h264 to h263 conversion is most likely related to export of videos encoded with h.264 codec to h.263 codec, which is doable but will most likely lower the overall video and perhaps also audio quality of the resulting file.
For this you can for example use the FFmpeg encoder and command line tool for Windows, Mac and Linux to convert H.264 video data to H.263 video format. Just Install FFmpeg and use the following command line command:
ffmpeg -i /path/to/your/file.h264 -vcodec copy -acodec copy /path/to/your/newfile.h263Open H264 file Open H263 file
Program for multimedia streaming and conversion
One of the most popular and succesfful free video conversion sofrware
A free universal media transcoder for Windows
Video converting software