Patent ID: 8111759

Claim:
A method for authoring or generating or coding an audio/video data stream that represents a video signal and one or more audio signals, said video signal having 24 Hz video frame frequency and said audio signal or signals having original speed, wherein said authoring or generating or coding comprises the following steps: encoding the video signal in 24p format and optionally adding 3-2 pull-down data items for facilitating a playback with 60 Hz or nearly 60 Hz field frequency, and encoding the one or more audio signals according to said original speed; encoding sub-title data, and generating menus related to at least one of said video signal, one or more audio signal and sub-title data; generating additional data items for facilitating a subjectively synchronized presentation of said audio and video signals with an average field frequency lying in the range between 48 Hz and 50 Hz, denoted 50i format, thereby including in said audio/video data stream video repetition information items which can be used in a presentation unit for said video and audio signals for controlling video signal field or frame repetition, and including audio dropping information items which can be used in said presentation unit for controlling audio signal frame dropping, this generating step comprising the further steps: automatically determining video and audio scenes in said audio/video data stream and automatically categorizing different types of said video and audio scenes with respect to a required video/audio presentation synchronism in said 50i format, including determining critical video and audio scenes in which no audio frame drop or video field repeat, respectively, occur; calculating for each one of said video and audio scenes the maximum manageable number of audio frame drops and/or video field repeats, respectively; calculating a corresponding distribution of audio frame drop information items and/or video field repeat information items for non-critical scenes, and calculating whether or not a video/audio delay introduced by a current critical scene can be compensated for by a corresponding number of audio frame drops and/or video field repeats in adjacent non-critical scenes, and if true, providing a corresponding number of video repetition information items and audio dropping information items for the non-critical scenes, said video repetition information items and said audio dropping information items forming a part of said 50i format additional data items, if not true, re-encoding in said 50i format audio data or video data for said current critical scene so as to form a part of said 50i format additional data items; and incorporating said 50i format additional data items into related data fields of said audio/video data stream or a copy of said audio/video data stream.