Patent Application
20070266398
When the user in
The bandwidth consumption will never exceed the bandwidth of the HDTV broadcast TV stream since 1,3 times the nominal SDTV bandwidth is less than the nominal HDTV bandwidth. Depending on the location of the video headend 101, bandwidth savings are realized on the last mile, i.e. the twisted pair loop 104, and also in the backhaul network 102. The implementation further realizes memory savings in the video headend 101 or an eventual video server integrated in or connected to the DSLAM 103 since the HDTV streams do no longer need to be cached. Only the lower resolution SDTV streams need to be cached but these require 4 to 5 times less memory than the corresponding HDTV stream.
Although the present invention has been illustrated by reference to a specific embodiment, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiment, and that the present invention may be embodied with various changes and modifications without departing from the spirit and scope thereof. For instance, the context of IPTV over ADSL was given as an example. The invention is not restricted to any particular underlying physical, network or transport layer technology, or to any specific encoding/decoding technique used for the IPTV streams. Another example is the location of the intelligence for switching from the low resolution to the high resolution channel. Although assumed to form part of the set-top box in the above described embodiment, such intelligence can be integrated in the video headend, in an intermediate network node like the DSLAM or a residential gateway, in a video server that is integrated in or coupled to the DSLAM, etc. Such intermediate network node must then be able to intercept the user's request for the high resolution channel, and replace it with a request for the corresponding low resolution unicast channel. Later on, e.g. when its buffers have reached a certain fill-level or upon signalling from the set-top box or the video headend, the intermediate element must be able to terminate unicasting the low resolution stream and ensure delivery of the corresponding high resolution multicast stream to the viewer. When the intelligence to switch between the unicast and multicast streams is integrated in the video headend, there is no need to replace the request for the high resolution TV channel with a request for the corresponding low resolution TV channel. The request for the high resolution TV channel may simply be responded with the low resolution unicast version of the channel up to the point in time where signalling is received from the set-top box or up to the point in time where the low resolution unicast stream has caught up with the high resolution multicast stream. The above described embodiment is to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In other words, it is contemplated to cover any and all modifications, variations or equivalents that fall within the spirit and scope of the basic underlying principles and whose essential attributes are claimed in this patent application. It will furthermore be understood by the reader of this patent application that the words “comprising” or “comprise” do not exclude other elements or steps, that the words “a” or “an” do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06290756.3 | May 2006 | EP | regional |
