May 2010 | Volume 13 / Number 5
Creating Video Quality for the Advent of New Mobile Applications
By: James Awad
Telecommunications products and services over many years were based on the tenet “if you build it, they will come.” Product designers and service providers led customers to new applications. More recently, however, customer-defined applications are driving product and service offerings. Video telephony is a case in point, and it’s quite clear that mobile video is not far behind.
In fact, a recent Infonetics (News - Alert) report, “IMS Plans: Global Service Provider Survey,” published in August of 2009, found that more than half of the service provider respondents plan to deploy video telephony and converged mobile/fixed-line services over the next 12 to 18 months. So while we’ve seen a first wave of video services being offered, within one or two years we should see a deluge of new products as competition from network operators increases.
Smartphones are making it possible to share or access video content on the go. For such services to really take off, it must be very easy for the consumer to get video from the mobile device onto the Internet. Conversely, when viewing video content on a mobile device, the video quality must be as good as on the desktop.
The key success factors for these video gateways are the quality of experience, the ease of use, and the affordability for the end user.
Applications Driving the Market
As the mobile video market matures, the number of applications will increase. The first applications to market were videoconferencing (over 3G-324M) and over-the-air television, appearing as early as 2003 and 2005 respectively. OTA television actually operates without using any network bandwidth. Phones that support standards such as DVB-H, T-DMB, 1SEG or Qualcomm (News - Alert)’s MediaFlo decode a broadcast RF signal in the UHF or VHF bands.
So, what are the applications that will drive demand and deployment in the market?
With the coverage of 3G networks increasing, new applications are taking over due to the large increase in downlink bandwidth. The most prevalent application is video streaming. Consumers want the YouTube (News - Alert) experience on the go, and it’s now possible over 3G networks.
Mobile videoconferencing will get another chance, but it likely remains a business-only application where a structured face-to-face meeting has the most value. What is more likely to take off with consumers is video sharing, also known as “see what I see,” which has much more potential. This is because it can be coupled with social networking and has the potential to grow in a viral fashion. People from the younger demographic already are snapping photos everywhere they go and uploading them to their favorite social networking sites, not to mention uploading videos. Imagine the potential if this could be real-time. Teenagers instantly will show their friends and family what they’re doing, what they’re looking at, whether it’s a rock concert or something funny that happened at the beach. Ultimately, everyone with a mobile video phone could have an always-on TV station, broadcasting to other mobile phones or the Internet. Web sites like www.Qik.com have already enabled this with today’s technology.
Last but not least is messaging – adapting multimedia messaging service messages to the target device. This also includes video mail and video ringback tones. Since MMS always has been a paying service, network operators have deployed systems to perform message adaptation. This has led to an increase in successful delivery rates and increased overall usage. The main difference between messaging and other applications is that it is non-real-time, and needs to support a very broad range of formats. For example, an H.263 video sequence can get converted to an animated GIF to make it compatible with a lower-end feature phone.
Barriers to Success: Cost and Quality
The most important roadblock to mobile video services is still cost. Video gateways installed in carrier networks are still too costly. Today, as with many emerging markets, stand-alone systems were designed to address these new video requirements. These dedicated systems have often been built using PC servers, which allowed visionaries to get to market very quickly. As this market matures, the video processing function will be integrated into the core media gateways that currently are processing voice streams.
DSP-based solutions offer the highest area density and lowest power consumption per channel. But the real cost savings come from DSP solutions that can perform both voice and video processing on the same device. This will lower the price per port to a level at which operators will be able to attract a large audience. DSP-based solutions also provide other benefits such as low-latency processing.
The second problem is related to video quality. Even if mobile video services were free, if the quality of experience is not up to par, it will not be adopted by consumers. No one wants to watch a jerky video that is not properly formatted for the mobile screen, that is blurry, or that gets cut off before the end.
If DSP-based solutions are the only way to reduce cost to an acceptable level, how does one select the right DSP solution? The two most important points to consider are: power consumption and quality of experience.
Power consumption is probably the most important selection criteria. This will translate directly into the number of channels that can be supported on a system blade, and therefore is key to lowering system cost. The most power-efficient solution on the market today can process 5 channels per watt in common intermediate format resolution at 30 frames per second. This is more power efficient than standard PC hardware by a factor of between 100 and 200 times. By 2010, this number will exceed 10 channels per watt. The reason for this huge increase in performance is the emergence of new DSP devices that take advantage of both multi-core and innovative self-clocking architectures.
Having the most cost-effective solution is worthless without providing a high QoE, however. The difficulties in delivering high QoE in the mobile world are related to the broad spectrum of disparate mobile devices and varying network resource availability. To address the broad range of endpoints, the video gateway must be able to change dynamically things such as the video codec, frame rate, image resolution and even bandwidth consumption.
While most solutions can handle effectively the codec and format conversions, adjusting the video quality to available bandwidth is a much more difficult task. In the case of mobile video, bandwidth is quite limited. Also, available bandwidth can change dynamically during the session as the network becomes more or less congested. The video gateway has to be able to adjust dynamically to the varying bandwidth constraints.
While most voice codecs address constant-bit-rate streams, video streams are variable bit rate. This means that if a sequence of images is encoded at a fixed quality level, the amount of bandwidth consumed varies according to the complexity of each frame. Therefore, to transmit a video sequence over a channel with relatively fixed bandwidth, it is important that the video encoder adjust the quality level at each frame. Video encoder algorithms include a component called the bit-rate controller which is responsible for determining dynamically the quality level.
A lot of research has gone into bit-rate controllers, and there are different approaches for different applications. Therefore, the algorithm used for encoding a Hollywood movie onto a DVD is quite different from that used in real-time communications for mobile video. The DVD encoding can be done using multi-pass encoding, where the encoder can make multiple attempts at encoding the whole movie before selecting the best approach. When operating in a real-time environment, decisions can only be made based on past information and heuristics.
We are finally seeing the deployment of video services to consumers. Driven by the deployment of 3G networks, high-performance smartphones and the market pull from social networks, video is definitely the next battleground for network operators. Unlike voice services, where poor quality leads to customer churn, video services are still a novelty, and therefore poor quality may simply hinder adoption. As carriers work to increase their average revenue per user, providing high-quality video services is the only way to get customers on board.
After the first wave of video services is deployed, what will we see next? Once again, the next wave will be driven by the increased performance of endpoints and the latest Internet trends. High-definition video encoding and decoding will be available on endpoints, meaning that video gateways will have to support ever-increasing resolutions. Pico-projectors embedded in cell phones will increase video consumption further as it will become even easier to share media at anytime on any surface. Last but not least, when 4G networks deliver on the promise of 50 to 100mbps uplink rates, we may see HD videoconferencing on the go within a decade.
In the next wave of the applications evolution, not only will service providers have to upgrade their networks, but media gateway manufacturers will need to seek out best-in-class video DSP solutions that will deliver the QoE consumers demand, while providing the cost savings and flexibility necessary for an ever-changing mobile landscape. IT
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