多個螢幕媒體設備之實作

Abstract

目前市面數位相框的功能設計為單一畫面顯示照片。欲讓使用者同時欣賞豐富的 色彩及影像，可將多台數位相框彼此串接，以達到多個畫面顯示之功能。 本研究以數位相框為例實作多個螢幕串接之媒體設備。我們透過 USB 連接線將多 台數位相框彼此連接起來及實作 USB 主機端(USB Host) 及 USB 裝置端(USB Device) 兩種角色的程式，並以自訂的協定來互相彼此溝通，以達到照片可直接在多個數位相 框螢幕上顯示之目的。本實作基於整體成本考量下，必須選用低成本的相關硬體，如 CPU(MIPS Clock 96MHz)、Memory(Clock 96MHz；8MB SDRAM)、JPEG Decoder(Clock 48MHz)。然而另外考慮的限制是，近日數位相機的高解析度技術不斷提昇，影像檔案 越來越大，效能表現較有限制。 在上述相關限制下，若要考量提升整體效率，我們必須在軟體上做相對的調整。 本實作將兩台數位相框串聯，以第一台數位相框為主，因 JPEG 檔案解壓縮成原始影像 資料的時間較為耗時，故將 JPEG 檔案解壓縮成螢幕尺寸之原始影像資料作為傳輸檔 案，以加快傳輸的速度，並可將螢幕尺寸之原始影像資料直接顯示在第二台數位相框 螢幕上，不需經過相關解壓縮過程，以增加顯示的效率。

Current market design of DPF features a single screen to display photos. However, to allow users to simultaneously enjoy the rich colors and images, numerous DPFs are cascaded to achieve the multiple screen display function. In this research, DPF is taken as an example and demonstrates the DPF multi-panel controller. Many DPFs are linked together through USB cable. DPF plays the roles as both USB Host and USB Device. The researcher controls the software of USB Host and USB Device, and makes them communicate through vendor protocols, so that the pictures can be displayed directly in a number of DPFs’ screen. For the overall cost of the implementation considerations, inexpensive hardware is utilized, such as CPU (MIPS Clock 96MHz), Memory (Clock 96 MHz, 8MB SDRAM), JPEG Decoder (Clock 48 MHz). In addition, another limitation is that, recently, with the improvement of the DPF high-resolution, the image sizes are bigger and bigger, which leads to the limited performance. Under the related limitation stated above, in order to improve the overall performance, the software must be adjusted relatively. In the experiment, two DPFs are cascaded with the first DPF as the base. It is time-consuming to decode JPEG files into the raw data. Hence, JPEG files are decoded into the scaled-down raw data as the transmission files to accelerate the transfer rate. This scaled-down raw data is shown directly on the second DPF screen without any related decoding process to increase the performance.