Produto                                    Model 2412                Imagem                  

Features
Hardware compression, decompression of PAL, NTSC into MPEG2 or MPEG1

30 fps on 704 x 480 size interlaced images

Programmable bit rates

Two RS-232 ports for controlling pan-zoom-tilt cameras

Display & Control software

DVR with optional storage

Internal web server and dynamic web pages

Several wireless options

Additional video channels with 512 adapters

Optional enclosures

Embedded Linux

Description
Model 2412 is a complete video server streaming solution.  It converts analog video into digital data, compresses it into MPEG formats and then transmits it over an Ethernet using the UDP or RTP protocol.  It is made from Sensoray’s 512 MPEG-2 codec, 301-6 CPU and 207 power supply. The 2412 has options to record video clips that may be played back locally on the 2412 or sent over the Ethernet for remote viewing. More sophisticated versions can process four video streams simultaneously and transmit them over a wireless Ethernet.  Since the 2412 is bi-directional, it can accept an Ethernet stream from another 2412 and convert the encoded digital video into composite video outputs.

Hardware Decoding
Although it is possible to use 2412 hardware to decode MPEG data, this process does not have low latency compared to Sensoray’s Display & Control software. 2412 hardware latency is 5 seconds, while our software player’s latency is less than one second.

Software Decoding
If the 2412 is programmed to stream data using the RTP protocol then Apple Computer's QuickTime stream player may be used.

Sensoray sells Display & Control software for the 2412 that allows viewing multiple image streams in near real time on Windows systems. It has less than one second of latency, which allows accurate camera adjustments.

Two versions of the stream player are for sale. One is a stand-alone Windows program and the other is a DLL for embedded systems. The viewer allows stopping the display on a single frame for viewing or printing. The image stream may also be sent to a disk file.

Software and Manuals
2412 Instruction Manual >> Released 11/7/02

Ethernet Protocols
The UDP format (user datagram protocol) offers the fastest data rates and minimum CPU usage at the expense of minimal error checking. The 2412-4 can uni-cast four MPEG2 data streams at full frame rates when using this protocol.

A disadvantage of the UDP format is that it cannot be played using popular stream players such as QuickTime. However, the latency i.e., the time delay between recording and displaying, while using these players, can be several seconds.

Multicasting
Video streams from 2412’s may be viewed simultaneously by several clients on the same network by using multicasting.  The 24xx automatically stops multicast streaming to RTP clients once they close their RTP player.  Multicasting may be replaced with uni-casting by sending a command to the 24xx’s command processor.

The RTP format (real time protocol) trades off CPU and memory usage for error correction and compatibility with QuickTime and Real Player. Sensoray sells a multi-stream, low-latency software RTP player for Windows 2000 and XP. The latency of Sensoray's software player can be as low as one half second when processed on a 2 GHz, Pentium-4 system.  A disadvantage of RTP is that it uses twenty-five percent of the 2412’s CPU time, while UDP uses less than five percent.  Hence, the 2412 can only support two RTP streams.

Wireless Options
Adding a 340-11b/1 option board to the PC/104 stack adds 802.11b wireless Ethernet to the 2412.  The 30 mW output from this board may be connected to our 2400-OMNI antenna and used for line-of-sight ranges of up to 500 feet.  The 340-11b/1 board is supplied with the 2412C3 cable that has a type-N bulkhead connector.  The operating range can be extended by using our 2400P patch antenna or 2400G reflector grid antenna.  The 340-11b option adds about one watt to the 2412’s power dissipation.

Long-range Wireless
The wireless range can be extended to beyond one mile by using the 340-11b/2 option in place of the un-amplified 340-11b/1.  The 340-11b/2 option adds a 500 mW linear amplifier.  This option adds approximately five watts to the 2412’s total power dissipation.  Model 340-11b/3 is available with 1000 mW linear amplifier (2400-1000RF). Adding this option increases the 2412’s power dissipation by an additional 10 watts. Using these power amplifiers in the U.S. may violate FCC regulations.  Sensoray requires a special statement-of-use form before sending these amplifiers to U.S. destinations.

The wireless Ethernet is bi-directional; hence, the other end of the data link must have an equivalent amplifier and directional antenna. Sensoray recommends using the 2400G, a reflector grid antenna, at both ends to minimize interference and maximize the range.

Antenna’s offered by Sensoray

Wireless Access Points 2412AP/1 and /2
The 2412 includes Ethernet router software that can route 802.11b wireless data to one of its 802.3 wired Ethernet ports. This allows the 2412 to operate as a wireless access point. When the 2412 is configured as a 30 mW access point it becomes a 2412AP/1.

When it is configured as a 500 mW access point its part number is 2412AP/2. The Sensoray access point products do not include an MPEG codec because they process just Ethernet data.

Sensoray's 2412AP/2 access point has the advantage of higher RF output power and higher input amplifier gain. Other brands of 802.11b access points hardware may be used with remote 2412's. These include Lucent's RG-1100 and Cisco Systems 350 series.

Display and Control Software
Sensoray's real-time Display and Control Software decodes and displays up to fifteen MPEG1 and/or MPEG2 streams with a low latency of 1/2 to one second. Thumbnail images from remote video servers may be positioned over a background such as a map or building plan. Multiple server images may be selected for expansion to full size and full frame rate.

Digital Video Recorder
Video clips may be stored on 2412 servers that have internal storage media as described in this section. The movies may be replayed from local or from remote 2412’s or they may be rapidly downloaded to remote clients. For example, the daily movies accumulated in a vehicle’s DVR may be rapidly transferred over an 802.3 wired Ethernet. 

Movies can be stored on a removable compact flash card.  In the local record mode, MPEG data from the codecs is recorded to storage media. Proper care is taken to prevent significant data loss in the event of a power loss.  While data is being recorded it is also available as composite video from the codecs.

Once MPEG video data is stored on the 2412 it may be decoded and viewed by using the 2412’s hardware decoding and composite video output channel.

Recorded movies can also be sent over the Ethernet for remote viewing with QuickTime or Real Player. In this case, the 2412 sends MPEG data which the software player must decode.

Video Storage
There are three storage options. Video clips may be stored on a 2.5 inch IDE hard drive by adding the 300TA interface board and IDE cable. IDE mechanical hard drives have limited temperature and vibration specifications, hence, they are not recommended for use in vehicles or outdoors environments.  Some 2.5-inch hard drives may draw too much power from the 2412's power supply and must be powered by an auxiliary power source. Mechanical IDE hard drives have the advantage of low cost and high density.

Web Server
The 24xx is an Ethernet appliance that executes commands from a Telnet command line, Sensoray's Display & Conrol software or from its internal Apache web server. Most browsers can control and display information from the 24xx. Each 24xx supports four video channels that are assigned to separate ports.

Micro Drives, a miniature hard drive mounted on a cardbus board, may be used with model 340 adapter board. They are more rugged than conventional IDE hard drives and do not require any cables. They are three to five times more expensive than IDE drives and limited to about one gigabytes of storage.

The dynamic web pages will only display data and selection boxes that are relevant to previously made selections. For example, DVR selection boxes are not displayed if the DVR function has not been previously selected. One of the web pages is shown below.

Compact flash modules may be used with the 340 option board. They are rugged solid state storage media with capacities up to one gigabyte. They appear as a mountable disk drive to the Linux OS. These modules are limited to 300,000 memory write cycles, hence, they do not have the versatility of mechanical hard drives. We have developed drivers for Luxor ATA and Sandisk modules.

Camera Control
The 2416's CPU sends pan, tilt and zoom command from the Ethernet to one of the RS-232 ports. Many cameras use serial ports for position control. PZT software is included for popular camera assemblies such as Sony (Visca), Pelco (D protocol) and Cohu (iDome).

To facilitate camera adjustment the digitized video can be looped back to the composite video output for viewing on a TV monitor. This is the default mode for the video output.

Bit Rates and Bandwidth
The data rates discussed below refer to the bit rate from the MPEG codec used by the 2412. The rates do not refer to Ethernet bit rates, which are fixed at 10 Mbits/sec or 100 Mbits/sec. The 2412's programmable bit rate allows trading image quality for bandwidth.

Higher bit rates from our MPEG codec give better quality images than lower rates.  Full-size interlaced images of 30 frames/sec will start to show distortions below 1 Mbits/sec, however, image quality improves only slightly above this rate.

 When low bit rates are selected e.g., 100 kbits/sec, the amount of distortion depends on the amount of motion in the scene. A chess game will have less distortion than a soccer game.

A variable bit rate may also be selected.  This mode tries to maintain good image quality by varying the codec bit rate according to the amount of motion in the scene.

It is also possible to decrease the bandwidth by decreasing the image size.  Selecting CIF size images of 320 x 240 pixels will reduce the required bit rate by four compared to 640 x 480 pixel images that occur at the same frame rate.

If there is not much motion in a scene, a lower frame rate may be selected to reduce the codec's bit rate. Lower frame rates will show motion artifacts from fast-moving objects. Even though such as stream can be recorded at a lower frame rate, most MPEG viewing programs will play the stream at 30 frames/sec for NTSC and 25 frames/sec for PAL. The stream will be playing in a fast-forward mode. For example, a 15-frame/sec recording will be displayed at twice the normal frame rate.

Programmable bit rates
A frame rate of less than 30 fps may be selected by programming a frame divider greater than 1.  For example, a frame divider of 3 will program the codec to process 10 fps. 

The effective bit rate may be throttled down to below 50 kbits/s by programming the frame divider and codec bit rate to high values. For example, specifying a codec bit rate of 1.5 Mbits/s and a frame divider of 15 will result in an effective bit rate of 100 kbits/s.

Embedded Linux
The board set is supplied with specially configured Linux for high reliability and fast response. After power is applied, the software is automatically loaded to RAM from flash memory. The 2412 will then stream MPEG data to the Ethernet port.

Sensoray has optimized Linux installation for the 301-6 CPU. Although it is possible to recompile the Linux kernel, Sensoray does not offer technical support for this operation.

Breakout board 2400TA
This termination board offers a convenient means of connecting signals to the circular connectors on a 2412SYS. It provides DB-9 connectors for the serial ports, an RJ-45 connector for the Ethernet port and coax connectors for the video. A line-operated 24VDC power supply, model 208 and two interconnecting cables are supplied. These connect the 2400TA to one of three types of 2412's: model 2412SYS, 2412 card stack and 2412SYS-Mini.

Enclosures
The 2412 is still available as an unpackaged stack of PC/104 boards. It is also available in one of three sealed enclosures. Models 2412SYS & 2412SYS-2 have space for four PC/104 boards and a small hard drive. A larger enclosure is also available that has space for 6 PC/104 boards.  A typical 2412SYS or 2412SYS-2 configuration is shown below. Optional storage media must be added for DVR operation.

2412 Stack

2412SYS-11b

Typical 2412SYS & 2412SYS-2 configuration
CPU >> 301-6L with Linux, web server
Codec >> Up to two 512’s
Wireless option >> 340-11b/1 board, 2400P antenna, 2400PM pole mount kit
PC/104 boards >> Four maximum

Figure 11. 2412SYS and 2412SYS-2

Model 2412SYS-3 & 2412SYS-4 has increased expansion compared to model 2412SYS. This larger size enclosure is designed for four MPEG channels and one 340-11b/1 wireless option. It has special thermal features that allow using an internal 20-watt power supply and 500 mW RF amplifier. Optional storage media must be added for DVR operation.

Typical 2412SYS-3 & 2412SYS-4 configuration
CPU >> 301-6L with Linux, web server
Codec >> Up to four 512’s
Wireless option >> 340-11b/1 board, 2400P antenna, 2400PM pole mount kit
PC/104 boards >> Six maximum

Model 2412SYS-MINI is a single channel system designed for use in limited space. It uses our 301-6L Linux CPU, model 206 power supply and one 512 codec.

Typical 2412SYS-MINI configuration
CPU >> 301-6L with Linux, web server
Codec >> One 512
Power supply >> 206
PC/104 boards >> Two maximum

Figure 12. 2412SYS-MINI

Our standard product, model 2412, uses our 301-6L Linux CPU. Variations of this product are shown below. Although our 24xx software may run on other CPU's only Sensoray supplied CPU's are supported. Sensoray will not assist anyone installing our software on other computers.