T 0854/10 15-01-2015

Reasons for the Decision

1. The appeal is admissible.

2. Main request: construction of claim 1

2.1 The examining division objected to the expressions "performance information relating to the video encoder" and "video frame recording information" in claim 1. However, as convincingly argued by the appellant, these expressions themselves are broad but nevertheless clear. The former has the meaning of information about the performance of the video encoder and the latter of information about the recording of video frames. In particular, in the context of the application the performance of the video encoder may be reflected in the result of the encoding process and thus may also be dependent on the characteristics of the input video frame including the complexity of its contents.

2.2 For the purpose of the present decision the board sees no need to take a position on whether all the examples of performance information and recording information given in the description and the dependent claims may be considered as "performance information relating to the video encoder" or "video frame recording information" within the meaning of claim 1 of auxiliary request IIa.

3. Main request:

inventive step (Article 56 EPC 1973)

3.1 It is uncontested that document D1 may be considered as the closest prior art for the assessment of the method of claim 1.

3.2 D1 discloses a video encoding method which is suitable for cellular phones, TV phone systems, and the like (see paragraph [0001]). The method comprises applying a filter (pre?filter 101) to a video frame before the video frame is forwarded to an encoder (encoding means 116) (see figures 1 and 19, and paragraphs [0010] to [0012]). The encoder encodes the filtered video frame (see paragraphs [0013] to [0056]). In particular, the encoder uses quantisation parameter information (quantiser scale Qp) to encode the filtered video frame (see paragraph [0023]]). The method of D1 also comprises receiving performance information relating to the video encoder at a filter control means 117, 117a (see paragraph [0014] and figures 1 and 19). Examples of performance information indicating the result of the encoding process are the encode volume and the parameters having a correlation with the encode volume, such as the inter/intra ratio (see paragraphs [0014] to [0017]). Furthermore, in D1 both the QP information and the filter are adjusted on the basis of the output of an encode volume control means 115, 115b (see paragraphs [0033] to [0036]). Details of the filter adjustment are described in paragraphs [0042] to [0052]. For instance the filter may be adjusted by providing filter characteristics control data K, which are determined based on both the encode volume and the inter/intra ratio, to the filter (see paragraph [0018] in conjunction with paragraph [0051]). The QP parameter is adjusted on the basis of the encode volume of the bit stream ultimately output by the encoder (see paragraph [0034]).

3.2.1 D1 also discloses in the context of the fourth embodiment illustrated in figure 19 the "external provision of parameters about controlling the encode volume", in particular in order to lower the target bit rate in the encoder if there are problems in the transmission path downstream of the encoder. Examples of such external input parameters are a compression rate and a bit rate. The external input parameter is input to the encode volume control means and the filter control means (see paragraphs [0080] to [0084]).

3.3 D1 does not disclose obtaining video frame recording information indicating video frame size, encoding bit rate, and frame rate. Consequently, D1 also does not disclose adjusting the QP information and the filter based on both the performance information and the recording information.

3.4 The board is not convinced that the inclusion of these features in their broad meaning allows the problem indicated by the appellant, i.e. to efficiently accelerate the adjustment of the filter and to further improve the video quality, to be solved. But the board accepts the more general problem formulated by the appellant, namely to find a better compromise to avoid overshooting as the problem underlying the invention. Indeed, in D1 the adjustment of both the QP information and the filter on the basis of the output of encode volume control means 115 constitutes a feedback loop which serves to control the encode volume (see paragraphs [0034] and [0036]). This feedback also allows a better control of the target bit rate, thereby avoiding overshooting (see D1, paragraphs [0090] and [0093]). This may lead to an improvement of the video quality at a given bit rate, or to a lower bit rate for a given video quality. Thus, in the present application the additional consideration of video frame recording information in the adjustment of the filter and the QP information is part of the considerations of a person skilled in the art, who always has to strive for a suitable compromise between coding bit rate and video quality.

3.5 It is common general knowledge that the bit stream output by the encoder should be in conformity with the external boundary conditions arising from the intended further use of the bit stream, such as transmission or recording in a desired quality. Also, the embodiments of D1 refer to target parameters (for instance, the target bit rate in paragraphs [0014] and [0017] concerning the first embodiment, or the target bit rate and the target compression rate in paragraphs [0081] and [0082] concerning the fourth embodiment). Such target parameters may arise from the external boundary conditions as discussed in point 3.2.1 above. Thus it would have been obvious to a person skilled in the art to include in the feedback loop of D1 other parameters reflecting such external boundary conditions than those explicitly discussed in D1, such as video frame recording information reflecting desired recording settings.

3.6 Also, the present application indicates that the specific parameters included in the video frame recording information specified in claim 1, namely video frame size, encoding bit rate, and frame rate, are the settings selected for recording a video sequence (see in particular paragraph [0032]). These settings may be selected by a user or an application and may refer to qualitative information such as high quality or large frame size (see paragraph [0037]). There is no disclosure in the present application of a specific relationship between the recording settings and the adjustment of the QP information and the filter. Instead, video frame size, encoding bit rate, and frame rate are merely examples of recording settings (see paragraphs [0044], [0054], [0065], [0068] and [0071]).

3.7 The appellant's argument that in the embodiment of figure 19 in D1 the filter was not adjusted on the basis of the input bit rate did not convince the board in view of the disclosure in paragraphs [0080], [0081] and [0090] and figure 19 of D1. Also the argument that in D1 the pre?filter control was based on only one or two of the encoding parameters of the video encoder, and thus led a person skilled in the art away from using additionally recording information, did not convince the board, in particular in view of the disclosure of the fourth embodiment. The disclosure of D1 as a whole aims at reducing the volume of computation by providing a data table (see D1, paragraphs [0005] and [0043]). This does not dissuade a person skilled in the art from taking into account parameters reflecting external boundary conditions.

3.8 In view of the above the board finds that the method of claim 1 of the main request does not involve an inventive step (Article 56 EPC 1973).

4. Auxiliary request I:

inventive step (Article 56 EPC 1973)

4.1 Claim 1 of auxiliary request I further clarifies the technical context of the invention in that it specifies a video recording system including a video front end, a video back end and a recording settings unit. The video front end includes a video sensor and the adjustable filter discussed above in the context of the main request, and the video back end includes the encoder discussed above and a video record or transmit device. This further distinguishes recording information originating from the recording settings unit and performance information originating from the video back end.

4.2 However, the application does not indicate that the general structure of a video recording system including a video front end, a video back end and a recording settings unit has an effect on the filtering or encoding. In particular, the application does not indicate that the filter adjustment and the QP information adjustment discussed in the context of the main request might be affected by the fact that the filter is included in a video front end and the encoder is included in a video back end. Also, the separate recording settings unit included in the video recording system according to the application merely allows the obtaining of the recording settings, i.e. the video frame recording information, but has otherwise no technical effect.

4.3 The appellant has not submitted any arguments based on this general structure of the video recording system which would change the assessment of inventive step made above in the context of the main request, and the board does not see any such arguments, either.

4.4 In view of the above the board finds that the method of claim 1 does not involve an inventive step (Article 56 EPC 1973).

5. Auxiliary request II:

clarity (Article 84 EPC 1973)

5.1 Claim 1 of auxiliary request II includes the feature that the performance information includes "frame variance information and bit?rate control information".

5.2 The expression "frame variance information" may have a number of different technical meanings, dependent on context. In the technical context of the present application a number of different meanings are conceivable. For instance, it could mean information about some content variation between different frames (temporal variation), or information about some content variation within a frame (spatial variation). Temporal variation might for instance concern consecutive or non-consecutive frames, or might concern entire frames or particular blocks within frames. Spatial variation might for instance concern luminance, chrominance or other colour-related value variations within a frame. Frame variance information might also mean the variation of some encoding parameter used when encoding different frames.

5.3 Thus the technical meaning of the expression "frame variance information" in the context of claim 1 is not clear. Also the fact that it is included in the "performance information relating to the video encoder" only excludes meanings which are independent of the performance of the video encoder.

5.4 In view of the above the board finds that claim 1 of auxiliary request II is not clear (Article 84 EPC 1973).

6. Auxiliary request IIa:

remittal (Article 111(1) EPC 1973)

6.1 The board admitted auxiliary request IIa into the appeal proceedings as a reasonable reaction to objections and arguments raised for the first time in the oral proceedings before the board.

6.2 Claim 1 of auxiliary request IIa further specifies claim 1 of auxiliary request II and includes features of claim 1 of the first and third auxiliary requests on which the decision under appeal is based.

6.3 However, the arguments given in the decision under appeal with respect to the then first and third auxiliary requests do not directly apply to claim 1 of the auxiliary request IIa.

6.3.1 First, claim 1 of auxiliary request IIa clearly specifies that the frame variance is included in the performance information relating to the encoder and indicates an amount of spatial complexity content in the frame (emphasis by the board). This implies that the spatial complexity of the encoded frame is being considered, not the spatial complexity of the input frame. The unencoded input frame does not reflect encoder performance. Of course, the two spatial complexities are interrelated, but they are not identical (see also paragraph [0040]). As convincingly argued by the appellant, the encoding process, for instance the quantisation, may influence the spatial complexity of the encoded frame. As a consequence, the relevance of D4 needs to be reconsidered, since the parts of D4 referred to in the decision under appeal take into consideration the complexity of the input frame (see equation (1) in column 17 of D4).

6.3.2 Furthermore, upon correct interpretation claim 1 of auxiliary request IIa specifies that each of the QP information and the filter are adjusted based on both frame variance and bit?rate control information as defined in claim 1.

6.3.3 Furthermore, the reasoning in the decision under appeal included the understanding that the problem to be solved (when compared with D1) could be formulated as "taking into account the characteristics of the input video". This formulation of the problem is, at least, not appropriate in view of the present wording of claim 1. This also entails the necessity of a fresh analysis of prior?art documents such as D1 and D4.

6.4 Moreover, the appellant has also requested that the further prior-art documents cited in the parallel US case be taken into account. Thus full examination of the amended claims is now necessary.

6.5 In view of the above, the board considers it appropriate that the examination of the amended claims and the further prior-art documents be carried out by the examining division. Full examination is the task of the examining division, not the board of appeal (see Decision of the Enlarged Board of Appeal G 10/93, OJ EPO 1995, 172, point 4 of the Reasons).

6.6 Thus the board decided to exercise its discretion under Article 111(1) EPC 1973 in remitting the case to the department of first instance for further prosecution.

7. Reimbursement of the appeal fee (Rule 67 EPC 1973)

7.1 The appellant requested the reimbursement of the appeal fee because the examining division allegedly had not taken into account in its decision the essential argument that the person skilled in the art would not have had an incentive to combine documents D1 and D4.

7.2 In the context of deciding on claim 1 of the first auxiliary request, the examining division analysed in point 4.1 of the decision under appeal the features of claim 1 which were known from D1, and in point 4.2 concluded that the subject-matter of claim 1 differed from the known method in that the performance information further included frame variance information. In point 4.3 it formulated the problem which it considered to be relevant for the assessment of inventive step, and in point 4.4 it stated that the differing feature was known from D4. It also stated that "it is well?known that intra?frame complexity, as defined in document D4, may be used also for quantisation parameter control, even if the wording of the claim is broad enough to include the case that only the filter is adjusted based on frame variance information, as disclosed in document D1." Point 4.5 then states that "the skilled person would therefore regard it as a normal design option to include this feature in the method described in document D1 in order to solve the problem posed."

7.3 Thus the examining division took the view that a person skilled in the art would have combined documents D1 and D4 because it was a normal design option to include the feature described in D4 in the method of D1. This is also consistent with the more complete discussion of the appellant's argument in the oral proceedings (see page 4 of the minutes: "The examining division argued that in the current application there are different embodiments using different control parameters and there is no detail on how these parameters are used in combination. No special technical effect could be seen in using particular parameters in combination. Since the application does not present a synergy effect using different parameters, the separate teachings of D1 and D4 could be combined to assess inventive step.")

7.4 Hence the appellant's allegation that the examining division had not taken into account the essential argument mentioned in point 7.1 above is not correct. The argument was implicitly taken into account, albeit in a manner which apparently did not convince the appellant.

7.5 In view of the above, the request for reimbursement of the appeal fee must be refused.