VideoCore

Alphamosaic marketed its first version as a two-dimensional DSP architecture that makes it flexible and efficient enough to decode (as well as encode) a number of multimedia codecs in software while maintaining low power usage.

Mobile multimedia devices require a lot of high-speed video processing but at low power for long battery life.

The ARM processor core has a high IPS per watt figure (and thus dominates the mobile phone market) but requires video acceleration coprocessors and display controllers for a complete system.

"Each processor has two vector floating-point ALUs which carry out multiply and non-multiply operations in parallel with single instruction cycle latency.

Internally the QPU is a 4-way SIMD processor multiplexed 4× over four cycles, making it particularly suited to processing streams of quads of pixels," according to Broadcom's VideoCore® IV 3D Architecture Reference Guide.

Of video compression algorithms currently in wide use, such as H.263, H.264/MPEG-4 AVC, MPEG-4, MPEG-2, MPEG-1, H.265, Daala, Theora, VP8 and VP9, Broadcom's VideoCore products support hardware acceleration of some operations.

For instance, typical non-multimedia tasks rarely require more than 32-bit bus width, while the VideoCore design employs multiple wide-bus-width cores.

The open source community has produced a C++ library called V3DLib for directly running custom compute kernels on the VideoCore GPU on all Raspberry Pi's.

Similar mobile multimedia chip ranges include Adreno, Texas Instruments OMAP, Nvidia Tegra, AllWinner A1X and Freescale i.MX.