Useful ffmpeg commands
FFMPEG conversion commands
First of all we need to see how to install ffmpeg on a debian based system.
This article describes some basic audio format conversions using ffmpeg utility. All ffmpeg format conversion commands use default ffmpeg setting. User should alter below commands to increase or decrease audio quality with additional ffmpeg options.
How to play files from command line?
To play wav files try to see if sox is installed on the system using command man sox to see a detailed explanation for the sox command. It will display information if the sox is installed
type in play <audio-filename.wav> to play the audio file of wav format.
To play mp3 from command line using this command.
sudo apt-get install mpg123
sudo apt-get install libsox-fmt-mp3
Then type in play <audio-filename.mp3>
Mix a single stereo stream down to a mono stream. Both channels of the stereo stream will be downmixed into the stream:
Output each channel in stereo input to individual mono files:
Output each channel in stereo input to individual mono streams in one output file with the channelsplit audio filter:
Create a stereo output from one mono input:
Create a stereo output from two mono inputs with the amerge audio filter:
Combine 6 mono inputs into one 5.1 (6 channel) output with the amerge audio filter:
Split a 5.1 channel input into individual per-channel files:
To downmix you can simply use -ac 2:
Combine two stereo inputs into one stereo output with the amerge and pan audio filters:
A similar situation as above, but instead use the left and right channels from the first input to make the left channel out the output, and use the left and right channels of the second input to make the right channel of the output.
Just change the channel specifications in the pan filter:
The left and right channels of the output will each contain both the left and right channels of the input:
Switch left channel to right and right channel to left:
This example will mute the first channel (the left channel) but keep the second channel as is:
First of all we need to see how to install ffmpeg on a debian based system.
$ sudo add-apt-repository ppa:jon-severinsson/ffmpeg
$ sudo apt-get update
$ sudo apt-get install ffmpegThis article describes some basic audio format conversions using ffmpeg utility. All ffmpeg format conversion commands use default ffmpeg setting. User should alter below commands to increase or decrease audio quality with additional ffmpeg options.
How to play files from command line?
To play wav files try to see if sox is installed on the system using command man sox to see a detailed explanation for the sox command. It will display information if the sox is installed
type in play <audio-filename.wav> to play the audio file of wav format.
To play mp3 from command line using this command.
sudo apt-get install mpg123
sudo apt-get install libsox-fmt-mp3
Then type in play <audio-filename.mp3>
1.1. WAV - Waveform Audio File Format
1.1.1. wav to mp3
Convert wav to mp3 with ffmpeg:ffmpeg -i audio.wav -acodec libmp3lame audio.mp3
to control the quality see this page Encodemp3
ffmpeg -i audio.wav -codec:a libmp3lame -qscale:a 0 audio.mp3
qscale is the one that controls the quality of the audio file
1.1.2. wav to ogg
Convert wav to ogg with ffmpeg:ffmpeg -i audio.wav -acodec libvorbis audio.ogg
1.1.3. wav to aac
Convert wav to acc with ffmpeg:ffmpeg -i audio.wav -acodec libfaac audio.aac
1.1.4. wav to ac3
Convert wav to ac3 with ffmpeg:ffmpeg -i audio.wav -acodec ac3 audio.mp3
1.2. OGG - Free, open standard container
1.2.1. ogg to mp3
Convert ogg to mp3 with ffmpeg:ffmpeg -i audio.ogg -acodec libmp3lame audio.mp3
1.2.2. ogg to wav
Convert ogg to wav with ffmpeg:ffmpeg -i audio.ogg audio.wav
1.2.3. ogg to aac
Convert ogg to aac with ffmpeg:ffmpeg -i audio.ogg -acodec libfaac audio.aac
1.2.4. ogg to ac3
Convert ogg to ac3 with ffmpeg:ffmpeg -i audio.ogg -acodec ac3 audio.ac3
1.3. AC3 - Acoustic Coder 3
1.3.1. ac3 to mp3
Convert ac3 to mp3 with ffmpeg:ffmpeg -i audio.ac3 -acodec libmp3lame audio.mp3
1.3.2. ac3 to wav
Convert ac3 to wav with ffmpeg:ffmpeg -i audio.ac3 audio.wav
1.3.3. ac3 to aac
Convert ac3 to aac with ffmpeg:ffmpeg -i audio.ac3 -acodec libfaac audio.aac
1.3.4. ac3 to ogg
Convert ac3 to ogg with ffmpeg:ffmpeg -i audio.ac3 -acodec libvorbis audio.ogg
1.4. AAC - Advanced Audio Coding
1.4.1. aac to mp3
Convert aac to mp3 with ffmpeg:ffmpeg -i audio.aac -acodec libmp3lame audio.mp3
1.4.2. aac to wav
Convert aac to wav with ffmpeg:ffmpeg -i audio.aac audio.wav
1.4.3. aac to ac3
Convert aac to ac3 with ffmpeg:ffmpeg -i audio.aac -acodec ac3 audio.ac3
1.4.4. aac to ogg
Convert aac to ogg with ffmpeg:ffmpeg -i audio.aac -libvorbis audio.ogg
FOR VIDEO Conversion commands
1. 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
2. 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
3. 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
4. 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 a 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
5. 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
6. 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
7. Convert a video into 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
8. 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
OR ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%3d.jpegThis will extract one video frame per second from the video and will output them in files named foo-001.jpeg, foo-002.jpeg. Images will be rescaled to fit the new WxH values
9. 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
10. 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
11. 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
12. 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
13. 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
14. 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
15. 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
16. 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
17. 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
18. 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
19. 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
20. 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
21. Check the properties of a file using ffmpeg
ffprobe <filename>
Source - https://trac.ffmpeg.org/wiki/AudioChannelManipulation
Manipulating audio channels with ffmpeg
stereo → mono stream
Mix a single stereo stream down to a mono stream. Both channels of the stereo stream will be downmixed into the stream:
ffmpeg -i stereo.flac -ac 1 mono.flac
Note: Any out of phase stereo will cancel out.
stereo → 2 × mono files
Output each channel in stereo input to individual mono files:
ffmpeg -i stereo.wav -map_channel 0.0.0 left.wav -map_channel 0.0.1 right.wav
or with the pan audio filer:
ffmpeg -i stereo.wav -filter_complex "[0:0]pan=1c|c0=c0[left];[0:0]pan=1c|c0=c1[right]" -map "[left]" left.wav -map "[right]" right.wav
stereo → 2 × mono streams
Output each channel in stereo input to individual mono streams in one output file with the channelsplit audio filter:
ffmpeg -i in.mp3 -filter_complex channelsplit=channel_layout=stereo out.mka
Note: Your player will likely play the first stream by default unless your player allows you to select the desired stream.
mono → stereo
Create a stereo output from one mono input:
ffmpeg -i input.mp3 -ac 2 output.m4a
or with the amerge audio filter:
ffmpeg -i input.mp3 -filter_complex "[0:a][0:a]amerge=inputs=2[aout]" -map "[aout]" output.m4a
Note: These examples will not magically create a "true"
stereo output from the mono input, but simply place the same audio into
both the left and right channels of the output (both channels will be
identical).
2 × mono → stereo
Create a stereo output from two mono inputs with the amerge audio filter:
ffmpeg -i left.mp3 -i right.mp3 -filter_complex "[0:a][1:a]amerge=inputs=2[aout]" -map "[aout]" output.mka
6 × mono → 5.1
Combine 6 mono inputs into one 5.1 (6 channel) output with the amerge audio filter:
ffmpeg -i front_left.wav -i front_right.wav -i front_center.wav -i lfe.wav -i back_left.wav -i back_right.wav \
-filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a]amerge=inputs=6[aout]" -map "[aout]" output.wav
All inputs must have the same sample rate and format. If inputs do not
have the same duration the output will stop with the shortest.
5.1 → 6 × mono
Split a 5.1 channel input into individual per-channel files:
ffmpeg -i in.wav \
-filter_complex "channelsplit=channel_layout=5.1[FL][FR][FC][LFE][BL][BR]" \
-map "[FL]" front_left.wav \
-map "[FR]" front_right.wav \
-map "[FC]" front_center.wav \
-map "[LFE]" lfe.wav \
-map "[BL]" back_left.wav \
-map "[BR]" back_right.wav
5.1 → stereo
To downmix you can simply use -ac 2:
ffmpeg -i 6channels.wav -ac 2 stereo.wav
Notes:
If you want to map specific channels and drop the rest you can use the pan audio filter. This will map the FL (Front Left) of the input to the FL of the output, and the FR (Front Right) of the input to the FR of the output:
- By default when using -ac 2 the LFE channel is omitted. See "Digital Audio Compression Standard (Document A/52:2012)", sections 6.1.12 and 7.8 for more downmixing info.
- ffmpeg integrates a default down-mix (and up-mix) system that should be preferred (the -ac option) over the pan filter unless you have very specific needs.
ffmpeg -i 6channels.wav -af "pan=stereo|c0=FL|c1=FR" stereo.wav
You can also map specific channels by number. This example will map the
first and third channels of the input to the first and second channels
of the output.
ffmpeg -i 6channels.wav -af "pan=stereo|c0=c0|c1=c2" output.wav
If the = in a channel specification is replaced by <, then the gains for that specification will be renormalized so that the total is 1, thus avoiding clipping noise. See the pan audio filter documentation for additional information and examples.
2 × stereo → stereo
Combine two stereo inputs into one stereo output with the amerge and pan audio filters:
ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2,pan=stereo|c0<c0+c2|c1<c1+c3[aout]" -map "[aout]" output.mp3
Or use -ac 2 instead of the pan audio filter:
ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2[aout]" -map "[aout]" -ac 2 output.mp3
Note: The output produced with the pan audio filter may not be identical to the output produced with -ac 2, so you'll have to listen to your outputs or view audio statistics to determine which output suits you.
A similar situation as above, but instead use the left and right channels from the first input to make the left channel out the output, and use the left and right channels of the second input to make the right channel of the output.
Just change the channel specifications in the pan filter:
ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2,pan=stereo|c0<c0+c1|c1<c2+c3[aout]" -map "[aout]" output.mp3
The pan audio filter has to be used in this situation instead of -ac 2 unlike the previous example.
Mix both stereo channels to stereo
The left and right channels of the output will each contain both the left and right channels of the input:
ffmpeg -i input.mp3 -af "pan=stereo|c0<c0+c1|c1<c0+c1" output.ogg
Switch stereo channels
Switch left channel to right and right channel to left:
ffmpeg -i stereo.ogg -map_channel 0.0.1 -map_channel 0.0.0 output.wav
or with the pan audio filer:
ffmpeg -i stereo.ogg -af pan=stereo|c0=c1|c1=c0 output.wav
Virtual Binaural Acoustics
FFmpeg can produce virtual binaural acoustics files using sofalizer filter, most known channel layouts are supported for input, output is always stereo.ffmpeg -i input.wav -af sofalizer=/path/to/sofa/file output.flac
SOFA files can be found on http://sofacoustics.org/data/database/ari/
Mute a channel
This example will mute the first channel (the left channel) but keep the second channel as is:
ffmpeg -i stereo.wav -map_channel -1 -map_channel 0.0.1 output.wav
Statistics
The astats audio filter can display information including length, DC offset, min/max levels, peak/RMS level dB:$ ffmpeg -i input.wav -af astats -f null -
…
[Parsed_astats_0 @ 0x168a260] Channel: 1
[Parsed_astats_0 @ 0x168a260] DC offset: -0.001829
[Parsed_astats_0 @ 0x168a260] Min level: -0.605072
[Parsed_astats_0 @ 0x168a260] Max level: 0.607056
[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.335430
[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.298984
[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.303891
[Parsed_astats_0 @ 0x168a260] RMS trough dB: -35.352893
[Parsed_astats_0 @ 0x168a260] Crest factor: 6.283154
[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
[Parsed_astats_0 @ 0x168a260] Peak count: 2
[Parsed_astats_0 @ 0x168a260] Channel: 2
[Parsed_astats_0 @ 0x168a260] DC offset: -0.001826
[Parsed_astats_0 @ 0x168a260] Min level: -0.585999
[Parsed_astats_0 @ 0x168a260] Max level: 0.608490
[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.314931
[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.519969
[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.056472
[Parsed_astats_0 @ 0x168a260] RMS trough dB: -36.784681
[Parsed_astats_0 @ 0x168a260] Crest factor: 6.460288
[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
[Parsed_astats_0 @ 0x168a260] Peak count: 2
[Parsed_astats_0 @ 0x168a260] Overall
[Parsed_astats_0 @ 0x168a260] DC offset: -0.001829
[Parsed_astats_0 @ 0x168a260] Min level: -0.605072
[Parsed_astats_0 @ 0x168a260] Max level: 0.608490
[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.314931
[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.408071
[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.056472
[Parsed_astats_0 @ 0x168a260] RMS trough dB: -36.784681
[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
[Parsed_astats_0 @ 0x168a260] Peak count: 2.000000
[Parsed_astats_0 @ 0x168a260] Number of samples: 1440706
Layouts
Output from ffmpeg -layouts:Individual channels:
NAME DESCRIPTION
FL front left
FR front right
FC front center
LFE low frequency
BL back left
BR back right
FLC front left-of-center
FRC front right-of-center
BC back center
SL side left
SR side right
TC top center
TFL top front left
TFC top front center
TFR top front right
TBL top back left
TBC top back center
TBR top back right
DL downmix left
DR downmix right
WL wide left
WR wide right
SDL surround direct left
SDR surround direct right
LFE2 low frequency 2
Standard channel layouts:
NAME DECOMPOSITION
mono FC
stereo FL+FR
2.1 FL+FR+LFE
3.0 FL+FR+FC
3.0(back) FL+FR+BC
4.0 FL+FR+FC+BC
quad FL+FR+BL+BR
quad(side) FL+FR+SL+SR
3.1 FL+FR+FC+LFE
5.0 FL+FR+FC+BL+BR
5.0(side) FL+FR+FC+SL+SR
4.1 FL+FR+FC+LFE+BC
5.1 FL+FR+FC+LFE+BL+BR
5.1(side) FL+FR+FC+LFE+SL+SR
6.0 FL+FR+FC+BC+SL+SR
6.0(front) FL+FR+FLC+FRC+SL+SR
hexagonal FL+FR+FC+BL+BR+BC
6.1 FL+FR+FC+LFE+BC+SL+SR
6.1 FL+FR+FC+LFE+BL+BR+BC
6.1(front) FL+FR+LFE+FLC+FRC+SL+SR
7.0 FL+FR+FC+BL+BR+SL+SR
7.0(front) FL+FR+FC+FLC+FRC+SL+SR
7.1 FL+FR+FC+LFE+BL+BR+SL+SR
7.1(wide) FL+FR+FC+LFE+BL+BR+FLC+FRC
7.1(wide-side)FL+FR+FC+LFE+FLC+FRC+SL+SR
octagonal FL+FR+FC+BL+BR+BC+SL+SR
downmix DL+DR
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