T 1228/08 26-11-2012

1. The appeal is admissible.

2. The invention

The application concerns the manner in which a signal is converted for transmission over a packet-switched network. The signal is broken down into "representations" of the signal and these representations are split into packets for transmission. A basic "core" representation contains the minimum information necessary to obtain an intelligible signal at the receiver and each successive "enhancement" representation provides more detail and improves the resolution of the received signal. The data is packaged according to the available connection speed so that the packet stream contains only those representations which can be reliably received are sent.

3. Main request

3.1 The Board considers that the requirements of Articles 84 and 123(2) EPC are satisfied.

3.2 Inventive step starting from D1

3.2.1 Document D1 discloses a multicast audio tool which uses hierarchical coding. The audio signal to be transmitted is sampled with 16 bits per sample. Each sample is divided into four groups consisting of four bits each. The groups are sent as separate data streams to the destination where they are re-assembled for playback. The data source will always send all four groups but, depending on the receiver's preferences, some of these groups may not be forwarded to the destination by the local multicast router. The more groups which are received at the destination, the higher the resolution of the re-assembled signal. One factor which is taken into account in the forwarding of groups from the multicast router to the destination is the available bandwidth.

3.2.2 The method of claim 9 is distinguished from the teaching of D1 in that the packaging of the signal for transmission is performed in dependence on the available connection speed. In D1, all data is packaged and sent irrespective of the connection speed; the local multicast router then controls the forwarding of the packets based on the connection speed but does not influence the packaging itself.

Moreover, the representations which are sent in the method of claim 9 (which correspond to the "groups" in D1) are packaged together as a single data stream and are not sent as separate streams as in D1.

3.2.3 In the contested decision, the examining division argued that in cases in which only a single client was expected to access a single file at any one time, the skilled person would see that the multicasting properties of the system of D1 were not required and that the local multicast router would be superfluous. In such cases, it would be obvious to transfer the task of selecting which groups to forward to the client to the server itself, allowing the server to package the data to be transmitted into a single stream. The music-on-demand service described on page 1, line 31 to page 2, line 17 of the present application as filed was cited to show that it was known to send a given version of a musical piece as a single data stream. To transmit just one stream was considered by the examining division to be a technological step back from the multicasting system of D1 and therefore not inventive. In other words, it would have been obvious to adapt the multicast system of D1 to provide a system in which data is directly transmitted in a single steam from the server to the destination without the intervention of a multicast router.

3.2.4 In the statement setting out the grounds of appeal, the appellant argued that if the multicasting properties of the system of D1 were not required then the system of D1 represented the wrong starting point for the assessment of inventive step. The question of how to adapt the system of D1 for use in data transmission when only one client would ever require access to the data would simply not arise because the skilled person would only consider using the system of D1 for multicasting. Thus, to suggest that D1 can be modified to dispose of the multicast router and to package the groups into a single data stream for direct transmission to the receiver was pure hindsight.

3.2.5 The Board agrees with the appellant's position. Although D1 discloses the use of hierarchical coding, which is indeed a major aspect of the present invention, the Board considers that this document does not represent a realistic starting point for an attack on inventive step. Following T 439/92 (not published in OJ EPO), a conscious choice of starting point not only determines the subject-matter serving as a starting point but also defines the framework for further development (see Case Law of the Boards of Appeal of the European Patent Office, I.D.3.5, third paragraph). Thus, using D1 as a starting point would mean that any further development would be carried out in the context of multicasting: it is unrealistic to suggest that, starting from this disclosure, the skilled person would go outside this framework - indeed take a technical step back, as observed by the examining division - to develop a non-multicasting system.

Furthermore, as the appellant has pointed out, the packet streams which are constructed in D1 are independent of the connection speed. All of the four-bit groups in D1 are sent individually to the multicast router which then forwards specific groups - again individually - to the receiver. This is what gives the multicast system of D1 the prerequisite flexibility: separate groups are sent in separate data streams so that at the router, individual groups may be selected for forwarding to the destination. To send a single data stream from the data source would be to lose the ability to select certain data building blocks at the router and to consequently lose the ability to adapt the data transmission to changing network conditions. In view of the fact that the whole idea in D1 is to allow maximum flexibility with regard to the data packets which are retrieved by the user, the Board is of the view that it would be counter-intuitive to provide a single stream in D1.

3.2.6 For these reasons, the Board is of the opinion that the method of claim 9, and correspondingly also the apparatus of claim 1, cannot be derived in an obvious manner when starting from the disclosure of document D1.

3.3 Inventive step starting from the prior art described in the application

3.3.1 The Board considers that the prior art discussed in paragraphs [0003], [0004] and [0013] of the published application represents a more realistic starting point. In this music-on-demand system, a server stores various compressed versions of a musical piece, each version corresponding to a different connection speed between the server and the client and consequently to a different quality. In delivering the music to a client, the appropriate version is packetized and communicated through a packet-switched network.

3.3.2 The method of claim 9 is distinguished from this prior art in that the signal to be communicated is broken down into at least first and second representations, the first representation containing core information and the additional representations containing additional detail. The data stream which is sent is made up of a collection of data building blocks, the collection comprising the "core" representation and - depending on the available connection speed - at least one "enhancement" representation.

3.3.3 As is apparent from the above discussion of the disclosure of D1, the concept of hierarchical coding was known at the priority date of the application. However, the only two documents, D1 and D3, on file relating to hierarchical coding discuss this concept solely in relation to a multicasting system. In such multicasting systems, as explained in D1, all of the data is sent group-wise to the multicast router from where the receiver can retrieve the specific selection of groups which can be successfully transmitted at the connection speed between the router and the client terminal. The purpose of the hierarchical coding in D1 is make individual data building blocks available at the multicast router such that different combinations of the groups can be selected by different clients. This permits multiple users to access the multicast router and to individually decide which building blocks - and consequently which resolution - to receive.

However, the Board is of the view that if the skilled person decides to turn to the hierarchical coding system of D1 in order to reduce the amount of memory space required for storing the data to be transmitted in the music-on-demand system described in the present application, then he must also adopt the manner in which the data blocks are sent, namely on a per-group basis. Indeed the whole idea behind the system of D1 is that the separate groups may be sent individually to the multicast router so that a selection thereof may be retrieved and reassembled by the client terminal. It is this flexibility which multicast systems are designed to achieve. In the view of the Board, the skilled person would not arbitrarily isolate a part of a document from its context in order to derive therefrom a technical information which would be distinct from the integral teaching of the document. Thus, the Board considers that even if the skilled person were to consider hierarchical coding, he would not separate the hierarchical coding from the per-group packaging of D1 which is necessary for the multicast functionality. The idea behind the prior art music-on-demand system discussed in the application is to send a single data stream containing the entire data corresponding to a specific version of the signal. The Board is of the opinion that this concept is not compatible with the multicast concept of D1 and that the skilled person would therefore not consider attempting to combine them. The skilled person would therefore not arrive at the subject-matter of method claim 9, or the corresponding apparatus claim 1.

3.3.4 For these reasons, the Board is of the opinion that the method of claim 9, and correspondingly also the apparatus of claim 1, cannot be derived in an obvious manner when starting from the music-on-demand system described in the prior art portion of the present application.

4. In conclusion, the claims according to the main request are allowable. However, since a patent cannot be granted until the description has been brought into conformity with the amended claims, the main request of the appellant cannot be allowed. Any adaptation of the description will have to be dealt with by the examining division.