Edge optimized transrating system
A system and method for bandwidth management by controlling the bit rate of a signal stream in real time according to available link bandwidth. Applications include multiple-channel video data streams over a limited-bandwidth link such as a Digital Subscriber Line. A video signal is transrated at the head end to multiple streams having different bit rates, by a multirating device which sends the multiple streams over a network, along with metadata containing information about the data structure and parameters of the streams. At the network access edge, a demultirating device uses the metadata to select the stream with the highest video quality whose bit rate does not exceed the available bandwidth of the end-user's access link. This scheme provides multiple unicast signals to different end-users in place of a single multicast signal, supports multiple high-definition channels over a limited bandwidth link, and is compatible with standard encryption methods.
1. A method for carrying video data from a video source via a first packet-based network to a video display over a second network, the first network carrying a first video stream in a data format from the video source, a second video stream that is derived from the first video stream and having a lower bit rate and the data format, and a third video stream distinct from the second video stream and having a lower bit rate and the data format that is derived from the first video stream, the method, by a device that comprises a router or a switch, comprising:
estimating a maximum bit rate that the second network is configured for transporting a data stream;
receiving the first, second, and third video streams from the first network;
selecting one of the first, second, and third video stream, based on the estimated maximum bit rate; and
transmitting the selected video stream to the second network.
2. The method according to claim 1 , further comprising selecting the second video stream, and reconstructing the first video stream from the second video stream by using a demultirater.
3. The method according to claim 1 , wherein the selecting comprises de-multiplexing of the second video stream.
4. The method according to claim 3 , wherein the selecting comprises statistical de-multiplexing.
5. The method according to claim 1 , wherein the device includes a single enclosure configured to house a receiver for the receiving, a selector for the selecting, and a transmitter for the transmitting.
6. The method according to claim 5 , wherein the device is part of, integrated with, or comprises, a multiplexer or a server.
7. The method according to claim 5 , further comprising forming, by a sequencer coupled between the selector and the transmitter, a unicast data stream that comprises the selected video stream.
8. The method according to claim 7 , further comprising buffering, using a cache between the sequencer and the transmitter, the unicast data stream.
9. The method according to claim 1 , wherein the device further comprising a software stored in a tangible data storage medium, and a processor for executing the software.
10. The method according to claim 1 , wherein the first network is a Metropolitan Area Network (MAN) or a core network, or wherein the first network implements a core layer or an aggregation layer.
11. The method according to claim 1 , wherein the first network uses a medium that is based on, comprises, or uses, an optical fiber.
12. The method according to claim 1 , further comprising connecting to the first network using an Ethernet interface.
13. The method according to claim 12 , wherein the Ethernet interface consists of, comprises, or is compatible with, a Gigabit Ethernet (1 GbE) that is according to, based on, or compatible with, IEEE 802.3-2008 standard.
14. The method according to claim 1 , wherein the second network is an access network or implements an access layer.
15. The method according to claim 14 , wherein the second network uses medium that uses, is based on, or comprises, a twisted wire pair.
16. The method according to claim 15 , wherein the second network uses, is based on, or comprises, a point-to-point connection.
17. The method according to claim 16 , wherein the second network uses, is based on, or comprises, Digital Subscriber Line (xDSL) technology.
18. The method according to claim 17 , wherein the second network uses, is based on, or comprises, Asymmetric Digital Subscriber Line (ADSL) technology.
19. The method according to claim 18 , wherein the second network uses, is based on, or comprises, ADSL2 or ADSL2+ technology.
20. The method according to claim 18 , wherein the respective ADSL2 or ADSL2+ technology consists of, is based on, is compatible with, or comprises, ITU-T G.992.5 standard.
21. The method according to claim 17 , further comprising a Digital Subscriber Line Access Multiplexer (DSLAM).
22. The method according to claim 1 , wherein the first network further carrying metadata associated with the second video stream, carried as an Out-of-Band (OOB) channel or with the second video stream.
23. The method according to claim 22 , further comprising receiving the metadata from the first network and handling the second video stream responsive to the metadata.
24. The method according to claim 22 , wherein the metadata comprises a video quality level indicator, a consumed bandwidth, a visual noise, spurious edges, a localized motion distortion, Image Structural Similarities (SSIM), Peak-Signal-to-Noise-Ratio (PSNR), a Group of Pictures (GOP) parameter, statistics on moving vectors, macroblock types, or density, relating to the second video stream.
25. The method according to claim 22 , further comprising receiving the metadata via the first network, and wherein the selecting one of the first and the second video stream is responsive to the received metadata.
26. The method according to claim 22 , wherein the metadata is indicated by a Packet Identifier (PID).
27. The method according to claim 22 , wherein the metadata comprises the minimum required bandwidth for properly carrying each of the first and second video streams.
28. The method according to claim 1 , wherein the estimating comprises measuring of a bit rate over the second network.
29. The method according to claim 1 , wherein the second video stream is derived from the first video stream using a multirater or a transrater, or wherein the third video stream is derived from the first video stream using a multirater or a transrater.
30. The method according to claim 1 , wherein the second network is operative to be in first and second distinct states, wherein the maximum bit rate is a first bit rate in the first state and a second bit rate in the second state, and wherein the selecting of the video stream comprises selecting the video stream associated with the highest bit rate that is lower from the first bit rate in the first state and the second bit rate in the second state.
31. The method according to claim 1 , wherein the selecting comprises selecting the video stream that is associated with the highest bit rate that is lower from the maximum bit rate.