy -movflags +faststart
  files.txt format:
  file 'filepath'

  ffprobe get videoinfo:
  ffprobe -v quiet -print_format xml -show_format -show_streams "filepath" > file.xml

  if override which sub track is default, use "-default_mode infer_no_subs"

  clear disposition (default sub):
  -disposition:s 0

  default or forced disposition:
  -disposition:s forced

  track metadata (audio):
  -metadata:s:a title="xx"
  track metadata (video):
  -metadata:s:v title="xx"
  global metadata:
  -metadata title="xx"
  -metadata description="xx"
  -metadata comment="xx"

  extract sound from video to mp4
  ffmpeg -i source_video.avi -vn -ar 44100 -ac 2 -ab 192k -f mp3 sound.mp3

  skip time (place after input file):
  -ss 00:05:00

  stop after:
  -t 00:05:00 

  Approx fast seek (place before input file):
  -ss 00:05:00 -noaccurate_seek -i ....
	
puzzlingcaptcha 2 hours ago [–]

I only have one, and it's for a rather niche use: fixing incorrect or missing h264/h265 bitstream metadata without re-encoding, for example:
    ffmpeg -i source.avc -c copy -bsf:v h264_metadata=colour_primaries=1:matrix_coefficients=1 output.h264
https://ffmpeg.org/ffmpeg-bitstream-filters.html#h264_005fme... https://www.itu.int/rec/T-REC-H.264-201906-I/en
	
bambax 47 minutes ago [–]

Here are two not present in the comments so far.
Print subtitles (useful for old TVs that can't select a subtitle from streams or files; I use this to get my kids to watch movies in English):

    -vf "ass=subtitle.ass"
or with .srt and in a huge yellow font
    -vf "subtitles=subtitles.srt:force_style='Fontsize=36,PrimaryColour=&H0000FFFF'"
Extract 1 second of video every 90 seconds (if you have very long footage of a trip from a dashcam and you don't know what to do with it, that makes for a much shorter "souvenir"):
    -vf "select='lt(mod(t,90),1)',setpts=N/FRAME_RATE/TB" -af "aselect='lt(mod(t,90),1)',asetpts=N/SR/TB"
	
mjaniczek 43 minutes ago [–]

  function grab-screen-lossless {
    ffmpeg -an -f x11grab -video_size 1920x1080 -framerate 60 -i :0.0 -c:v h264_nvenc -preset llhq -tune zerolatency -crf 0 -qp 0 "${1}"
  }
  
  function grab-screen {
    ffmpeg -an -f x11grab -video_size 1920x1080 -framerate 60 -i :0.0 -c:v h264_nvenc -preset llhq -tune zerolatency -qp 10 "${1}"
  }
  
  function vid_compress {
    ffmpeg -i "${1}" -codec:v libx264 -preset:v fast -pix_fmt yuv420p "${2}"
  }
	
paol 1 hour ago [–]

Gladly. There's even some relatively advanced stuff in there:
  # Save a RTSP stream to file
  ffmpeg -i rtps://someserver/somevideo -c copy out.mp4

  # encoding quality settings examples
  #   H264
  ffmpeg -i input.mp4 -a:c copy -c:v libx264 -crf 22 -preset slower -tune film -profile:v high -level 4.1 output.mp4
  #   H264 10bit (must switch to a different libx264 version)
  LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu/x264-10bit ffmpeg -i input.mp4 -a:c copy -c:v libx264 -crf 22 -preset slower -tune film -pix_fmt yuv420p10le -profile:v high10 -level 5.0 output.mp4

  # resize 
  ffmpeg -i in.mp4 -s 480x270 -c:v libx264 out.mp4

  # change source fps
  ffmpeg -r 10 -i in.mp4 out.mp4

  # resample fps
  ffmpeg -i in.mp4 -r 10 out.mp4

  # extract the audio from a video
  ffmpeg -i inputfile.mp4 -vn -codec:a copy outputfile.m4a

  # merge audio and video files
  ffmpeg -i inputfile.mp4 -i inputfile.m4a -codec copy outputfile.mp4

  # cut (reencoding)
  #   set the start time and duration as HH:MM:SS
  ffmpeg -ss 00:00:40.000 -i input.mp4 -t 00:00:10 -c:v libx264 output.mp4
  #   set the start time and duration as seconds
  ffmpeg -ss 40.0 -i input.mp4 -t 10.0 -c:v libx264 output.mp4
  #   skip an exact number of frames at the start (100)
  ffmpeg -i input.mp4 -vf 'select=gte(n\,100)' -c:v libx264 output.mp4

  # cut (w/o reencoding - cut times will be approximate)
  ffmpeg -ss 40.0 -i input.mp4 -t 10.0 -c copy output.mp4

  # save all keyframes to images
  ffmpeg -i video.mp4 -vf "select=eq(pict_type\,I)" -vsync vfr video-%03d.png

  # encode video from images (image numbering must be sequential)
  ffmpeg -r 25 -i image_%04d.jpg -vcodec libx264 timelapse.mp4

  # flip image horizontally
  ffmpeg -i input.mp4 -vf hflip -c:v libx264 output.mp4

  # crop and concatenate 3 videos vertically
  ffmpeg -i cam_4.mp4 -i cam_5.mp4 -i cam_6.mp4 -filter_complex "[0:v]crop=1296:432:0:200[c0];[1:v]crop=1296:432:0:200[c1];[2:v]crop=1296:432:0:230[c2];[c0][c1][c2]vstack=inputs=3[out]" -map "[out]" out.mp4

  # 2x2 mosaic (all inputs must be same size)
  ffmpeg -i video1.mp4 -i video2.mp4 -i video3.mp4 -i video4.mp4 -filter_complex "[0:v][1:v]hstack=inputs=2[row1];[2:v][3:v]hstack=inputs=2[row2];[row1][row2]vstack=inputs=2[out]" -map "[out]" out.mp4

  # picture-in-picture
  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "[1:v]scale=iw/3:ih/3[pip];[0:v][pip]overlay=main_w-overlay_w-20:main_h-overlay_h-20[out]" -map "[out]" out.mp4

  # print framerate of every file in dir
  for f in *.mp4; do echo $f; mediainfo $f|grep "Frame rate"; done

  # print selected info of every file in dir in CSV format
  for f in *.mp4; do echo -n $f,; mediainfo --Inform="Video;%Duration%,%FrameCount%,%FrameRate%" $f; done
	
pchm 47 minutes ago [–]

mov2gif:
    ffmpeg -i input.mov -vf "fps=10,scale=600:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" -loop 0 output.gif
	
jonplackett 1 hour ago [–]

-pix_fmt yuv420p
Every damn time I have to export from after effects and need a file I can actually open.
	
ducktective 2 hours ago [–]

There is tldr: https://github.com/tldr-pages/tldr/blob/master/pages/common/...
reply

cooper12 2 hours ago [–]

    ffmpeg -i foo.mp4 -c:v h264_videotoolbox -b:v 1600k foo_out.mp4
On macOS, this uses hardware acceleration to reencode a video at a lower bitrate. 
My macbook is from 2012, so this does make a notable difference. 
There's also "hevc_videotoolbox" for H.265 if your machine supports it.