Extract audio from .webm to .mp3
FILE="the-file-you-want-to-process.webm"
ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -y "${FILE%.webm}.mp3"
Credits: Bytefreaks.net
Merge subtitle (srt) files with video files
ffmpeg -i video.mp4 -i subtitle.srt -c:s mov_text -c:v copy -c:a copy merged.mp4
Credits: StackExchange
Convert .mkv to .mp4
ffmpeg -i input.mkv -c:v copy -c:a copy output.mp4
Extract text subtitles from a video file to separate .srt files
This uses ffprobe and jq to extract the subtitle streams from the input file and then uses ffmpeg to extract the subtitle streams to separate files.
# Assuming the file is named input.mkv
ffprobe -hide_banner -loglevel quiet -select_streams s -show_entries stream=codec_name,codec_type:stream_tags=language -print_format json input.mkv | jq ".streams | to_entries | map({codec_name: .value.codec_name, language:(.value.tags.language // \"sub\"), index:.key})[] | select(.codec_name == \"subrip\") | \"\(.language)\(.index)\"" --raw-output | xargs -L1 -I % -t zsh -c 'ffmpeg -hide_banner -loglevel quiet -i input.mkv -map 0:s:$(echo % | sed "s/[^0-9]//g") %.srt'
Embed thumbnail into an mp4 video file
Here we want to apply thumbnail from image.png to input.mp4 and save the result to output.mp4.
ffmpeg -i input.mp4 -i image.png -map 1 -map 0 -c copy -disposition:0 attached_pic output.mp4
# Note: attached_pic here is a keyword to the disposition option
Credits: StackOverflow
Remove chapters from a video file
Here we want to remove embedded chapter markings from input.mp4 and save the result to output.mp4.
ffmpeg -i input.mp4 -map_chapters -1 -c copy output.mp4
Delay subtitles
ffmpeg -itsoffset <amount-to-delay-in-seconds> -i input.srt -c copy output.srt
This will create a new file output.srt with all subtitles delayed by the specified amount. You can use this command to delay subtitles by any amount of seconds. Negative and decimal values are also supported. For example:
# This would delay the subtitles by 2.5 seconds
ffmpeg -itsoffset 2.5 -i input.srt -c copy output.srt