[FFmpeg-user] Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument

[RITESH MEHANDIRATTA]

i am a beginner in ffmpeg tool . i am trying to encode a video and audio
stream of a sample.mp4 file .i am using this command

ffmpeg -re -i sample.mp4 -c:v libx264 -c:a libfdk_aac -f rtp rtp://
127.0.0.1:1234 > 100011.sdp

what i am trying to accomplish is i am first streaming thes both streams
then generating corresponsinf sdp file and use this sdp file for receiving
end (wowza media server).when i use above command.i am getting error

Could not write header for output file #0 (incorrect codec parameters ?):
Invalid argument what should be the argument we have to provide for
encoding this mp4 file ?? please guideline !!