The following U.S. Utility patent applications are hereby incorporated herein by reference in their entirety and made part of the present U.S. Utility patent application for all purposes:
1. U.S. Utility patent application Ser. No. ______, entitled “Channel Condition Prediction Employing Transmit Queuing Model,” (Attorney Docket No. BP22763), filed on the same date herewith, pending, which claims priority pursuant to 35U.S.C. §119(e) to the following U.S. Provisional Patent Application which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility patent application for all purposes:
2. U.S. Utility patent application Ser. No. 13/240,906, entitled “Selective Intra and/or Inter Prediction Video Encoding,” (Attorney Docket No. BP22759.1), filed on Sep. 22, 2011, pending, which claims priority pursuant to 35 U.S.C. §119(e) to the following U.S. Provisional Patent Application which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility patent application for all purposes:
3. U.S. Utility patent application Ser. No. 13/223,250, entitled “Dynamic Wireless Channel Selection and Protocol Control for Streaming Media,” (Attorney Docket No. BP22783), filed on Aug. 31, 2011, pending, which claims priority pursuant to 35 U.S.C. §119(e) to the following U.S. Provisional patent application which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility patent application for all purposes:
4. U.S. Utility patent application Ser. No. 12/197,781, entitled “Source Frame Adaptation and Matching optimally to Suit a Recipient Video Device”, filed on Aug. 25, 2008, pending.
The following standards/draft standards are hereby incorporated herein by reference in their entirety and are made part of the present U.S. Utility Patent Application for all purposes:
1. “WD3: Working Draft 3 of High-Efficiency Video Coding, Joint Collaborative Team on Video Coding (JCT-VC),” of ITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11, Thomas Wiegand, et al., 5th Meeting: Geneva, CH, 16-23 March, 2011, Document: JCTVC-E603, 215 pages.
2. International Telecommunication Union, ITU-T, TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU, H.264 (March/2010), SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS, Infrastructure of audiovisual services—Coding of moving video, Advanced video coding for generic audiovisual services, Recommendation ITU-T H.264, also alternatively referred to as International Telecomm ISO/IEC 14496-10—MPEG-4 Part 10, AVC (Advanced Video Coding), H.264/MPEG-4 Part 10 or AVC (Advanced Video Coding), ITU H.264/MPEG4-AVC, or equivalent.
The following IEEE standards/draft IEEE standards are hereby incorporated herein by reference in their entirety and are made part of the present U.S. Utility patent application for all purposes:
1. IEEE Std 802.11™—2007, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” IEEE Computer Society, IEEE Std 802.11198 —2007, (Revision of IEEE Std 802.11—1999), 1233 pages.
2. IEEE Std 802.11™—2009, “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements; Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications; Amendment 5: Enhancements for Higher Throughput,” IEEE Computer Society, IEEE Std 802.11n™—2009, (Amendment to IEEE Std 802.11™—2007 as amended by IEEE Std 802.11k™—2008, IEEE Std 802.11r™—2008, IEEE Std 802.11y™—2008, and IEEE Std 802.11r—2009), 536 pages.
3. IEEE P802.11ac™/D1.1, August 2011, “Draft STANDARD for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Amendment 5: Enhancements for Very High Throughput for Operation in Bands below 6 GHz,” Prepared by the 802.11 Working Group of the 802 Committee, 297 total pages (pp. i-xxiii, 1-274).
1. Technical Field of the Invention
The invention relates generally to wireless communication systems; and, more particularly, it relates to adaptive video encoding to accommodate video transmission over a packet-based, lossy communication channel.
2. Description of Related Art
Many approaches for improving video error robustness/concealment have been proposed, and these approaches can generally be divided into two groups. The first group is related to network layer solutions that attempt to recover the error/packet loss at packet layer, by providing an error free A/V stream to the video decoder. Such solutions usually require redundant codes and retransmissions. The second group is related to video layer solutions, especially post-processing, that will accept a corrupted video stream and try to mitigate gaps and mismatches in the decoded video frames.
As may be understood, both of these groups (network layer solutions and video layer solutions) have their strengths and weaknesses. In particular, a heavily protected network layer might be very robust and resilient to errors, but usually this is accompanied by a reduction in the constant throughput of the channel and/or an increase in the effective latency of the channel. For the video layer, one of the primary considerations is the overall user experience (e.g., the perceptual experience of a user). Video should appear smooth and natural, even under variable network conditions. Under variable channel conditions, providing an acceptable user experience can be particularly challenging for real-time (or near real-time) video streams, as both packet loss and channel delay can have deleterious effects on perceived video quality (e.g., blocking or blurring effects, video freezing or jerkiness, and audio/video synchronization issues).
More particularly, during real-time video encoding and transmission, a packet transmission incremental delay greater than a frame interval might have the same effect as a dropped or lost packet. The video decoder typically needs to decode and present each video frame within a relatively short time period. Consequently, if a packet is delayed too much over the network it might be impossible to complete frame decoding in time for display. If a delayed or dropped frame is also a reference frame for other frames, decoding errors for multiple frames may occur. Particularly in the context of wireless communications, the present art does not provide an adequate means by which communication of media related content may be effectuated in a robust, reliable, and perceptually acceptable manner.
A novel approach is presented herein for optimizing video transmission over a packet based, lossy communication medium/channel in order to improve the end user experience. The novel approach is related to the combination of predictive estimates of channel conditions and adaptive video encoding so that better error concealment, error resilience and bandwidth usage is achievable during, for example, real-time video encoding for packet network transmission.—
The present invention is generally related to digital video compression, and generally applicable to video compression standards, protocols, and/or recommended practices (e.g., MPEG-4 Part 2, H.264 (AVC), WMV, AVS, RealVideo and Quicktime, among others). While the novel approach presented herein oftentimes employs wireless packet-based transmissions in exemplary embodiments (e.g., UDP/IP), the various aspects and principles, and their equivalents, can also be extended generally to any network transmission (regardless of the particular type of communication medium being employed such as wired, wireless, optical, etc.) over a communication channel that is lossy or variable.
Referring more specifically to the figures,
The network 104 can be a dedicated video distribution network such as a direct broadcast satellite network or cable television network that distributes video content 108 from a plurality of video sources, including video source 102, to a plurality of wireless access devices and, optionally, wired devices over a wide geographic area. Alternatively, network 104 can be a heterogeneous network that includes one or more segments of a general purpose network such as the Internet, a metropolitan area network, wide area network, local area network or other network and optionally other networks such as an Internet protocol (IP) television network. Over various portions of a given network, the video content 108 can be carried as analog and/or digital signals according to various recognized protocols.
Wireless access device 106 can include a base station or access point that provides video content 108 to one or a plurality of video subscribers over a wireless local area network (WLAN) such as an 802.11a,b,g,n, WIMAX or other WLAN network, or a cellular network such as a UMTS, EDGE, 3 G, 4 G or other cellular data network. In addition, the wireless access device 106 can comprise a home gateway, video distribution point in a dedicated video distribution network or other wireless gateway for wirelessly transmitting video content 108, either alone or in association with other data, signals or services, to video device 110 and/or mobile video device 112.
Mobile video device 112 can include a video enabled wireless smartphone or other handheld communication device that is capable of displaying video content. Video device 110 includes other video display devices that may or may not be mobile including a television coupled to a wireless receiver, a computer with wireless connectivity via a wireless data card, wireless tuner, WLAN modem or other wireless link or device that alone or in combination with other devices is capable of receiving video content 108 from wireless access device 106 and displaying and/or storing the video content 108 for a user.
The network 104, wireless access device 106, video device 110 and/or mobile video device 112 include one or more features of the present invention that will be described in greater detail in conjunction with
In the illustrated embodiment, video content is provided by a video source 102 to the wireless access device 106 for encoding (or further encoding or transcoding) and transmission. The video content 108 may be communicated to the wireless access device 106 by various means/networks such as those described above. In one embodiment, the video source 102 comprises a gaming console, cable or satellite set top box, media server or the like that is coupled to the wireless access device 106 by a standardized interconnect/interface 212. The standardized interconnect/interface 212 may comprise, for example, an audio/video cable such as an HDMI cable (in which case the wireless access device 106 may take the form of a wireless dongle), a high bandwidth wireless link (e.g., a WiGig or WirelessHD compliant link) capable of transmitting uncompressed, standard or high definition video content, or various combinations of such technologies.
Wireless access device 106 includes a video encoder(s) 204 that receives and encodes video content for transmission (in the form of encoded video stream 202) by network interface 206 over wireless channel 226. As described more fully below with reference to
Encoded video content from the encoder 204 is provided to network interface 206 for transmission to video device 110/mobile video device 112 (hereinafter referred to collectively or in the alternative as video device 110). In the disclosed embodiment, the network interface 206 includes medium access control (MAC) 208 and physical layer (PHY) 210 circuitry or functionality. A main purpose of the MAC 208 is to allocate the bandwidth of the wireless channel 226 and coordinate access when multiple video devices 110/112 or similar are sharing the channel. Among other functions, the PHY 210 establishes and terminates connections to the wireless channel 226. In the disclosed embodiment, PHY 210 generates and transmits modulated RF signals containing the encoded video stream 202 over the wireless channel 226. As noted, the MAC 208 and PHY 210 may operate in accordance with a wide variety of packet based communication protocols, such as an IEEE 802.11 compliant network.
In the illustrated video device 110, a network interface 214 receives RF signals (over the wireless channel 202) containing the encoded video stream 202. The PHY 218, in cooperation with the MAC 216, then demodulates and down converts these RF signals to extract the encoded video stream 202. In turn, the decoder 220 operates on video data from the extracted video stream 202 to generate a decoded video stream for display on a video display 222.
An optional interconnect/interface 224 (including, for example, the various embodiments disclosed above in conjunction with interconnect/interface 212) may be utilized to provide decoded video content to, for example, a high definition television or projection system. In such embodiments, as well as other embodiments, the video display 222 may be part of or a separate component from the video device 110. Further, the video device 110 may function as relay to other (mobile) video devices.
The network interface 214 of the disclosed embodiment also provides various transmissions to the wireless access device 106 including, for example, signaling in accordance with an acknowledgement (ACK/NACK) protocol 232, status information relating to the operation of the PHY 218 (for example, bit error rate before error correction or a signal-to-noise ratio (SNR)), and decoder queuing information 234. Such receiver information/feedback 230, in conjunction with transmitter side channel throughput indicia 302, may be utilized to generate estimates of current and/or expected channel throughputs under a variety of operating conditions.
Hereinafter, the terms “ACK”, “acknowledgement”, and “BA” are all meant to be inclusive of either ACK or BA (block acknowledgement) and equivalents. For example, even if only one of ACK or BA is specifically referenced, such embodiments may be equally adapted to any of ACK or BA and equivalents. One of the benefits of video encoding in accordance with the present invention may be a significant reduction in number of NACKs received by the wireless access device 106. It is noted, however, that ACKs may not provide an immediate indication of channel conditions when, for example, an ACK is the result of successful error correction on the receiving side of the wireless channel 226.
Video encoder 204 and encoder rate adaptation layer 200 can be implemented in hardware, software or firmware. In particular embodiments, the video encoder 204 and encoder rate adaptation layer 200 can be implemented using one or more microprocessors, microcomputers, central processing units, field programmable logic devices, state machines, logic circuits, analog circuits, digital circuits, and/or any devices that manipulate signals (analog and/or digital) based on operational instructions that are stored in a memory module. The function, steps and processes performed by video encoder 204 or encoder rate adaptation layer 200 can be split between different devices to provide greater computational speed and/or efficiency. The associated memory module may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static random access memory (SRAM), dynamic random access memory (DRAM), flash memory, cache memory, and/or any device that stores digital information. Note that when the video encoder 204 and/or encoder rate adaptation layer 200 implement one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory module storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry.
Further, within each of the wireless access device 106 and video device 110/mobile video device 112, any desired integration or combination may be implemented for the various components, blocks, functional blocks, circuitries, etc. therein, and other boundaries and groupings may alternatively be performed without departing from the scope and spirit of the invention. For example, all components within the network interface 206 may be included within a first processing module or integrated circuit, and all components within the network interface 214 may be included within a second processing module or integrated circuit. Likewise, while shown as separate from video source 102, encoder(s) 204 and encoder rate adaptation layer 200 could be incorporated into video source 102 or other network element of network 100. Further, all or portions of the encoder rate adaptation layer 200 may be incorporated into the encoder 204.
As noted, packet-based networks can provide high throughput, but often cannot guarantee a combination of low transmission delays, constant throughput and a low level of net data losses under “noisy” channel conditions. Channel conditions can be influenced by a variety of factors, including signal strength, pattern noise (e.g., microwave bursts), interference from other carriers, and network congestion on specific nodes. Transient impulse noise can also have a short term detrimental effect on the available bandwidth of a wireless channel. To the extent practical, it may be advantageous to account for such impulse noise in order to minimize unnecessary adjustments to encoding parameters.
The term channel throughput is used generally herein to refer to an average useful bit rate (including link layer protocol overhead) over the wireless channel 226. For real time streams such as video, relevant throughput values may be subject to latency constraints (effectively isochronous throughput) and have typical values that are less than total throughput. Although throughput is typically measured in bits per second (bps) or megabits per second (Mbps), data packets per second or data packets per time interval may also be used. Many factors (as generally represented by throughput indicia 302 and receiver information 330) may impact channel throughput and/or be utilized in accordance with the present invention to generate an indication of channel throughput. Such factors include PHY characteristics (e.g., operational frequency/band), the selected modulation and coding scheme (MCS), the size of the MAC protocol data units (MPDUs) and the use of packet aggregation, supported PHY rates of the transmission protocol, channel bandwidth (e.g., 20/40 MHz), guard intervals (GIs), the relevant transmission acknowledgment policy (e.g., Normal ACK/NACK, B-ACK (Block Acknowledgment) or aggregated acknowledgment, No-ACK), average size of the data (e.g., MPDUs) in an encoded stream, channel load, the number of transmit streams, etc. Such channel/transmission characteristics could further include a raw bit error rate, packet error rate, power mode information, signal-to-noise ratio (SNR), packet retransmission rate, and various reception parameters or other metrics that describe the ability of the RF channel to effectively send the encoded video stream 202 to the video device 110. Channel throughput estimation in accordance with various embodiments of the present invention may utilize one or more indicia of the above channel characteristics. Use of a relatively large number of indicia may increase the precision of the channel throughput estimation model.
In the illustrated encoder rate adaptation layer, various throughput indicia 302 are congregated and analyzed by a channel throughput estimation 300 function. The channel throughput estimation 300 utilizes the received throughput indicia 302 to generate channel throughput estimations. Such estimations may include, for example, expected supportable throughputs for a plurality of supported PHY data rates (PHY rate), or a revised throughput estimation for a given PHY rate based on changes in the throughput indicia 302. Output from the channel throughput estimation 300 process is provided to encoder bit rate adjustment 304 functionality for use in adaptively altering one or more encoding parameters (e.g., bit rate) of the encoder 204.
Throughput indicia 302 may include status information relating to one or more of channel bandwidth/GI 314, acknowledgment policy parameters 316, packetizer parameters 318, channel load 320, gain estimate 322 from, for example, a multi-variable common filter, etc. Although useful estimation is possible by utilizing a relatively small set of inputs such as those listed above, use of a larger number of inputs may generally increase precision of the model.
While the illustrated throughput indicia 302 are generally available from network interface 206 itself, channel estimation according to certain embodiments may also utilize various receiver information/feedback 330. For example, raw bit error rate information or other short term feedback from a receiving device(s) (such as video device 110 or mobile video device 112) could be used in the channel throughput estimation 300 process. Information from the receiving device can be communicated, for example, in periodic action frames or through other frame types/subtypes.
In the illustrated embodiment of
Encoder bit rate adjustment 304 in accordance with the illustrated embodiment may utilize one or more estimated throughput table(s) 306 generated by the channel throughput estimation 300 process. An exemplary estimated throughput table 306 (Table 1) is shown below. In this embodiment, estimated target throughput rates (Tr) are calculated for a variety of modulation and coding schemes (MCSs) supported by the wireless access device 106. Supported MCSs may comprise all or a subset of MCSs specified by a given communication standard (e.g., IEEE 802.11n). The value of an estimated Tr corresponding to a particular MCS generally reflects an estimated upper limit for the throughput rate of the wireless channel 226, with a possible reduction(s) for desensitization purposes, and is generally less than the relevant associated maximum PHY rate. Tr values may be influenced by a number of throughput indicia 302, including but not limited to channel bandwidth, ACK policy, aggregation parameters, channel load (possibly including channel load measured by an associated BSS), etc.
In the embodiment of
Referring now to
Following detection of a new or pending PHY data rate (Pr)/MCS selection for the wireless channel in step 502 (e.g., in accordance with a standardized communication protocol or separate PHY data rate selection process), the method continues in step 504 and an estimated target encoder rate Tr is identified for the subject Pr value. Note that step 502 may be omitted following an initial determination of Tr values. As shown in step 506, the method next compares the identified Tr value to the current encoder bit rate (Er) (calculated in Mbps in the illustrated embodiment).
If the current encoder bit rate Er is greater than the Tr value, the encoder bit rate is reduced in step 508, thereby effectively increasing the compression ratio of the video stream in order to improve utilization of the anticipated throughput of the wireless channel. Reduction of encoder bit rate may occur in one or more adjustments, including incremental or stepwise adjustments.
If the current encoder bit rate Er is not greater than the Tr value as determined in step 506, the encoder bit rate is left unchanged or, alternatively, increased as shown in step 510. An increase in encoder bit rate to better approximate the Tr value will effectively decrease the compression ratio of the video stream, ordinarily resulting in improved utilization of any excess available throughput in the wireless channel.
Increases in encoder bit rate may occur in one or more adjustments, including incremental or stepwise adjustments. Anticipation of channel deterioration and/or prospective PHY rates in accordance with the invention may be advantageously employed, for example, to modify an encoder bit rate prior to an actual change in PHY data rate, thereby potentially avoiding excessive buffering of video data.
In one embodiment according to the present invention, the estimated throughput table 306 or equivalent is computed dynamically as shown generally by step 512. In step 512, which may occur at other points in the illustrated method, estimated target encoder rates are refreshed following a change in one or more throughput indicia 302 as described above in conjunction with
In addition to or in lieu of encoder bit rate parameters, estimated channel throughput information may be used to adjust other video encoding parameters, such frame rate or use of different frame types. For example, the use of intra-frame prediction in the video coding process might be restricted for estimated channel throughputs or expected PHY data rates below a certain threshold. For such estimated channel throughputs or PHY data rates, the video encoder could be instructed to make greater use of inter-frame prediction in order to improve channel utilization. Additional such embodiments are described below in conjunction with
Referring now to step 602, the MAC transmit data queue is monitored for purposes of generating/maintaining an indication of the average transmit queue latency for a portion of the video stream. An exemplary embodiment of step 602 is illustrated in
If the average transmit queue latency exceeds the predetermined threshold as determined in step 604, the encoding bit rate (or related encoding parameter) is adjusted in step 606. For example, the encoding bit rate may be lowered or raised as necessary to decrease or increase the transmit queue depth to a desired level. If the average transmit queue latency does not exceed the predetermined threshold as determined in step 604, or following step 606, the method returns to step 602 for continued monitoring of the transmit data queue.
In one embodiment of the method, prior indication(s) of average transmit queue latency are optionally flushed in step 608 if the encoding bit rate of the video stream is adjusted, including in step 606. It is contemplated that step 608 may also be triggered, for example, by changes in transmitter side channel throughput indicia and/or feedback from a device receiving the video stream.
If the average transmit queue latency value is less than the predetermined maximum tolerated delay threshold, no resultant adjustments are made to the encoder bit rate (Er) as shown in step 708. If the average transmit queue latency value is found to exceed the predetermined maximum tolerated delay threshold, the method continues by calculating (or retrieving, in the case of predetermined Er data) a new encoder bit rate (Er′) that is likely to result in reduced transmit queue latency. Subsequently, in step 706, the encoder bit rate for the video stream is adjusted to match the new encoder bit rate Er′, effectively lowering the bit rate of the video stream for purposes of reducing the average transmit queue latency.
If the average transmit queue latency value is greater than the predetermined minimum tolerated delay threshold, no resultant adjustments are made to the encoder bit rate (Er) as shown in step 808. If the average transmit queue latency value is found to be less than the predetermined minimum tolerated delay threshold, the method continues by calculating (or retrieving, in the case of predetermined Er data) a new encoder bit rate (Er′) that is likely to result in increased transmit queue latency. Subsequently, in step 806, the encoder bit rate for the video stream is adjusted to match the new encoder bit rate Er′, effectively increasing the bit rate of the encoded video, improving the typical quality of the video stream, and increasing the average transmit queue latency in order to more fully utilize the bandwidth of the associated wireless channel.
The value of Er′ in the methods of
Referring first to step 900, individual or aggregated video packets in an encoded video stream are marked with an indication of the time at which the respective packets are generated or submitted for transmission over a wireless channel. In one embodiment, for example, MAC protocol data units (MPDUs) or the like are marked with an additional field in the transmit descriptor portion of the header in order track frame submission time. The frame submission time is utilized to calculate the delay between the frame submission and completion/acknowledgement of transmission (including, for example, inter-frame-spacing, any retransmission time, B/ACK duration, and protection duration).
Video packets, including marked video packets, are next transmitted over a wireless channel for receipt by a video device in step 902. Next, the method resumes in step 904, and transmission delays for the marked video packets are calculated by comparing frame submission times and associated transmission acknowledgement indications. The calculated transmission delays are subsequently used in step 906 to generate and/or maintain average transmit queue latency information relating to one or more video streams. A delay value may be automatically assigned for packets which are not successfully delivered (e.g., no acknowledgement is received prior to packet expiration or following a maximum number of retransmission attempts). The delay value may correspond, for example, to an associated media frame duration.
In addition to adaptive encoder rate adjustment and the alternate embodiments of the invention described above (e.g., alteration of frame rate or the use/frequency of predictive frames), it is contemplated that channel throughput estimation according to the present invention may be used for additional or alternate purposes. By way of example, channel throughput estimation according to the invention may be utilized to govern or modify wireless quality of service (QoS) parameters, employment of CDMA or other coding overhead, schedule changes to decoder configuration (e.g., following a change in encoder bit rate or use of predictive frames), restrict the use of inter/intra-frame prediction in the video coding process, adaptively alter display mode configurations, etc.
Referring now to
If time permits, scheduling transition of a video stream may involve an evaluation of various available delivery approaches and configurations such as those described below. Alternatively, transitions may be scheduled immediately, and may involve identification of previously transmitted video packets that should be discarded (assuming the relevant decoder is not capable of making such determinations).
Referring more specifically to step 1002, the transmitting device (possibly in conjunction with a recipient device) determines a suitable time or position in the pertinent video stream for scheduling a transition. As illustrated in blocks 1004 and 1006, such scheduling may involve an examination of a recipient device buffer and/or be based, at least in part, on the rate of channel deterioration/improvement.
Scheduled transitioning of a video stream to address changes in operating conditions may be accomplished by a variety of methods or combination of methods, such as those illustrated by blocks 1008, 1010, 1012 and 1014. In the exemplary embodiment of block 1008, transitioning of a video stream involves selectively transmitting or forcing intra-frames/streams to a recipient device in an attempt to improve the decoding process when, for example, a temporary disruption(s) in the video stream may result from alteration in the encoding process, transmission parameters, etc. It is noted that switching between intra-prediction and inter-prediction may be performed generally in accordance with a step function. In other embodiments, switching between these respective operational modes may be performed incrementally through a series of step-wise, gradual changes in order to achieve a desired level of the smoothness in the transition. Various exemplary approaches for switching between operational modes are described in certain of the documents incorporated by reference herein.
In other embodiments, decoding functionality of a recipient device may be instructed to propagate the last received intra-frame until the next intra-frame is received, or commence other available error concealment actions. Alternatively, or in combination, the transmitting device may retransmit a select portion(s) of the video stream. In such an embodiment, decoding functionality of the recipient device may further preferentially drop certain received portions of the video stream (e.g., in order to mitigate possible propagation of decoding errors that might otherwise occur during a transition) or undertake other available error concealment actions.
As shown in block 1010, scheduled transitioning of a video stream may comprise alterations to the characteristics and/or contents of a transmit queue of the transmitting device. For example, transmission of queued video packets may be temporarily suspended. Alternatively, certain video packets (such as those corresponding to intra-frames) may be identified for retransmission, possibly in lieu of other video packets in the transmission queue.
In the embodiment of block 1012, transitioning of a video stream may involve re-encoding or transcoding video packets for transmission during the transition period. By way of example, select motion compensation information in the encoded video stream may be re-encoded or transcoded to compensate for packets that might be lost, dropped or delayed.
In yet another embodiment, illustrated by block 1014, the transition process may involve transmission of a separate video stream that is related to the source video for the incumbent or default video stream. This separate video stream may comprise, for example, relevant portions of the source video that are encoded at a higher or lower resolution than the incumbent video stream.
It is noted that the various modules and/or circuitries (e.g., encoding modules and/or circuitries, decoding modules and/or circuitries, encoder rate adaptation modules and/or circuitries, etc.) described herein may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The operational instructions may be stored in a memory. The memory may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory (ROM), random access memory (RAM), volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. It is also noted that when the processing module implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory storing the corresponding operational instructions may be embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. In such an embodiment, a memory stores, and a processing module coupled thereto executes, operational instructions corresponding to at least some of the steps and/or functions illustrated and/or described herein.
It is also noted that any of the connections or couplings between the various modules, circuits, functional blocks, components, devices, etc. within any of the various diagrams or as described herein may be differently implemented in different embodiments. For example, in one embodiment, such connections or couplings may be direct connections or direct couplings there between. In another embodiment, such connections or couplings may be indirect connections or indirect couplings there between (e.g., with one or more intervening components there between). Of course, certain other embodiments may have some combinations of such connections or couplings therein such that some of the connections or couplings are direct, while others are indirect. Different implementations may be employed for effectuating communicative coupling between modules, circuits, functional blocks, components, devices, etc. without departing from the scope and spirit of the invention.
Various aspects of the present invention have also been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claimed invention.
Various aspects of the present invention have been described above with the aid of functional building blocks illustrating the performance of certain significant functions. The boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claimed invention.
One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof.
Moreover, although described in detail for purposes of clarity and understanding by way of the aforementioned embodiments, various aspects of the present invention are not limited to such embodiments. It will be obvious to one of average skill in the art that various changes and modifications may be practiced within the spirit and scope of the invention, as limited only by the scope of the appended claims.
The present U.S. Utility patent application claims priority pursuant to 35 U.S.C. §119(e) to the following U.S. Provisional Patent Application which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility patent application for all purposes: 1. U.S. Provisional Patent Application Ser. No. 61/491,838, entitled “Media communications and signaling within wireless communication systems,” (Attorney Docket No. BP22744), filed May 31, 2011, pending.
Number | Date | Country | |
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61491838 | May 2011 | US |