Video On Demand—The Next Big Ticket

The advent of 3G has opened up new and exciting avenues for Indian operators to cash on. Video-on-demand is one such avenue which will differentiate offerings and push VAS in India. Juxtaposed with recent developments in the mobile video content and applications space, video-on-demand services is set to gain maximum traction in the market. Leveraging 3G technology, application developers, content creators/aggregators are aggressively building on video products. There are a few companies in India that are betting big on mobile by launching mobile video portals wherein users can avail all features, view catalogs, and watch movies on their phones. Bagged by premium content and next-generation technology, video-on-demand services are set to enhance user experience multifold.

While entertainment is set to be the biggest driver for the adoption of video-on-demand, particularly on the mobile, there are several other avenues for growth such as news, sports and devotional content. For example, Indian users could watch special events at prominent temples on their mobile phones, or could send a greeting to a friend or a loved one. Hence operators can tap these segments and generate new revenue to combat the declining ARPU. Adoption of these services will be high since users can watch the services of their choice in real-time and at their convenience. With mobile handsets that have high-resolution screens available at affordable prices, we foresee 3G spurring a huge demand in video-on-demand services.

Technical Challenges

As consumer demand for mobile video increases, operators will need to find a way to keep up with the pace. There are many challenges associated with delivering mobile video content, and most operators are not equipped to handle them. Operators will have to overcome the challenges of high transfer rates over longer distances and efficient bandwidth so their consumers can seamlessly watch any content at any time.

Since content must be delivered to all types of devices, it needs to be converted to fit different screen sizes, bandwidth constraints, media/codec processing and protocol capabilities. The conversion from one format to another usually involves several intricate steps. Secondly, there is the media adaptation process, which is performed on-demand, in real-time or in an offline (batch) mode. The most basic operation of media adaptation is video encoding, transcoding and bitrate adaptation.

Video Encoding

While video codecs are defined by standards, all encoders are not created equal. Standards define valid bitstream structures and decoders, but not encoders or encoding strategies. Therefore, as long as compressed video bitstreams are compliant to the specification, then the standard has served its purpose. For example, most modern video standards make use of what is called a motion prediction tool. Motion prediction is typically about determining whether a portion of a video frame (eg, a 16x16 pixels macroblock) is present in a previously encoded frame. If it is, then the amount of bits needed to encode that portion can be significantly reduced by reusing the portion. To do this, the encoders need to first determine the best matching block in an area surrounding the macroblock in the previous frame (motion estimation); then on the basis of that match, determine whether the macroblock is unchanged (encoder can skip) or some differences exist and can be encoded (the encoding of the differences will yield fewer bits than the encoding of the macroblock itself).

Each of these 2 steps can be implemented in various ways-some being more efficient (compute cycles and memory utilization) and others providing much greater quality. In fact, the second step can be invoked in a variety of ways according to an encoding strategy and the context of the application (ie, constant versus variable bit-rate, offline-mode versus real-time transcoding, etc). Hence, when it comes to video quality, the adherence to a video standard is not a measure of quality.

Real-time Transcoding

Real-time or on-demand transcoding is challenging because the transcoder has to convert the media stream from one codec to another while maintaining appropriately short input to output latency. The transcoder does not have the benefit or luxury of multiple passes over the incoming bitstream in order to transcode while maintaining bandwidth efficiency using information from a time later in a clip.

Dynamic Bit-rate Adaptation

While bandwidth variations are common in many networks, they are more severe in mobile and wireless networks. In today's 3G networks, quality of service (QoS) is often shaky, and best effort approaches are used. For example, available bandwidth to a 3G user typically varies from 64 Kbps to 300 Kbps-these types of fluctuations in available bandwidth result in severe degradation to the customer experience.

Dynamic bit-rate adaptation (DBRA) is a general term used to describe the ability of a delivery system to adjust its transmitted bandwidth to match network fluctuations. DBRA approaches are different for RTSP and HTTP progressive download (PD). In RTSP, there is a standardized approach that is increasingly being adopted by infrastructure providers and handset vendors. For the RTSP DBRA scheme to be of value, handset support, and the support of RTSP streaming and relay servers is essential. For HTTP PD, there is no standardized way today to implement DBRA. Different terminals and media-player technologies implement different strategies. Some streaming and media player technologies like the iPhone (iOS3 and beyond), require that a multiplicity of bitrates be listed in the content asset, and the decision of which one to select is left to the iPhone media player.

Leveraging Value-added Services

These strategies for smart encoding, real-time transcoding, and dynamic bit-rate adaptation are available today through value-added services (VAS) providers and should be taken advantage of by the operators as their customers increasingly demand video content. VAS providers can provide these essential ingredients for scalable software-based deployments to help operators deliver a high quality customer experience at a reasonable cost
If the operators are able to satisfy consumer demand, the adoption of the video-on-demand services could be monumental and the next big thing for the telecom sector. Huge investments and developments will need to be made in the 3G VAS segment such as increased mobile bandwidth, more bandwidth efficient coding, power efficient decoding, and improved quality transcoding technologies which will carve the future of seamless streaming of video on mobile phones.

hese capabilities will then lead to larger revenue opportunities and a higher level of customer satisfaction, both of which will positively impact the industry.

Marwan Jabri
The author is vice president, video products unit, OnMobile
vadmail@cybermedia.co.in