Network Bandwidth Considerations
Given that modern signage systems need to support Quadruple Play - video, audio, graphics and scrolling text simultaneously - network bandwidth is a critical component of the design. Some early market signage players have used a 10/100 Ethernet solution in their design. However, effective 10/100 data rates of between 30 and 60Mbps do not enable support of multiple streams of MPEG2 or H.264 video streams in addition to supporting voice and on-the-fly data (text) modifications. Highly effective alternatives are Gigabit Networking processors (10/100/1000) with effective data rates between 250-500Mbits.
A first to market solution from Moschip Semiconductors, the MCS8144 network appliance processor offers a solution that fulfills the needs of a typical digital signage player. Additionally, higher end signage players can also offer the option of supporting wireless networking (802.11n), enabling seamless transfer of content from the signage server to the signage player. Technology enhancements in the 802.11n standards have made 802.11n a viable solution for reliable, secure transfer of video and data. An 802.11n solution can interface with the network processor using either a PCIe or USB interface. The MCS8144 supports PCIe as well as multiple USB 2.0 ports providing the engineer with additional connectivity flexibility.
A digital signage player is the critical component of a digital signage system. There are several design elements and features to concentrate on and consider when selecting a network application processor for a signage player. A medium end digital signage player supports the following features:
| Features | |
| Content | Video / Audio / Graphics / Scrolling text |
| Video Format | MPEG-1/ 2/ 4, WMV9 |
| Audio | MP3, WMA |
| Graphics | JPEG, BMP |
| Output Resolution | WXGA, XVGA |
| Video Output | DVI, VGA, Video |
| USB Port’s | 2 USB 2.0 Ports |
| Built-in Storage | 60GB-80GB |
| Ethernet | 10/100 Mbps Ethernet |
| Screen Size | LCD and Plasma TV of any size available |
| Wireless | Optional |
Digital Signage Player Functions and Design
There are several functions required of a digital signage player. It must have an ability to decompress different compressed video formats like MPEG-1/2/4, WM9, etc. Local storage for files downloaded from a DS server through USB HDD or PCIe based SATA/IDE HDD is an important storage connectivity option. In addition, the player must be able to synchronize content between the digital signage player and the digital signage server. The DS player also needs to be in sync with the DS server at all times. In this way, the player can get the play list and the media files after synchronization with the server and then keep on playing the items in the play list in a round robin way or as desired. As well, support for connecting an LCD / Plasma display, through LVDS FPD Link / RGB / DVI interfaces is an important configuration option. Considering such functionality into the design process, embedded designers can better approach their solutions from the ideal viewpoint of system configuration capabilities.
Fig. 3: A Gigabit network application processor enables multi-stream digital signage systems.
There are various embedded design elements to consider when architecting a digital signage player, particularly from a system configuration point of view. At the heart of such a design lies a network application processor that lays the foundation for system connectivity, network connectivity, display interfacing, various AV support mechanisms and embedded software that expedites design cycles to ensure faster time to market. An additional design option would be a multiple chip solution that consists of a Media Processor and a USB to 10/100 Ethernet Adapter. However, from a cost, functionality, design time, software validation and future proof viewpoint, using a single chip solution that supports all the key features is the preferred option.
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