Qualcomm Pushes Mobile to UltraHD - Linley Group · Qualcomm Pushes Mobile to UltraHD ©2013 The...

Qualcomm Pushes Mobile to UltraHD

By Linley Gwennap Principal Analyst, The Linley Group

January 2014

www.linleygroup.com

©2013 The Linley Group - 1 -


By Linley Gwennap, Principal Analyst, The Linley Group

Qualcomm’s new Snapdragon 805 processor redefines the mobile experience to focus on video and imaging capabilities. It is the first mobile processor with end-to-end 4K support, enabling users to capture, decode, and display video in UltraHD resolution. When paired with Qualcomm’s next-generation Gobi 9x35 LTE Advanced modem chip, the platform offers the fastest cellular down-loads as well. This white paper describes the momentum behind 4K video and explains how the Snapdragon 805 platform offers the best support for this emerging standard.

Introduction

We’re on the verge of a new era of advanced display technology as High Definition television (HDTV) will be replaced by a next generation of displays offering far better picture quality. The new display technology, called 4K or UltraHD, features four times the display resolution of 1080p HDTV. Unlike the 3D TV technology of a few years ago, no glasses will be required to appreciate the crisp display of UltraHD.

This new technology is not just for watching movies on the big screen. Qualcomm’s newest Snapdragon processor has the bandwidth and processing capability to keep pace with this new challenge and do so within mobile power constraints. Smartphones and tablets using this Snapdragon 805 processor will be able to display 4K movies and capture 4K video using the device’s cameras. The device itself can have a high-quality 4K display, providing the ultimate viewing experience in a handheld device, or it can drive video to an external UltraHD TV.

Building Blocks of the Snapdragon 805

The Snapdragon 805 processor is fully plumbed for the emerging 4K video standard, being capable of encoding, decoding, and displaying video and graphics in that format. It can display this content on an external UltraHD TV or on a local display with up to 3,840x2,160 resolution (8.3Mpixels). Both GPU and memory performance are amped up to support these large displays.

The processor has been completely re-engineered to provide a platform to handle the latest in UltraHD content. The Krait CPUs have been refined to offer higher clock speeds without increasing power consumption. The video processor has increased in speed and capability to be able to upscale to and decode 4K video. The GPU complex has increased display resolution support and also has added new capabilities for the latest graphics and CPU compute APIs. Supporting the additional performance requirements is a new memory interface that doubles the memory bandwidth using new packaging.

As seen in Figure 1, Qualcomm can provide the complete processing and connectivity solution for smartphone and tablet OEMs. While the company did not integrate its cellular modem in the 805, the company can pair it with either the present Gobi 9x25 LTE Advanced chip or the next-generation 20nm LTE Advanced Gobi 9x35.


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Figure 1. Smartphone using Qualcomm’s Snapdragon 805 (APQ8084) processor. This design also includes the MDM9x25 LTE-Advanced modem chip and an external Wi-Fi combo chip from Qualcomm.

4K Is Already Here

4K video, sometimes called 2160p, offers four times the resolution of 1080p. From a standard TV-viewing distance, most people don’t notice the extra resolution on screens that measure less than 50 inches (diagonal). Even smaller TVs, however, can benefit from other features of the new standard, including improved color encodings, wider dynamic range, and the option of 60fps and 120fps frame rates.

So far, the demand for UltraHD TVs has been limited, mainly because of high prices and a lack of content. Less than three million are expected to ship this year. Prices have now fallen below $1,000, however, and industry watchers are forecasting rapid growth in 2014 and beyond. After the 3D-video debacle, however, TV networks are hesitant to commit to broadcasting in UltraHD. Qualcomm hopes to jumpstart the technology by enabling users to shoot their own 4K video.

UltraHD content will come from other sources. Production companies are converting their movie libraries to the 4K format, which has the resolution and color gamut to better capture 35mm film. Many new movies and even some TV shows are shot using 4K digital cameras. To boost sales of its UltraHD TVs, Sony has mandated that all new TV shows from Sony Entertainment be shot in 4K. Netflix plans to deliver this 4K content to its 40 million web-based subscribers starting as early as next year. YouTube has sup-ported 4K videos since 2010, allowing users to upload and view UltraHD content. For example, they can shoot 4K video using the Samsung Galaxy Note 3, which employs the Snapdragon 800, and share it on YouTube.



Snapdragon Is Ready For The Big Screen

The chip includes a new display processor that performs a range of color-correction and picture-adjustment functions. It can map between the standard color gamut and the UltraHD extended color gamut. Users can adjust the hue, saturation, and intensity of the display, but the display processor is smart enough to identify and lock down foliage, sky, and skin tones when adjusting other picture elements. Qualcomm has found that distortions in these common colors often appear unnatural.

The 805 also adds hardware support for decoding cutting-edge H.265 video compres-sion (HEVC) standard, which reduces file sizes by about 40% compared with H.264. Even so, an HEVC-encoded 4K video file will be more than twice as large as an H.264-encoded 1080p video. The enhanced processing power of the 805 allows the H.265 video to be encoded using software.

The 805 supports HDMI 1.4, which can connect to UltraHD TVs as well as HDTVs. The display processor can drive internal displays of up to 4K resolution and can mirror content on the internal display and external TV at 4K resolution at up to 24fps. When connected to a home-theater system, the processor can enhance this movie-quality video with multichannel 5.1 or 7.1 audio in Dolby or DTS format.

In addition to the upgraded video capability, the 805 has the first mobile image signal processor (ISP) capable of processing 1 Gigapixels/second. This rate supports 20Mpixel images at up to 50 per second, enabling users to rapidly capture a sequence of high-resolution photographs and choose the best one. The ISP can process images for higher dynamic range and greater sharpness, and it can compensate for low-light conditions.

The CPU is Still Really Krait

One area of the 805 that did not change is the CPU. The new processor uses the same proven Krait architecture as the Snapdragon 800, which currently delivers industry-leading CPU performance. Per-clock performance on CoreMark will remain unchanged, but larger apps will see a small (single-digit percentage) benefit from the doubling of peak memory bandwidth. Qualcomm is delivering an increase in clock speed resulting from an improved circuit design. The company says this speedup won’t increase power, meaning we could see a 2.7GHz 805 in smartphones as well as in tablets.

The Krait CPU supports the same physical address extension (LPAE) that Cortex-A15 uses. This extension allows the chip to handle more than 4GB of DRAM, although each program can access only 4GB at a time. Linux already supports LPAE, but at present memory configurations larger than 4GB are not been required for smartphone and tablets.

Dealing with the larger files and higher bit rates of UltraHD requires greater memory bandwidth. The 805 is the mobile industry’s first processor with a 128-bit-wide memory interface, doubling the bandwidth of today’s processors. Using two 64-bit channels of LPDDR3-1600, the chip generates peak DRAM bandwidth of 25.6GB/s. This produces a



total peak memory BW is 25.6 GBps for best-in-class memory performance. Most high-end mobile processors have two 32-bit DRAM channels, and some have only one.

Offering this bandwidth in a stacked (PoP) configuration required Qualcomm to design a new package that routes 128 data lines (plus address and control signals) to pads on top of the package. A single memory package with two 64-bit-wide DRAM channels can then be placed atop this package using standard PoP assembly techniques. PoP memory options include 2GB, 3GB, and 4GB of DRAM. The total height of the two packages is just 1.2mm, allowing its use in thin smartphone designs.

Adreno 420 Pushes More Pixels

Qualcomm also focused on the 805’s GPU, hoping to improve image quality and main-tain frame rates as customers move to higher-resolution screens. The chip uses the company’s own fourth-generation Adreno design, which delivers new features along with greater power efficiency.

Figure 2. Adreno 420 pipeline. The new GPU includes several new pipeline stages (outlined in red) to add capabilities and improve performance for advanced APIs such as OpenGL ES 3.0 and DirectX 11.

The hardware includes several new pipeline stages to help support the latest OpenGL ES 3.0 and DirectX 11.2 APIs, as Figure 2 shows. These blocks assist the programmable shaders by offloading tasks related to tessellation, the process of subdividing polygons



to allow finer control in shading and rendering. The new hull shader takes a single polygon (or patch) from the vertex unit and computes a set of new points that lie on the edge of or inside the polygon. The tessellation unit uses these control points to create a set of 10–12 new polygons that completely fill the input patch. The domain shader calculates the vertices of each of these new objects. Finally, the geometry shader analyzes the new objects and may cull or join some of them to simplify later processing. Figure 3 shows an example of how these new features improve image quality.

Figure 3. Tessellation on the Adreno 420. Compared with current-generation Adreno 330, the new GPU can create images with much greater detail.

The Adreno 420 raises performance by offering more shaders and more cache memory as well as wider paths to these memories. In addition, the texture pipe delivers more than twice the throughput (texels/s) compared with the Adreno 330. The 805 includes a new bus that connects the GPU directly to the high-bandwidth DRAM, reducing latency. Alternatively, the GPU can run at a lower voltage and frequency while delivering the same performance as the older design, reducing power by about 20%.

The company has not released any benchmark data, but it expects commercial devices using Adreno 420 to deliver up to 40% better scores than the Adreno 330’s already industry-leading numbers. That would put the 805 at about 100fps on the GFXBench 2.5 Egypt Offscreen test and about 50fps on the T-Rex Offscreen test. On a full 4K display, these frame rates would be quartered, giving the processor a respectable 25fps on Egypt but an unusable 12fps on the more challenging T-Rex test. Properly rendering high-end games at 4K resolution would require far more power than the 3–4W that a tablet normally can handle.



For greater power efficiency, the Adreno 420 implements upscaling. In this mode, the GPU can render Android game content at 1080p and then break each pixel into four subpixels, mapping the content to a 4K display. The Adreno 420 includes hardware to blend and smooth the original content, yielding high-quality 4K images that can approach the visual effect of native 4K rendering at a fraction of the power. A game with visual complexity similar to T-Rex will probably use upscaling to 4K, whereas a simpler game could be natively rendered at 4K if desired.

Gobi Modem Provides Top Data Rates

Today’s LTE modems operate at LTE Category 3 or Category 4 speeds, meaning they can reach downlink speeds of up to 150Mbps and uplink speeds of 50Mbps. These LTE Release 9 modems can achieve such high data rates only when using a single 20MHz-wide channel. Unfortunately, some carriers have only a single 20MHz band, and most have only 5MHz and 10MHz bands. To solve this problem, Qualcomm implements carrier aggregation in its Gobi 9x25 modem, which is currently in production. This LTE Release 10 chip can simultaneously operate on two 10MHz bands, making it much more likely to achieve the full 20MHz data rate on most networks

The Gobi 9x35 takes another step forward, implementing Release 11 features and boost-ing the downlink rate to 300Mbps. (The uplink stays the same at 50Mbps.) The chip achieves this maximum rate by combining two 20MHz bands. To more efficiently enable carrier aggregation, the new WTR3925 RF transceiver chip integrates a second receiver. The company says these two chips support “all known” band combinations (more than 50) that are in use or planned for use by major carriers worldwide.

The Gobi 9x35 will be the industry’s first 20nm modem chip. Most RF chips use trailing technology, but the WTR3925 is built in 28nm RF CMOS. Because of these advanced process nodes, the new platform requires 15% less board area than the Gobi 9x25 plat-form. The new chips use 15% less power at the same data rate, but running at the peak data rate will still increase the operating power. At the higher rate, however, downloads will complete sooner, allowing the modem to return to a low-power sleep state; thus, total energy use will fall. Power-amplifier (PA) efficiency can be maintained using the company’s QFE1100 chip for envelope tracking.

This performance and feature set will keep Qualcomm ahead of competitors that are promising to deliver carrier aggregation in 2014. The company also has a proven, mature modem that is certified at all major LTE carriers worldwide. Competitors, in contrast, have certified at only a handful of carriers, limiting the number of markets that a custo-mer can sell into. We expect LTE competitors to gain little share in 2014.

Conclusions

Qualcomm hopes to redefine the smartphone experience to focus on video and imaging capabilities, arguing that today’s CPUs are sufficient for most apps. The focus on 4K video gives users a new capability, but it is also brings improvements to existing functions—capturing and viewing video and graphics. Few people have 4K screens today, but when 805-based devices appear in 2014, this number will have increased



considerably. To make this capability possible, the company has built the first mobile SoC with a 128-bit memory interface and paired it with the best LTE data rates.

The 805 enables mobile devices with 8Mpixel screens, more than twice the resolution of high-end tablets and four times the resolution of high-end smartphones. More pixels is usually an easy sell, as Apple found when promoting its Retina displays. The 805 also brings the capability to capture 4K on a smartphone and display the full resolution video connected to an UltraHD TV. The chip will enable some tablets to implement a 4K display, but the most likely use of 4K output will be to connect to an UltraHD TV. Even on a smaller screen, such as a tablet or phone, users can appreciate the improved color and dynamic range of UltraHD content.

The Snapdragon 805 and Gobi 9x35 will power the most advanced smartphones and tablets in the second half of 2014. These chips set the stage for even more powerful modem-integrated products that will debut soon thereafter using 20nm fabrication. Qualcomm has set the bar that all other competitors will be challenged to meet. ♦

Linley Gwennap is founder and principal analyst of The Linley Group and coauthor of “A Guide to Mobile Processors.” The Linley Group offers the most comprehensive analysis of the mobile-silicon industry. Our in-depth reports covers topics including application processors, cellular-baseband processors, Wi-Fi combos, and other connectivity chips. For more information, see our web site at www.linleygroup.com.

Trademark names are used throughout this paper in an editorial fashion and are not denoted with a trademark symbol. These trademarks are the property of their respective owners.

This paper is sponsored by Qualcomm, but all opinions and analysis are those of the author.

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