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Bandwidth adaptive stream selectionRelated Patent Categories: Pulse Or Digital Communications, Bandwidth Reduction Or ExpansionBandwidth adaptive stream selection description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070160127, Bandwidth adaptive stream selection. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] Conventional multi-media streaming systems typically stream a single audio stream and a single associated video stream from a source to a destination. The combined bandwidth of the audio and video streams is the required channel bandwidth between the source and destination. If this channel bandwidth is reduced due to network congestion, for example, conventional systems have very limited means of adequately dealing with the reduction. Modern multi-media delivery systems therefore employ various techniques that allow a source to adapt to the changing source-destination bandwidth. [0002] Video data is generally processed and transferred in the form of bit streams. Rate control involves the process of allocating bits for a group of pictures, a picture, a slice or a macroblock. A desirable rate control scheme should maximize picture quality for a given bit-rate. There are three general types of rate control, including constant bit-rate, variable bit-rate and exact bits. The length of a sequence may or may not be known. If it is known, one can achieve exact bits for the compressed stream, which can be useful for some storage applications. Constant bit-rate can be used for constant bit-rate transmission channels, such as in broadcast, for example. Constant bit-rate only requires a small buffer and is normally used in a push mode. Variable bit-rate can be used for variable bandwidth channels, such as for digital video disks. Variable bit-rate typically requires a large buffer and is normally used in a pull mode. Because any channel has a limited bandwidth, variable bit-rate has two parameters. One variable bit-rate parameter is maximum bit-rate, and the other is average bit-rate. The variable bit-rate maximum bit-rate is set for a channel, and the variable bit-rate average bit-rate is set for storage space. [0003] A typical technique is to make multiple alternate audio and video streams available to the source, where the alternate streams are encodings of the same content but with different bandwidths. This gives the source choices from which to select the most appropriate audio/video streams for transmission to the destination. [0004] Unfortunately, such prior methods have drawbacks such as inadequate adaptation to the changing source-destination bandwidth or bit-rate, high picture quality variation and blocking within pictures. Embodiments of the present disclosure address these and other issues. SUMMARY [0005] These and other drawbacks and disadvantages of the prior art are addressed by an apparatus and corresponding method for bandwidth adaptive stream selection. [0006] An exemplary apparatus for selecting one of a plurality of alternate input streams for transmission includes input determination means for determining bandwidth requirements for each of the plurality of alternate input streams, output measurement means for measuring bandwidth currently available for transmission, and stream selection means for selecting for transmission one of the plurality of alternate input streams that has the highest determined bandwidth requirement less than or equal to the measured bandwidth currently available for transmission. [0007] The exemplary apparatus may further include an encoder in signal communication with the input determination means, a sub-sampler in signal communication between the input determination means and the stream selection means, and a receiver in signal communication with the output measurement means. [0008] A corresponding exemplary method for selecting one of several alternate input streams for transmission includes determining bandwidth requirements for each of the alternate input streams, measuring bandwidth currently available for transmission, and selecting for transmission one of the alternate input streams that has the highest determined bandwidth requirement less than or equal to the measured bandwidth currently available for transmission. [0009] These and other aspects, features and advantages of the present disclosure will become apparent from the following description of exemplary embodiments, which is to be read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The present disclosure teaches bandwidth adaptive stream selection in accordance with the following exemplary figures, in which: [0011] FIG. 1 shows a flow diagram for bandwidth adaptive stream selection in accordance with the principles of the present disclosure; [0012] FIG. 2 shows a block diagram of a video encoder with bandwidth adaptive stream selection in accordance with the principles of the present disclosure; [0013] FIG. 3 shows a block diagram of a system with video encoding and sub-sampling for bandwidth adaptive stream selection in accordance with the principles of the present disclosure; [0014] FIG. 4 shows a table of streams with frame types for bandwidth adaptive stream selection in accordance with the principles of the present disclosure; and [0015] FIG. 5 shows a block diagram of a system with multiple stream video encoding and sub-sampling for bandwidth adaptive stream selection in accordance with the principles of the present disclosure. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0016] The present disclosure defines a method for dynamically selecting the appropriate alternate stream and an optional sub-sampling thereof that is responsive to input and output bandwidth. Thus, the stream bandwidth may be optimally matched to the source-destination channel capacity at all times. [0017] In further embodiments, each alternate stream is sub-sampled such that the source selectively transmits only parts of an alternate stream. This provides more choice in adapting the stream bandwidths to the actual source/destination channel capacities. [0018] The streams may include data types such as video, audio, or video and audio. For example, if an encoder or other source produces more than one audio encoding stream, bandwidth adaptive stream selection may be used to chose the appropriate audio encoding to transmit for current or instantaneous network or transmission line conditions. [0019] To make the selection method adapt to the ever changing dynamics of the system and the streams, an exemplary embodiment continuously measures both the source-destination channel capacity and all of the possible audio/video stream bandwidths from which a source can choose. [0020] As shown in FIG. 1, a method for bandwidth adaptive stream selection is indicated generally by the reference numeral 100. The method includes a start block 110 that passes control to an input block 112. The input block 112 receives alternate input streams and their sub-sampled versions, and passes control to a function block 114. The function block 114 measures the bandwidths of the alternate input streams and each of their sub-sampled versions, and passes control to a function block 116. The function block 116, in turn, measures the available bandwidth for output, and passes control to a function block 118. The function block 118 selects one specific sub-sampled version of one specific alternate stream such that the selection has the highest bandwidth of all possible choices equal to or less than the available output bandwidth. The function block 118 passes control to an end block 120. Continue reading about Bandwidth adaptive stream selection... Full patent description for Bandwidth adaptive stream selection Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Bandwidth adaptive stream selection patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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