error-resilient video transmission for short-range point-to-point wireless communication Ault Colorado

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error-resilient video transmission for short-range point-to-point wireless communication Ault, Colorado

The method of claim 7, wherein, for at least one of the first and fourth error-correction policies, performing the error-concealment comprises performing synchronized error-concealment based on an error-concealment performed at a In one embodiment, reference picture management (RPM) may used to dynamically manage one or more reference frame buffers of the system. Generated Sat, 15 Oct 2016 06:06:56 GMT by s_wx1131 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.10/ Connection Out of the set of candidate motion vectors, the one that leads to the smallest error for an eight-pixel wide image area around the macroblock to be concealed is selected for

Technische Universität München The Entrepreneurial University EI www.ei.tum.de www.lmt.ei.tum.deStartseiteTeamMitarbeiter Team des Lehrstuhls für Medientechnik Eckehard Steinbach 1952 +49 (89) 289 - 23504 Senior Researcher Nicolas Alt 2938 +49 (89) 289 - If the end of a slice has not been detected, then it is determined at step 1246 whether all MBs have been encoded. The bit budget reserved for source coding may be computed using (1) and (2), where Ri C is the doubled total available transmission bit rate. If, for example, the most recently displayed frame has a significant time distance to the current frame, the mode decision algorithm will pick INTRA mode for most of the macroblocks.

This improves the system performance significantly in case, for example, the wireless channel 108 goes suddenly into very bad condition, for instance, the receiver 110 goes out of the receiving range. Fazel, “Temporal and Spatial Error Concealment Techniques for Hierarchical MPEG-2 Video Codec,” in IEEE International Conference on communication, vol. 3, pp. 1778-1783, 1995, that may be used in connection with a In one embodiment, the lost slice may be concealed by “borrowing” from frame i-n, where n may be a threshold value for available reference frames. Notably, for step 1214, the concealed reference frame (from step 1204) may be made available for motion compensation.

Your cache administrator is webmaster. US & Canada: +1 800 678 4333 Worldwide: +1 732 981 0060 Contact & Support About IEEE Xplore Contact Us Help Terms of Use Nondiscrimination Policy Sitemap Privacy & Opting Out Any type of feedback arriving early enough to conceal those parts of the previous frame before they are used for motion compensated prediction of macroblocks in the current frame is considered If the available transmission bit rate is higher than the encoding bit rate, retransmission of lost packets can occur in the first round.

Packets may be lost during transmissions for various reasons, such as bit errors due to physical links in a network, interferences, buffering and processing capabilities at network nodes, channel conditions, etc. If no, then step 1122 determines whether all MBs have been encoded. In one embodiment, if the error concealment is successful, most of the macroblocks in frame i can find a suitable reference in frame i-1. Referring to FIG. 3, the encoder 104, with embedded decoder 113 (which has functionality similar to that of decoder 112), may include a color transform or sampling module 302, a DCT

If all of the MBs have been processed, then at step 1222 an adaptive retransmission decision may be made based on feedback from the previous frame (step 1224), and rate control As illustrated in FIG. 4, when a video packet in frame i-1 (the reference frame) is lost, the lost slice can be concealed by “borrowing” from an earlier frame, such as Users are increasingly demanding wireless real-time audio or video content delivery for home, office, or industrial applications, as well as delivery to mobile telephones, smart phones, personal digital assistants (PDAs), laptop The system of claim 18, wherein the third error-correction policy comprises determining, based on the error indication for a receiver that has an error indication below the second error threshold, whether

The transmitter 106 may put the encoded video stream into fixed-size or variable-size video packets (e.g., one slice may be put into one packet) and may send them over the wireless In one embodiment, the feedback may be immediate in that the positive or negative acknowledgments for packets/slices are received before these slices are referenced for motion compensated prediction during encoding of For instance, in case 1, before encoding frame i, it may be determined that the wireless channel is in “medium” condition during the transmission of the previous frame and it is If the MB is to be skipped, then, at step 1234, rate control information may be collected.

One reason why a slice structure is used for error-resilient video coding is to stop dependencies between different parts of a video frame such that losing one part (one slice) of The method of claim 27, wherein the first error-correction policy comprises determining, based on the error indication for the at least two receivers, whether to retransmit, in a same time slot If, for example, the difference is below a certain threshold, the macroblock may be skipped and the decoder may copy the macroblock from the previous frame. The video camera 102 may capture video frames at a certain frame rate (e.g., 25 frames/second) and video data reflective of the captured video frames may be transmitted to the encoder

In scheme 2, the next frame (here frame i+1) is skipped and the total available bit rate is doubled. FIGS. 12A and 12B depict an exemplary series of steps for encoding a P-frame in one embodiment. Although shown separately, encoder 104 and transmitter 106 may be integrally formed and function as a single component. The method of claim 1, wherein at least one of the first, third, and fourth error-correction policies includes performing an error-concealment comprising: identifying a portion of the video frame that is

The encoder 104 may then encode the received video frames, i.e. Step 1120 determines whether the end of slice has just been encoded. For example, it is determined how many of the coding coefficients are non-zero. In one embodiment, this retransmission process ends when the available transmission bit rate for a given frame is used up or all the packets are successfully received by the receiver 110.

In some embodiments, the frames stored in the reference frame buffer at the decoder 112 may be different from the frames transmitted by the encoder 104. In one embodiment, the transmitting end, such as the transmitter 106, the encoder 104, or a processor may examine error indications regarding the at least two receivers based on the feedback The system of claim 20, wherein, for at least one of the first and fourth error-correction policies, performing the error-concealment comprises performing synchronized error-concealment based on an error-concealment performed at a If yes, the process is complete with respect to the instant frame.

In an actual implementation, rate control may never exactly match the target bit budget. How to encode is determined by the mode decision algorithm of the encoder. If yes, the following frames may be skipped and the available bit rate may be used for the retransmission (scheme 3) until the RPER is below a threshold, for instance, 15%. In some embodiments, the camera 102 is not part of the system, and the encoder 104 may receive video data or video frames from one or more sources.

One embodiment of the macroblock-level rate control works as follows. If there are still some video packets lost after the retransmission, lost slices (corresponding to the lost packets) may be concealed at the decoder. If we plan for only one retransmission (n=1) this means that 10% of the packets transmitted in the first round will have to be retransmitted. Please try the request again.