`ffmpeg` is FLOSS (no cost), plus is the best executable to transcode/trim/demux/mux. Android OS/iOS/Linux/Windows all have this.
A few example use howtos
ffmpeg is FLOSS (no cost), plus is the best executable to transcode/trim/demux/mux. ffmpeg is on Windows/Linux/Android OS/iOS/OSX.
[This post allows all uses] [Version of post is ?TranscodeMuxHowto.md Can use examples with Termux · SwuduSusuwu/SubStack@686a6b5]
https://play.google.com/store/apps/details?id=protect.videoeditor (Video Transcoder) (a visual interface to ffmpeg) was cool versus most “video editor” apps -- but is not available for new versions of Android OS, can not loop (just has trim + convert (which can act as demux) + resize + compress), is slow (can not pass -c copy to ffmpeg, thus always reincodes inputs.)
Now use https://play.google.com/store/apps/details?id=com.silentlexx.ffmpeggui (FFmpeg Media Encoder from SilentLexx) with much success; has a visual interface to ffmpeg but can process commands from text. Alternative (have not used): https://play.google.com/store/apps/details?id=com.crossplat.ffmpegmobile (FFmpeg from CrossPlat).
For misc Linuxes (suchas Android-Termux); apt-get install ffmpeg && termux-setup-storage. For iOS; https://shaunhevey.com/posts/how-to-use-ffmpeg-on-ios/. For OSX; brew install ffmpeg --with-fdk-aac --with-ffplay --with-freetype --with-libass --with-libvorbis --with-libvpx --with-opus (or alternatives). For Windows; FFmpeg - Official app in the Microsoft Store.
[Notice: have moved /Music/ to /Sounds/, /Movies/ to /Visuals/]
[Notice: Can use examples with FFmpeg Media Encoder or Termux as-is (use absolute paths).]
Example visuals.mp4 was 4gb, to compress to 224mb used ffmpeg -i "/storage/emulated/0/Visuals/screen-20240629-045526.mp4" -framerate 30 -c:v libx264 -crf 32 -preset slower "/storage/emulated/0/Visuals/visuals.mp4"
The libx264 codec compresses visuals best. -preset slower instructs it to compress more. You can replace -crf 32 with -b:v 2m to set an exact goal of “compress to 2mbps”.
[Notice: On some devices, Android OS’s permissions require to output to /storage/emulated/0/Download/]
Suppose you want to mux sounds.mp4 with visuals.mp4,
but you want to skip sounds.mp4’s 4 second intro, plus limit output to 2 minutes:
To demux sounds, pass -ss 4 to skip 4 seconds, pass -t 2:00 to output 2 minutes, pass -map 0:a:0 (zero-indexed) to demux first input as sounds, pass -c copy for instant process, output as .m4a: ffmpeg -i "/storage/emulated/0/Download/sounds.mp4 -ss 4 -t 2:00 -map 0:a:0 -c copy "/storage/emulated/0/Sounds/demux.m4a"
Now sounds.m4a is 2 minutes, but visuals.m4a is much longer; pass -stream_loop -1 to mux sounds as loop to match visuals.mp4:
ffmpeg -i "/storage/emulated/0/Visuals/visuals.mp4" -stream_loop -1 -i "/storage/emulated/0/Sounds/demux.m4a" -map 0:v:0 -c copy -map 1:a:0 -shortest "/storage/emulated/0/Visuals/mux.mp4"
Suppose you want the mix the sounds from visuals.mp4 with the loop from sounds.mp4:
ffmpeg -i "/storage/emulated/0/Visuals/visuals.mp4" -stream_loop -1 -i "/storage/emulated/0/Sounds/demux.m4a" -map 0:a:0 -map 1:a:0 -filter_complex amix=inputs=2:duration=shortest "/storage/emulated/0/Sounds/demux2.m4a"
ffmpeg -i "/storage/emulated/0/Visuals/visuals.mp4" -i "/storage/emulated/0/Sounds/demux2.m4a" -map 0:v:0 -c copy -map 1:a:0 -shortest "/storage/emulated/0/Visuals/mux2.mp4"[Notice: -c copy is not compatible with -filter_complex; unless you want to reincode the visuals (slow), is 2 steps to do this]
Suppose you wish to produce a 10fps HD .gif from the first 24 seconds of visual.mp4: ffmpeg -i "/storage/emulated/0/Visuals/visual.mp4" -map 0:v:0 -pix_fmt rgb24 -r 10 -s 1920x1080 -t 24 "/storage/emulated/0/Visuals/visual.gif"
Lists of commands which ffmpeg can use; https://ffmpeg.org/ffmpeg.html
https://gist.github.com/tayvano/6e2d456a9897f55025e25035478a3a50#file-gistfile1-txt
How to use extra tools which ffmpeg's GPLv2 version has; https://github.com/FFmpeg/FFmpeg/blob/master/LICENSE.md
visual.gif syntax was used to produce: https://www.deviantart.com/swudususuwu/art/BUD-Robos-hold-you-loop-v0-4-3-2-S-Simulator-1004148092 https://www.deviantart.com/swudususuwu/art/Sakura-School-Simulator-howto-use-robot-props-loop-1019774750
mux.mp4/mux2.mp4 syntax was used to produce:
