ffmpeg -i input.mp4 -c:v h263 -s qcif -r 10 -b:v 150k -c:a libopencore_amrnb -ar 8000 -ab 12.2k output.3gp
Search for "3gp kingcom" today, and you will find: 3gp kingcom
Understanding "3gp kingcom": The Evolution of Mobile Video Formats and Web Search Legacies ffmpeg -i input