ffmpeg

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

You can run ffmpeg -formats to get a list of every format that is supported.

Cut⚑

Cut video file into a shorter 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

Split a video into multiple parts⚑

The next 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

Crop an audio file⚑

To create a 30 second audio file starting at 90 seconds from the original audio file without transcoding use:

ffmpeg -ss 00:01:30 -t 30 -acodec copy -i inputfile.mp3 outputfile.mp3

Join⚑

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. Create a input file with a list of all source files that you wish to concatenate and then run this command.

Create first the file list with a Bash for loop:

for f in ./*.wav; do echo "file '$f'" >> mylist.txt; done

Then convert

ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

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

Mute⚑

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

ffmpeg -i video.mp4 -an mute-video.mp4

Convert⚑

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

Convert a x265 file into x264⚑

for i in *.mkv ; do
    ffmpeg -i "$i" -bsf:v h264_mp4toannexb -vcodec libx264 "$i.x264.mkv"
done

• ffmpeg -i "$i": Executes the program ffmpeg and calls for files to be processed.
• -bsf:v: Activates the video bit stream filter to be used.

• h264_mp4toannexb: Is the bit stream filter that is activated. Convert an H.264 bitstream from length prefixed mode to start code prefixed mode (as defined in the Annex B of the ITU-T H.264 specification).

  This is required by some streaming formats, typically the MPEG-2 transport stream format (mpegts) processing MKV h.264 (currently)requires this, if is not included you will get an error in the terminal window instructing you to use it. * -vcodec libx264 This tells ffmpeg to encode the output to H.264. * "$i.ts" Saves the output to .ts format, this is useful so as not to overwrite your source files.

Convert VOB to mkv⚑

• Unify your VOBs

  cat *.VOB > output.vob
  

• Identify the streams

  ffmpeg -analyzeduration 100M -probesize 100M -i output.vob
  

  Select the streams that you are interested in, imagine that is 1, 3, 4, 5 and 6.

• Encoding

  ffmpeg \
    -analyzeduration 100M -probesize 100M \
    -i output.vob \
    -map 0:1 -map 0:3 -map 0:4 -map 0:5 -map 0:6 \
    -metadata:s:a:0 language=ita -metadata:s:a:0 title="Italian stereo" \
    -metadata:s:a:1 language=eng -metadata:s:a:1 title="English stereo" \
    -metadata:s:s:0 language=ita -metadata:s:s:0 title="Italian" \
    -metadata:s:s:1 language=eng -metadata:s:s:1 title="English" \
    -codec:v libx264 -crf 21 \
    -codec:a libmp3lame -qscale:a 2 \
    -codec:s copy \
    output.mkv
  

Convert a video into animated GIF⚑

ffmpeg -ss 30 -t 3 -i input.mp4 -vf "fps=10,scale=480:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" -loop 0 output.gif

• This example will skip the first 30 seconds (-ss 30) of the input and create a 3 second output (-t 3).
• fps filter sets the frame rate. A rate of 10 frames per second is used in the example.
• Scale filter will resize the output to 320 pixels wide and automatically determine the height while preserving the aspect ratio. The lanczos scaling algorithm is used in this example.
• Palettegen and paletteuse filters will generate and use a custom palette generated from your input. These filters have many options, so refer to the links for a list of all available options and values. Also see the Advanced options section below.
• Split filter will allow everything to be done in one command and avoids having to create a temporary PNG file of the palette.
• Control looping with -loop output option but the values are confusing. A value of 0 is infinite looping, -1 is no looping, and 1 will loop once meaning it will play twice. So a value of 10 will cause the GIF to play 11 times.

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 frame after every 4 seconds.

ffmpeg -i movie.mp4 -r 0.25 frames_%04d.png

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

Convert opus or wav to mp3⚑

ffmpeg -i input.wav -vn -ar 44100 -ac 2 -b:a 320k output.mp3

• -i: input file.
• -vn: Disable video, to make sure no video (including album cover image) is included if the source would be a video file.
• -ar: Set the audio sampling frequency. For output streams it is set by default to the frequency of the corresponding input stream. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options.
• -ac: Set the number of audio channels. For output streams it is set by default to the number of input audio channels. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options. So used here to make sure it is stereo (2 channels).
• -b:a: Converts the audio bitrate to be exact 320kbit per second.

Extract⚑

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

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 400×300) 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

Extract metadata of video⚑

ffprobe {{ file }}

Resize⚑

Resize a video⚑

Change the Constat Rate Factor⚑

Setting the Constant Rate Factor, which lowers the average bit rate, but retains better quality. Vary the CRF between around 18 and 24 — the lower, the higher the bitrate.

ffmpeg -i input.mp4 -vcodec libx265 -crf 24 output.mp4

Change the codec as needed - libx264 may be available if libx265 is not, at the cost of a slightly larger resultant file size.

Change video resolution⚑

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

Reduce the bitrate size⚑

If you want to stick to H.264 reduce the bitrate. You can check the current one with ffprobe input.mkv. Once you've chosen the new rate change it with:

ffmpeg -i input.mp4 -b 3000k output.mp4

Additional options that might be worth considering is setting the Constant Rate Factor, which lowers the average bit rate, but retains better quality. Vary the CRF between around 18 and 24 — the lower, the higher the bitrate.

ffmpeg -i input.mp4 -vcodec libx264 -crf 20 output.mp4

Presentation⚑

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 ⅕).

ffmpeg -r 1/5 -i img%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p slideshow.mp4

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

Add subtitles to a movie⚑

This will take the subtitles from the .srt file. FFmpeg can decode most 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

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

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

For the transpose parameter you can pass:

• 0 = 90° counterclockwise and vertical flip (default)
• 1 = 90° clockwise
• 2 = 90° counterclockwise
• 3 = 90° clockwise and vertical flip

Note that this will re-encode the audio and video parts. You can usually copy the audio without touching it, by using -c:a copy

You can't overwrite the file directly, you need to move it to a temp and then to move it. This python script does it for you

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 (⅛) faster or use setpts=4*PTS to make the video 4x slower.

ffmpeg -i input.mp4 -filter:v "setpts=0.125*PTS" output.mp4

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.

bash 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.

References⚑

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