This is a collection of command line one-liners for manipulating with audio and video files

audio-video-manipulation.md

Audio/Video Manipulation Command-Line One-Liners

• concatenate-video.sh
• convert-to-h265.sh
• crop-video.sh
• delay-audio.sh
• extract-audio.sh
• image-to-video.sh
• info-video.sh
• preview-video.sh
• resize-video.sh

concatenate-video.sh

## Write list of videos in a text file

$ cat mylist.txt
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'

## Concatenate videos

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

# -f concat => filter concatenate
# -safe 0   => safe mode for paths
# -i        => input
# -c copy   => use the same codec as origin

convert-to-h265.sh

## Convert video to H.265/HVEC

ffmpeg -i input.mp4 -c:v libx265 -tag:v hvc1 output.mp4

# -c:v libx265 => for video use codec H.265 (HEVC)
# -c:v hevc_videotoolbox => for video use codec H.265 (HEVC) with hardware acceleration on Apple (faster, but lower quality)
# -tag:v hvc1  => enable playing in Apple QuickTime

crop-video.sh

## Crop video

ffmpeg -i input.mp4 -vf "crop=output_w:output_h:x:y" output.mp4

# output_w => output width
# output_h => output height
# x:y      => left top corner

# -vf "crop=input_w/2:input_h/2:input_w/2:input_h/2"
# input_w  => input width
# input_h  => input height

# -vf "crop=320/2:240/2:320/2:240/2"

# -vf "crop=in_w:in_h-40"

## Detect cropping boundaries

ffplay -i input.mp4 -vf cropdetect

delay-audio.sh

## Combine video with audio, audio is delayed (shifted, in offset) 75 seconds

ffmpeg -i video.mp4 -itsoffset 75 -i audio.m4a -c:v copy -c:a copy -map 0:v -map 1:a output.mp4

# -itsoffset 75 => following file input is 75 seconds delayed
# -c:v copy     => copy video codec
# -c:a copy     => copy audio codec
# -map 0:v      => from the first input take a video stream
# -map 1:a      => from the second input take a audio stream
# -i            => input file

extract-audio.sh

## Inspect original audio format

ffprobe video.mp4

## Extract audio

ffmpeg -i video.mp4 -vn -c:a copy audio.m4a

# -vn          => -vn / -an / -sn / -dn options can be used to skip inclusion 
#                 of video, audio, subtitle and data streams respectively
# -c:a copy 5  => audio codec copy

image-to-video.sh

## Convert image to video 1.

convert -quality 100 -delay 5 image.png video.mp4

# -quality 100 => quality of compression (0 worst quality -- 100 best quality)
# -delay 5     => 5 seconds length of video


## Convert image to video 2.

ffmpeg -loop 1 -i screen-00.png -c:v libx265 -t 10 -pix_fmt yuv420p screen-00.mp4

# -loop 1          => ???
# -t 10            => length od 10 s
# -pix_fmt yuv420p => pixel format.

info-video.sh

## Print info about video

ffprobe input.mp4

preview-video.sh

## Preview video

ffplay -i input.mp4 -vf "crop=in_w:in_h-40"

resize-video.sh

## Resize video

ffmpeg -i input.mp4 -vf scale="720:480" output.mp4

# -vf scale="720:-1"    => width 720 px and keep ratio
# -vf scale="720:-2"    => width 720 px, keep ratio and round height to even number (important for h.264)
# -vf scale="iw/1:ih/2" => keep the same width and divide height by 2