download and combine
ffmpeg -protocol_whitelist file,http,https,tcp,tls,crypto -i "http://xxx.com/upload/43f6fd9740cfaac0fb73a04fad3c4c96.m3u8" -c copy filename.mp4
https://www.makeuseof.com/tag/aria2-fast-multiprotocol-power-downloader-app/
aria2c -x 4 -j 4 -Z -P http://server/image[000-100].png
