44% faster encoding by OpenCL/GCD

Contrary to nVidia's CUDA,  Apple's OpenCL API is compatible with both nVidia and ATI graphics card. Like the so-called Grand Central Dispatch (GC) technology, OpenCL is an addition to the new version 10.6 "Snow Leopard" of the Mac OS X operating system. Because it's an open standard however, it can also be used on Windows-based systems.

An application where certain technologies are welcome is the encoding and decoding of video, done by MovieGate in Mac OS X. The developer of the software, Christophe Ducommun, recently published test results that show OpenCL and GCD significantly improve the performance of his program.

Snow Leopard reaches up to 150 frames per second when encoding MPEG2-video, while the older version of Leopard didn't exceed 104 frames per second. This is a performance increase of 44%. All tests were done using the same hardware, a Mac Pro 2007 with a 2,66 GHz quadcore and an nVidia GeForce 8800 GT. It has to be mentioned that GCD enhances the performance on multicore systems, making it possible that the increase percentage is lower on a dualcore computer.

Ducommun also reports a decrease in the CPU load while decoding MPEG-2 video from 165% to 70%. The encoding of MPEG-2 video with ffmpeg is paired with a higher CPU load, namely 130% in Snow Leopard, compared to 100% in Leopard.

MovieGate's 44% performance increase thanks to OpenCL and GCD is still exceptional, since other programs are not yet optimized for Snow Leopard's new technologies. It does show that certain GPGPU API's can enhance a system's performance without requiring better hardware, meaning the available computing power is used more efficiently.

Tags: geforce gpgpu cuda opencl apple

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