METHOD AND SYSTEM FOR CONTROLLING A PROCESSING OF VIDEO DATA

Abstract: A method and system for controlling a processing of video data such that said video data may be transmitted over a connection in a communication network, where said connection employs a plurality of protocol layers. The processing of video data for transmission is performed at a first layer. A value or values of one or more transmission condition parameters indicative of transmission conditions in the network are acquired, where these transmission condition parameters are specific for a second layer provided lower than said first layer. Then one or more values of one or more video control parameters usable at said first layer are derived from said value of said at least one transmission condition parameter and the processing of video data is performed in accordance with the derived one or more values.

Description: METHOD AND SYSTEM FOR CONTROLLING A PROCESSING OF VIDEO DATA Field of the invention The present invention is directed towards a method, system and unit for controlling a processing of video data such that said video data may be transmitted over a connection in a communication network, where said connection employs a plurality of protocol layers. Background of the invention Video transmission or video streaming within communication networks, such as ISDN networks or the Internet has become an important application of such communications networks. In the future, packet oriented mobile networks like GPRS (General Packet Radio Service) and UMTS (Universal Mobile Telephone Standard) will be commonly used to connect mobile users to fixed communication networks like the above-mentioned ISDN networks or the Internet. It is therefore important to employ efficient and intelligent support of high quality video streaming into wireless radio networks. A radio channel is a critical resource since its bandwidth is limited. Furthermore, it is a highly unreliable data channel, which requires special techniques to obtain a desired quality-of-service. Additionally, packet switched wireless networks provide variable user data rates depending on the number of concurrently ongoing communications within the same cell. In order to support data applications (such as file transfer etc.), which require a reliable data link, a combination of forward error correction (FEC) and retransmission-based automatic repeat request (ARQ) is commonly used. Both of these concepts are well known in the art. Compared to reliable data transmission, video streaming has rather different requirements. Namely, video streaming is usually less sensitive against data losses, but very delay sensitive. Data transmissions have opposite characteristics, i.e. they are very sensitive to data loss, but not very sensitive to delay. In other words, in the case of video streaming, the loss of certain parts will lead to a certain deterioration of picture quality, which is usually tolerable to a certain degree, but a strong delay (as for example caused by packet retransmission) will require complicated buffering mechanisms and make real-time transmission impossible. Therefore, video streaming is typically conducted by adjusting appropriate parameters, such that the data rate of the video transmitter (for example a video coder) can be easily adapted to the available transmission bandwidth. For example, the input rate of video data into a coder can be controlled, the coding mode can be controlled, or the amount of overhead employed for error correction, such as forward error correction, can be controlled. Existing wireless transmission schemes in mobile networks neither address the special requirements of video streaming nor the advantages resulting from the ability to control the bit rate of a video data source in an appropriate and efficient way. Problem underlying the invention A number of mechanisms have been proposed for appropriately controlling a video source. One such suggestion is the use of receiver feedback information to control the data rate of a video transmitter, for example to avoid network congestion or to avoid high packet loss rate. This requires that the video receiver sends appropriate messages back to the video sender, where said messages indicate the conditions on the receiver side, for example the number of lost or damaged packets etc. Usually, operating a video transmitter at a low data rate, where only a small amount of packets are lost, gives a substantially better subjective picture quality than operating the transmitter at a high data rate where more packets are lost. This is true although the amount of correctly received packets is the same in both cases. Consequently, the sending control unit will typically reduce the data rate in response to message indicating increased packet loss. An example of such a receiver feedback or end-to-end feedback system is known from the article "Rate Control for Robust Video Transmission over Burst-Error Wireless Channels" by Chi-Yuan Hsu et al, IEEE Journal on Selected Areas in Communications, vol. 17, No. 5, May 1999. This article proposes a mechanism which uses feedback information from the receiver and a channel model that makes use of the feedback information for adjusting the transmission rate. However, sending end-to-end feedback information has several disadvantages, especially in a mobile or wireless network. Namely, feedback information can get lost or it reaches the sender with an unpredictable delay, the transmission of feedback information requires additional bandwidth, which is especially disadvantageous for radio channels, and the feedback information can only be based on the receiver's measurements and only implicitly reflects the network conditions. Misinterpretation of the measured performance is possible. Moreover, there exist certain types of transmission that do not allow an end-to-end feedback, such as multicasting or broadcasting. The article "Robust H.263 Video Communication Over Mobile Channels" by Guy Cote et al, 1999 IEEE International Conference on Image Processing (ISBN 0-7803-5470-2) , discusses a mechanism that does not require a feedback channel. The concept proposed in this article is based on the assumption that two things are known, namely the error concealment method employed by the decoder, and the error rates of the network. Then the probability of a block being in error is calculated on what is referred to as the "channel average bit error rate" which as already mentioned, is assumed to be known. It is stated that information about the bit error rates can be obtained from the network or can be assumed a priori. In other words, this document proposes a video transmission scheme that assumes that the video transmitter knows the average bit error rate of the network. This implies some form of network feedback, but gives no further indication of how this is to be accomplished. The two basic mechanisms of end-to-end feedback and network feedback are schematically shown in Fig. 6, where a control unit in a video transmitter controls the processing of video data for transmission over a network on the basis of such network feedback and receiver feedback. Object of the invention The object of the invention is to provide an improved method and system for controlling the processing of video data, such that the video data may be transmitted over a connection in a communication network with improved quality, especially in the case of transmitting over a radio link. Summary of the present invention This object is solved by the method of claim 1, the system of claim 15 and the unit of claim 30. Advantageous embodiments are described in the dependent claims. 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CQ £ Ti υ rH 4-J said radio link to the unit controller, who in turn derives video control parameters there from to be used for controlling the processing of the video data at the application layer. More generally, the processing of video data can be done not only in a mobile station, but also in a base station of a wireless communication network, in an interworking function between such a wireless communication network and a fixed network, in a terminal device in such a fixed network, or in a proxy server provided in either the wireless communication network or the fixed network. As already mentioned, the acquiring of transmission condition values can be performed in the same unit or in another unit as the video data processing. This provide a high amount of flexibility, especially in view of arranging the system architecture. For example, according to one preferred embodiment of the invention, the inventive concept is applied to the downloading of video data from a server in a given network, e.g. the Internet, to a mobile station (mobile telephone, portable computer, etc.). The transmission condition values are then acquired at the base station handling the radio link to the mobile station, and used by the server sending the video data or an intermediate proxy server, for controlling the transmission of video data. The term processing of video data is to be understood broadly as relating to any type of processing that prepares video data for transmission, such as coding or transcoding, forward error correction or packetization. In other words, the present invention does not only apply to coding, but e.g. also to the preparation for transmission of stored coded video data. The example of transcoding as a type of processing is especially advantageous in the embodiment where video data is to be downloaded from a server or via a proxy. Examples of transmission condition parameters whose values may be acquired are the current transmission delay, the bandwidth allocated for a specific user, the current or actual bit error rate, and the current frame erasure rate. Other examples that specifically relate to a link are the current or actual carrier to interference ratio and the current power-level. These are only examples and the present invention is not restricted thereto, as any type of transmission condition parameter may be employed. The present invention is preferably applied to the transmission of such video data that is present in scalable form, e.g. having a base stratum and at least one enhancement stratum, where the decision regarding the inclusion or exclusion of the enhancement stratum in the transmitted video data is performed on the basis of the derived values of video control parameters. This provides a simplified processing of the video data, which in turn means that hardware and software for applying the invention need not be complicated. The application of the present invention to the transmission of scalable video data is especially well combinable with the concept of downloading video data from a server or via a proxy server, because then the transcoding can be very simple. Namely, the server or proxy can then switch the enhancement stratum (or enhancement strata) on or off depending on the transmission conditions to the mobile station. This is very simple type of processing that does not require very much processing capacity. The present invention is also applicable to other forms of scalable video representations, e.g. where two or more independently coded bitstreams of different bit rate are present (for example one bitstream having a low bitrate and one having a high bitrate) that both relate to the same video information, such that one suitable bitstream can be selected in accordance with the transmission conditions . This again provides the advantage of very simple processing, and has the additional advantage that the required decoders at the receiver need only handle a single bitstream. The method of the present invention can be implemented in the form of software, hardware or combinations of both. As such, the present invention can also be realized as a computer program product and a storage medium for such a computer program product . The present invention will more readily be understood by studying the following detailed description of embodiments, which are only given for the purpose of explanation and do not restrict the scope of the invention, and by referring to the enclosed figures, in which Fig. 1 shows a schematic structure for explaining the concept of layering and for explaining the present invention; Fig. 2a shows an embodiment of the present invention; Fig. 2b shows another embodiment of the present invention; Fig. 3a shows another embodiment of the present invention; Fig. 3b shows another embodiment of the present invention; Fig. 4 shows a schematic representation of two networks employing a proxy server; Fig. 5 shows a flow chart for explaining a simple control mechanism usable in the context of the present invention; Fig. 6 is a schematic representation explaining the concepts of receiver feedback and network feedback; Fig. 7 is a schematic representation for explaining an example of scalable video data; and Fig. 8 is a schematic representation for explaining another example of scalable video data. Detailed description of the embodiments Fig. 1 is a schematic diagram for explaining the terminology used in the present application and for explaining the present invention. The concept of layering (OSI model) in communication is well known and shall therefore only be explained briefly. Fig. 1 shows a general example of a connection between a terminal A and a terminal B, where said connection is established through layer based communication. A protocol stack is a vertical hierarchy of protocols, where each protocol (or a group of protocols) fulfils a certain function. For example, a network protocol provides the means for forming a network, a transport protocol handles the transport of packets, or a link control protocol handles the traffic of packets across a certain type of link. A protocol or group of protocols performing a certain function constitute a layer. The example of Fig. 1 shows three layers, namely the application layer AL, the network layer/transport layer NL/TL and the link layer LL. The basic purpose of layering is to enable the independent performance of functions, mainly by making each layer transparent to the other layer. In other words, the box 1 represents a so-called peer at the application layer, which establishes a protocol session with the receiving peer 2 in terminal B in accordance with an application layer protocol . Such sessions are indicated by horizontal dash line double arrows between peers. When data is sent from terminal A to terminal B, the application layer AL passes data to the network layer/transport layer, represented by peer 3, which has a protocol session with peer 4 provided in an interworking rl rd M φ a Cn a . CQ 33 φ SH td 0 Ti Φ a -H X CQ SH 0 0 fa Φ 4H ~ 4-J -H a xi -H rH a ti Φ SH CQ r-- rd 3s 0 H rd 4-J fd 4-J M -H Φ M Φ SH rH • o 4-J 0 Ti fd <- ti Φ rH Φ a ft td td Ti rd a rH φ £ • rH - a 0 rd rH ft -H o CQ Φ Ti H SH 0 Cn Cn a Φ a Φ Φ 35 SH Cn Xl rH Φ rH a rH fa α. -H 4-J rd rd rH -H a CQ τ-t -H Φ CQ ti Ti 0 a CJ o a Xl Φ rH !S ω rd Φ • Φ 4H fa -H ft Φ ft . ε 5 rd φ 4-J a fa -H td CJ Φ 4-J O Φ a H H : CJ xl a 0 SH SH Ti id Xl ε XI x> id CQ fa o -H £ 4H U 0 4-J 0 4-J Φ Φ Φ a a J id TJ Φ Φ Q - rH a . 4 33 ^ Ti 4-1 rH a X! -H Xl Xl -H Φ a 4-J X φ 4-J X! rd CQ -H -. » TJ fd • 0 4-J M rd Φ TJ 0 rd Cn 4-J SH rd £ EH Q Φ 0 Φ Ti CQ PQ Φ φ CM Φ ti SH X! a -H a CQ a • rd Φ rH CQ a -H a o Φ Φ a rH Ti H ft X! 0 a 4-J -H -H -H cn 4-> < * . • 3 4H 4H a Φ o rH <-\ id rH ft -H rH 33 Φ Φ 0 O ε CQ • a fd ti SH a 0 0 0 T) rd 0 Φ on ft Φ rd ε > a SH φ CQ 4-1 si TS SH CQ a SH m Φ Φ rH Φ Φ 0 ti Φ SH £ ε ti Ti a td 0 0 Φ > 33 φ 4-1 0 a Φ φ ε Xl -H ti φ CQ Φ ft 4-J Ti td -H a -H X ti Φ -H 0 a a Φ 4H 4-J rH J ^ Cn ti Cn rd 4-> rd CQ 4-J a rH Φ a X 3 rd ε φ ft CQ ft 4-J SH φ Xl fd 0 M φ Φ -H rH id td ft a Φ XI rd Φ SH -H U ti CQ Λ Φ 4 Cn Xl a SH ti CQ x; Xl 4-J rH u Φ Ti 0 X) td Φ Φ a φ ti Φ td CQ Xl υ -H a ft o cn SH a rH J a a o SH TJ 4J rd X! Φ Φ ft Φ • 4-J CQ -H -H ε £ SH -H Φ Φ Φ a φ a td CQ 0 o 0 CQ 0 ti CQ φ rH Cn rd X Xl ti ! 4-J 0 Xl Xl 33 ε 4H xi 0 -H id -H CM 4H -H a Ti a rd Φ rH Φ • a ti £ Φ rH Φ 4J 0 Cn 4-J CJ a ε 4-J — - a rH rd Xl rH ti X! ti φ -H 4-J 0 4 Φ a ^^ td rH Φ 5 H ϋ ~. H Φ td a υ 4-J a -H CQ $ a ε a ε CO XI 0 Φ 0 CQ Φ o H Xl 0 x id o 3 a 35 a ti -H Xl rd Φ 0 ε 0 Φ 4-J Xl a • SH a o M 4-J fa CQ 4-J a TJ rd 0 Φ H o a x; -H 0 ti Xl ti a EH M Cn Φ a H X ti 3: CQ M id -H Xl fd CJ SH 4-) \ -H 4-J 4-J ti 4H 4-J 0 £ CQ -H >ι 0 ti 0 a H -H a Xl rH 4-J TJ SH - IH a X! * . td 4H o Φ . rH fa id CJ CQ 0 & Φ -H 4-J -H φ a 00 id >, -H £ a xi rH CQ 4H a X! 4 m ^-1 rH M 35 4-J Φ Φ CQ rH Ti 33 Xl -H id X 0 Cn a rd 4-J 0 o CQ td Φ 4-J φ a 4-J Φ 3 Xl -H Φ a CQ Ti rH rH Φ SH a -H a CQ 4-J Φ -H rH rH 33 rd 4H Xl -H Φ a 4-) 4-J Xl 4H rH rd Φ id M a rH Φ l 0 -H 4-J 0 ft td M CQ 4-J CQ Φ td XI 0 4-J rH a Φ 4-J 0 X! J Ti a td a 4-J ∑s o SH td Ti O 4-J id -H ti a 0 4-J 4H X! a -H » a -H 4H 4-J a xl o td Φ rH -H CQ ti rH CQ 4H -H Φ . 4-> CQ rd Φ rH l td a Φ H a 4-J a 4H ft X a CQ Φ ε rH Ti Φ Φ 0 -. ! a CQ ti Ti Xl Ti 4-J -H • a H 4H Φ o ϋ CQ SH rH ti fd φ . CQ J , ^ 35 rH Φ a 0 φ SH 4-J o CQ a id >ι CQ — id id ft & Φ 4-J ■ i Cn -H Φ ω M 4-J rH o ft φ 0 -H SH a TJ LΠ rd a ; O CQ Cn 4-J ft rd ι ε 4-J φ 0 a -H ti Ti PQ ti Φ fd ε ft CJ TJ Φ 0 rH Φ SH -H rd Cn a rd CJ rd td SH a a fa ft 0 0 X! ti id 0 Ό X! td φ SH rd TJ Φ Φ o 4H ft a -H TJ rd a rH X 0 td • ε a ti 35 a CQ M rd SH ft a ti 5 35 -H -H CQ 4-J Φ φ 4-> SH Φ SH 4H 0 Φ 4-> TJ 4-J SH rH φ Ti φ CQ rd 4-J 4-J CJ ε CQ 4-J td Φ a Φ X! Φ 0 CJ td •-A Φ a id Φ rd a Φ rd a Xl Φ td Φ φ Φ td rd id td TJ CQ si a : 0 xi r a td £ rH rd -H 4-> φ rH 4-J < 4-J X! a ft ε SH ft Xl a 4-J -H 4J 0 Φ PQ Ti 0 rH CQ rH id CQ φ rd d CQ 4H 4-J 0 rd 0 rH 4-> SH CQ rd rH a a _ • id -H Ti CJ -H 33 • U CQ Ti fa Ti 4-J Φ 4-J φ Xl Xl td td a rH ε & rH rd 4-) 0 fa ^ ε M Φ -H 4-J fa -H SH & a td -H Φ Xl CQ a ε Cn CQ a 4-J 4H td CQ ε rd a -H 3: rH CQ 4-> a rH Ti o φ Ti Φ fd H rd 4-J 4-J a -H a -H a rd a 0 4- ) H Φ -H -H rH a o Λ Oi a Φ CQ 4-J td rd Cn 0 Φ ε Φ TJ Ti SH X -H o rd > SH 0 -H H -H ft Q ~- a rH td -H - Φ TJ a ti Xl ti ε Φ rH 0 Φ ε rH ϋ a -H 0 -. H rH rH Φ © o Ti -H Xl SH rH ε Φ -H Xl 4J Φ n a a SH td a -H o 4-J Φ a 4-J a M o 0 σ> a 4-J -H φ 4H 4J ft rd Ti Ti 4-J 4-J Φ -H 0 SH Φ Φ a 0 a -H J SH rH φ a o a J CJ φ td ^ 4-J 4-J rH 0 SH SH Ti Ti Φ CQ rd si Φ xi 4 -H -H a 4-J Φ Φ ft φ 0 -H -H 0 0 Ti Φ U ϋ id a Xl SH Φ Φ φ Φ id SH ε rH CQ Cn 4-J ε 4-J ε J ft Cn ε 3 J CQ rH 4-J 4-J a £ -H o a ϋ 4H ϋ ft a >κ Q ,0 4-J Φ 0 Ti ft SH Ti ti td ε a CQ SH td 4-1 CQ o 0 fd 4-J Ti O a 0 a ft Φ rd 3 3 id Xl SH a X 4-J td a a 4-J 0 a Φ rd X φ CQ Φ 4H SH φ a 4H rH m CQ fd Cn rH φ Φ Ti 3= 4H rd φ H ■H H rd 4-J CQ ϋ 4H SH rH φ X! -H H ft ft co X) -H o LΠ o LΠ m H H co As already noted above, the example of Fig. 1 is only a schematic example and, in this sense not a complete representation of an actual data transmission. For example, there will typically be provided a further layer below the link layer, namely the physical layer. This has not been shown in order to not make the representation too complicated. Due to the very concept of layering, each peer at any layer can anyhow essentially be oblivious to the actions and operations occurring at other layers. When data is passed from a lower layer to a higher layer, the encapsulation or segmentation is reversed, such that the application layer peer 2 finally receives the data iτ the same form as it was passed downwards by the application layer peer 1 on the sending side. The same holds true for all other peer pairs shown, for example the network layer peer 4 receives the data in the same form as it was passed down from network peer 3 etc . In accordance with the present invention, the peer 1 at the application layer is a processing element for processing video data to be sent over the connection to terminal B. This can e.g. consist in a video coding process of uncoded video data received from yet a higher layer or from a suitable generator of video data, or can consist in preparing stored coded video data for transmission. The term element is used in the context of the present application as referring to any suitable means for performing a given function, be it software, hardware or a combination of both. Therefore a peer in a communication is an example of an element for processing data or an element for controlling a link etc. The control of the processing, which occurs at the application layer, is performed with the help of values of transmission condition parameters acquired at one or more lower layers, for example the link layer or the network layer/transport layer. More specifically, a value or values of one or more transmission condition parameters present at one of the lower layer peers . rd SH CQ Φ U) ^ rd 0 φ 0 >1 Φ Φ 4-> ^ a Φ rH φ CQ a Cn xl CQ a ε H 4H CQ 4H rH xi H -H r-- SH Cn Φ -H a 4-J -H o Xl 0 -H 0 rd 4-J 4-J rd Φ ti ti o Φ a SH a Φ -H -H CQ Ti 4-J . > a ϋ SH Φ ft >> td 0 -H rH 4-J SH > Φ rd -H CQ Cn CQ rH φ 4-J TJ -H rd 0 o rd α. J SH Φ X! rd -H Φ -H SH X! φ SH M Φ a Φ 0 a CQ fd φ Φ 35 rd SH SH rH 4H SH X! rd rH > Φ Φ X! 0 a a -H a ti 0 > rH & 4-J rH ω ft O 0 φ Ti Φ 4-> Q -H rd SH υ Xl fd Cn -H rH ft rH 4-J -H Φ rd rH -H 4-J 4H ft H 4H a 3 a 4-> -H fd X) Φ Φ 33 a ■H rH rd ft id a -U SH 4-J O X! o φ fd U 0 CQ 4-J td Ti a a td o CQ SH CQ td td > rd > 0 -H rd fd > 0 rH CQ > α. Φ -H Φ SH 0 CQ Xl ft 4-J ^ td J 4-J ε o TJ Ti a ε rH -H Xl H 4-) a cn rd xi J rd rd Φ M a id rH rH a CQ -H -H Φ 4-> 4-J X! rd rH a £ 4-> ι a o Cn Xl ti Φ CQ 0 xl O ti 0 Φ o Φ o id 35 4-J ϋ -H -H ϋ td -H rH SH -H a CQ a CQ 4-J o > φ -H 4-J ti 0 ti Xl ϋ a Φ CQ fd Φ 35 CQ -H ε Ti 0 3= td O -H -H 33 SH a CQ 4-J 4-J 4-J rH Ti SH Φ SH -H ft a rH SH td 4H -. Φ Ti TJ 4-1 Φ rH SH CQ a a a a rd -H Φ rH Φ ti CQ SH 0 ft Φ 0 0 -. Φ rd Ti SH rd a Φ CQ rd Φ Φ 0 0 0 ti 0 > > Φ ft <-{ ft Φ Φ ft ft SH 4H SH cn a X! 4-J -H 0 4-J id a > > rH υ -H o 0 -H ft ε rH o SH Xl CQ rd 0 SH X) a o td > J rd M a X! CQ 4H CQ rH 4H rd 0 SH 4-J Φ ε Φ -H -H a Ti ϋ TJ .. Φ a rH 0 rd 0 SH 0 CQ 0 0 Xl X ti ft Φ 0 rl φ ft Ti ε 4-J rd xi 4-J rH -H 0 o 4-J Φ Φ Φ Φ -H SH 4-J Φ 4-J ft Xl l SH O SH td CJ 0 4-J 0 Φ -H rH SH Ti > TJ rH ε 4-J Cn o a td 4-J Φ ti 4-J 0 SH 0 0 N Φ -H • Φ a Λ 4-J id Φ -H a -H XI CQ a a X! SH o Xl φ 0 • 4-J 4H -H H TJ 35 ϋ Ti ti 0 o a rH > 0 > -H a 0 -H 0 J CQ 4-J 4-J rH 4-J Φ 4H 4-J CQ ti 4-J -H 4-1 -H Φ ε -H • o X! J CQ rd CJ CQ 4-J 4H a td rH rd a a ti Φ Φ • > ^ - ^ Φ 4-J Ti CQ o X! td Xl 0 a SH CQ td Φ a φ 0 o CQ Φ Φ ft M Cn Φ a rd id φ 4-J 4-J Φ 4-J o 4-> 0 Φ Xl _ xi SH rH TJ ti Cn SH CQ TJ υ -H Cn rH - 4H H SH a 0 φ -H -H Xl a ft Φ CJ 4-J 4-J 4-J 0 -H x> a Φ Φ a - td fa a -H M O a rH Φ rH a 35 4-J -H CQ Φ TJ 0 -H 4-J ti > a -H > 4-J Φ a Cn ft -H X! ti Φ -H Φ rd Ti & CQ Φ Xl -H ti Φ a -. td 4-J 0 0 CQ -H Φ X! a • a > 0 0 Φ Xl Xl > -H ε CQ 4-J CQ ti 4-J > ft CQ a M Xl a SH o CQ SH ε Φ -H Cn CQ -H -H ε 35 υ 4-J a 4-J > td Cn Φ rd Φ rd ti 4-J 0 ft Φ Φ fd 0 X! Ti a Φ Φ 4-J ti 0 rH X a a l a ti Φ Φ Φ CJ rH O J Φ J Ti SH 4-J 0 -H rH a J SH Φ a Φ -H a 0 Φ φ -H rH 4-J rH Φ ti CQ x; id 3s ti rH x: 0 td 0 ϋ ε & 35 Φ 0 a 0 rH 4-J 0 SH Xl CQ td td rH Q id 4-J Φ u 4-J 0 SH rH 4-J SH rH ft rd 4-) CQ SH ε 0 SH CQ ft rd 4J 4-J SH a > Φ > rH xi J Xl -H Φ CQ Φ td ft rH 4-J a 0 td Xl TJ fd ε 4-J CQ a 0 rH 0 3 Cn 4-J CQ a CQ Φ Xl o -H rH td CQ rd 4H X CQ Ti Φ Φ td CQ a o Cn 4H a a X! a ti xi a ι Φ ft CQ 4-J 0 £ 0 Ti -H SH SH Φ a X a l X 0 u a 0 o -H 0 4-J ti CJ -H a Xl m ϋ Φ SH 4-J Φ m id -H -H 4-J φ φ -H -H -. -H -H CQ -H a φ -H rH H ft CQ 0 Φ Φ Ti Ti ti 4-J 0 Cn ft Φ 4H rH 4-J 0 > >-. 4-J 4-> CQ 4-J 0 Xl Ti φ SH xi rH Φ -H Φ a φ a ^ CQ Ti σ> *— ^ SH ^ SH -H -H Φ -H id td -H O -H u fd 35 a • Φ rH ft 4-J a SH rH 0 Ti -H Cn SH Φ a a Φ Φ 0 X! TJ TJ SH 33 ti T5 ft Ti rH rd M ε Φ 0 TJ SH rH o -H CQ a 0 Xl rd -H Φ > rH 4H 0 a -H Φ Φ a a φ a xi Φ rd SH SH CD 0 φ Φ 0 > ω -H ~ ^ . 4-J Ti ϋ SH ft l SH 0 φ TS TJ ε 0 > Ti Φ ft 0 rH 0 Xl φ -H CQ -H ϋ 4H a X a -H Φ ε -. u rH 0 u rH U 4-J xi SH td 33 -H -H ε CQ 4-J 4-J Φ 4H J 0 a 0 Φ > CQ td M td Cn 4H X! Φ 4-J «. Φ rH Φ ε rH Φ a a Ti O o CJ id 4-J rH CQ Φ X ti a a 0 td Cn a £ a a TJ rH Xl id Ti a id Cn 0 -H SH td TJ rd φ 0 CQ 0 -H 4-J a 0 0 -H 4-1 φ rH a 4-J φ a 0 ti a υ > cn ft a a Ti a SH 3 -H -H SH a -H -H -H ι -H id SH 0 0 4H H fd 4-J -H a -H 0 Φ -H 0 Φ .. Ti 4-J CQ -H 0 a ft CQ rH CQ Ti -H ti -H a 0 cn xi 4- ) 1~~ rH CQ Φ -H ε -rl 4-> ε 4H a ti Φ Φ rH CQ a -H CQ ft CQ rH CQ φ ti a 4-J 4-J -H o a rd φ rH -H rH CQ SH 4-J 4-1 U SH o Φ rl a rd -H D 1 4-> fd -H td -H ε φ CJ 1 a fd a -H CQ Xl f o X! 0 Xl X! CQ Φ CQ o -H φ Φ x; 4-J SH a ε υ 0 ε ε a ε SH φ J 0 U Φ 0 CQ Φ 4-J SH 4-1 fd Φ 4-> -H φ SH 4-J J ft a Φ a -H CQ rd rd a CQ d 1 CQ 0 ft rd J -H Ti -H rH o rH 4-J 4-J U CQ SH 4-J -H Φ ft 4H Φ ε a rd rd a Φ a 4H rH -H 4-J fd a Xl o rH a Ti -H O φ a SH CQ φ > rH ε φ > rl fd ti Φ rd rd SH φ φ Φ ft CQ td Ti ϋ -H 0 a a ti Xl o 0 Φ Xl Φ Φ o SH -H φ SH 0 Xl a , rl Q SH Φ Xl SH Xl ft Φ 4 φ o a 35 u id CQ ft EH J cj SH EH Ti 4-J υ ft cn 4-> 4-J 4H EH -H X! -H 4-J ft 4-J rd 4-J td SH CQ X! ε CQ M CQ Ti ^ 4 SH a φ CQ Φ u Φ Φ Φ 0 Φ 4 φ -H a -H 4-J -H rd Xl id ε xi Cn a 4-J 0 id x; rH rH J 4H 4-J 4J 4-J Φ 4-J a a Φ a 0 4-J rd 4-J a -H rd . id Xl -H -H CQ ε CQ TJ Φ Φ > H Ti υ Ti rH a 4H TJ CJ Ti rH -H rd CQ SH Xl SH Xl a φ a 0 td 0 CQ TS a H SH ti -H Φ CQ 4-) 0 O 4-J a 0 • 0 ft 0 0 SH φ rH CQ Φ rd 0 a Φ rd φ SH fa Q- 0 Φ Φ u CQ -H Φ 4-) a 4J Xl td Cn -H Xl SH o CJ ft Φ ft Φ SH ω • -H Ti rH 4-J Ti a -H X 4-J a a Xl CQ ti -. 4-J -H rd a SH Φ 0 Φ • H n 4 -H a φ φ -H -H Φ o φ Ti -H EH -H φ CQ a 4-> rH Φ CQ Φ a ft 4- ) 4H Xl Ti U -H > Ti X) Xl TJ > si υ φ 4-> Cn -H SH rH φ Φ o a SH Φ Xl Φ a 4-J φ α. Φ Ti 0 4 a 4-J a a a > φ • X! ft Ti J Φ Φ rd Ti 4-J Φ SH Φ CQ 4-J a 4-J ε a 0 φ 0 0 0 -H -H a rd -H > a ft -H 5 Φ CQ rH 4-J fd 4-> 0 a rd a J l Cn Φ TJ 0 CQ Ti td 0 4-J φ CQ SH a 0 CQ > 4-J 4-J φ rd td Φ id U ft rH J 0 4-J a Ti CQ a rH -H CQ Xl Φ 0 -H a 0 a Φ rd SH ti Xl ft xl 4-J 0 a -H -H φ Φ rd -H 4-J φ 4-J SH 4H 4-J rd SH X! X! rH ft Φ 4-J Φ 4-J a a SH CQ Cn 0 CQ rH > X! Xl ft Φ υ 4-J td SH ft ε SH 0 0 4-J Φ a -H Φ rH 4J φ l Φ φ xi CQ 4-J a 4-J .. cn SH Φ a x; Φ -H a a -H CQ rH rd Ti a Xl 4-J a X! u φ a Φ Ti ι SH a Φ xi a u Φ rH CQ a 0 rH Ti CQ Ti a Φ -H a A 4-J a -H a Φ CQ Φ SH rH Φ -H S 4-J a X! XI CQ SH J rd a -H a Cn 4-J fd -H 4H 0 • Xl rH ε Φ a φ a >ι rH 0 Φ CQ -H -H a > Φ ε rd -H SH Cn ! x; 0 u Cn £ rd Φ rl -H ^ 0 rd rH rH 4H u 4-J CQ ε 4-J Cn a CQ Xl CQ Φ td Φ rH Cn • rH ft fd rd rH rd 0 a ~ 0 CQ CQ a ti Φ a rH Φ a φ n Φ a Φ . 4-J rH SH a Φ Φ H a O a a -H Φ Ti rd 4-J ti a a & ε 0 Ti a -H a CQ φ X! Φ ti Cn Xl 4-J ti ft rd -H CQ 4-J SH td 0 0 rd ε rd -H -H a 0 Φ Φ Xl 0 4H Φ φ -H 4-J • a Φ • rH ti CQ Φ •. 4-J Xl 4H υ o rd a x; CQ rH td 4-J -H A TJ 4-> O ft Xl CQ CQ Φ 4H Cn rH 0 4-J rH Φ ε 4-J X 4-) 4J rH υ -H 4-J 4-J -H a Cn ~ SH ε φ -H fd CQ rH O rd fd Φ ε SH CQ φ ^ a td a -H CQ Xl o 4-1 SH -H rH CQ Φ -H SH fa Xl TJ -H O ti 3 xl 4-J CQ 0 -H H ε o a a a Ti xi Φ Oi -H ft Φ xl 0 Ti Φ TJ CQ td a 5 ti rd 4-J -H -H xl SH SH Cn 0 a J SH a 4-J Φ SH SH ft 0 φ CQ Φ ft ft φ a a CQ EH 0 • 0 TJ -H -H Φ o -H o rd CJ rd rd 4-J 0 Xj ε id CQ a CQ 4-J rH Cn a td Φ 4H Cn 4H φ CQ 4-J Xl J Xl rd Xl ε a rH a 35 SH 3 td 4-1 Φ rd 0 4H X! a Xl a . -H 4-J U 4-J 3 4-J 4-J rl 0 4-J 0 Φ Φ CQ CQ a xi rH Xl φ 0 td -H Φ U rH Ti -. fa TJ a Ti Φ a rd rH 0 J rl td υ SH 4-J Φ X) rH 4-J Ti H SH x: Φ rd Φ φ Φ Φ a 4H 0 a TJ rd 4H Φ Φ rd Ti φ a 3 td -H SH -H -H 4-J ε > 4-J td a ε ε 4-J a o -H -H a υ £ TS SH Xl rH φ l φ ω CQ Xl - > Φ CQ a a 5 -H rd Φ rd 0 CQ 0 4-J -H -H 0 φ φ 4-J ti 4 ε rH -H CQ Φ 4H Φ J 1 4H Φ a Φ SH rH U J rl CQ 4-J Φ td CQ rH > 0 SH ti Φ φ rH Φ CQ Ti u O rH 0 ε φ a 4H ft -H Φ -H -H Ti xl 4H td 0 0 Φ φ CQ rH 4-J Φ a xi a td A -H Φ rH 35 ε Ti cn rH ε a -H 4-J 0 A Φ rH a Xl 4H Φ Φ φ IH rH Ti 4-J td Ti Φ td 4-J rH A 0 -H Φ a rH CQ a > xi ft φ H Cn Φ CQ CQ a 0 ti a SH Ti 4-J -H ft id xi rH TJ -H 0 a TJ n φ 4-J ε CJ -H ti 4-J φ . a Ti ε 0 4-J rd O -H -H Ti ε SH CQ Φ Φ rH SH rd Φ 4H φ a Xl Φ a Xl ft a Xl CQ 0 4-J 4H CQ a a -H -H 4-J X! td rH 4-J SH xi 0 4-J -H 4-J ^ Φ CQ Xl Φ 4-J Φ ε a CQ φ 4-> CQ 0 CQ Φ rd rd a 4-> 4-J 0 CQ Φ ti SH Φ rd J rH a 0 CQ -H rH 4-J a υ Φ Φ ε -H a a 0 Cn a a «. rH SH Φ Φ xi -H td 4H rH rH -H Φ Xl A a o rd X! 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O 4-1 rd Φ X! 33 O CJ υ Ti 4-J > ft transmission condition values relate to the link 79 between peer 7 in terminal A and peer 13 in the base station. The advantage of the embodiment shown in Fig. 3a with respect to the embodiment shown in Fig. 2a is that no modification of terminal B is necessary. This is especially advantageous, if terminal B resides in a different network than terminal A, for example terminal B is a standard fixed terminal in a PSTN network or ISDN network, and terminal A is a mobile station in a wireless network. Namely, it is then possible to use the invention, even it is not implemented in the terminal at the other end of the connection. The example of Fig. 3a shows a case in which the transmission condition values relate to the radio link between terminal A and the base station controller. As can be seen, the transcoding can be performed in direct response to the transmission condition of the radio link both in the uplink and the downlink direction, because the transmission condition values are in both cases acquired in the same unit in which the video processing is performed. This achieves a fast response and thereby very efficient video processing control . The present invention can however also be implemented differently when employing an intermediate unit between the two end terminals, i.e. is not restricted to implementing the inventive concept in the base station. The intermediate unit can also be e.g. the interworking function between the two different networks, or can a proxy server provided in the network of terminal A or the network of terminal B. If one of the networks is a wireless network, then the proxy is preferably provided in the wireless network. This is shown in Fig. 3b, where the element 9 for acquiring transmission condition values is associated with the radio link towards terminal A, and therefore resides in the base station communicating with terminal A, whereas the upper layer (LI) element 15 responsible for transcoding the video data being sent is provided in an intermediate unit, e.g. the interworking function IWF or a designated proxy server. In the examples of Fig. 3a and 3b, it was explained that the intermediate unit could be an interworking function, a base station controller, or a proxy server. When implementing the present invention in an interworking function or a base station controller of a wireless network, it is necessary to adapt all of these units in the wireless network. Although this is advantageous with respect to a system in which all terminals in networks outside of the wireless network (such as the shown terminal B in a fixed network) need to be adapted to the present invention, it nonetheless leads to a certain expense. An alternative solution consists in implementing the invention for downlink traffic in a dedicated proxy server, where this proxy server is preferably provided in the wireless network to which mobile station A belongs. This is shown schematically in Fig. 4. In Fig. 4 network I is a mobile network and network II is a fixed network. The network II can be an ISDN network, where video source terminal TB can e.g. be an ISDN device with video telephone capability, or network II can be a data transmission network such as the Internet, and video source terminal TB can e.g. be server for downloading video data to receiving terminal TA. The interworking function between the two networks is arranged such that calls containing video streams are directed to proxy 50, which then plays the role of the intermediate unit shown in Fig. 3b. This provides the possibility of implementing the present invention in only a few units associated with the mobile network I. For example, the proxy server could be located in the mobile switching centres of mobile network I. As shown in Fig. 3b, it is preferable in this case that the acquisition element for acquiring transmission condition values is located in the base station controllers associated with each mobile switching centre, such that the transmission condition values relate to the respective radio link to the mobile stations. However, the video processing, (e.g. transcoding) will be performed in a centralized manner in the proxy at the mobile switching centre. It is however equally well possible to provide the proxy 50 in network II. For example, if TB is a video server or web server in the Internet, 50 can be a proxy server that is also located in the Internet, and is adapted to handle video transmissions from any server in the Internet that are directed towards mobile units in network ιl . As in the case described above, such an arrangement provides the advantage that only a few servers, namely the proxy servers, need to be adapted to the present invention, whereas all of the remaining servers could remain unchanged. Regarding the transmission condition parameters for which values are acquired, it may be noted that any such parameters that in any way reflect the transmission condition are suitable for use in the present invention. This includes past, present and future transmission conditions. For example, the current bit error rate on a specified link (e.g. the radio link) is a present condition, where a handoff information in conjunction on conditions or characteristics of the cell into which the handoff shall take place, relates to a future condition. The term parameter is to be understood broadly as relating to any suitable type of information. This also applies to the use of the term parameter in connection with the video processing control. Therefore any information available in the communication network that relates to the past, present or future lower layer transmission condition could be made available as a basis for deriving video control values. As already mentioned previously, the transmission condition values are preferably r-- © o α. ω SH H Φ ζj Φ Q- ft U -H 4H -H ϋ Φ ft CQ id 0 4-> 4-1 ϋ r"1 Φ N ft CQ Φ SH l 4-1 -H 3 T! Φ a -H rd 4-1 Xi 0 SH 0 r-- TJ o o Φ SH ^ -H rl o a Φ CJ 1 >ι O J td rd rH φ Φ . TJ xi xi CQ X! SH rH SH SH Φ 0 Φ φ 4-J 4-J Φ φ rH 4-> 0 Φ CQ O 4-1 Xl 4H S SH J Ti > rd 4-1 ft fa Xl id EH CQ 4-1 0 4-J φ CQ SH rH a 33 M 0 Φ 0 -H a rd £ n CJ g CQ Ti -H Cn SH rH a 4-1 0 ti 4-J Φ ε Ti υ Φ Ti • φ φ -H 5 Φ Φ 4H a rH -H © rd rd 0 a Xl SH 0 xi SH a φ SH rd CQ a X! Xl φ -i SH CQ H 0 td 4H o a CQ φ rd 33 rH 4-J 0 rd ft Φ a Xl ε • Φ Φ a -H a a Q- SH n Φ H Cn rH 4-J rd 4H l CQ 4H » 0 rd a CQ 4-1 0 CO 3ϊ • 4-1 W 0 ω Φ -H SH SH a Q a Φ -H o 4H SH H 4H rH -H td Φ Φ SH fa -H 0 Φ υ u H 4-J C a -H CJ a υ 4-1 0 Φ 4H -H rH 4-1 4- ) CJ Ti l a 4H fa 35 ft X! φ a M φ U Φ M υ 4-1 -H -H ft O • Ti td -H rd -H 4-1 -H CD 1^ TJ a xi Φ α. ε fa a a 4-J Φ 4H CQ φ SH CJ TJ Xl Cn > φ ,— . 4-1 a id Φ -H 4-> X! rd O -H xi a SH xi Φ 4-J CQ cn 4-1 Φ td -H a 4-1 a 0 TJ 4-1 rH 0 j -H rd rH SH rH SH J3 rH 4-1 0 fd 4-J a 0 rd a a 4-1 4H 0 -H SH a a ft 4-1 g ε u 0 TJ rd ft T3 υ ft Φ rH CJ -H Φ Φ n -H CJ CQ Ti ft td td ε Q CQ SH Φ Ti 4-> rH ft Φ a -H X! CQ υ ε ε a O Φ 0 4-1 fd ^ -> J a -. Φ xi Φ a Xi 33 l i CQ 0 a a . rd -H Φ £ 4J J Xi ti SH X O rd a Xl 4-1 Cn CQ 0 a EH CQ TS A -H 4H CQ φ -H rd O SH TJ ft φ rd J φ 0 φ fa Ti SH 0 Cn rd a J 0 CQ a xi -H 3 rH rH td -H CQ a CJ 0 -H > & fa a 4-1 -H -H CQ 0 -H • Φ rd a 4-J Φ -H >-. td & ft > -H φ Xi 0 ε ti CD id 4 Xl rH -H -H cn 4-) co J X! 0 4-J 4-J SH A ε 0 0 Φ Ti TJ 35 Ti -H 0 X! Φ rd a > 4-1 a -H fa ϋ -H ti a -H rd Φ a SH 4-1 xi a -H a 4H Φ Φ Xi 4-1 Φ 0 a -H -H TJ fa id 4H 4-1 o CQ Ti CQ Ti O ft 4-1 -H * . id Cn TJ 4-1 CQ Xl φ TJ CQ a ϋ 0 td 4H td ^ Φ CQ id Φ -H Ti Φ Xl rH - Ti -H 4-1 a CQ 0 0 4-J Φ a 4-> φ O Xi 4-J rH Φ o a φ 4-J rH SH H J3 0 Φ TJ Φ 0 Φ υ a 4-1 4-1 CQ TJ ε 0 rd J rH 4-1 -H rH CQ 4J 0 xi rd id id Φ 4-J CQ a φ i u J -H a Φ -H CJ φ Ti Φ a -H 4-J SH -H > SH rd o xi 4-1 0 a Ti a Φ a rd 4-J 0 a • CQ a O CQ 4-1 4H υ o 0 isr! Cn X! CJ Xl 0 TJ φ 0 rH CQ id rH Cn -H 0 φ CQ td «. rd 0 Φ Ti J , a CQ id ft CJ ft Φ 33 ε -H CQ Φ u rH . • u id X! Φ ε 4-J ft a co P -H φ CQ φ Φ CQ a 0 rd A -H SH -H rd rH Φ Φ CJ SH 4-J rd Φ CQ rd fa J 4-1 xl φ SH Φ CQ 0 CQ a rH 0 0 a rH rH a 0 a 0 0 -H TJ Cn Φ X! fa IS td 4-1 CJ M Φ -H rH Φ B Φ 4H a 4H rd 0 ft 0 4-1 rd SH 4H J Ti CD rH 0 a Cn Ti ε ,- ^ rd Xi SH Φ s 0 -H 4-J ε -H u ft a fd SH Φ Φ ε 1 rd φ SH φ 0 a -H CQ fa 4-1 ti fd SH 3 u rd CQ SH -H ft Φ rH ti φ Ti M A ft φ 4-1 -H > a co CQ rd Φ 0 SH φ Φ X CQ Φ a Cn rd i 35 rd 4-1 Φ cn X! - rd E3 -H Φ H CQ l CJ Φ ft a Φ -H > 0 a SH u Cn 0 CQ J a a TJ Cn Ti rH Φ SH a cn 4-> Q CQ Ti ε 0 -H -H Φ -H a CQ a -H o φ a CQ φ rd xi 4-J 4-1 -H u rd Q 3 φ 4-1 CQ Ti 4-1 Ti in Xl M a CQ id -H Ti -H rd CQ a 4-1 Cn -H ti -H rH CQ O a CQ a a a td 0 O Φ 0 1 i rH 4-1 -H Ti Xl a n . td rd Φ 4-1 4H -H J a CQ Φ rd rd id ε J Ti xi rd φ -H SH a ft td > 0 -H «. rd rH a Ti SH o -H n 4-1 SH xi SH CQ a Cn i 4-J Φ H ft ε 0 J rH Φ CQ CQ 4-1 4H 4H Φ rd φ 4-1 ffi 4 a SH 4-1 0 a td -H Φ SH -H 4-1 — rd ti Φ X! CQ id o i o ft 4-J H a CQ fd 0 fd 4H td xi l Ti Ti a 0 ft 0 > a Φ Ti Φ 33 4-J rd id Φ -H xl ft td a SH -H • a -H O ε 4H φ Φ a φ J φ 4-1 rd 4-J • SH Xl J ε Cn -H 4-1 φ rd > 0 fa Φ a CQ TJ rH rd X! 0 CQ rH td a Φ CQ a 4H SH EH -H CQ a i 0 4-1 J TJ fa 4-1 -H -H -H CJ 33 SH CQ 0* 4-1 0 rH SH 0 0 a a td -H φ SH 4-J CQ ti -H Φ CD CQ > ti ft φ B CQ -H A 0 M -H O . 0 • ε xi O Φ ft rH Cn rH 1 ι Φ Xi Φ φ rH td 4-1 -H 4H a 4-J φ a -H M ti a SH 4-1 4H Ti id a rH W CQ Xl υ φ 35 4-1 CQ a X . rd CQ -H id CQ Φ 0 4-1 SH φ 0 0 Cn -H -H 0 a -H rd 4-1 -H Xl 0 td a 0 Φ Φ a 4-1 CQ Φ rH 4-J rd Xi -H rd 0 > -H 4H .. a > 4-1 CJ 1 >, O SH CO xi 4-J ft SH Xl U -H CQ 0 rH ft CQ CJ 4-J 4-J SH 35 4-1 SH -H -. 0 a O SH ^ 35 H 4-1 a o SH rH ft X! a rd a 4-> ti td φ 4-1 Ti Φ SH Ti φ rd O s rH rH ε 4-1 fd Ti o Φ ft φ id Φ Φ rH CJ cn Φ φ ε ft -H 0 rH ft Φ SH ft CQ S Φ ^ 0 a -H . J 0 X! a rH CQ rH a rH Xl Id -H -H a i ti U CJ -H φ -H Ti 4-J a rH 4H 4-1 0 a td & 4-1 a ε O a rH SH ε X! rH -H SH 4-J -H -H ε rH ft 4-1 0 rd CD rd a Φ 4-J -H Φ rH ft o o s X! id 4-> A td Cn " ft a Φ 0 4H φ ft Φ id rH td o u td > a X Φ > ft o a o o 4-J > 4H Q O a -H ft o Xl a a Xl td X! X Φ TJ -H υ 4H O a Xl Φ o rd Xl Φ ft 0 ε H rd o 3 rH r-i CQ rd CJ 4J < -H £ u 4-1 φ J td ft td 0 4-> IH o rH u 3 4-1 rH rd 4-> A simple example of how the processing of video data for transmission can be controlled on the basis of transmission condition values obtained from lower layers is shown in Fig. 5. It maybe noted that the process shown in Fig. 5 is implemented at the layer LI handling the video data processing, i.e. in the module controlling the video data processing. This module receives values of the bandwidth allocated for a link as transmission condition values. Step SI symbolizes the acquisition of the current bandwidth allocated for a link in the connection. In step S2 it is determined if the acquired current bandwidth is sufficient for transmitting a generated video data stream. If the answer is no, then the process branches to step S5, where the video quality level and the amount of generated video data is reduced. On the other hand, if the bandwidth is sufficient, then the procedure passes to step S3, in which it is determined if the current bandwidth is sufficient to transmit a higher video quality. If this is the case, then the process passes to step S4, in which the video quality level and the amount of generated data is increased. As can be seen from the example of Fig. 5, the video control values derived from the transmission condition values can be broadly understood as any type of information suitable for controlling the video processing, such as command values for increasing or decreasing the quality and/or quantity of transmitted video data. According to a preferred example of the present invention, the concept of the present invention is applied to the transmission of video data that is provided in scalable form. A well known example of scalability is explained briefly in connection with Fig. 7. Scalability in this example implies that the coded video is provided in a base stratum (sometimes also referred to as a base layer, but in order to avoid confusion with the above-described protocol layers, the term Φ Φ 4-1 a Xi a 1 CQ Xl SH • Ti • a φ 3 TJ 0 4-1 • Φ 1 X! -H ϋ H Φ 4J Φ Xl a Xl a 4H Φ Ti -H ^ in 3 Φ SH a r-- Xl a a 4-1 0 4-1 4-J 0 SH φ CQ Xl ^^ Φ xi Φ Xl Ti rd CQ φ H o 35 0 a -H Ti ε rd Φ ti CQ 4-> X! • u 4-1 > ϋ Φ 4-1 Φ Φ ϋ Φ 0 ε -H td 4H SH . 4H -H -H -H co Cn a a > td xi SH ^ a o «. Ti ε SH 35 Φ -H 4-J 4-1 4H CQ ε 5 i -H rd a CQ ε Φ SH EH 4H φ rd a rd α. 3 -H id Φ rH Ti Xi fd CQ -H O Φ CQ SH ti fa Xl 0 -H -H 4-1 O SH 0 Ti ω a J> 4J rH a 4-1 4-1 SH ϋ T a Φ 0 Φ Φ a >1 Xl Q O φ -H ti 4-J SH φ -H id fd O 4-1 -H Φ rd rH Xl > Xl Φ Cn CQ ti u a CQ ε 4J 4-1 O rd Ti Φ Ti 35 X! a TJ a rH -U Cβ SH X! td 4-1 4-1 a -H fd 4-J 0 3 rd rd J Q- SH Φ Xl φ Φ - φ ft td 4-1 td ro CQ -H Φ -H Xl > a -H ti SH SH ε J 4-1 Ti 4-1 SH ε 4H xi Φ a ε ε SH 0 a a -rl ? xi TJ EH cn φ 4-J 0 0 SH rd CQ 0 SH ft a 0 4-1 Xl 0 -H 4-1 Φ -H • Φ 4-1 jQ a a ε rd 4H 4J 0 0 a 4-> 4-1 -H u CQ id Xl Cn Xl 4-1 a Φ . ti -H φ 4-> 0 -H 4H a 4-1 a 4H 4H id 4-1 CQ a 4-1 Φ 4-1 3 -H 4-1 -H 0 x: ft a -H Φ u a SH 35 A a -H a Φ 0 SH a Φ Cn CQ td Φ rd 4-> O fa a -H J Φ 0 a X! a Φ Φ 4-1 -H φ id 4-1 a rH a -H xi Xl Ti fd 0 u φ a 4-1 4-J Ti -H & rd CQ Xl 4-1 Ti 3 4H Φ CQ 0 A -H ε a 4J ti 4J φ CQ CJ -H 4-1 Φ >i xi Φ 4-J φ a 0 φ Φ 0 CQ SH ε fd TJ CQ Φ Φ rH φ a Φ Φ SΪ 4H rd SH 4-1 a SH 0 SH Φ φ 4-1 0 φ a φ rd r- a a CQ xl rd a rH CQ rd 4- ) a CQ 4H 4-1 -H Φ ft Φ SH Ti CJ a 4-) -H 4-J CQ ■ ri rH rd Φ -H 4-1 4-1 0 Φ — •- ϋ td a 0 CQ 4-J rH Φ 0 xi Φ -H Φ id a SH ϋ rd Ti rd CJ SH xi td -H £ Φ -H 0 a 0 -H Φ in 4-1 35 4H > r-i Xl a SH -H X! Φ > a 4-1 4-1 ι 0 Ti 4-1 4J X! TJ J Φ ti Φ a X! SH 4H Φ a 0 rd ft a id -H -|3=- - 4-1 a >> -H φ xi 0 rH td O O φ • -H Φ CQ Φ 3 U Φ -H Φ a -H Φ Φ rH a ^ ε a 4-J -H CQ rH 3 Φ rH Cn TJ ε rd ϋ Xl ε CQ . Xi Φ a rH -i Xl > rH a SH ti -H a X! Φ fd TJ A • fd Φ Φ 3 -H 4-1 ti -H X! 4-J xi 0 -H 4-) 4-1 a rd Φ Φ a 0 O 0 u SH ■ ri rd φ 4H CQ X! a ϋ a CQ KV 4-1 -H X! -H -H -H Φ > 4-1 Ti td 3 TJ CQ 0 > ϋ 0 "^ Ω -H 4-1 CN U td 4H 4-> Xl TJ 0 CQ rd rH cn ϋ 4J SH a Φ u ^^ -H -. φ a CQ rd X! O Φ 4-1 Φ 4-> .. CQ rH td a 4-1 Φ id Φ ■ ri a id φ 4-J 4H Φ φ r-i CQ CQ Xi id 4-1 rd SH TJ Ti a CQ -H rd a -H a ft -H CQ -H 4-J 4-1 Xl id O a rH ft a ε 4-1 ϋ CQ X! 4-J id a Φ -H 0 -H Φ 3 U er- 4-1 Φ CQ Ti φ id -H id 4-1 xl 0 X! ft 0 rd rd CQ 0 SH 35 rl CQ CQ CQ ft CQ Φ Φ > xi r-i a rl 4-1 Φ rd td -H Φ O ε φ rd CQ -H ft Ti ft 3 td a Φ rd φ ε X 4-1 ft a 4-1 0 rH TJ rH 4-1 SH 4-1 rd rH 4-1 φ CQ a ε a Φ rd 4H SH Ti rl CQ ti 0 X CQ 4-J Cn & a rd O rd 4-1 Φ Q a TJ CQ rd id -H 4-J ti SH O a rd ft -H Φ SH >1 Φ Φ a ε rd CJ CQ 4-1 Q Φ ti 4-1 Φ φ -H -H X! id u 4J 4-1 4-1 ft X! 4-J 4-1 CQ -H rd Q ιH a 4J 4J 4J fd -H ε > ε Φ Φ ti φ Φ o 4H φ rd a CQ td a a CQ X 3 id φ -H id CQ ti Φ 0 CQ SH 4H X! 4-J TJ rd Cn -H 0 >i xi 4-1 -H Ti Ti td -H φ 0 CQ Φ a td CQ A rH 4-1 Ti ti o SH a -H 0 CQ rd ft 4-1 4-1 fd Φ Φ Ti ε -H φ • 4-J CQ Φ Φ -H a td a ft rd a a xl 3 4-1 SH -H Ti a X! ε φ Φ Φ 4-J 0 >ι Ti rd 4H -H SH Ti SH X! fd ϋ td ti CJ 1 4-1 fd 4-J 4-1 0 a 0 0 rH 4H td -H SH rH ε J -H 0 4-1 φ ti 0 ft φ Xl .— > ε 4-1 φ a J a J ti rd φ rd 0 0 ti 0 ft SH a TJ SH -H Xi 4-J a Φ TJ xl φ 3 a a SH a Φ -H 4H > Ti - a Φ n O 4H ε Φ td a ft J -H CQ φ 0 ti 0 4-1 rH Ti a Φ 4-J Φ 0 κ 3 £ Ti -H a CJ 1 a TJ a CQ SH td 4-J i 0 rd SH rH -H CJ 0 X! φ 4-> rd Xl , ε 4-1 φ TJ Ti td 0 0 -H -H Φ Φ X a a J 4H ft U Φ H 4-1 - rd -H J a Φ -H Φ -H & 4-> 0 X! rd CQ fd Φ S > CQ Ti ft φ -H Φ 0 rd Q CQ 3 a Φ 1 4J a rl xi 4J a rH a rd > J Φ 4-1 SH 4-1 a a U Φ rd fd Φ TJ rH 4-J -H 4-> 4-1 Q TJ 0 ti rd rd X! 0 -H Xl U a id φ Φ Cn SH Φ ti 0 φ Ti X! X > -H 4-1 rd a CQ CQ a φ a Xl 3 4H 4-1 Φ 4-1 ϋ rH m Xl a 0 Xi 0 -H a Cn Φ a > a X! CQ -H Ti 0 rd > Cn CJ 1 a 4H Φ ■ ri a u -H A 0 X ) • H 4H Xl — CQ a φ Φ -H Φ 4J r-- Φ a -rl rH rl Φ 0 SH ϋ Cn a -H rH rd Ti CQ 4-1 -H > a Φ Φ Ti Φ o o ε CQ rd CQ >κ rH id Φ φ a 0 ft ft rH 4-1 CQ O -. .. ε -H CQ 0 0 a 4-1 rH a 4-J a a rd rd 4-1 rd rH SH Φ 4-1 Φ ft -H o ft rd ft id J φ *1 H a 3 φ CQ A 0 a A Φ a 0 ^ 4-1 A -. A -H ϋ a Xi a X! CQ 4-> 0 id U Φ CQ r H 4-1 CQ rH Φ rd Cn Φ rd ft φ H rd rd rH -H id 4-J 4-J a ft id φ CQ CJ xl a Q> Φ id a ft J a 1 CQ rH Φ CQ 4-1 o ti Φ 4-J Φ td CJ £ 0 a Φ fd TJ Φ a J rd B ε SH id ε O φ -H rH φ id Ti Φ rd O 4-1 l rd X! a 4H -H a 3 fd Xl TJ 1 -H Xl 4H 0 a SH -H id 4-1 SH -H SH xl CQ a rl J a SH xi CQ 4-1 Ti EH iJ 1 4J H ft -H <d CJ EH id X! > EH 0 ϋ CQ 4-1 CQ 5 4-J CQ ft En a O ft CQ -H ft 4-1 with the transmission conditions. This is shown schematically in Fig. 8. The example of Fig. 8 shows one bitstream having a low bitrate and one having a high bitrate, where the quality control selects the high bit rate video stream or the low bit rate video stream, depending on the transmission conditions. This again provides the advantage of very simple processing and low processing capacity, and has the additional advantage that the required decoders at the receiver need only handle a single bitstream. Although the present invention has been described on the basis of preferred embodiments, it is to be understood that the preferred embodiments do not restrict the scope of the invention, which is defined by the enclosed claims. Reference signs serve the purpose of better understanding and also do not restrict the scope.

Claims: Claims 1. A method for controlling a processing of video data such that said video data may be transmitted over a connection in a communication network (I, II), said connection employing a plurality of protocol layers (LI, L2; AL, NL/TL, LL) , said method including: performing said controlling of the processing of video data at a first layer (LI; AL) , acquiring a value of one or more transmission condition parameters indicative of transmission conditions in the network (I, II), where said one or more transmission condition parameters are specific for a second layer (L2; NL/TL, LL) provided lower than said first layer (LI; AL) , deriving one or more values of one or more video control parameters usable at said first layer (LI; AL) from said value of said at least one transmission condition parameter, and performing said controlling of the processing of video data in accordance with said derived one or more values. 2. The method of claim 1, characterized in that said connection comprises a predetermined link (100, 200, 300; 79; 2223) and said one or more transmission condition parameters relate to a condition of said predetermined link. 3. The method of claim 2, characterized in that said one or more values of said one or more transmission condition parameters are acquired at said second layer on a sending side of said predetermined link (100, 200, 300; 79; 2223) . 4. The method of claim 2 or 3, characterized in that said predetermined link (100, 200, 300; 79; 2223) is a radio link (79; 2223) . 5. The method of one of claims 1 to 4, characterized in that said first layer (LI; AL) pis an application layer (AL) and said second layer (L2; NL/TL, LL) is a link layer (LL) . 6. The method of one of claims 1 to 5, characterized in that said communication network (I, II) is a wireless communication network (I) , and said method is applied to the processing of video data in one or more of a mobile station in said wireless communication network, a base station in said wireless communication network, an interworking function between said wireless communication network and a fixed network, a terminal device in said fixed network, and a proxy server (50) provided in said wireless communication network or said fixed network. 7. The method of one of claims 1 to 6, characterized in that said processing of video data comprises the coding or transcoding of said video data. 8. The method of one of claims 1 to 7, characterized in that said processing of video data comprises the forward error correction of said video data. 9. The method of one of claims 1 to 8, characterized in that said processing of video data comprises the packetization of said video data. 10. The method of one of claims 1 to 9, characterized in that said one or more transmission condition parameters are selected from a group consisting of the current transmission delay, the biandwidth allocated for a specific user, the current bit error rate, and the current frame erasure rate. 11. The method of claim 2 or a claim dependent on claim 2, characterized in that said one or more transmission condition parameters are selected from a group consisting of the current carrier to interface ratio on the predetermined link and the current power-level on the predetermined link. 12. The method of one of claims 1 to 11, characterized by transmitting said video data in scalable form by having a base stratum and at least one enhancement stratum, and by deciding on the inclusion or exclusion of said enhancement stratum in the transmitted video data on the basis of the derived one or more values of said one or more video control parameters. 13. The method of one of claims 1 to 11, characterized by transmitting said video data in scalable form by having at least two independent bitstreams of video data, and by selecting one of said bitstreams as the transmitted video data on the basis of the derived one or more values of said one or more video control parameters. 14. A computer program product loadable into a memory of a digital computer device, including software code portions for performing the method of one of claims 1 to 13 when said computer program product is run on said computer device. 15. A storage medium for computer program products characterized by having the computer program product of claim 14 stored thereon. 16. A transmitting system (A, B) for transmitting video data over a connection in a communication network (I, II) that employs a plurality of protocol layers (LI, L2; AL, NL/TL, LL) , comprising: a processing element (1; 2) arranged to process video data to be transmitted at a first layer, an acquisition element (7, 22; 9, 23) arranged to acquire a value of one or more transmission condition parameters indicative of a transmission condition associated with said connection, said one or more transmission condition parameters being specific for a second layer (L2; NL/TL, LL) lower than said first layer (LI; AL) , and an element for deriving one or more values of one or more video control parameters usable by said processing element (1; 2) at said first layer (LI; AL) from said value of said one or more transmission condition parameters, where said processing element (1; 2) is arranged to control the processing of video data in accordance with said derived one or more values . 17. The transmitting system according to claim 16, characterized in that said acquisition element (7, 22; 9, 23) is a part of a control element provided for controlling the transmission of data over a predetermined link (100, 200, 300; 79; 2223) forming part of said connection, where said one or more transmission condition parameters are indicative of a transmission condition associated with said predetermined link (100, 200, 300, 79; 2223) . 18. The transmitting system according to claim 16, characterized in that said predetermined link (100, 200, 300, 79; 2223) is a radio link (79; 2223) . 19. The transmitting system of claim 18, characterized in that said acquisition element (7, 22; 9, 23) is arranged such that said one or more values of said one or more transmission condition parameters are acquired at said second layer (L2; LL) on a sending side of said radio link. 20. The transmitting system of one of claims 16 to 19, characterized in that said first layer (LI; AL) is an application layer (AL) and said second layer (L2; NL/TL, LL) is a link layer (LL) . 21. The transmitting system of one of claims 16 to 20, characterized in that said communication network (I, II) is a wireless network (I) , and said processing element (1; 2) is provided in one or more of a mobile station in said wireless network (I), a base station (BSC) in said wireless network (I), an interworking function (IWF) between said wireless network (I) and a fixed network (II), a terminal device (B) in said fixed network (II), and a proxy server (50) provided in said wireless network (I) or said fixed network (II) . 22. The transmitting system of claim 21, characterized in that said processing element, said acquisition element and said element for deriving values of video control parameters are all provided in one unit (A, BSC) . 23. The transmitting system of claim 21, characterized in that said acquisition element (7, 22; 9, 23) is provided in a different unit than said processing element (1; 2; 14; 15) . 24. The transmitting system of claim 23, characterized in that said processing element (2; 15) is provided in one of a terminal device (B) of said fixed network (II) and a proxy server (50), and said acquiring element (9) is provided in a base station (BSC) of said wireless network (I) . 25. The transmitting system of one of claims 16 to 24, characterized in that said processing element (1; 2) is arranged to perform coding or transcoding of said video data. 26. The transmitting system of one of claims 16 to 25, characterized in that said processing element (1; 2) is arranged to perform forward error correction of said video data. 27. The transmitting system of one of claims 16 to 26, characterized in that said processing element (1; 2) is arranged to perform packetization of said video data. 28. The transmitting system of claim 17 or a preceding claim dependent on claim 17, characterized in that said one or more transmission condition parameters are selected from a group consisting of the current transmission delay on the link, the bandwidth allocated for a specific user on the link, the current bit error rate on the link, and the current frame erasure rate on the link. 29. The transmitting system of claim 18 or a preceding claim dependent on claim 18, characterized in that said one or more transmission condition parameters are selected from a group consisting of the current carrier to interface ratio on the radio link and the current power-level on the radio link. 30. The transmitting system of one of claims 16 to 29, characterized in that said processing element is arranged to control the transmission of said video data in scalable form by having a base stratum and at least one enhancement stratum, and is arranged to decide on the inclusion or exclusion of said enhancement stratum in the transmitted video data on the basis of the derived one or more values of said one or more video control parameters . 31. The transmitting system of one of claims 16 to 29, characterized in that said processing element is arranged to control the transmission of said video data in scalable form by having at least two independent bitstreams of video data, and is arranged to select one of said bitstreams as the transmitted video data on the basis of the derived one or more values of said one or more video control parameters. 32. A transmitting unit for transmitting video data over a connection in a communication network that employs a plurality of protocol layers, comprising: a processing element arranged to process video data to be transmitted at a first layer, an acquisition element arranged to acquire a value of one or more transmission condition parameters indicative of a transmission condition associated with said connection, said one or more transmission condition parameters being specific for a second layer lower than said first layer, and an element for deriving one or more values of one or more video control parameters usable by said processing element at said first layer from said value of said one or more transmission condition parameters, where said processing element is arranged to control the processing of video data in accordance with said derived one or more values . 3. The transmitting unit of claim 32, characterized in that said communication network is a wireless network, and said unit is one of a mobile station in said wireless network, a base station in said wireless network, an interworking function between said wireless network and a fixed network, a terminal device in said fixed network, and a proxy server provided in said wireless network or said fixed network.

Inventors: HORN UWE, SCHIEDER ANDREAS, HORN, UWE, SCHIEDER, ANDREAS
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 2001
Main classification: H04N7
IPC codes: H04L1, H04N7