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IPTV Protocol: How it works!

Discussion in 'Tutorials & Installation Guides' started by Cuvillier, Apr 30, 2016.

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  1. Cuvillier

    Cuvillier Reseller Reseller Active Member

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    Today there are many ways to receive TV. One of the methods that in recent years comes into force is IPTV. As its name suggests, IPTV, or Internet Protocol Televison is based on the use of internet protocols, ca means that these services tend to be used by telecommunications operators with internet lines. However, all services that can convey data is likely to be used (private network, GSM ..).
    [​IMG]
    IPTV has many advantages and it opened to telecommunication service providers a lucrative market. They have developed new services such as VoD, Replay, information services (weather ...) generating new revenue. It is logical to think that in the coming years, IPTV will be a major element of the world of information and entertainment.

    The basics

    There are two ways to process the information of the IPTV network. Broadcast or Multicast and Unicast
    Take for example the installation of an IPTV solution in a hotel.
    - All hotel rooms receive TV channels, information such as the weather ... This signal is broadcast in broadcast or multicast (broadcast to multiple IP).
    - By cons if a customer buys a movie VoD, the signal will be transmitted Unicast (distribution to a single IP)
    As the distribution is multicast, it is important to be able to better manage bandwidth. To do this, two main formats are used. MPEG-2 and MPEG-4 standard. The latter is mainly used because of its better performance.
    For the user, the IPTV equipment is based on a Set Top Box (Satellite receiver equivalent) and now comes to market the connected TV with integrated SetTopBox. The Set Top Box receives the data, reassembles the packets and decodes them to broadcast on TV or other media like PCs, tablets ....
    From the supplier side, the necessary equipment is a little more complex and requires more elements to allow the system to operate either in Broadcast / Multicast or Unicast.
    A streamer receives the signal (analog or digital) the congregation, and encodes the cut in distributable packets over an IP network to route them to the / destination (s).
    The signal then goes to the IPTV server which will be responsible for encrypting the data and disseminate authenticated users.

    The IGMP multicast service

    One aspect of IPTV systems is that the user must have the ability to change the channel at any time without suffering any slowdown. For this, the SetTopBox should not be overloaded with data. It was at this moment comes IGMP. It will indeed allow the box to receive only one channel at a time.
    In the diagram below, the switches do not have the enabled IGMP. Network heart gets all the video stream from the IPTV server. If each video stream occupies 10 Mbps, network heart then convey x 3 = 10 Mbps 30 Mbps of traffic.
    As IGMP is not enabled on the switches, the 30 Mbps will broadcastés on all switches and distribution to all users.
    [​IMG]
    In diagram 2, the distribution switches have IGMP snooping enabled and the heart of the network is configured for IGMP query.
    - The IGMP snooping: is a network traffic listener protocol. The switch is going to "listen" to the conversation between the user and the IPTV server. Listening to these conversations, the switch will create a list of IP part of the multicast group. This then allows filtering traffic to specific destinations.
    - The IGMP query holds all the addresses that can be part of the multicast group. So when a member of the switch IGMP snooping receives a request to join the multicast group, it sends a request to the querier to confirm registration.
    The heart of switch still receives all traffic (30 Mbps in this example)
    The switch 1 only receives 10 Mbps for a single user's request. Note also that the stream is sent to that user.
    Switch 2 only receives 20 Mbps, for 2 users have requested.
    [​IMG]
    Thus, for the calculation of bandwidth of an IPTV system, it is considered that the network receives heart all flows but that the end user receives him only one stream at a time.

    Unicast: VoD

    For users to access the video on demand, another service must be configured. The IPTV server must open a single data stream to the user making the request. The protocol used in this case is called RTSP (Real Time Streaming Protocol). It controls the flow and allows the user to pause, stop, forward ... the video he is watching.

    Quality of Service (QoS)

    One of the key elements of IP networks is now the Quality of Service. To maintain proper video signal and thus avoid mismatches images / sound, and other pixel pitches, it is essential to ensure that QoS is properly configured. So we must put in place a high priority on video and audio type packets and lower the priority of Internet browsing can she tolerate packet loss.

    Collision detection

    Collisions and errors like packet loss ... are common on a network which poses even more problems on an IPTV network for a packet of pictures = lost or lost. To detect and correct these errors, we must initially determine the diffusion type. For a video on demand, unicast, it is relatively simple for the user to send a new request to the server if a packet is lost. However, this can not be done on a multicast as there is no exchange between the transmitter and receiver. It is therefore very important to ensure that the equipment used to implement the solution is properly sized and powerful enough to reduce errors to the fullest. In addition, error correction solutions are now integrated with SetTopBox, ConnectedTV, PC ... Including the FEC (Forward Error Correction) which allows the user to reconstruct a missing or corrupted data.
    [​IMG]

    Conclusion

    The use of IPTV is increasing thanks to the increased flow of domestic connections between other. It is therefore logical that the IPTV-related technologies are still developing in the coming years with the possibility of recording their favorite programs in the cloud, integration into the SRC (Smart Room Control) developed by Swisscom Hospitality http: // vimeo .com / 46089933, which allows for home automation (control lighting, thermostats ...).
    By combining several technologies, internet service providers will thus be able to offer a better TV Service (unlimited series rebroadcast of emissions, more VOD ...) and compete illegal downloading directly.
     
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