[FFmpeg-user] can not add audio code/fourcc

[Sebastien WILLEMIJNS]

Hello,

>   Duration: 00:00:29.05, start: 0.000000, bitrate: 390 kb/s
>    Stream #0:0: Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 320x240 [SAR 9:8 DAR 3:2], 244 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc
>    Stream #0:1: Audio: aac ([255][0][0][0] / 0x00FF), 44100 Hz, stereo, fltp, 125 kb/s

how to change the 0x00FF code on the audio part of this movie extract ?
i want to see "mp4a" data instead of 0x00FF

i have tried to extract audio before 
ffmpeg.exe -i video.3gp -c:v copy -c:a aac -strict experimental
%dir%\son.aac -atag mp4a