User demand for flexible access to video content and the abundant availability of bandwidth in the Internet have changed the main way in which video is being distributed. Traditional broadcasting models using dedicated networks, or post mail delivery methods have been surpassed by Video-on-Demand (VoD) using the Internet. This transition has been possible because of the increasing capacity (and decreasing cost) of storage, bandwidth, and computing resources, combined with the availability of advanced video codecs.
In recent years cloud computing has also emerged as a key technology that has allowed different type and size of VoD operators to have access to the necessary resources to distribute content to their audiences. As a result, VoD distribution has become the video distribution channel with the higher growth and market potential. It is currently reshaping the media industry, and, at the same time, it is changing the viewing habits and expectations of the audience.
In the early stages of Internet video streaming users were only able to access very low quality content, e.g.: very low resolution, reduced frame rates, low bitrate and corresponding compression artifacts, and constant buffering events. As VoD platforms become more popular and display technology has evolved, user expectation for high quality is constantly increasing. Users expect high quality content, with high resolution, adequate frame rates, smooth video playback, no buffering events, short joining times, and no noticeable compression artifacts. The combined effect of all these factors is called the Quality-of-Experience (QoE).
User engagement reduces when the QoE offered is not matching user expectation. VoD providers compete in the market for better QoE by adopting new technologies that can improve any of the factors that affects quality. New technologies are being introduced constantly and rapidly with the purpose of improving quality in different ways, and some of the recent advances include: dynamic adaptive streaming techniques, high efficiency video coding, advanced content distribution networks and caching systems, and advanced security and protection mechanisms. Among all the mentioned technologies the video codec plays a central role because it controls the quality and bitrate tradeoff. In several cases VoD providers are forced, due to codec, computations and network limitations, to tradeoff video quality for saving bitrate.
H.264/AVC standardized in 2003, is the most widely used video codec for VoD and many other applications. High Efficiency Video Coding (HEVC/H.265) ratified in 2013, and is a next generation video coding standard addressed towards higher quality and higher compression for Internet video and other applications. The new codec is capable of reducing the bitrate compared to H.264/AVC by 50%.
Introducing a new video codec in the VoD chain requires a complete update of the platform. First, an efficient encoder is needed in order to encode the content within a reasonable use of resources (computation and time) and good quality/bitrate level. Second, web video players must be updated to support the new codec without the need of external plugins or third party tools. Third, a good knowledge of the codec capabilities is needed to understand what kind of quality improvement is available for a concrete application scenario. For example, providers might decide to keep the bitrate constant and use the new codec capabilities to increase the resolution to High Definition (HD) or Ultra-HD (UHD), or they might decide to keep the quality constant and reduce the bitrate to save costs, or some intermediate solution. Fourth, and finally, after the codec upgrade, VoD providers must be able to measure the effect on the final user QoE. For this it is necessary to develop and integrate tools that can collect and analyze quality related metrics.
The Film265 project addresses the challenge of the codec upgrade for small European VoD providers. The project brings together an interdisciplinary consortium composed of a research institution with long term experience in video codecs (Technical University of Berlin), a provider of solutions for the VoD film industry (reelport), and two partners who run VoD platforms for the film industry: Cinando, the online Film database and VoD service of the Cannes Film Festival, and LevelK, a Danish film distributor that runs the Stream4pro service addressed to professionals in the film industry.
Overall, the main objectives of Film265 can be summarized as follows:
- To develop a video codec system for cloud-based VoD applications using the new video codec standard H.265. The use of the new codec has two main objectives: i) to make the VoD operations more efficient by reducing the bandwidth and storage required to transmit and store the video files, and ii) to improve the quality of the video content. The combined effect of the two objectives is to have a better QoE for the final user. Compared to state-of-the-art solutions using the H.264/AVC standard, the enhanced system will deliver video files 25% smaller and at the same or better subjective quality.
- To develop a quality assessment tool for VoD applications. This tool will allow the VoD content providers to understand how video quality affects user experience with web-based video delivery. For this purpose, the tool will collect quality related metrics such as join time, buffering ratio, average bitrate, dropped frames, etc. With this information a server side tool will estimate the most important metrics according to different application scenarios.
- To integrate the new video codec and the new quality assessment tool into a market-ready VoD delivery solution. The new video codec and the quality assessment tool will be integrated into a VoD delivery system based on the cloud.
By the end of the project, all of these objectives have been met.
