B. Girod, N. Frber, "Feedback-Based Error Control for Mobile Video Transmission," Proceedings of the IEEE, Special Issue on Video for Mobile Multi-media, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....and distinguishes this scheme from our previous work in the area of radio transmission over ad hoc networks [4] which used multiple description coding with no feedback. Feedback based video coding techniques include error tracking, error confinement and reference picture selection (RPS) [5]. The RPS technique encodes the current video frame with reference to a previous frame selected based on the feedback information instead of always using the last transmitted frame. It can stop error propagation without incurring excess loss of coding efficiency, and has been included in the ....

B. Girod and N. Frber, " Feedback-based error control for mobile video transmission," Proc. IEEE, vol 87, pp. 17071723, Oct. 1999.

....action (i.e. error concealment) is performed at the decoder, attempting to gure out the best alternative for the lost portion. Usually, no normative error concealment method is de ned for most MCP video compression standard. Various forms of error concealmentschemes have been proposed [9] [10]. The temporal concealmentscheme exploits the temporal correlation in video signals by replacing a damaged MB with the spatially corresponding MB in the previous frame. This straightforward scheme, however, can produce adverse visual artifacts in the presence of large motion, and the ....

....and where # # and # # are, respectively, the loop lter strength and a parameter that characterize the PSD shape of an error signal. The parameter #[#] in above is called ##### ######## ###### after t time steps. This analytical model as given in (3) has been veri ed by experimental results [5, 10]. While the statistical propagation behavior of an error can be analyzed with this model, it is dicult to estimate the loss e ect for a packet composed of several MBs (i.e. the GOB unit) in general. Thus, in the next section, we extend the propagation behavior analysis by incorporating additional ....

B. Girod, \Feedback-based error control for mobile video transmission," Proceedings of the IEEE ,vol. 87, no. 10, Oct. 1999.

....Services related to video transmission over wireless channels are expected to grow exponentially in the near future. In section 1.1, we summarize the current state of applications. Problem of video transmission over wireless channels has been addressed in literature [1] 2] 3] 4] 5] [6], 7] In this paper, we will present a review of these techniques. However, we will mainly focus on different characteristics of wireless channels and their implications on video transmission framework. Therefore, before discussing specific tools in section 4, we first present the characteristics ....

Bernd Girod and Niko Farher, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE, vol. 87, no. t0, pp. 17071722, October 1999.

.... error propagation based on feedback [4] 5] When the encoder learns through the feedback channel that a previous frame is lost, instead of using the most recent frame as a reference, it can code the next P frame based on an older frame that is known to be correctly received at the decoder [6], 7] The multiframe prediction support in Annex N was later subsumed by the more advanced Annex U of H.263 and is now an integral part of the emerging H.26L standard [2] In our work [3] we extend the RPS concept by allowing the use of a reference frame whose reception status is uncertain but ....

B.GirodandN.Farber, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE, vol. 87, no. 10, pp. 1707 -- 1723, Oct. 1999.

....on MB basis a combination with the optimized MB mode selection and reference frame selection according to Section 4.1 is appropriate. A simple yet powerful approach suitable for video codecs using just one reference frame such as MPEG 2, H.261 or H. 263 version 1 has been introduced in [58] and [59] under the acronym Error Tracking. When receiving a NACK on parts of frame n d or the entire frame n d, the encoder attempts to track the error to obtain an estimate of the quality of frame n 1, which serves as reference for frame n. Hav ing tracked the error, the encoder can perform one ....

....frames n d, n d q 1, n 1 such that the reference frames in encoder and decoder match. Whereas a) and b) are rather straightforward in implementation and can be used in combination, c) is more difficult as encoder and decoder have to apply the identical error concealment, see e.g. 58] [59], 60] and [61] Note that with this concept error propagation in frame n is only removed if frames n d q 1, n 1 have been received at the decoder without any error. We will discuss these issues in further detail when adapting the presented methods to JVT coding. A technique addressing ....

B. Girod and N. Fzirber, "Feedback-Based Error Control for Mobile Video Transmission," Proceedings of IEEE, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.

....to terminate error propagation based on feedback. With RPS (proposed in Annex N of H. 263 [7] when the encoder detects that a previous frame is lost, instead of using the most recent frame as a reference, it can code the next P frame based on an older frame that is known to be correctly received [8]. The scheme in [6] employs the RPS NACK mode [8] by always choosing the last frame that is believed to be transmitted reliably as the reference frame. When the transmission channels are in good state, prediction is made using the most recent frame as a reference. Although the coding efficiency ....

....With RPS (proposed in Annex N of H. 263 [7] when the encoder detects that a previous frame is lost, instead of using the most recent frame as a reference, it can code the next P frame based on an older frame that is known to be correctly received [8] The scheme in [6] employs the RPS NACK mode [8] by always choosing the last frame that is believed to be transmitted reliably as the reference frame. When the transmission channels are in good state, prediction is made using the most recent frame as a reference. Although the coding efficiency is higher than VRC, error resilience is limited ....

B.GirodandN.Farber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol. 87, no. 10, pp. 1707 -- 1723, Oct. 1999.

....since encoder and decoder predict from different reference frames in the motion compensation process. Therefore, a feedback from the decoder to the encoder is introduced. Exploiting feedback in wireless video communication systems based on standard video codecs has recently been studied in [1]. In this work, we present error protection and feedback strategies for wireless progressive video transmission. The remainder of this contribution is organized as follows: In Section 2 we introduce the system components of the wireless transmission system and give a general overview. Section 3 ....

B. Girod and N. Farber, "Feedback-based Error Control for Mobile Video Transmission," Proc. IEEE, vol. 97, pp. 1707-- 1723, October 1999.

....the decoder notifying the encoder to (1) reinitialize the prediction loop, or (2) which frames were correctly erroneously received and therefore which frame should be used as the reference for the next prediction (NewPred in MPEG 4 Version 2 and Reference Picture Selection (RPS) in H. 263 Version 2 [2, 3]) NewPred RPS can be very valuable in the case of a point to point link which also has a reliable back channel and sufficiently short round trip delay; otherwise the visual degradation can be quite significant [2] Layered or scalable approaches essentially prioritize data and thereby support ....

B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE, pp. 1707--1723, October 1999.

.... insert bits to make the bit stream more resilient to potential errors [2, 4] ii) error concealment at the decoder, which recovers or conceals lost information [3, 5] and (iii) interactive error control, which assumes a backchannel and allows the decoder to communicate losses to the encoder [6, 7]. In all of the above methods, the spatial error propagation is assumed along one direction and can be localized by inserting a resynchronization block. However, in MPEG 4, Intra DC AC prediction has been adopted to increase the coding efficiency. This method allows the DC AC coefficients of the ....

B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol.87, pp.1707-1723, Oct 1999.

....action (i.e. error concealment) is performed at the decoder, attempting to figure out the best alternative for the lost portion. Usually, no normative error concealment method is defined for most MCP video compression standard. Various forms of error concealment schemes have been proposed [7][8]. The temporal concealment scheme exploits the temporal correlation in video signals by replacing a damaged MB with the spatially corresponding MB in the previous frame. This straightforward scheme, however, can produce adverse visual artifacts in the presence of large motion, and the ....

.... = 3) where ### # ## # # # is a parameter describing the efficiency of the loop filter to reduce the introduced error, and [#] is the power transfer factor after # time steps. This analytical model as given in Eqs. 1) 3) has been verified in experimental results [3][8]. While the statistical propagation behavior is analyzed with this model, it is difficult to estimate the loss effect for each packet composed of several MBs, i.e. the GOB unit, in general. Thus, in the following section, we are extending its propagation behavior by incorporating additional ....

B. Girod, Feedback-based error control for mobile video transmission, #######################, vol. 87, no. 10, Oct. 1999.

....transmission aspects, in particular, the design of an intelligent multimode videophone transceiver. IV. SYSTEM DESIGN ASPECTS OF VIDEO TRANSCEIVERS A. State of the Art The state of the art in this field has been portrayed, e.g. in the special issue [111] based on the invited contributions of [112] [118] Specifically, Girod and Frber [112] have been influencing the wireless video communications community and the research trends in the field for years, and in their contribution to this issue, they considered feedback based video transmission arrangements. In an effort to reduce the ....

....of an intelligent multimode videophone transceiver. IV. SYSTEM DESIGN ASPECTS OF VIDEO TRANSCEIVERS A. State of the Art The state of the art in this field has been portrayed, e.g. in the special issue [111] based on the invited contributions of [112] 118] Specifically, Girod and Frber [112] have been influencing the wireless video communications community and the research trends in the field for years, and in their contribution to this issue, they considered feedback based video transmission arrangements. In an effort to reduce the sensitivity of the system to transmission errors, ....

B. Girod and N. Frber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol. 87, pp. 1707--1723, Oct. 1999.

....reduction in coding efficiency. Here, we describe some techniques that adjust the encoder operations based on the feedback information from the decoder. These approaches can reduce the coding gain loss, at increased complexity. A more extensive review of techniques in this category can be found in [ 43 ]. 20 C.1. Reference Picture Selection (RPS) based on Feedback Information One way of taking advantage of an available feedback channel is to employ RPS. If the encoder learns through a feedback channel about damaged parts of a previously coded frame, it can decide to code the next P frame not ....

....is more complicated. In either approach, the decoder will recover from errors completely at frame n d . Option (a) is the simplest to implement, but may suffer higher coding gain loss than the other two options. More information on error tracking, correction and fast algorithms can be found in [ 44 , 45 , 43 , 1 ]. Experimental results have shown that option (a) is less efficient than the RPS approach [ 46 ] 21 III. Error Resilience Tools in ITU T H.263 A. Introduction As is the case for all current video coding standards, the ITU T Recommendation H.263 entitled Video coding for low bitrates [ ....

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B. Girod and N. Frber: "Feedback-based error control for mobile video transmission", Proc. IEEE, Special Issue on Video for Mobile Multimedia, vol. 87, pp. 1707-1723, Oct. 1999.

....In particular, completely INTRA coded key frames are not usually inserted in real time encoded video as is done for storage or broadcast applications. Instead, only single MBs are encoded in INTRA mode for image regions that cannot be predicted eciently. The Error Tracking approach [4] 5] [6], 7] utilizes the INTRA mode to stop inter frame error propagation but limits its use to severely impaired image regions only. During error free transmission, the more e ective INTER mode is utilized, and the system therefore adapts to varying channel conditions. Note that this approach requires ....

B. Girod and N. Farber, \Feedback-Based Error Control for Mobile Video Transmission", Proceedings of the IEEE, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.

.... error propagation based on feedback [1] 2] When the encoder learns through the feedback channel that a previous frame is lost, instead of using the most recent frame as a reference, it can code the next P frame based on an older frame that is known to be correctly received at the decoder [3], 4] The multiframe prediction support in Annex N was later subsumed by the more advanced Annex U of H.263 and is now an integral part of the emerging H.26L standard [5] In this work, we extend the RPS concept by allowing the use of a reference frame whose reception status is uncertain but ....

B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE, vol. 87, no. 10, pp. 1707 -- 1723, Oct. 1999.

No context found.

B. Girod and N. Frber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol. 97, pp. 1707--1723, Oct. 1999.

....of the test sequence Mother Daughter over channels with different average burst lengths L for symbol error rates P = 1 ; 5 , and 10 . such that . We are mainly interested in the variance of the propagated error signal and in its average over time. The analysis is an extension of previous work [38], 39] that first appeared in [21] We assume that a separable loop filter is applied to the reconstructed frames after each time step. This loop filter shall describe the overall effect of various spatial filter operations that are performed during encoding. Spatial filtering can either be ....

B. Girod and N. Frber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol. 87, pp. 1703--1723, Oct. 1999.

....with concealment leads to temporal error propagation which causes deviating reference frames at encoder and decoder. A popular technique to stop temporal error propagation is to encode macroblocks in INTRA mode. To invoke INTRA coding appropriately, the Error Tracking approach has been presented [2, 3], where the propagated error is tracked upon receipt of a feedback sent from decoder to encoder. Adaptive INTRA coding based on concealment distortion measures and transmission error characteristics has also been proposed for cases when no feedback is available [4, 5] Another method to stop ....

B. Girod and N. Farber, \Feedback-Based Error Control for Mobile Video Transmission", Proc. IEEE, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.

....that the residual error u[x; y] is introduced at t = 0 (after resynchronization and error concealment) such that v[x; y; 0] u[x; y] We are mainly interested in the variance 2 v [t] of the propagated error signal and in its average over time. The analysis is an extension of previous work [38, 39] that rst appeared in [21] We assume that a separable loop lter is applied to the reconstructed frames after each time step. This loop lter shall describe the overall e ect of various spatial lter operations that are performed during encoding. Spatial ltering can either be introduced by an ....

B. Girod and N. Farber, \Feedback-based error control for mobile video transmission", Proc. of the IEEE, vol. 87, no. 10, pp. 1703-1723, Oct. 1999.

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B. Girod, N. Frber, "Feedback-Based Error Control for Mobile Video Transmission," Proceedings of the IEEE, Special Issue on Video for Mobile Multi-media, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.

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B. Girod, and N. Frber, "Feedback-Based Error Control for Mobile Video Transmission," Proceedings of IEEE, vol. 97, no. 10, pp. 1707-1723, Oct. 1999.

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B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE, pp. 1707--1723, October 1999.

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B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," in Proccedings of the IEEE, pp. 1707 -- 1723, 1999.

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B. Girod and N. Frber, "Feedback-based error control for mobile video transmission," Proc. IEEE, vol. 97, pp. 1707--1723, Oct. 1999.

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B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proc. IEEE,vol.87, no. 10, pp. 1707--1723, Oct. 1999.

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B. Girod and N. Farber, "Feedback-based error control for mobile video transmission," Proceedings of the IEEE , pp. 1707--1723, October 1999.

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