Mobile Television
Tina Mani tells us what is a mobile television, the more widely deployed method of viewing mobile television and what does video on demand do in this blog post.
What is mobile television?
Mobile television as the name suggests, is the ability to view regular television channels over your mobile. The term mobile television also can include Video on Demand (VoD) services, where a central collection of videos is made available to view any time on the mobile on a rental or monthly subscription model.
The set of channels available on mobile is usually less than the content provided on traditional television. The reason is that viewing of content on different medium (like satellite, IPTV, mobile) requires rights to be purchased specific to that medium. Also, many content providers are still not comfortable with their live content to be broadcast on the mobile, mainly because of piracy concerns.
The basic flow of content from the source to the mobile is described below:
- Integrated Receiver Decoders (IRDs) are used to unscramble the DVB-S signal from the satellite and convert it to a standard digital format.
- This content is then further encoded to various formats and bit rates suited for mobile consumption by encoders, and saved in a local storage. The purpose of this step is to perform video compression to various bit rates so that the video can be efficiently transmitted on connections of different bit rates.
- This encoded content from this storage is then streamed to the mobile from a streaming server, and decoded back to a viewable format by the mobile.
Mobile Television requires a bandwidth of at least 100 kbps to give a decent user experience on a small screen like a mobile. However with the right encoding techniques, decent quality can also be seen on bandwidth as low as 64 kbps.
There are two primary methods for streaming to the end user from a technology point of view. One is a broadcast, i.e., one-to-many method, like traditional television, and the other one is a unicast (or point to point, one to one method). The unicast method utilizes the exact same technology and spectrum as regular data on the phone (over 2G/3G/4G networks), and does not need anything special from the mobile operator. It usually also does not require special handsets because it can utilize the standard video players available on all data phones.
The mobile broadcast method is technology dependent and works only on handsets that support this technology.
Mobile Television - Unicast
The more widely deployed method of viewing mobile television is the unicast method, or simply put, video streaming from point to point. Each individual user gets a separate stream from the streaming server.
A stream is nothing but a digitally encoded file cut into several a sequence of small files that are sent to the mobile and played out continuously. There are two primary methods for streaming. The traditional approach uses a protocol called RTSP (Real Time Streaming Protocol), and another approach is using progressive download based on HTTP (used by YouTube).
A 2G/3G/4G data connection is used to download the digitally encoded files and a media player on the mobile plays the video.
Video streaming has been used on PCs through the internet for many years now, but optimal rendering of the video on a mobile requires more advanced technology because the data bandwidth available to the mobile usually varies with time and place. Also mobiles have multiple screen sizes and resolutions, and hence the video format has to be adapted to the mobile screen size.
An Electronic Service Guide (ESG) which is similar to your programming guide on a regular TELEVISION has to be available on the mobile to be able to switch channels easily. Each time a channel is changed, a different set of files is sent to the mobile. For good user experience, techniques for fast channel switching need to be employed.
Below is an example of a mobile TELEVISION ESG, showing multiple categories of channels, a list of channels per category, and then selection of a single channel.
In India most of the telecom operators have provided mobile TELEVISION as a value-added-service (VAS) available to data users with a GPRS or UMTS (3G).
Video on Demand
Video on Demand (VoD) gives the ability to select and view a video from a central collection that is available all the time, compared to a television viewing where the program timings are dictated by the channel.
Except for sports or very critical news, where watching live TELEVISION can be very convenient, the usage of VoD is more popular because it allows more flexibility to view the content on the move at the convenience of the user.
Services like Netflix and Hulu available in the US are very popular VoD services. There is a service called BigFlix launched by Reliance BIG TV, and available on PC as well as mobile devices for a monthly subscription fee. YouTube provides movies for free, but with advertisements.
The author, Tina Mani works with Wavesncloud Consultants
