The error message ECOM00101 translates to “Could not write header for output file.”
The specified codec that you have selected does not support what you are requested of it as an output file. You may be including or omitting certain parameters that are not supported for this format. In addition to that, you may need special parameters to be specified. Please check if you are explicitly allowed the specified video and audio codecs for this format. For example: the 3GP format requires the libamr_nb audio codec for correct encoding.