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Hitachi Case Study

Hitachi logoHitachi's Customers Get The Highlights in Recorded Video Using ADI's High Performance Blackfin to Handle Complex Algorithm, Heavy I/O Load —

Digital video recorders (DVRs) have progressed steadily since their inception. Functions such as "instant freeze-frame and rewind," which were used to replay exciting moments of sporting event broadcasts by early commercial DVRs, have long been eclipsed by feature-rich consumer models. Today, with a Hitachi Wooo D series recorder from Hitachi, Ltd., home users can enjoy a timesaving feature known as "automatic digesting" that automatically recognizes, extracts and plays back highlights from recorded video. Viewers can then simply enjoy a contiguous playback of just the high points of a concert or a sporting event without having to fast-forward past advertisements or uninteresting content.

Hitachi_DVR_Woo_DV-DH1000While in the design phase of its new DVR, Hitachi looked for a signal processor capable of hosting the new automatic digesting feature as part of a custom algorithm. The company also wanted a signal processor that could process video and audio, and handle I/O interfacing to a host storage device. Hitachi said there were many signal processors on the market that could do the job, but the company chose a Blackfin ADSP-BF531 signal processor from Analog Devices, Inc. (ADI), noting that the other processors they evaluated were overly complicated and too expensive. At 400 MHz, Hitachi said the Blackfin® ADSP-BF531 provided the right amount of performance with enough headroom for future growth, and at a reasonable price point.

Hitachi's Wooo D Series

Hitachi_DVR_Woo_DVDH1000S_mHitachi's Wooo D series of recorders feature up to 1 terabyte (TB) of media "storage and record" in Hi-Vision, a Japanese high-definition (HD) format. All hard disk drive/digital video disk (HDD/DVD) recorders in the series, which includes the DV-DH1000D, DV-DH500D, DV-DH250D, and DV-DH160D, come equipped with the new automatic digesting feature. These DVD recorders include a twin digital tuner system, comprised of two terrestrial digital tuners and two broadcast satellite and communications satellite (BS/CS) digital tuners, to enable simultaneous recording of two broadcast programs with HD quality. Additionally, the new models feature a unique graphical user interface that allows users to easily sort, select, and play programs recorded in large-capacity HDD. Hitachi has also adopted the Blackfin ADSP-BF531 processor for its latest S series models, including the DV-DH1000S, the DV-DH500S and the DV-DH250S.

The main reason Hitachi chose Blackfin was for the processor's ability to execute sophisticated, computationally intensive algorithms, especially for the automatic digesting code. The algorithm automatically identifies important material on a recording by correlating "importance" with perceptual changes to audio and video outputs, such as an increase in volume, or a change in the brightness or color distribution. Automatic digesting is prominently featured in the Wooo D series of recorders and the feature enables viewers to get to the good part of a program without a lot of skipping around or fast-forwarding. With 400 MHz of processing power and 52kbytes of on-chip memory, the Blackfin ADSP-BF531 processor emerged as the ideal choice to handle Hitachi's complicated audio/video processing algorithm.

In addition to automatic digesting, the basic functions of hard drive-based DVR systems typically include other convenience features such as the ability to skip over commercials, pause live TV, and instantly replay interesting scenes. Such features also constitute a heavy I/O burden, as stored video must be accessed in real time. Plus, satellite and digital cable signals are typically encrypted to prevent unpaid subscribers from viewing programs, so satellite/cable signals must be decrypted before they can be recorded, which requires heavy lifting from a signal processor. Because of its high performance and ability to optimize audio/video, the Blackfin ADSP-BF531 processor was also chosen for its ability to easily handle "routine" audio/video processing and to interface with the host storage device.

Blackfin Ideal

Blackfin processors are the platform of choice for next-generation applications like Hitachi's, which require RISC-like programmability, multimedia support, and leading-edge signal processing in one integrated package. The processors embody a new type of 16/32-bit embedded processor specifically designed to meet the computational demands and power constraints of today's embedded audio, video, and communications applications.

Blackfin processors deliver breakthrough signal processing performance and power efficiency with a RISC programming model. Blackfin processors present high performance, homogenous software targets, which allow flexible resource allocation between hard real-time signal processing tasks and non real-time control tasks. System control tasks can often run in the shadow of signal processing and video tasks. The Blackfin processor's unique combination of processing attributes eliminates the need for separate digital signal and control processors, which reduces bill of material costs (BOM) and greatly simplifies hardware and software design tasks.

The easy programmability of the Blackfin architecture was another major reason that the Blackfin ADSP-BF531 processor was chosen for this series of high-end DVRs. Hitachi's R&D team had already written an automatic digesting algorithm for the company's successful PC-based DVRs, and the team found it very easy to port the algorithm to the Blackfin ADSP-BF531 processor for the new Hitachi Wooo D series of recorders.

To facilitate their efforts, Hitachi developers leveraged VisualDSP++ license status for 90 days from the date of installation and documentation. VisualDSP++ is an integrated software development and debugging environment (IDDE) that enables efficient management of projects from start to finish from within a single interface. It includes an easy to use assembler, an archiver, a linker, a loader, a cycle-accurate instruction level simulator, a C/C++ compiler, and a C/C++ runtime library that includes DSP and mathematical functions.

The EZ-KIT Lite board is a low-cost hardware platform that includes a Blackfin processor surrounded by several other devices such as audio codecs, video encoders, flash, SDRAM, and more. Each kit also includes an on-board JTAG emulator. Via the processor's JTAG port and the VisualDSP++ software, one can set breakpoints, single step through code, view memory, fill/dump memory, perform real-time data manipulation, profile execution and memory access, plot data, and use standard I/O.

Without a doubt, Hitachi is relying on Blackfin to help differentiate its new Wooo D series of recorders, bringing innovative new features such as automatic digesting to consumers. Fast-forward to the future and Hitachi says Blackfin will be included in its product lineup.

For more information, please visit Hitachi, Ltd.

"Blackfin processors are the platform of choice for next-generation applications like Hitachi's, which require RISC-like programmability, multimedia support, and leading-edge signal processing in one integrated package."