Multicast IPTV Support for DVBCore
Published on Wednesday, 7 October 2020 08:57
In today’s news we’d like to provide an insight into one the projects that OBS is working on for DTVKit and its members – ‘Multicast IPTV’ support. Multicast is not widely used as a TV delivery mechanism as Operators need to invest in a managed network but some Operators have chosen to go down this path for their IPTV services. The benefit of a ‘managed’ IPTV network is that it enables the Operator to control how traffic is routed and prioritised across the network to ensure efficient use and the best quality of service for the consumer.
DVB-IP is the standard which as its name suggests, covers how DVB services can be delivered by IPTV and is typically used as the basis for Operator deployments. We say ‘basis’ as although most Operators follow the standard for the transport of IPTV services, they often employ their own individual service discovery mechanisms.
At its heart, DVB-IP employs MPEG-2 TS streams as per a traditional broadcast service, which are then encapsulated in RTP packets for transmission via multicast. In order to be able to enable a DTV or STB using DTVKit to process these streams we’ve had to make some modifications to DTVKit’s DVB Stack – ‘DVBCore’. The most significant change has been the inclusion of an ‘IP Tuner’ type in addition to the normal DVB-S, T & C tuner types together with the ‘IP Tuner’ module itself. The ‘IP Tuner’ module is responsible for receiving the multicast stream for the desired service, processing of the RTP packets and forwarding the encapsulated MPEG-TS for processing by the DVB stack in the normal way.
Network delivery, as opposed to broadcast delivery, has its own set of unique problems: dropped packets, corrupted packets, and jitter (data does not arrive smoothly, but in bursts). To compensate for these potential problems, the IP Tuner module also supports forward error correction and has a variable jitter buffer that can be tuned to the characteristics of a particular network. These ensure that the output of the ‘IP Tuner’ (the MPEG-2 TS stream) can be readily processed by the DVB stack and decoded and displayed by the underlying platform without errors and artefacts.
As mentioned previously, service discovery is something that is included in the DVB IP standard but Operators frequently define their own methods. Accordingly, service discovery is something we have left for the main application to handle, and instead have provided a set of APIs for the application to update DVBCore’s service database with the relevant information, e.g. Service ID, name, preferred LCN, URL and port and FEC type. This provides manufacturers the freedom to use whatever service discovery mechanism is required by the target Operator.
The updates we have made to DVBCore to support Multicast IPTV are largely platform independent and can be used on all platforms supported by DTVKit i.e. RTOS, Linux, RDK, and Android platforms.
Ocean Blue Software can also provide a range of support and development services to help manufacturers integrate the multicast IP tuner module, or any of the other DTVKit software components into their products.
We are currently in the testing phase of our multicast support development and aim to have a first release to DTVKit members in November. For further information please contact your DTVKit representative or email us at info@oceanbluesoftware.co.uk.