Technology Highlights

While multicasting technology exists for a long time already and from the very beginning MAYAH devices do support it not everyone knows how to establish a multicasting connection.

Multicasting connections in the audio and video broadcasting industry are mostly used for content distribution. So they’re also mainly unidirectional. At the multicasting IP connection the signal is not delivered from a transmitter to each receiver directly. The packets are being duplicated by the network equipment upon request from the receiver in the network segment nearest to it. By this the network load can be reduced dramatically.

To establish an outgoing multicasting connection on any of MAYAH audio codecs there’s no need to make any specific settings. It is recommended though to choose the direction of the stream as „send only“ and type in the desired Multicast Address.

On IP-level there is a specific range of the so called class-D addresses reserved for Multicast. The four significant bits of the class-D addresses are set to 1 1 1 0. The 28-bit number following these four bits is called „multicast group ID“ which spans from 224.0.0.0 to 239.255.255.255. Therefore most of the multicast addresses are traditionally starting from 224.x.x.xx or 225.X.X.X

As soon as the same multicast address (and if necessary an IP port number) is entered for the receiver the network routers or switches provides it with the data packets from the encoder.

To avoid a danger of an uncontrolled multiplication of data there’s usually no multicast services available at the Internet connections unless they’ve been specifically agreed and configured at the Internet provider level. Multicast is mainly used in the local or corporate networks.

What to do if you must feed one stream to multiple destinations which are not in the same network and probably connected to the Internet via different providers? There’s no other way as to establish multiple point-to-point (unicast) connections from one transmitter to each receiver. An appropriate bandwidth must be checked on the transmitter (encoder) side. Unlike the traditional Web Radio which is generally works in the same manner, professional signals should not be transmitted by using TCP protocol. If the packet is missing it is re-requested by the receiving side and if there’s any kind of a 'traffic jam’ on the route it may lead to significant interruptions and drops. When using the state-of-the-art protocol for multimedia transmission, RTP, even if some IP packets are missing the receiver just goes on with the decoding, so that minor drops may be not hearable at all.

It is very easy to benefit from the advantage of the Multiple Unicast feature of MAYAH Audio Codecs. At the decoder side just type in the IP address of the encoder, choose stream direction “receive only” and establish the connection.

When working as an encoder C11 Audio Codecs support up to 11 such unicast connections at the same time. The audio is not being processed multiple number of times. It’s just the IP packets which are multiplied by the device and send to the decoder.