Under adaptive streaming, the quality of streamed video is adjusted to changing network conditions, to ensure the best possible playback quality for the end user. The ITU-T (International Telecommunications Union - Telecommunication Standardization Sector) recently published its P.1203 recommendation. It is the first standard worldwide to enable analysis of the quality of streaming services such as YouTube, Amazon Prime Video and Netflix.
Video streaming is one of the most used Internet services today, and adaptive bitrate streaming mechanisms are often used to balance the media delivery according to any variations in the available bandwidth. This is also important for mobile scenarios, where the bandwidth can vary due to interference and user movement. While adaptation improves the possibility of an interrupt-free delivery, it also creates quality variations in the audiovisual media that can be disturbing to the end user.
The internationally recognized P.1203 standard now specifies algorithms ("models") that can calculate the quality of the audio and video signal based on the streams transmitted over the network. Different model realizations are used for different levels of content encryption and computational complexity. In addition, an integration algorithm makes it possible to analyze the overall quality of a video session, taking quality variances and rebuffering (expressed as frozen streams) into account. The latter two points in particular make this standard unique worldwide, because previous models do not reflect these aspects completely.
Increased audio and video quality improves the customer experience
In addition to Deutsche Telekom, in collaboration with TU Berlin and the Ilmenau University of Technology, six other companies worked together on P.1203: Ericsson AB, Huawei, NETSCOUT SYSTEMS, NTT Network Technology Laboratories, OPTICOM and SwissQual/Rohde&Schwarz.
The seven participating companies submitted their initial model candidates for an ITU-T evaluation procedure. These candidate models were tested using extensive subjective data in a multi-category competition. The best performing algorithms – the winner in each category – were finally merged into one single standard. The high quality of the T-Labs algorithms was impressive across the board. In fact, the algorithm in one category was developed exclusively by T-Labs. As such, it has made a significant contribution to the final standard.
T-Labs has conducted research and development in the video quality analysis area since its founding in 2004, in collaboration with TU Berlin – for example in 2013-15 with its endowed chair "Assessment of IP-based Applications", headed by Prof. Dr. Alexander Raake, who is once again working closely together with T-Labs through his teaching activities at the Ilmenau University of Technology.
T-Labs develops and tests a variety of programs for measuring network and video streams, resulting in a number of scientific publications and contributions to standards, as well as many innovations for Deutsche Telekom. In one example, in a joint project with Service & Demand Management and Fixed Mobile Engineering Deutschland, a monitoring tool was developed that enables the continuous, near-customer measurement of video quality through the deployment of measurement devices throughout Germany.
"Deutsche Telekom needs modern, accurate models like P.1203 to perform representative measurement of the quality of the video services that its customers use. These measurements go far beyond mere broadband analyses and also consider how actual customers experience video. Based on these measurements, Deutsche Telekom can improve the quality of video services for all customers, permanently improving the customer experience," says Werner Robitza, expert for quality of experience and PhD student at T-Labs.
The P.1203 recommendation currently supports adaptive bitrate video streaming services for H.264/MPEG-4 AVC-encoded videos up to HD format. As a next step, in its ongoing work ITU-T is extending the standard to cover up to 4K/UHD format video, then including three video codecs, namely H.264/MPEG-4 AVC, H.265/HEVC and VP9.
More in-depth information about P.1203: