Some ffmpeg commands

ffmpeg_commands.txt

Convert videos to mp4:

Move MOOV atom to the beginning so that the video can be streamed:
ffmpeg -i orig.mp4 -movflags faststart -c copy out.mp4

ffmpeg -i S04E04.1080p.mkv -c:a copy -c:v libx264 -preset faster -f mp4 -s hd720 -hide_banner S04E04A.720p.mp4

# to specify profile and level for h264 coding:
# to output 8bit, use `-pix_fmt yuv420p`
ffmpeg -i video.mkv -c:a copy -c:v libx264 -profile:v high -level:v 4 -preset faster -pix_fmt yuv420p -f mp4 -s hd720 -hide_banner output.mp4

ffmpeg -i input_video_file_name -c:a aac -b:a 128k -c:v libx264 -preset fast -s hd720 -f mp4 -hide_banner output.mp4

ffmpeg -i input_video_file_name -c:a aac -b:a 128k -c:v libx264 -preset medium -crf 18 -f mp4 -hide_banner output.mp4

Extract mp4 from mkv container:
ffmpeg -i input.mkv -codec copy output.mp4

Extract subtitle:
ffmpeg -i yourFile -codec:s srt sub.srt
ffmpeg -i foo.mkv -map 0:2 foo.ssa
OR
1) perform track identification
ffmpeg -i yourFile
2) extract the subtitle track with
ffmpeg -i yourFile -codec:s srt sub.srt
with X.Y the track number indicator you found from the cmd (1) .

# Add a subtitle as a stream into a mp4 file
ffmpeg -i infile.mp4 -f srt -i infile.srt -c:v copy -c:a copy -c:s mov_text outfile.mp4

# Burn a subtitle into a mp4 file
https://trac.ffmpeg.org/wiki/HowToBurnSubtitlesIntoVideo
Draw subtitles on top of input video using the libass library. This filter requires ffmpeg to be compiled with --enable-libass. See the ​subtitles video filter documentation for more details.
If the subtitle is a separate file called subtitle.srt, you can use this command:
    ffmpeg -i video.avi -vf subtitles=subtitle.srt out.avi
If the subtitle is embedded in the container video.mkv, you can do this:
    ffmpeg -i video.mkv -vf subtitles=video.mkv out.avi

# starting at 20s, extract 5 seconds of video
ffmpeg -i example.mp4 -f mp4 -ss 20 -t 5 -c:v libx264 -preset fast -c:a aac summary.mp4 -hide_banner

# extract 10 seconds starting at 1 min
ffmpeg -i input.mkv -c copy -ss 00:01:00 -t 10 output.mkv

# extract starting at 1 min and ending at 2 min
ffmpeg -i input.mkv -c copy  -ss 00:01:00 -to 00:02:00 output.mkv

# extract only audio
ffmpeg -i input.mkv -vn audio_only.ogg

# concatenate files:
(for %i in (*.wav) do @echo file '%i') > mylist.txt
ffmpeg -f concat -safe 0 -i mylist.txt -c copy output

# rip dvds
ffmpeg -i concat:"e:VIDEO_TS\VTS_01_0.VOB|e:VIDEO_TS\VTS_01_1.VOB|e:VIDEO_TS\VTS_01_2.VOB" -c:v libx264 01.mp4

ffmpeg -i concat:"e:VIDEO_TS\VTS_02_0.VOB|e:VIDEO_TS\VTS_02_1.VOB|e:VIDEO_TS\VTS_02_2.VOB" -map 0:v -map 0:a:1 -c:v libx264 02.mp4

ffmpeg -i concat:"e:VIDEO_TS\VTS_03_0.VOB|e:VIDEO_TS\VTS_03_1.VOB|e:VIDEO_TS\VTS_03_2.VOB" -map 0:v -map 0:a:2 -c:v libx264 03.mp4