Real time Streaming on Mobile Devices
Real time streaming delivers content rich data to users of mobile devices. Streaming is a process whereby video or audio data is sent over the Internet and this data is played as it arrives. With streaming video or audio, there is no need to download the file before it is played by the user. The user only needs a player in order to view or listen to the files (video or audio) respectively. With streaming the data arrives in a continuous flow and it is played as it arrives. This is why it is said to play the file in “real time,” because the file is played at the same time as it is sent over the internet to the mobile device. Once the data arrives the “player” uncompresses the files and they can be viewed or listened to. When the file is uncompressed, the audio files are sent to the speakers so that they can be listened to and the video files are sent to display so that they can be viewed. In a nutshell, streaming refers to the process whereby information (usually audio or video) is delivered over the Internet in such a way that it is played by the receiving computer or mobile device at the same time as it is delivered. While the data is sent it comes in a continuous flow which is referred to as a stream. The “player” is a program which can be downloaded from the internet. One popular player is the real time player.
0.2 Real time streaming: technical considerations.
On the Internet, downloading is a popular way of obtaining content. However, on mobile devices, streaming is a preferred option to bring multimedia to users. Downloading usually provides the option of saving the file onto the computer. On the other hand, streaming plays the data and once the user is satisfied the real time player is switched of. Real time streaming is useful for services such as: weather reports, stock market reports, live charts, historical charting, speeches, business news, entertainment, etc. With real time streaming, a parent who was absent from their child’s school play can view the event on a mobile (cellular) phone or other mobile device. Furthermore, with streaming geographical location software can be made more useful to the populace. There is a whole range of possibility with streaming media.
Real time streaming on mobile devices is a recent phenomenon. In recent times, mobile (cellular) phone operators have improved the technology in order to ensure that data streaming is possible on these mobile devices. These improvements are notably about speed. The shift by these mobile operators to 3G and 3.5G ensure high speed which is needed to bring feature rich applications such as real time streaming to their subscribers. 3G and 3.5G wireless networks are preferable to 2 G wireless networks because the latter runs at speeds below 64Kbps- which is not good enough.
Real time streaming on mobile devices is possible when the bandwidth is reduced to ensure that the process is successful. For example, the compression techniques which are used in MPEG-4 enable a lower bandwidth needed for video streaming to take place. Cellular phones, smart phones, personal digital assistants (PDA), laptop computers, pocket PCs, etc. Furthermore, Gualdi, Prati, & Cucchiara (2008) highlight the importance of real time streaming to video surveillance and maintaining security.
0.3 The process of real time streaming
In real time streaming the following happens:
– A continuous flow. Data is sent in a continuous flow called a stream. As the data is sent it is received gradually on the mobile device. The bits of data received on the mobile device can be played while the remaining data is gradually and eventually received.
– Plays on arrival. The data that is sent arrives gradually. However, the unique attribute of streaming is that the data that is received can be played while the remaining data is still coming in. This is why it is said that the file is played in “real time” as it is received on the mobile device. It is played on the receiving computer at the same time as it is being sent.
– Unlike downloading. Real time streaming is different from downloading. In downloading, all the data is received before the video or audio file can be played. On the other hand, streaming is restricted to audio and video files. Files that contain text cannot be handled by real time streaming.
– Compression. Before data is sent over the internet using real time streaming, it needs to be compressed using the appropriate software. Compression is important in real time streaming because it ensures that there is enough band width for the file to be sent over the internet to the mobile device.
– Speed. In order to facilitate real time streaming, the mobile device which is receiving the data should have a very fast speed. The speed of the mobile device needs to be fast because the file (being received) is not stored on the mobile device.
– Real time player. The real time player needs to be downloaded from the Internet onto the mobile device. Toward this end, the mobile device needs to have enough memory to enable it contain the real time player. The real time player is necessary to accept the streaming data and display video on the screen or play audio in the speakers. In short the real time player refers to the client software which needs to be loaded on the mobile device in order to play back the continuous flow (stream) of data being received. Without the player, streaming will not be useful. There are a variety of players which can be downloaded over the Internet- Windows Media Player (WMP), Real Time Player, Quick Time Player, etc.
– Buffering. Buffering refers to the reception of the streams of data being sent in packets. It always takes a gradual process to receive these packets (i.e. buffer). Gualdi, Prati, & Cucchiara (2008) write that buffering is essential to avoid the loss of data.
0.4 Challenges to streaming on mobile devices
Although streaming is beneficial in many respects, there are a number of hurdles that come in its way. The major constraints that affect streaming include: the amount of program memory available; slow processor speed; absence of devoted sound cards; loss of streaming data due to fluctuation of internet connections to wireless devices, capabilities of the terminal mobile device (i.e. the receiving device). Yoon and Banks (2008) assess the five (5) key challenges which face streaming on mobile devices, especially mobile (cellular) phones. These challenges are as follows: streaming quality is limited by the wireless data rate; fluctuations in the wireless network; handset compatibility issues; handset feature settings; and integration with back-end systems. Some mobile phones and other mobile devices are not compatible with certain players which handle streaming content. In this light, such mobile devices cannot receive streaming content. The feature settings on mobile phones are limited. It is not possible download a player and upgrade it later. On the other hand, players on PCs may offer more quality. Some streaming services on mobile devices are not free thus they need to be connected to some back end systems which handle the billing. This is not often easy to accomplish.
Real time streaming on mobile devices is essential in today’s multimedia world. Streaming is very technical and differs essentially from downloading. Real time streaming is economical of bandwidth because it compresses data before it is sent. Furthermore, there are a few challenges which affect streaming on mobile devices. However, with careful planning, these obstacles can be overcome.
Gualdi, G, Prati, A & Cucchiara, R, 2008 “Video Streaming for Mobile Video Surveillance” IEEE Transactions on Multimedia Vol. 10 No. 6 pp.1145-1146
Yoon, A & Banks, R 2008, “Mobile versus Internet Streaming: Key Challenges” Vidiator, Vidiator Inc, Bellevue