Grzegorz Sokół, Developer in Warsaw, Poland
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Grzegorz Sokół

Verified Expert  in Engineering

Video Encoding Developer

Warsaw, Poland
Toptal Member Since
June 10, 2020

Grzegorz is a seasoned embedded developer with 15 years of experience. He has delivered everything from low-level driver code through middleware, applications, and UIs. He has deep expertise in image processing, multimedia, streaming, digital signage, and DRM, and he is a native-language (C/C++) coder with vast experience in developing high-availability and high-performance back-end solutions. Grzegorz is also an Android developer and experienced in developing electronic payment solutions.


EMV, Cryptography, C++, Android, Transport Layer Security (TLS)...
OpenWRT, WiFi, Networking, Yocto, C++, C
Atende Software
Buildroot, Yocto, Embedded Systems, CCTV, Digital Rights Management (DRM)...




Preferred Environment

GCC, Android Studio, Linux

The most amazing...

...solution I've developed was a set of algorithms for removing motion blur from drone footage taken at high velocities so that it could be used in photogrammetry.

Work Experience

Android Engineer

2019 - 2021
  • Implemented a SoftPos application for receiving contactless payments on the off-the-shelf Android phone instead of a dedicated POS terminal.
  • Delivered software for interfacing with the Samsung Knox security framework.
  • Maintained the software in the field with security and stability upgrades and new features.
Technologies: EMV, Cryptography, C++, Android, Transport Layer Security (TLS), JSON Web Tokens (JWT)

Software Engineer

2018 - 2019
  • Developed a software stack for managing wireless extender devices.
  • Participated in developing a WiFi extender device with mesh capabilities.
  • Contributed to bringing up new hardware, including platform verification, build system setup, and hardware modifications.
Technologies: OpenWRT, WiFi, Networking, Yocto, C++, C

Software Engineer

2016 - 2019
Atende Software
  • Built a scalable and highly efficient Apple FairPlay DRM license server.
  • Developed software for acquiring data from online energy meters through various transport protocols and media.
  • Improved video-on-demand and live encoding software.
Technologies: Buildroot, Yocto, Embedded Systems, CCTV, Digital Rights Management (DRM), Video Encoding, Streaming, C++, Apple FairPlay, WebRTC, HTTP Live Streaming (HLS), Android

Software Engineer

2014 - 2016
Livesystems AG
  • Developed an onboard infotainment and ad system for public transport services in Switzerland.
  • Participated in bringing up new hardware and porting existing software bases to new platforms such as new chips, boards, and features.
  • Developed auxiliary software for ad owners and an Android app used by the clients to monitor their ad campaigns.
Technologies: Buildroot, Yocto, Android, GStreamer, OpenMAX, Video Streaming, Video Encoding, Embedded Systems

Software Engineer

2012 - 2014
Atende Software
  • Developed encoding and authoring applications for multi-profile live encoding of multimedia content.
  • Created a distributed voice on demand (VOD) encoder farm using both software-accelerated and hardware-accelerated (NVENC) encoding.
  • Developed an RTSP live streaming service deployed within a content delivery network.
  • Co-developed an Android RTSP test player with DRM capabilities.
Technologies: Android, RTSP, Streaming, NVIDIA Grid SDK, H.264, FFmpeg, C++

Software Engineer

2009 - 2012
  • Developed payment applications for major banks in the UK.
  • Implemented support for new payment standards and developed solutions to improve security and prevent fraud.
  • Maintained software in the field, managed software updates, and implemented test and host emulation software.
Technologies: Cryptography, EMV, C++, C

Software Engineer

2005 - 2009
Samsung Electronics
  • Participated in developing a common digital TV software stack for European markets.
  • Assisted with porting digital TV software to new platforms and bringing up new hardware.
  • Contributed to the success of one of Samsung's first TV sets that became a best seller in Europe. This was considered an important milestone for the company.
Technologies: MHEG, DVB-S, Linux, C++, C, Embedded Systems

Multistandard CCTV System
I developed a multistandard video signals integrator to seamlessly aggregate CCTV feeds from various inputs, including major video management systems, portable embedded encoders, and IP cameras. This was part of a large research and development project.


This solution turns an off-the-shelf Android phone into a POS terminal capable of accepting contactless payments, including PIN transactions. Unlike mPOS devices, this solution does not require additional hardware. Furthermore, the user can still enjoy all the mobile phone functionalities without any disruption from the payment app.

Real-time Pedestrian Tracking
For my thesis project, I developed this real-time pedestrian tracking solution, using various motion detection, clustering, and pattern matching techniques, and a fuzzy logic classifier. My solution was valuable because of its simplicity and effectiveness with low-quality video.

Digital Signage and Infotainment System

I developed this software solution for onboard infotainment computers. This included building a new hardware platform and transitioning from the older platform, developing live streaming and transcoding software, and integrating route information and timetable services.

Image Recognition for an Automated Production Line
This image recognition project was for a client who was designing a manufacturing process. The items produced by the machinery needed to be validated, discarded if invalid, or flipped over if necessary.
2006 - 2008

Master of Science Degree in Computer Engineering (Electronics)

Warsaw University of Technology - Warsaw, Poland

2002 - 2005

Bachelor of Science Degree in Engineering

Warsaw University of Technology - Warsaw, Poland


FFmpeg, Sockets, Libav, wxWidgets, OpenCV, Libcurl, OpenSSL, Libpng, WebRTC, OpenMAX, OpenAL, x264, BouncyCastle


Apple FairPlay, Valgrind, GNU Debugger (GDB), CMake, GNU Make, Android NDK, Buildroot, Android Studio, GCC, NVIDIA Grid SDK


C++, C, Java, C++11


Linux, Embedded Linux, Android, OpenWRT


Socket Programming


GStreamer, JNI, JSON Web Tokens (JWT)


Video Streaming, Video Encoding, Embedded Systems, Multithreading, Debugging, HTTP Live Streaming (HLS), Transport Layer Security (TLS), HTTP, HTTPS, WebSockets, TCP/IP, Yocto, Cairo, Linux Internals, OkHttp, Applied Cryptography, Public-key Cryptography, EMV, DVB-S, MHEG, Cryptography, H.264, Streaming, RTSP, Digital Rights Management (DRM), CCTV, Networking, WiFi, Computer Engineering, Electronics, Engineering, Image Recognition, Tracking

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