DVR cards: Software solutions top R&D agenda for DVR capture cards

China suppliers of DVR capture cards are focusing R&D on solutions rather than the physical design since the latter is basically the same for most units.

All DVR capture cards have a hardware platform that converts video stream to digital format. Products embedded with the same chipset have similar specifications. Other functions, including recording, playback and monitoring, are made possible by the software programmed into the DVR.

A maker’s core competency is measured by the encoding algorithm and application software it uses and, more importantly, its ability to develop them.

The majority of companies in the country offer DVR capture cards bundled with solutions but only a few can produce them in-house, most of them tier 1 enterprises.

One such supplier is Shenzhen Wave-particle Intelligent Co. Ltd, which also engineers its own hardware unlike the majority that relies on reference blueprints from design houses.

The mainstream application software kit is Windows XP- or Vista-based but some manufacturers provide versions with the relatively more complex Linux OS.

The standard DVR capture card has preview, recording, playback, storage and PTZ control functions. Networking via IP and data administration are likewise basic. Advanced features allow multiscreen monitoring, split-screen display, view rotation, motion detection, image color adjustment, and recording through multiple HDDs.

Mainstream models have 4 to 8-channel video input, CIF resolution, and MPEG-4 and H.264 compression algorithm software solution.

The current product development thrust is on creating, or choosing, the solution that facilitates multichannel video input, higher image resolution and compression algorithms that support diverse formats.

Some China suppliers release models capable of 16-channel realtime recording. Such devices have several decoder chips embedded in the module that make this function possible.

DVRs that use these capture cards input more than 32 channels of video data. A few provide units that afford D1 and even full HD resolution.

Entry-level models with 4-channel input and CIF resolution are priced about $10 to $20. Midrange 8-channel units usually have CIF resolution as well and are $30 to $50. High-end versions, which have 16-channel video input, are approximately $100.

The video decoder chip is the most important part of a DVR capture card. It determines the image quality, resolution and frame capacity.

Makers largely source these from Techwell, Conexant and NXP-Philips.

The bus of a capture card, meanwhile, is based on the video decoder chip or PCI-E bridge chip. These include Conexant’s 8-bit CX25878 and 10-bit CX23881, NXP’s 9-bit SAA7130HL, and Techwell’s 10-bit TW6802.

Suppliers that offer products with high-precision analog-to-digital conversion adopt these code chips. Some have a 3D comb filter and the new horizontal and vertical scaling algorithm, which likewise enhances image quality.

Only a few low-end models still adopt the CX25878 chip from Conexant, and mainly because they cost less.

As regards frame capacity, most DVR capture cards can work in both realtime and nonrealtime modes at different input channels.

For example, an 8-channel model with a 100-frame capacity can operate in realtime with four available video inputs. At the same time, it can run in nonrealtime mode with eight video inputs.

The PCI-E bus is edging out erstwhile mainstay PCI bus, which has become insufficient for models with a higher data exchange requirement. The former has nearly double the bandwidth of PCI bus. It also boasts a more stable power supply and increased flexibility.

Most DVR capture cards adopt Conexant’s CX23888 and CX2585x, and Techwell’s TW2815/TW2835 bridge chips.

Techwell’s TW2835 video decoder is optimized for flexible resource configuration. It incorporates dual display controllers and dual video encoders that let users adjust the recording resolution, bit rate and image quality via the application software.

As for compression algorithms, those for H.264 continue to dominate.

Many suppliers are turning to third-party programs to simplify the R&D process and save on costs.

There are currently 70 DVR capture card makers in China, most of which engage in mixed production.

Many are established suppliers of CCTV products. Others are primarily consumer electronics and computer accessories suppliers that regard DVR capture cards as a secondary line.

Guangdong, specifically the city of Shenzhen, is the primary manufacturing hub. Companies in the province account for about 90 percent of China’s aggregate DVR capture card output.

Because of the availability of the technology, many makers are optimistic that the industry will continue to grow in coming years.

Only tier 1 companies have the logistics to develop their own application software.

Midsize manufacturers usually work with third-party institutions.

Small enterprises, meanwhile, conduct mostly minor revisions on outsourced application software.

This article "DVR cards: Software solutions top R&D agenda for DVR capture cards" is originally posted in Global Sources.

Chateau Technical Corp.
Shenzhen Success Electronics Co.,Ltd
Shenzhen Yishi Electronic Technology Development Co. Ltd