Delgrossi, L., Halstrick, C., Hehmann, D., Guido, R., Krone, O., Sandvoss, J., Vogt, C.: Media scaling in a multimedia communication system Multimedia Systems vol2 p172-180 (Springer-Verlag, 1994)  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Table 6: Dynamic QoS Management Functions 45 Adaptationby media scaling requires multiple versions of the source to be stored, and a system where swapping between versions during presentation, while maintaining position in the record, is required. Various scaling techniques are examined in [DELGROSSI 94, FRY 97] In general, tasks such as changing resolution of an MPEG video stream in real time is computationally expensive. SISALEM 97] describes the use of an algorithm for adapting multimedia flows in a multicast application in response to monitored network conditions. LI 98] gives an example ....

....in Mobile Environments A2.4.2.1 ADAPTIVITY AND MEASURED CHANGE As stated above, one of the key concepts in applying QoS to mobile environments is that of change, and adaptation to change. These changes manifest themselves in various ways, we describe three classes below, although others such as [DELGROSSI 94] approach this issue with regard to transparent and non transparent scaling of media: Large grained change . Fine grained change . Hideable change Large grained change is characterised as changes due to types of end system, or network connection in use. Typically these will vary ....

Delgrossi, L., Halstrick, C., Hehmann, D., Guido, R., Krone, O., Sandvoss, J., Vogt, C.: Media scaling in a multimedia communication system Multimedia Systems vol2 p172-180 (Springer-Verlag, 1994)

....e.g. a high quality video stream can not be used because it requires more than the available bandwidth. This brings out the need for adapting a media collection to fit into the available resources. Traditionally, this has been done for media elements by defining scalable codecs (e.g. MPEG 2 etc. [2]) or media transcoding (e.g. in [1] We extend this notion of scalability to media elements. Our approach is based on a layered media element model that defines scalability through the concept of layering. The concept is inspired by the layered (or progressive) encoding techniques of digital ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. Herrtwich, O. Krone, J. Sandvoss, and C. Vogt. Media Scaling in a Multimedia Communication System. ACM Multimedia Systems Journal, 2:172-- 180, 1994.

....QoSA agents interrogate ACs: if the available resources are not enough for the required QoS, QoSAs can coordinate and reduce their resource requirements by scaling the stream. In particular, they are capable of dropping frames in Motion JPEG streams and of reducing image resolution in MPEG 2 ones [3, 13]. At the moment, we are testing our adaptation infrastructure within the framework of the MOSAICO project, by using DiVA (http: grid.grid.unina.it projects diva ) as the service provider and the video client. Finally, we are also working on the implementation of hard QoS in SOMA. We are ....

Delgrossi, L., et al. Media Scaling in a Multimedia Communication System. ACM Multimedia Systems, Vol. 2, 1994.

....with associated QOS. For 68 CAMPBELL multicast flows, individual receivers (both wired and wireless) may have differing capability to consume flows [20] This could be due to either fluctuating network resources with mobility or imposed by individual applications. Bridging this heterogeneity gap [9] in mobile multicast environments [6] while simultaneously meeting the individual mobile devices QOS requirements is an area of research that remains to be resolved. Third, radio channel s varying QOS characteristics and device mobility, fundamentally impact our ability to deliver hard QOS ....

....guarantees to enhancement layers (viz. E1 and E2) of multimedia flows based on the availability of resources in the wireless environment; and . adaptive and active transport, supports the transfer of multilayer flows through the provision of a QOS based API and a set ATOs (e.g. media scaling [9]) and static transport objects (STOs) e.g. playout control. STOs are statically configured and execute at mobile and fixed devices only. In contrast, ATOs are dynamically dispatched to the mobile devices, base stations or ATM switches to support valued added QOS at strategic nodes. Media scaling ....

Delgrossi et al., "Media scaling in a multimedia communications system," ACM Multimedia Systems Journal, Vol. 2, No. 4, 1994.

....function. 19, 37] Adaptation The applications adapts to changes in the Application dependent adaptation may be needed after QoS of the system, possibly after renegotiation or if the Qos management functions fail to renegotiation. maintain the specified QoS. Often achieved by media scaling [27, 38, 39]. Synchronization Combining two or more streams with This involves representing each stream in a format where temporal QoS constraints between them, temporal information is stored with the data, allowing cross e.g. synchronization of speech and referencing between the streams. video streams. ....

....Movement on QoS, one of the key concepts in managing QoS for mobile environments is adaptation to changes in QoS. In the following we discuss three classes of change which have to be catered for, although others approach this issue with regard to transparent and non transparent scaling of media [38]. Large grained change is characterized as changes due to types of endsystem, or network connection in use. Typically these will vary infrequently, often only between sessions, and thus are managed largely at the initialization of interaction with applications, possibly by means of context ....

Delgrossi, L., Halstrick, C., Hehmann, D., Guido, R., Krone, O., Sandvoss, J., Vogt, C., Media scaling in a multimedia communication system Multimedia Systems vol2 pp. 172--180 (Springer-Verlag, 1994.

....specified QoS. Often achieved by media scaling. Adaptation by media scaling requires multiple versions of the source to be stored, and a system where swapping between versions during presentation, while maintaining position in the record, is required. Various scaling techniques are examined in [DELGROSSI 94, FRY 97] In general, tasks such as changing resolution of an MPEG video stream in real time is computationally expensive. SISALEM 97] describes the use of an algorithm for adapting multimedia flows in a multicast application in response to monitored network conditions. LI 98] gives an example ....

....in Mobile Environments 4.2.1 Adaptivity and Measured Change As stated above, one of the key concepts in applying QoS to mobile environments is that of change, and adaptation to change. These changes manifest themselves in various ways, we describe three classes below, although others such as [DELGROSSI 94] approach this issue with regard to transparent and non transparent scaling of media: Large grained change . Fine grained change . Hideable change Large grained change is characterised as changes due to types of end system, or network connection in use. Typically these will vary ....

Delgrossi, L., Halstrick, C., Hehmann, D., Guido, R., Krone, O., Sandvoss, J., Vogt, C.: Media scaling in a multimedia communication system Multimedia Systems vol2 p172-180 (SpringerVerlag, 1994)

....and the rate adaptation is achieved by adjusting certain encoding parameters, e.g. the quantization level, the frame rate or the pixel resolution. The adjustment of the video data rate through adjustment of compression parameters is sometime called media scaling. The paper by Delgrossi et al. [19], reporting on video multicast within the Heidelberg Transport System HeiTS, is perhaps one of the first instances of the use of media scaling in the context of multicast video transmission. The paper contains a good description of the different scaling options. Similar feedback control schemes ....

....finding maximum bandwidth available to the destinations, developed schemes to optimally assign bandwidth to the layers to maximize overall reception quality, and proposed error control procedures. This work has the assumption of admission control and resource reservation. The HeiTS media scaling [19] schemes include discrete scaling for multicast. The scheme is built on the same philosophy that receivers should receive a certain level of the multimedia layers commensurate to their bandwidth constraint. The rate control is receiver initiated and each receiver opens or closes ST II multicast ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. G. Herrtwich, O. Krone, J. Sandvoss, and C. Vogt, "Media scaling in a multimedia communication system," ACM Multimedia Systems, vol. 2, pp. 172--180, 1994.

....active control and transmitter active control. When the data source, i.e. the transmitter of the data, dynamically adapts the required performance profile considering the actual performance capacity of the system, the underlying scheme is called a transmitter controlled scheme 12 , e.g. [13, 26]. In contrast to that, if the adaptation is controlled by the receiver of the data, the underlying scheme is called a receiver controlled scheme, e.g. 20] Some concrete solutions involve feedback messages issued by the receiver 10 In more concrete terms, precision with respect to presentation ....

Delgrossi, L., et al.: "Media Scaling in a Multimedia Communication System ", Proc. of the First ACM Multimedia Conference, Anaheim, Ca., USA, August, 1993, pp. 99--104

....into a hierarchy of information layers, as is for instance possible with MPEG 2. Then two approaches can be followed for the hierarchical coding. In the first approach, the application splits the data into streams and sends them independently. This has been described in various papers as in [DHHH94], where ST 2 is additionally used to reserve resources for the base layers, or as in [BTSW94] and [ChGu96] where a similar approach using an IP multicast group for each layer has been taken. A refinement of this is the use of error detection within the receiver driven layered multicast approach ....

L.Delgrossi, C.Halstrick, D.Hehmann, R.Herrtwich, O.Krone, J.Sandvoss, C.Vogt: "Media Scaling in a Multimedia Communication System", ACM Multimedia Systems Journal, Vol. 2, No. 4, 1994.

....a subset of the full information. The removal of data requires that the full stream has been encoded into a hierarchy of information layers, as is for instance possible with MPEG 2. Then the application can split the data into streams and sends them independently, as has been described, e.g. in [8] using one ST 2 stream and in [4] using one IP multicast group for each layer. A refinement is the use of error detection within the receiver driven layered multicast approach ( 10] where receivers start out to receive the base layer and add further enhancement layers until they have either ....

L.Delgrossi, C.Halstrick, D.Hehmann, R.Herrtwich, O.Krone, J.Sandvoss, C.Vogt: "Media Scaling in a Multimedia Communication System", ACM Multimedia Systems Journal, 1994.

....conditions; e.g. an audio stream can not be used because it requires more than the available bandwidth. This brings out the need for adapting a media collection to fit into the available resources. Traditionally, this has been done for media elements by defining scalable codecs (e.g. MPEG 2 etc. [8,9,13]) or media transcoding (e.g. in [7] We extend this notion of scalability to media collections. Our approach is based on a layered media element model that defines malleability through the concept of layering. The concept is inspired by the layered (or progressive) encoding techniques of digital ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. Herrtwich, O. Krone, J. Sandvoss and C. Vogt, "Media Scaling in a Multimedia Communication System", Multimedia Systems Journal, Springer-Verlag, 2, 1994.

....probability that the process will be denied the use of the resource at certain time. Hence, the assignment represents a tradeoff between the peak rate multiplexing (pessimistic approach) and the statistical multiplexing (optimistic approach) Resource reservation allocation tables and functions [8] are used to detect and solve resource conflicts: ffl Resource Table: A resource table contains information about the managed resources. This includes static information like the total resource capacity available, the maximum allowable message size, the scheduling algorithm used, dynamic ....

....Monitoring can add overhead during multimedia transmission, which should not cause violation of QoS guarantees. Hence, monitoring should be flexible, which means that (1) most of the monitoring variables should be optional; and (2) monitoring should be able to be turned on and off [8]. There are two possible modes to operate resource monitoring: end user mode and network mode. The former requests a status report about the resources; the later reports regularly the resource status on different nodes along the path between the communicating end users. It should be pointed out ....

[Article contains additional citation context not shown here]

L. Delgrossi, Ch. Halstrick, D. Hehmann, R. G. Herrtwich, O. Krone, J. Sandvoss, C. Vogt, "Media Scaling in a Multimedia Communication System", Multimedia Systems, Springer-Verlag, 1994, pp. 172-180

....can be kept to a minimum by sending the refinement signals via an available best effort channel. Many different types of hierarchical coding exists. Two popular methods partition the image data over the temporal and spatial domains, respectively. In a temporally hierarchically encoded transmission [2], a periodic subsequence of frames is sent over the reservation channel, and the remaining image frames are sent using best effort. In a typical scenario, the reservation channel carries I frames (a full refresh image frame) while the best effort channel carries predictive frames (motion and error ....

.... an available best effort channel (e.g. ABR UBR in ATM) This way, video images can be decoded and displayed in a timely fashion using only the essential data while the refinements are used to enhance the quality of the decoded image (if they are received in time) Temporal domain encoding schemes [2] periodically send I frames over the reserved channel, and send the remaining P frames over the best effort channel. In internet based video conferencing, one cannot transmit I frames frequently because of the lack of total available bandwidth. Because of the long time span between two consecutive ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. G. Herrtwich, O. Krone, J. Sandvoss, and C. Vogt. Media scaling in a multimedia communication system. Multimedia System, 2:172--180, 1994.

....or multicast) with associated QOS. For multicast flows, individual receivers (both wired and wireless) may have differing capability to consume flows [11] This could be due to either fluctuating network resources with mobility or imposed by individual applications. Bridging this heterogeneity gap [14] in mobile multicast environments [12] while simultaneously meeting the individual mobile devices QOS requirements is an area of research that remains to be resolved. Third, radio channel s varying QOS characteristics and device mobility, fundamentally impact our ability to deliver hard QOS ....

....QOS guarantees to enhancement layers (viz. E1 and E2) of multimedia flows based on the availability of resources in the wireless environment; and . adaptive and active transport, supports the transfer of multi layer flows through the provision of a QOS based API and a set ATOs (e.g. media scaling [14]) and static transport objects (STOs) e.g. playout control. STOs are statically configured and execute at mobile and fixed devices only. In contrast, ATOs are dynamically dispatched to the mobile devices, base stations or ATM switches to support valued added QOS at strategic nodes. Media ....

Delgrossi et al,"Media Scaling in a Multimedia Communications System", ACM Multimedia Systems Journal, Vol. 2., No. 4, 1994.

....decrease the number of wired pages of these segments since it is difficult to predict which pages will be accessed in future for processing media data. However, dynamic data segments may be decreased by reducing the quality of media by using media scaling techniques and dynamic QOS control schemes[5, 14, 15], and the size of a buffer in a dynamic data segment can be decreased. For example, decreasing the rate of a media stream or the size of respective video frames reduces the total amount of data that must be stored in the buffer in every period. Figure 4 illustrates how applications change the size ....

L.Delgrossi, C.Halstrick, D.Hehmann, R.Herrtwich, O.Krone, J.Sandvoss, and C.Vogt, "Media Scaling in a Multimedia Communication System", Multimedia Systems, Vol.2, No.4, Springer-Verlag, 1994.

....scalable multimedia scheduling. Scalable multimedia is a general framework of multimedia presentations consisting of multimedia objects with spatial and or temporal scalabilities, and is an effective way of handling receiver heterogeneity and limited or changing bandwidth situations [6]. In scalable multimedia, actual presentations are generated through presentation scheduling with the given constraints and scalabilities. Based on our results of optimal bandwidth delay tradeoff, we derive the exact feasibility condition for scalable multimedia presentation with a given bandwidth ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. Herrtwich, O. Krone, J. Sandvoss, and C. Vogt. Media Scaling in a Multimedia Communication System. Multimedia Systems Journal, SpringerVerlag, 2:172--180, 1994.

....at a regular rate to minimize the perceived degradation of quality and as early as possible in the pipeline to minimize handling costs [13] Frame dropping is one example of subsampling a data stream in time. Other examples include subsampling an audio stream and spatial subsampling of an image [18]. Another lossy optimization is the use of a less expensive and lower quality dithering algorithm. For example, an error diffusion dither generally yields the best image quality for pixel depth reductions, but a simple truncation of pixel values to the required depth is much faster [81] 2.2.5 ....

Delgrossi, L., Halstrick, C., Hehmann, D., Herrtwich, R. G., Krone, O., Sandvoss, J., and Vogt, C. Media scaling in a multimedia communication system. Multimedia Systems 2, 4 (October 1994), 172--180.

....16] at the expense of more complex network operation. Based on our experiments over the Mbone, we compare the bandwidth requirements of our proposed scheme with those of an idealized version of this approach. Finally, another approach for dealing with the unfairness problem has been proposed in [17]. Their method encodes temporally scaled media hierarchically and transmits streams on separate ST II connections [18] that can have differing service guarantees (i.e. priorities) The scheme relies on the stream group feature of ST II to synchronize message delivery from different connections ....

....Compression We used a constantly repeating subset of the tennis player video sequence that was available with the Berkeley MPEG 1 player distribution [24] We used the quantization scale factor 8 [19] as the only variable parameter for video compression. Although other possibilities exist (see [7, 17]) we found the quantization scale factor adequate for our purposes as it provides a simple way to control data rates and video quality. Ideally we would have liked the source to be equipped with a hardware MPEG encoder (with real time parameter change capabilities) for each stream. Lacking this ....

L. Delgrossi, C. Halstrick, D. Hehmann, R. G. Herrtwich, O. Krone, J. Sandvoss, and C. Vogt, "Media scaling in a multimedia communication system," Multimedia Systems, vol. 2, pp. 172--180, 1994.

No context found.

Luca Delgrossi, Christian Halstrick, Dietmar Hehmann, Ralf Guido Herrtwich, Oliver Krone, Jochen Sandvoss, and Carsten Vogt. Media scaling in a multimedia communication system. Multimedia Systems, 2:172--180, 1994.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC