Pulse or digital communications – Bandwidth reduction or expansion
Reexamination Certificate
1999-10-18
2002-11-12
Kelley, Chris (Department: 2713)
Pulse or digital communications
Bandwidth reduction or expansion
C375S240000, C375S240250
Reexamination Certificate
active
06480537
ABSTRACT:
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
This invention relates generally to video communications, and, more particularly, to methodologies and concomitant circuitry for dynamically injecting video coding software into a transmitted video stream so that receivers are capable of playing video encoded in any format.
2. Description of the Background
Currently there are many different types of video coding standards which can only be utilized for video playback at a receiver if the receiver has the correct software pre-loaded. As the number of different encoding techniques grows and existing video encoding software is updated, the receiver must load all the new and updated software in order to play current video streams.
Representative of the conventional arrangement to transmit video frames via packets through a packet network is the high-level depiction of video system
100
shown in FIG.
1
. Each video frame produced by a standard source (not shown), as exemplified by frame
110
serving as the input to transmitter
101
, is compressed by encoder
120
with reference to an encoding program stored in program memory
125
, and the encoded output appearing on lead
121
is formatted into packets
131
by data packetizer
130
. Transmitter processor
135
controls the interactions of encoder
120
with program memory
125
, and also provides the necessary control information so as to form packets
131
. In turn, packets
131
are transmitted via packet network
140
as propagating packets
132
which are detected by receiver
102
, where the packets are processed by data extractor
150
to produce, on lead
151
, the received counterpart of compressed output
121
in transmitter
101
. The resulting data stream on lead
151
is decompressed by decoder
160
to produce received frame
111
, a reproduced version of original frame
110
.
In order to reproduce frame
111
, it is necessary for decoder
160
to have available decoding software which corresponds to the encoding software of encoder
120
. Conventionally this is accomplished by the prior loading and storing of the corresponding decoding software in decoder
160
so as to display the video stream. Unfortunately from the point of view of loading and storage, there are many different video coding standards, including MPEG-1, MPEG-2, MPEG-4, MPEG-7, JPEG, H.261, and H.263. The standards also keep evolving. Thus, it is sometimes the case that receiver
102
receives a video stream
132
which cannot be played back because decoder
160
lacks suitable decoding software, either because decoder
160
has not been loaded with the commensurate software or the decoder is not compatible with the older or newer version of compressed video. Currently users of system
100
are responsible for installing each unique piece of software that may be required in decoder
160
in order to decode a particular video stream.
The subject matter of the present invention relates to: (a) encapsulating the appropriate video decoding software, including the encoding algorithms, via transmitter
101
; (b) bundling the decoding software with the actual video packet streams; and (c) transmitting the encoded video along with specific decoding instructions to receiver
102
. This provides any properly equipped receiving terminal with the ability to play any type of encoded video stream without having the associated decoding software pre-loaded, thus creating a highly flexible and dynamic video transmission environment. The methodology and concomitant circuitry of the present inventive subject matter engenders what is referred to as “active techniques” for video.
Recently, the notion of “active networking” has been introduced; active networking is intended to effect a significant change on the historical network paradigm, namely, a change from a passive carrier of analog/digital signals to a more general computational ability associated with network components, and has especially been applied to switches and/or routers used to provide telecommunications services. However, such efforts to this point in time have been devoted more to outlining the benefits that such a paradigm could achieve, without elucidating specifics of such an approach except in a few special cases.
For example, the paper entitled “On Active Networking and Congestion” as authored by Bhattacharjee, Calvert, and Zegura (BCZ) in January, 1996 and published as Georgia Institute of Technology Technical report GIT-CC-96/02, focuses on applying active networking concepts to handling network congestion. In BCZ, the model of what happens when a packet arrives at a node (used interchangeably with switch or router) is as follows—for purposes of discussion, a packet is composed of a header part and a payload part:
(1) The output destination port for the packet is computed as usual.
(2) If a packet contains a valid Active Processing Function Identifier (ACPI), it is sent to an active processor and processing continues; otherwise, it is transmitted as usual.
(3) The function specified in the ACPI is computed, using the packet's association descriptor and user data as inputs.
(4) If the result of the function is transformed data (e.g., reduced length), the packet's network-level header and ACPI are recomputed as necessary; the node's state is updated as required by the specified function.
(5) The (possibly modified) packet is transmitted to its next-hop node.
It is extremely important to reiterate that the above procedure requires an Active Processing Function Identifier (ACPI) to differentiate between conventional processing and additional, that is, active processing. As BCZ further point out, the obvious place to put the ACPI is in the same header used to switch the packet. However, BCZ concludes that such an approach is unacceptable for at least two reasons. First, the approach does not work for ATM or any other technology where the switched unit is too small to accommodate additional overhead of the ACPI. And second, the approach is not backward-compatible, requiring that all network protocols become “active-aware”. BCZ proposes that an alternative to placing the ACPI in the network header itself is to define a “generic” location for the ACPI function, sufficiently high in the protocol stack that the additional processing overhead is not prohibitive, but sufficiently low in the protocol stack to allow its location by switching nodes without too much knowledge of higher-level protocols. Thus, BCZ immediately rules out the use of the packet itself for differentiating between conventional and active processing. However, use of the packet (either the header, payload, or both) overcomes what BCZ deems to be unacceptable, that is, use of the packet itself eliminates additional packet overhead, and network protocols need not be “active-aware”.
Moreover, in the BCZ approach, there is no program portion in the packet. Programs are embedded into the node. There is only a set of predefined computations which can be performed in the node. A node which has the computational power is called an active processor (AP). Header information in each packet specifies which computation is to be performed on it. For example, for MPEG packets, the fields in the header indicate the priority of particular packets (for example, I, P, and B frames, as further discussed below). This priority is used in the AP to decide which packet should be dropped to avoid congestion.
Consequently, the prior art is devoid of teachings or suggestions relating to: encapsulating the appropriate video decoding algorithms and software, bundling them with the actual video streams, and transmitting the encoded video along with specific decoding instructions to the receiving terminal, which then allows properly equipped receiving terminals the ability to play any type of encoded video stream without having the associated decoding software pre-loaded, thus creating a highly flexible and dynamic video transmission environment.
SUMMARY OF THE INVENTION
Shortcomings and limitations of the prior art are obviated, in accordance
Agrawal Prathima
Chen Jyh-Cheng
Famolari David
An Shawn S.
Giordano Joseph
Kelley Chris
Telcordia Technologies Inc.
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