To remove background of video, in order to play on keynote, I try many methods, from ffmpeg, website online tools. to iMovie.

Here is the final methods I use:

• cd

• Input: png + pngs
• Codes: ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[0]scale=2180:1120, overlay=560:30" my2_1.mp4 -y, PERFECT!.
• Remark: frame rate = 10
• Useful resources: just codes, PNG+PNGs

• Use R to derive start date and end date of each time window and write in txt.
• Use python to read txt and write SRT file as subtitle.

• Codes ffmpeg -i my2_1.mp4 -vf "subtitles=timewindow.srt" -y my2_2.mp4.
• Useful refrence: Video subtitles using FFMPEG.

1. Video tutorial for transparent website video for a golf ball on Mac. Output is mov. Tool: Adobe after effects(not free), Shutter Encoder. The very important step is done by Adobe after effects.
2. Use ffmpeg to replace green background with transparent background.
3. Use iMovie to combine video and png, replace green background with selected png.
4. Videezy: video resources.
5. Use ffmpeg to import images with alpha to a video with alpha in stackoverflow, codes are ffmpeg -i network_%03d.png -vcodec png my2.mov. Cannot display.
6. Online tool deposiphotos, which can transform black background to green background.
7. Use ffmpeg to output alpha mov, found in CSDN, codes are ffmpeg -f image2 -r 10 -i network_%03d.png -vf fps=25 -vcodec png my2.mov -y. Cannot display.
8. Combind 2 videos and make one transparent, found in CSDN blog.
9. Use ffmpeg to import images with alpha to generate video with alpha, found in CSDN, codes are ffmpeg -r 10 -i network_%03d.png -vcodec qtrle my2.mov -y, cannot play. ffmpeg -r 10 -i network_%03d.png -vcodec ffvhuff my2.avi -y, cannot play. ffmpeg -r 10 -i network_%03d.png -vcodec huffyuv my2.avi -y`, cannot play.
10. Use ffmpeg to import images to make a mov and set framerate as 10, codes are ffmpeg -r 10 -i network_%03d.png -pix_fmt yuva420p my3film.mov. Can work but not transparent.
11. Different formats supporting video with alpha in IOS and Android, found in CSDN. Seems like IOS only supports H265 with alpha channel.
12. Use ffmpeg, inputs are a mp4 and a png, output is mp4, codes usecolorchannelmixer, found in Youtube.
13. RiskMakes personal website for ffmpeg.
14. Use ffmpeg to remove green background and replace it with transparent background. Use vp9, output is webm. Codes are ffmpeg -i my2film.mp4 -c:v vp9 -filter:v "chromakey=0x000000:0.1:0.2" my1.webm -y. Cannot play.
15. Using ffmpeg to make an H.265 file compatible with Quicktime, found in RiskMakes website, codes are ffmpeg -i input.mp4 -codec copy -tag:v hvc1 output.mp4. My version ffmpeg -i my2.mov -codec copy -tag:v hvc1 my2_1.mov cause error.
16. Use ffmpeg to create transparent timer.
17. Use ffmpeg to create transparent scrolling credits.
18. Use ffmpeg to convert pngs to a mp4, codes are ffmpeg -r 10 -i network_%03d.png -pix_fmt yuv420p my1.mp4.
19. Chinese tutorials for how to install and use ffmpeg, very clear.
20. Encoder Apple ProRes supports alpha channel and can play on Quicktime, codes areffmpeg -r 10 -i network_%03d.png -c:v prores:v -profile 4 -pix_fmt yuv444p10 my1.mov -y. or ffmpeg -r 10 -i network_%03d.png -c:v prores_ks -profile:v 4 -pix_fmt yuv444p10 my1.mov -y . Not transparent.

Create a background using one png ffmpeg -loop 1 -i background.png -c:v libx264 -t 17 -pix_fmt yuv420p -vf scale=1320:640 my2.mp4 -y.

Add pngs to video:

• ffmpeg -i my2.mp4 -i network_001.png -filter_complex "[0:v][1:v]overlay" -vcodec libx264 my2_1.mp4 -y. png too big
• ffmpeg -i my2.mp4 -r 10 -i network_%03d.png -filter_complex "[0:v][1:v]overlay" -vcodec libx264 my2_1.mp4 -y. only 1 png
• ffmpeg -i my2.mp4 -framerate 10 -pattern_type glob -i "network_%03d.png" -filter_complex "[1:v][0:v]scale2ref=iw:ih[ovr]; [ovr][0:v]blend=all_mode='overlay':all_opacity=0.7[v]" -map [v] my2_1.mp4 -y as in here.
• ffmpeg -i my2.mp4 -i network_001.png -filter_complex "[0:v][1:v]overlay=50:50:enable='between(t,0,1)'" -pix_fmt yuv420p -c:a copy my2_1.mp4 -y as in Youtube. Time in (0,1), scale not solved.
• ffmpeg -i my2.mp4 -i network_001.png -filter_complex "[1]scale=50:50;[0:v][1:v]overlay=50:50:enable='between(t,0,1)'" -pix_fmt yuv420p -c:a copy my2_1.mp4 -y, scaled, but awful.
• ffmpeg -i background.png -i network_%03d.png -filter_complex "overlay" my2_1.mp4 -y, works but no scaled, thanks to this.
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "overlay" my2_1.mp4 -y, change frame rate, works but no scaled.
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[1:v]scale=1080:1080, overlay" my2_1.mp4 -y scale background, background on the top
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[0:v]scale=1080:1080, overlay=50:50" my2_1.mp4 -y scale pngs, pngs on the top
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[0:v]scale=1080:1080, overlay" my2_1.mp4 -y scale pngs, pngs on the top
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[0]scale=2180:1120, overlay=560:30" my2_1.mp4 -y PERFECT!
• ffmpeg -i background.png -r 10 -i network_%03d.png -filter_complex "[0:v]scale=720:740, overlay=(main_w-overlay_w)/4:(main_h-overlay_h)/4" my2_1.mp4 -y, no movie