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IP Distribution

Today, media content is distributed over the Internet in addition to traditional broadcasting. Catch-up videos and live video streaming are also available for the PC, smartphones and tablets as well as on Internet-enabled TV sets (HbbTV). For this, the standards DVB, H.264 / AVC, H.265 / HEVC HE / AAC, MP4-ISO and HTML5 / MSE are used. The transport is realized as download, pseudo-streaming or live streaming using various protocols (RTP, RTMP/E, HTTP). Bottlenecks to the participant are balanced by load balancing and caching of Content Delivery Network Providers (CDN) in the backbone or by client-based transport methods such as Adaptive Streaming (MPEG-DASH, HDS, HLS).

In order to limit the cost of optimizing for the preparation of television and radio offers for the large number of popular devices, device-spanning and interoperable coding profiles have to be found which represents the best possible compromise between quality and technical range.

For this purpose, the IRT cooperates with terminal and encoder manufacturers, as well as CDN and cloud providers, and offers end-to-end tests that are publicly available to manufacturers. The insights gained are used to support the updating of the ARD format catalog and the introduction of new technologies like MPEG-DASH Livestreaming for HbbTV or 360 ° audio and video streaming.

At the same time, interoperability stands for a maximum range of widespread devices with a high AV quality of the network connections.

AV Streaming test portal

Streaming Testcases

IRT opened an extensive repository of differently encoded Audio- and Videostreams for PC, Smartphones, Tablets and HbbTV-Devices.

Launch the Testportal

Various Testcases are presented in a user interface as progressive download and adaptiv for MPEG-DASH, Apple HLS and Adobe HDS in multiple encodings (H.264, H.265, HE/AAC, E/AC3), containerformats (MP4, MPEG-TS) and resolutions (SDTV, HDTV, UHD, 576i, 720p, 1080i, 1080p, 50Hz…)

The testcases are offering an easy to use option for broadcasters, manufacturers, service operators and skilled users to test the playback capabilities of their connected devices under different encoding and transport conditions. With the help oft he UI, all relevant encoding parameters of various renditions from the same source footage can be viewed and compared on a given screen and audio setup. The responsive UI for mobile devices and the PC offers the selection of different webbased mediaplayers (JWplayer, VideoJS, Flowplayer…) to be compared decoding the same streams. For the testcase IRT Referenzclips 10min“ special testing sequences have been rendered, which facilitate immediate experts viewing of critical criteria like Safe Area, Framerate, Interlaced Mode, Timecode, Overscan, Audio- Channelmapping etc. being applied to the given transmission chain. The presented streams also implement the most current encoding requirements from the german public broadcasters of ARD. Some of the testcases are updated occasionally and my exceed constraints of common decoders, as they are intended to be used for trial annd error, to find out what a given device or broadband-connection can handle or not. So it should be noted that any failed playback attempt may be regarded sinply as test result and not necessarily as a problem of the provided service or application.

If you have any comment to the encodings, questions regarding the application, or if you would like us to assist you in providing testresults and custom encodings, please don’t hesitate to contact us.

We thank all developers of the free software tools which are being used for the preparation of these testcases: GPAC MP4box, VideoLAN x264, ffmpeg, x265, DASH.js, MediaInfo, BITMOVIN und video.js.

With the cooperation of IRT and Romain Bouqueau (GPAQ) a HbbTV 1.5 compliant segmentation for MPEG-DASH in MP4box is now publicly available.

How to use
How to use

Data privacy compliant quality measurement with Argos

Every day, a large amount of audio and video content is distributed via the Internet. In order to guarantee quality assurance and technological improvement of the delivered content, the IRT is currently developing the Argos system. This tool enables the detection of the playback quality in the end device to examine the technical delivery of the content. Defective content or problems with the distribution are thus recognised in order to improve the delivery quality. Argos can be used across platforms, from smart phones to HbbTV television sets, and enables the analysis of all current streaming formats – whether live or on-demand. In addition, Argos complies with the applicable data protection guidelines in Germany and Europe. This means that personal data is not collected, stored or processed and that personal user data is protected at all times.


In the field of webcasting, IRT examines the influence of various mechanisms on the quality of audiovisual content distributed via live streaming and podcasts. We focus in particular on new codecs and the impact which transport layers and application layers have on transmission. The selection of certain coding/transport parameters can play a crucial role in the technical quality of reception. Practical, real-world advice is designed to help content providers optimise the production of online services.

Quality assurance of online audiovisual content
The online transmission of audiovisual content is possible only with very limited bandwidth. It is therefore usually necessary to compress data, which in turn reduces quality.

During compression, a wide variety of factors affects the quality of audio and video in streaming applications (e.g. MPEG-4, H.264, Apple’s QuickTime, RealNetworks, Windows Media). The efficiency of a given encoder and decoder as well as the content of sequences which require coding are very important. Sequences which feature a lot of motion and details necessitate a higher data rate than sequences which have steady and uniform content. And if the compressed audiovisual signal is transmitted via the Internet, then transmission errors such as packet loss, jitter, delay and scrambled packets are likely.

And by means of AIDA and VIDA, IRT made it possible to compare different codecs with various types of reference content and at common data rates.

Researching MulticastIRT specialists also examine the impact of multicasting on the quality of audio and video in streaming applications. 

Data are conventionally transferred between two points online: a transmitter and a receiver. If large amounts of data – during a live video broadcast, for example – need to be distributed online, then a lot of point-to-point links are created (i.e. unicasting) and the data are transferred several times over long segments. In this situation it would be more sensible, however, to send the data just once by means of multicast to all recipients who wish to receive the content stream. Multicasting means that data are first replicated by a network’s routers and then sent to individual recipients. This technology is especially important for broadband applications. Wireless transmission via Real Time Protocol (RTP) and User Datagram Protocol (UDP) does not necessarily, however, guarantee delivery of all IP packets to recipients. Providing feedback to service providers about the number of clients and their quality must also be done differently than with unicasting.

Your contact

Alexander Erk
Head of Department
Tel. +49 (0)89 32399-282
Martin Schmalohr
Project Manager
Tel. +49 (0)89 32399-250