We need 3 DirectShow filters to get MP4 output files.
H264 encoder must be made using Intel Media SDK 2015 (that's available with source code, but need to be tuned if required). We're require 4K resolution support, that's available in Intel encoder. You must add constant frame rate support for H264 encoder (variable by default, can be configured using API).
AAC encoder must be made using any free AAC encoder, that can be linked statically and have license like LGPL/BSD/MPL. Also you can use encoder from Intel Media SDK, that's better.
MP4 muxer can be based on GDCL or any other, or written from zero. All profiles available fro H264 encoder must be supported. Filter must provide correct AV syncronization.
Test sources - webcams, video files, RTSP network streams.
All filters must have interfaces to set required parameters.
We're require x86 and x64 versions, VC++ 2010 or 2015.
Test version with some nag-screen must be made before final payment.
Source code can be based on Intel or open-source projects, with license restrictions as I wrote before.