Mark Kalman

I'm looking to hire a (Senior) Engineering Manager for Twitter's Media Technologies Backend team, the team that powers media at Twitter, enabling images, video-on-demand, live broadcasting, and real time communication for 100s of millions. Please check out the job description for more details!

Periscope's video streaming service is expanding within Twitter and we need to grow our team. If you are a generalist developer with video engineering or distributed systems expertise, please take a look at the job description I've linked below! At Periscope, I developed the video streaming service and LHLS streaming protocol. LHLS gives us the scalability of HLS while meeting Periscope's 2-5 second latency requirement. See the LHLS talk and blog post linked below.

Led the media streaming technologies team for Amazon's AppStream AWS service.

Tech lead and architect of media streaming for Amazon's AppStream AWS service.

-- Responsible for the design and evolution of the interfaces that allow partner devices to integrate with and run Netflix. Devices include game consoles like PS3 and Wii, smart TVs, set-top boxes and BluRay players from all the major consumer electronics companies, and tablets and mobile devices running Android or iOS. The job involves continually gathering requirements as new features are introduced, surveying for capabilities and feedback from teams across the range of devices, designing interfaces, implementing reference code, writing documentation, and assisting developers as they implement the interfaces. -- As codec and standards expert, design media packaging formats, answer partner questions about our encodings and packaging, and diagnose stream issues. -- Design and code features with the Netflix SDK development team.

--- Built and managed high-performing team responsible for video playback, codecs, transcoding, and editing in FlipShare desktop software. As hands-on manager, worked with team on projects including adding DXVA-accelerated H.264 decoding, CUDA H.264 encoding with Flip compatible encoding profile, and platform-independent video editing optimized for efficiency. --- Managed relationships with technical partners including Apple, AMD, Intel, NVidia, Microsoft, and internal Cisco groups. Collaborated with partners on APIs for HW-accelerated H.264 decoding and encoding, and compatibility between Flip cameras and partners' software. --- Worked on a cross-functional team with camera engineers and program managers to specify camera encoding file format parameters. Worked out compromises between what was good for FlipShare software and what was good for the camera team. --- Served as engineering release manager on a cross-functional team with product, project, and UI managers to scope features and iterate on requirements. Worked with cloud, web, and desktop architects to scope and design features. --- Served as technical lead for scoping effort to build in-house FlipShare video hosting. Analyzed traffic traces and built queuing model to estimate required transcoding capacity and bandwidth requirements. --- Led scoping and proof-of-concept effort for a Flip camera live streaming feature. Built proof of concept with Linux-based RTP uplink client/server, RTSP connection to Wowza server. Scoped cloud infrastructure based on capacity requirements.

As engineering lead, was responsible for video playback, codecs, transcoding, and editing in FlipShare desktop software on Mac and Windows. --- Implemented platform-independent H.264 / AAC / MP4 transcoding based on Intel IPP samples. Modified H.264 encoder for compatibility with Flip camera decoders which only support a non-standard subset of H.264 Main. --- Implemented DirectShow H.264 and AAC encoder and decoder filters, MP4 splitter and multiplexer filters. Implemented H.264 decoder frame dropping control for real-time AV sync. --- Implemented cross-platform MP4 file utilities including MP4 file trimming, tagging, re-multiplexing in "streamable" form, rotation, media file information query. --- Implemented video editing back-end via DirectShow Editing Services on Windows and QuickTime API on Mac. --- Implemented video playback on Mac via QTKit API with GPU-accelerated decoding on Macs that support it. As senior software engineer, developed novel image and video processing algorithms for Pure Digital’s image processing server. --- Developed and implemented demosaicking algorithm that outperforms the widely used Hamilton-Adams method. US Patent filed. --- Developed and implemented an adaptive image sharpening algorithm that eliminates common sharpening artifacts like overshoot at high-contrast edges, intensified color fringing, and noise in dark regions. US Patent filed. --- Developed and implemented an automatic focus algorithm that analyzes a target image and finds line spread functions for edges. Computes resolution as a function of position, orientation, and color channel. --- Developed and implemented an adaptive anti-flicker filter for still images shown on interlaced displays. --- Extensively used Intel IPP libraries, Intel SIMD Intrinsics, and multi-core programming techniques for fast image and video processing implementations.