# Multimedia Vision for the Visually Impaired through 2D Multiarray Braille Display
## 3 Proposed eBook Reader Application for 2D Braille Display
### Communication between Braille Display and Smartphone  
Braille OS was installed on both the smartphone and tablet, and the messages produced on the eBook reader application and the braille pad simulator were sent and received between the two devices. For this, the Android OS Message object was used, which is provided by default in the Android OS, and is based on Bluetooth [30]. This object facilitated the sending and receiving of messages between devices via a handler, and the key code used for a message was defined in its own library in this study. The key code was transmitted from the braille pad simulator and can be controlled by the VI user. The simulator has a total of 21 buttons and can control the smartphone remotely. Each key consists of several bits. When a key is received in the smartphone, certain operations are performed. Each key can be used independently as a single key, and as other braille displays, a combination of keys can also be used and transmitted. Moreover, by using a long click, a corresponding defined operation can be performed.  
Braille OS is a background app, and, when the on/off button is pressed on the pad, the Braille OS application activity [31] pops up on the smartphone, after which the user controls the smartphone remotely through the braille pad. Next, the user opens a desired application in the braille application list. The mentioned application, i.e., the eBook reader developed in this study, can be selected among other applications. Next, the role of the eBook application is performed, as shown in Figure 6. For every task, an operation is performed in the smartphone, which is controlled by the braille pad, and the list and text contents expressed on the smartphone, as shown in Figure 7a,c. Thus, the contents of the eBook are expressed as the contents of the braille display shown in Figure 7a. All this information is computed on the page of the corresponding stage in the smartphone and sent in byte arrays; the reason  
\begin{table}
\begin{tabular}{c p{284.5 pt}} \hline \hline
**Sequence** & **Activity and Results** \\ \hline
1 & When an eBook reader application is run through the Braille OS, a book is opened by searching the corresponding book in the smartphone storage, or through using the open last book, bookmark, or favorites placeholders \\ \hline
2 & When an MP3 file exists for a book, a selection is made to open the MP3 and text content. If not, the list of chapters in the book is opened immediately. \\ \hline
3 & With the help of the chapter list, the multimedia contents can be read chapter-wise. \\ \hline
4-1 & When the text player is used, the text contents are translated to braille, which can be used together with the text-to-speech (TTS) feature. \\ \hline
4-2 & When the MP3 player is used, the play/pause mark is displayed on the pad screen, and the content is automatically played (in this case, TTS is not supported). \\ \hline
5-1 & For both the text player and MP3 player, bookmark favorites setting is facilitated and saving, and fetching are possible. \\ \hline
5-2 & When there are images in the braille page, the corresponding image file can be read from the image list and viewer. \\ \hline \hline \end{tabular}
\end{table}
Table 2: The sequence of braille eBook reader application.  
for sending information in byte arrays is because a single braille cell has eight dots, which have binary values, and is expressed in a byte. Since the display comprises \(12\times 12\) multiarray braille cells, the number of corresponding braille cells is 144; and to efficiently express this on each braille cell, a transmission unit of a byte array is used. All contents are delivered to the pad through the braille translation module, as shown in Figure 6.