VideoCore is a low-power mobile multimedia processor originally developed by

Alphamosaic Ltd Alphamosaic Ltd was a fabless semiconductor company specialising in low power mobile multimedia processors, based on their VideoCore architecture. Alphamosaic was founded in Cambridge, UK by Robert Swann and Steve Barlow in October 2000, as a ...

and now owned by

Broadcom Broadcom Inc. is an American designer, developer, manufacturer and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data center, networking, software, broadband, wirel ...

. Its two-dimensional DSP architecture makes it flexible and efficient enough to decode (as well as encode) a number of multimedia codecs in software while maintaining low power usage. The

semiconductor intellectual property core In electronic design, a semiconductor intellectual property core (SIP core), IP core, or IP block is a reusable unit of logic, cell, or integrated circuit layout design that is the intellectual property of one party. IP cores can be licensed t ...

(SIP core) has been found so far only on Broadcom SoCs.

Technical details

Multimedia system constraints

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. The amount of data passing between these chips at high speed results in higher power consumption. Specialised co-processors may be optimised for throughput over latency (more cores and data parallelism, but at a lower clock speed), and have instruction-sets and memory architectures designed for media processing (e.g. saturation arithmetic, and handling of specialised data formats).

3D engine

The VideoCoreIV-AG100-R found in the

Raspberry Pi Raspberry Pi () is a series of small single-board computers (SBCs) developed in the United Kingdom by the Raspberry Pi Foundation in association with Broadcom. The Raspberry Pi project originally leaned towards the promotion of teaching basic ...

1, 2 and 3, is documented to fully support

OpenGL ES OpenGL for Embedded Systems (OpenGL ES or GLES) is a subset of the OpenGL computer graphics rendering application programming interface (API) for rendering 2D and 3D computer graphics such as those used by video games, typically hardware-accele ...

2.0 and

OpenVG OpenVG is an API designed for hardware-accelerated 2D vector graphics. Its primary platforms are mobile phones, gaming & media consoles and consumer electronic devices. It was designed to help manufacturers create more attractive user interfac ...

1.1. The 3D engine is composed of various subsystems, the most abundant being the QPUs. A QPU is a 16-way

single instruction, multiple data Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA), but it should ...

(SIMD) processor. "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.'

"QPUs are organized into groups of up to four, termed slices, which share certain common resources," the document continues. cf. Vertex (computer graphics), Vertex and

shader In computer graphics, a shader is a computer program that calculates the appropriate levels of light, darkness, and color during the rendering of a 3D scene - a process known as ''shading''. Shaders have evolved to perform a variety of speci ...

. These "slices" correspond roughly to AMD's Compute Units. At least VC 4 (e.g. in the Raspberry Pi) does not support S3 Texture Compression (S3TC). It probably also does not support Adaptive Scalable Texture Compression (ASTC).

Video compression algorithms

Of video compression algorithms currently in wide use, such as

H.263 H.263 is a video compression standard originally designed as a low-bit-rate compressed format for videotelephony. It was standardized by the ITU-T Video Coding Experts Group (VCEG) in a project ending in 1995/1996. It is a member of the H.26x fam ...

, H.264/MPEG-4 AVC,

MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related t ...

MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, ...

MPEG-1 MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making ...

, H.265, Daala,

Theora Theora is a free lossy video compression format. It is developed by the Xiph.Org Foundation and distributed without licensing fees alongside their other free and open media projects, including the Vorbis audio format and the Ogg container ...

, VP8 and VP9, Broadcom's VideoCore products support hardware acceleration of some operations. In some cases only decompression, only compression or both up to a certain resolution (e.g. 720p or 1080p) and up to a certain frame rate (e.g. 30 or 60 frames per second).

VideoCore key features

* Instruction set written with video processing in mind from the start. For example,

saturation arithmetic Saturation arithmetic is a version of arithmetic in which all operations, such as addition and multiplication, are limited to a fixed range between a minimum and maximum value. If the result of an operation is greater than the maximum, it is se ...

so that the sum of two bright pixels does not 'wrap around' into dark values. * An array of

graphics processing unit A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, m ...

s for

parallel computing Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different f ...

of video data at relatively low clock speed. * Very high integration puts CPU, GPUs, memory and display circuitry on a single chip, removing the power burden of driving fast off-chip buses.

Variants

The VideoCore I-based VC01 provides video and multimedia capabilities to various Samsung phones, including SCH-V540, SCH-V4200, SCH-V490. The VideoCore II-based VC02
BCM2722
processor provides video capabilities for

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...

's 5th generation iPod. The VideoCore III-base
BCM2727
processor provides video, still and 3D graphics capabilities for the Nokia N8. The VideoCore I
BCM2763
processor improves on the VideoCore III with support for

1080p 1080p (1920×1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen ve ...

encode and decode, along with higher resolution camera support and faster 2D and 3D graphics, all at very low power. It is used in the Nokia 808 PureView, some versions of

Roku Roku ( ) is a brand of hardware digital media players manufactured by American company Roku, Inc. They offer access to streaming media content from online services. The first Roku model, developed in collaboration with Netflix, was introduced ...

hardware and the

(2835/2836 models for versions 1/2 accordingly). The VideoCore I
BCM28155
processor supports for 1080p encode and decode, improved 2D and 3D graphics with

dual-core A multi-core processor is a microprocessor on a single integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions. The instructions are ordinary CPU instructions (such ...

ARM Cortex-A9 The ARM Cortex-A9 MPCore is a 32-bit multi-core processor that provides up to 4 cache-coherent cores, each implementing the ARM v7 architecture instruction set. It was introduced in 2007. Features Key features of the Cortex-A9 core are: * ...

CPU in BCM28155 chipset. It is used in the Samsung Galaxy S II Plus,

Samsung Galaxy Grand The Samsung Galaxy Grand is a smartphone developed by Samsung Electronics, first announced on December 18, 2012. The phone has a dual core Cortex-A9 1.2 GHz processor and a RAM of 1 GB, with an internal memory of 8 GB which can be extende ...

and

Amazon Fire TV Stick Amazon Fire TV (stylized as amazon fireTV) is a line of digital media players and microconsoles developed by Amazon. The devices are small network appliances that deliver digital audio and video content streamed via the Internet to a connected ...

. The VideoCore
BCM7251
processor supports 2160p60 decode and transcode or dual 1080p60 encode/decode, features improved codec support (H.265), DDR3 and DDR4 support, USB 3.0, PCIe, Gigabit Ethernet and 802.11ac on a

ARM Cortex-A15 The ARM Cortex-A15 MPCore is a 32-bit processor core licensed by ARM Holdings implementing the ARMv7-A architecture. It is a multicore processor with out-of-order superscalar pipeline running at up to 2.5 GHz. Overview ARM has claimed th ...

Brahma15 dual core CPU.

Table of SoCs adopting VideoCore SIP blocks

VideoCore products

VideoCore chips can run complete applications - they are not simply video DSP chips that require a separate processor to supply and collect data. In practice though, they are often used like simple accelerators, as companies usually prefer to cautiously assimilate new technology rather than take a big risk in porting a large amount of application code from an existing ARM-based design. The VideoCore may also not be optimally power-efficient at non-DSP tasks, but may be coupled with a highly efficient CPU core, 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 Apple video iPod is a good example of this approach. Low-power laptops use low-power processors and graphics chips, and therefore often struggle to play video at full frame rates. It isn't desirable or practical to port a full operating system onto a VideoCore chip, so only the video decoding need be offloaded onto a video accelerator board (e.g. using the BCM70015 chip). Blu-ray players can also use it as a low-power video accelerator. Noting that VideoCore chips were usually used with ARM-based chips, the latest chips have VideoCore and ARM processors.

Linux support

On 28 February 2014, on the day of the second anniversary of the

, Broadcom, together with the Raspberry PI foundation, announced the release of full documentation for the VideoCore IV graphics core, and a complete source release of the graphics stack under a 3-clause BSD license. However, only a minor part of the driver was released as open source; all of the video acceleration is done using a firmware coded for its proprietary GPU, which was not open sourced. The entire SoC itself is managed by a ThreadX-based

RTOS A real-time operating system (RTOS) is an operating system (OS) for real-time applications that processes data and events that have critically defined time constraints. An RTOS is distinct from a time-sharing operating system, such as Unix, which ...

that is loaded into the VideoCore's VPU during bootup. An architectural overview of the VideoCore based system was compiled (based on reverse engineering & patent research) by Herman Hermitage and is available on GitHub. In June 2014, Emma Anholt left Intel for Broadcom to develop a free driver ( DRM/

KMS driver The Direct Rendering Manager (DRM) is a subsystem of the Linux kernel responsible for interfacing with GPUs of modern video cards. DRM exposes an API that user-space programs can use to send commands and data to the GPU and perform operations ...

and

Gallium3D Mesa, also called Mesa3D and The Mesa 3D Graphics Library, is an open source implementation of OpenGL, Vulkan, and other graphics API specifications. Mesa translates these specifications to vendor-specific graphics hardware drivers. Its most im ...

-driver) for VC4 (VideoCore 4). After one week, she reported noteworthy progress. The freely licensed 3D graphics code was committed to Mesa on 29 August 2014, and was first released as part of Mesa 10.3.

Market competitors

Similar mobile multimedia chip ranges include

Adreno Adreno is a series of graphics processing unit (GPU) semiconductor intellectual property cores developed by Qualcomm and used in many of their SoCs. History Adreno (an anagram of AMD's graphic card brand ''Radeon''), was originally developed by ...

, Texas Instruments OMAP, Nvidia Tegra, AllWinner A1X and Freescale i.MX. These are ARM-based with arrays of graphics processing units.

Data sources

The Broadcom YouTube page has videos demonstrating the video processing capability, but their website only goes as far as providing product briefs. Detailed data and development tools are only available under NDA, and then only for manufacturers with a market for very many units. However, on 28 February 2014, on the day of the second anniversary of the Raspberry Pi, Broadcom, together with the Raspberry Pi Foundation, announced the release of full documentation for the VideoCore IV graphics core, and a complete source release of the graphics stack under a 3-clause BSD license.

References

{{Graphics Processing Unit Broadcom Digital signal processors Graphics processing units