ffmpeg tips

[aben20807]

ffmpeg tips

[aben20807]

Convert video to gif

• ref

ffmpeg -y -i input.flv -filter_complex "fps=4,scale=1920:-1:flags=lanczos,split[s0][s1];[s0]palettegen=max_colors=256[p];[s1][p]paletteuse=dither=bayer" output.gif

scale and max_colors impact the output gif's size

[aben20807]

Concat (w/o re-encode - fast)

• ref
• input: A.mp4, B.mp4, C.mp4, ...

ffmpeg -safe 0 -f concat -i <(find . -type f -name '*.mp4' -printf "file '$PWD/%p'\n" | sort) -c copy output.mp4

Concat (w/ re-encode - slow)

• remove -c:v h264_nvenc if there is no GPU driver

ffmpeg -i A.mp4 -i B.mp4 -filter_complex "concat=n=2:v=1:a=1" -c:v h264_nvenc output.mp4

if error when different DAR

[Parsed_concat_4 @ 0x55c55ae4d400] Input link in0:v0 parameters (size 1280x720, SAR 1:1) do not match the corresponding output link in0:v0 parameters (1280x720, SAR 8001:8000)
[Parsed_concat_4 @ 0x55c55ae4d400] Failed to configure output pad on Parsed_concat_4
Error reinitializing filters!

Correct the aspect of one of videos first.

ffmpeg -i tmpA.mp4 -aspect 16:9 -c copy A.mp4

[aben20807]

Convert webp images into jpeg format

• ref

find . -iname '*.webp' -exec bash -c 'ffmpeg -y -hide_banner -loglevel error -i "$1" -q:v 1 -qmin 1 -qmax 1 "${1%.*}.jpg"; printf "$1\n"' _ {} \;

轉換完後刪除原檔

find . -iname '*.webp' -exec bash -c 'ffmpeg -y -hide_banner -loglevel error -i "$1" -q:v 1 -qmin 1 -qmax 1 "${1%.*}.jpg"; printf "$1\n" && rm "$1"' _ {} \;

[aben20807]

Reduce file size

• -crf N: N: 0–51, where 0 is lossless, 23 is the default, and 51 is worst quality possible
• -b 800k: limit the bitrate (optional)

ffmpeg -i input.flv -c:v h264_nvenc -crf 30 -c:a aac -b:a 192k -vf format=yuv420p -movflags +faststart output.mp4

[aben20807]

Combine video and audio

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

optional

 yt-dlp -F {youtube url}