in=... ; out=... # or eg. out="${in/%.mov/-small.mov}"

ffmpeg -i "$in"

-c:v libx264 -pix_fmt yuv420p -tune film -crf 20 -g 50
-preset slow # (veryfast fast medium slow slower veryslow)

Can be used with -crf

-maxrate 6M -bufsize 6M

• Prores proxy: -profile:v 0
• Prores LT: -profile:v 1
• Prores SQ: -profile:v 2
• Prores HQ: -profile:v 3

-c:v prores_ks -profile:v 1 -vendor apl0
-c:a pcm_s16le

See https://trac.ffmpeg.org/wiki/Scaling for details.

If using -s WxH, you need to calculate the right sizes to preserve the aspect ratio. It's easier and generally better to use -vf scale=..., which offers various shortcuts, and allows selecting the resizing algorithm.

Examples:

-vf "scale=hd1080"
-vf "scale=hd1080:flags=lanczos" # same, but with lanczos algorithm instead of default bilinear
-vf scale=640:-2      # width 640px, height as needed but divisible by 2
-vf "scale=iw/2:ih/2" # half width and height of original
-vf "scale=iw/2:-2"   # same (half width and height), but height divisible by 2
etc.

start=00:05:12.000    # or just seconds: start=312
duration=00:01:05.000 # or just seconds: duration=65

ffmpeg -i "$in" -ss $start -t $duration -c:v copy ...

If -ss $start is before the -i input, it may be faster in some cases. But with codecs like h264, the resulting output may also miss the needed keyframes at the start, and the beginning of the video may be corrupted.

All frames as .png:

in="file.mov"; out="${in%.*}.%06d.png"
ffmpeg -i "$in" -f image2 "$out"

Here a frame at 5 seconds, and a frame at 300 seconds from the start

in="file.mov"
for start in 5 300; do ffmpeg -ss $start -i "$in" -r 1 -vframes 1 -f image2 "${in/%.mov/}-at-$start-sec.png"; done

Output one image for every I-frame:

ffmpeg -i input.flv -vf "select='eq(pict_type,PICT_TYPE_I)'" -vsync vfr thumb%04d.png

Output all frames for a given duration (in seconds):

in="file.mkv"
start=00:09:38.000
duration=20
out="${in%%.mkv}-$start.%04d.png"
ffmpeg -ss $start -i "$in" -t $duration -f image2 "$out"

See also ffmpeg's Create a thumbnail image every X seconds of the video.

Frames to animated .webp :

in="test-tiff%08d.tif"; out="tiff-2.webp"
ffmpeg -r 25 -i "$in" -c:v libwebp_anim -lossless 1 -loop 0 -preset default -an -vsync 0 -s 480x270 "$out"

Animated .gif to .webp (copied from Convert GIF to WebM with ffmpeg)

ffmpeg -i my-animation.gif -c vp9 -b:v 0 -crf 41 my-animation.webm

-c:a aac -b:a 192k

Move "moov" atom to start of file (https://ffmpeg.org/ffmpeg-formats.html#Options-8). (Implies file copy after encoding)

-movflags faststart

I think that since -map is used, -map:v must be added too or the output is without video.

-filter_complex "[0:a:0][0:a:1]amerge,channelmap=channel_layout=stereo[st]" -map 0:v -map "[st]"

-r 25 or -vf "fps=fps=25"

Example to check what it does:

ffmpeg -f lavfi -i testsrc=duration=10:size=854x480:rate=60 \
-vf "drawtext=text=%{n}:fontsize=72:r=60:x=(w-tw)/2: y=h-(2*lh):fontcolor=white:box=1:boxcolor=0x00000099" test.mp4

dir="/path/to/output_dir"; mkdir -p "$dir"
for f in *.flac; do
  f2=$(basename "${f%.flac}.mp3"); \
  out="$dir/$f2";                  \
  ffmpeg -i "$f" -c:a libmp3lame -q:a 0 -c:v copy "$out"
done

-q:a 0 with libmp3lame makes it use best quality VBR. See https://trac.ffmpeg.org/wiki/Encode/MP3

-c:v copy makes it copy album art if there is any (instead of converting it to .png)

The metadata from FLAC is preserved by default, and written to a ID3v2.4 header. To write an ID3v2.3 header instead, add the -id3v2_version 3 option.

Can be done with flac instead of ffmpeg:

for f in *.wav; do
  flac "$f" --keep-foreign-metadata -V -o "${f%%wav}.flac"
done

This was slow? 330 mn. for a 167 mn. / 600GB file with 16 audio channels. Not slow on 30GB 16channels quicktime. But doesn't separate channels!

time ffmpeg -i "$in" -map 0:a -af "volumedetect" -f null - 2>&1 | tee "$in-volumedetect.txt"

ffmpeg -i "$in" -vn -sn -dn -map 0:a -af "astats=measure_overall=none" -f null - 2>&1

See also https://ffmpeg.org/ffmpeg-filters.html#toc-ebur128-1

For a file with 12 mono audio tracks:

for t in {0..11}; do ffmpeg -nostats -i "$in" -map 0:a:$t -filter_complex ebur128 -f null - > $(printf "ebur-$in-a%02d.txt" $t) 2>&1 ; done

Example with Fuji .MOV files, to add the "Create Date" time as a timecode:

• Check file extensions

find . -type f | perl -ple 's/^.*\.(\w+)/$1/' | sort -u

• Prepare destination

dest=/mnt/share/temp
mkdir -p "$dest"

• Extract time, add as TC, preserve original file date

find . -type f -name "*.MOV" \
| while read f; do \
    b=$(basename "$f");
    t=$(exiftool -CreateDate "$f" | awk '{print $NF}');
    tc="$t:00";
    echo "====== $f $tc";
    ffmpeg -loglevel warning -i "$f" -codec copy -map_metadata 0 -movflags use_metadata_tags -timecode "$tc" -f mov "$dest/$b" </dev/null || break;
    touch -r "$f" "$dest/$b";
    echo;
  done

From https://reto.ch/training/2017/201706/FFmpeg.html

f1=... # file 1
f2=... # file 2
t="-t 60" # limit time
out=delta.mp4
ffmpeg -i "$f1" -i "$f2" $t \
  -filter_complex "[1]format=yuva444p,lut=c3=128,negate[1_with_alpha_channel];[0][1_with_alpha_channel]overlay" "$out"

How to add resize? How to add different start times for input files?

Or see https://stackoverflow.com/questions/25774996/how-to-compare-show-the-difference-between-2-videos-in-ffmpeg :

ffmpeg -i "$f1" -i "$f2" $t \
  -filter_complex "blend=all_mode=difference" \
  -c:v libx264 -crf 18 -c:a none "$out"

And FFmpeg Filtering Guide

Or http://dericed.com/2012/display-video-difference-with-ffmpegs-overlay-filter/

ffmpeg "$f1" -i "$f2" $t \
  -filter_complex '[1:v]format=yuva444p,lut=c3=128,negate[video2withAlpha],[0:v][video2withAlpha]overlay[out]' \
  -map [out] "$out"

$  ffmpeg -i "$filename" -map 0:a -codec copy -f md5 "$filename.md5"

$  ffmpeg -i "$filename" -map 0:a -codec copy -hide_banner -loglevel warning -f md5 -

$  ffmpeg -i input.mp4 -map 0 -c copy -f streamhash -hash md5 -
...
0,v,MD5=50224fec84bc6dfde90d742bcf1d2e01
1,a,MD5=1d2a32ed72798d66e0110bd02df2be65

See also:

• http://ffmpeg.org/ffmpeg-formats.html#hash
• https://trac.ffmpeg.org/wiki/framemd5%20Intro%20and%20HowTo
• https://stackoverflow.com/a/897594/111036
• https://stackoverflow.com/questions/63608312/how-to-md5-the-video-track-only-in-ffmpeg

-nostdin

Verbosity:

-hide_banner -loglevel warning -stats
# or
-hide_banner -loglevel info -stats

ffmpeg -loop 1 -r 1 -i "$in_img" -i "$in_a" \
 -c:v libx264 -pix_fmt yuv420p -crf 22 -preset veryfast -tune stillimage \
 -c:a copy -shortest "$out"

Source is 4K (3840x2160), 50fps progressive, 8 mono tracks.

Wanted output : HD 1920x1080, 25 fps, 1 stereo audio from source tracks 1 + 2.

ffmpeg -i "$in" -vf "scale=hd1080" -r 25 \
-c:v libx264 -pix_fmt yuv420p -tune film -crf 20 -g 50 \
-filter_complex "[0:a:0][0:a:1]amerge,channelmap=channel_layout=stereo[st]" \
-map 0:v -map "[st]" \
-c:a aac -b:a 192k \
"$out"

Sample output:

ffmpeg -i "$in" -t 300 -vf "scale=hd1080" -r 25 -c:v libx264 -pix_fmt yuv420p -tune film -preset fast -crf 20 -g 50 -filter_complex "[0:a:0][0:a:1]amerge,channelmap=channel_layout=stereo[st]" -map 0:v -map "[st]" -c:a aac -b:a 192k "$out"
 
ffmpeg version 4.2.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
...
[mxf @ 0x6225a40] decoding for stream 0 failed
Guessed Channel Layout for Input Stream #0.1 : mono
Guessed Channel Layout for Input Stream #0.2 : mono
...
Guessed Channel Layout for Input Stream #0.16 : mono
Input #0, mxf, from 'fdv20190808pgm.mxf':
  Metadata:
    operational_pattern_ul: 060e2b34.04010101.0d010201.01010900
    uid             : bd7136e0-ba0f-11e9-8fed-ac1f6b48c8ac
    generation_uid  : bd7136e0-ba0f-11e9-8fee-ac1f6b48c8ac
    company_name    : oc
    product_name    : OCtk
    product_version : 2.10
    product_uid     : 3a4fe380-0d01-11e4-869f-3cd92b5c1dfc
    modification_date: 2019-08-08T21:07:17.708000Z
    material_package_umid: 0x060A2B340101010501010D2013000000BD6EECF0BA0F11E98FB2AC1F6B48C8AC
    timecode        : 21:07:16:08
  Duration: 02:47:16.24, start: 0.000000, bitrate: 524301 kb/s
    Stream #0:0: Video: h264 (High 4:2:2 Intra), yuv422p10le(progressive), 3840x2160 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 50 tbn, 100 tbc
    Metadata:
      file_package_umid: 0x060A2B340101010501010D2013000000BD6AF550BA0F11E98F81AC1F6B48C8AC
    Stream #0:1: Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s
    Metadata:
      file_package_umid: 0x060A2B340101010501010D2013000000BD6AF550BA0F11E98F81AC1F6B48C8AC
    Stream #0:2: Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s
    ...
    Metadata:
      file_package_umid: 0x060A2B340101010501010D2013000000BD6AF550BA0F11E98F81AC1F6B48C8AC
    Stream #0:16: Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s
    Metadata:
      file_package_umid: 0x060A2B340101010501010D2013000000BD6AF550BA0F11E98F81AC1F6B48C8AC
    Stream #0:17: Data: none
    Metadata:
      file_package_umid: 0x060A2B340101010501010D2013000000BD6AF550BA0F11E98F81AC1F6B48C8AC
      data_type       : vbi_vanc_smpte_436M
Stream mapping:
  Stream #0:1 (pcm_s24le) -> amerge:in0 (graph 0)
  Stream #0:2 (pcm_s24le) -> amerge:in1 (graph 0)
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  channelmap (graph 0) -> Stream #0:1 (aac)
...