The invention relates to the processing of video signals prior to encoding or other compression operations, and, more particularly, to a method for encoding video signals corresponding to a sequence of frames each of which consists of two fields F1 and F2. The proposed method comprises the steps of receiving successive frames of an input video signal and delaying them with at least a "two fields" duration delay, and detecting any dominance change and adjusting said delay. When a change from an F1 dominance to an F2 dominance is detected, the first field of the first F2 dominant frame is suppressed, and said delay is decreased by a quantity equal to "one field" duration; when a change from an F2 dominance to an F1 dominance is detected, the last field of the last F2 dominant frame is repeated, and the delay is further increased by a quantity equal to "one field" duration.The invention also relates to a method for encoding a sequence of frames including either video-type images or film-type images, and to an encoding system that carries out said method by incorporating the first solution hereinabove presented. If a sequence of film-type is detected, the inverse 3:2 pull-down technique is applied on the input frames, while in the opposite case, said technique is de-activated and replaced by said first solution: preprocessing according to the type of dominance change.

Video assets are fetched from a data storage device and buffered based on the video rate associated with the video assets. The arrival deadline for each buffer is tracked. As the contents of a buffer are consumed by the video decoder, the buffering plan is computed. The intent of the buffering plan is to maintain enough buffering in prefetched buffers to cover a data storage device underflow. The proper amount of buffering to cover an underflow is computed by subtracting both the arrival deadline and buffer time of the next buffer to be consumed from the arrival deadline of subsequent future buffers. This computation must be performed for each future buffer until the difference is greater than or equal to the maximum storage device underflow period. If the difference is less than the storage device underflow period, then a fetch of the buffer from the data storage device must be performed. To rapidly build the buffering when the play list is first started or when device underflow substantially depletes the buffers, a higher priority I/O may be utilized.

A controller allocates a bit size for a current frame in a group of pictures of a first compression-encoded digital video signal that is to be spliced following transmission of the group of pictures with a second compression-encoded digital video signal. The signals are spliced after a predetermined switching time. The spliced signals are buffered by a decoder buffer and then decoded by a decoder. When the second signal has a variable bit-encoding rate and the current frame is not decoded until after the predetermined switching time, the maximum bit size is determined in accordance with an estimate of the decoder buffer fullness at the predetermined switching time. When the second signal has a predetermined maximum variable bit-encoding rate and the current frame is not decoded until after the predetermined switching time, the minimum bit size is determined in accordance with the predetermined maximum bit-encoding rate of the second signal.

A multimedia terminal comprising: a first encoder (100) for producing a first bit-stream (107) of a first media type and having a first bit-rate; a second encoder (110) for producing a second bit-stream (112) of a second media type and having a second bit-rate; a multiplexer (120) for combining at least the first (106) and the second (112) bit-streams into a third bit-stream (123). The terminal comprises an input element (130) for receiving preference information (131) coupled to the first encoder (100) and the second encoder (110), said preference information (131) indicating a preferred combination of the first and the second media types in the third bit-stream and affecting the first and the second bit-rates. Thus, the transmission capacity is utilised in a more optimised manner and the proportions of different media types are better adjusted to the purpose of the information transfer.

A method and apparatus are provided for detecting scene changes between successive fields in a digital television signal. I-frames, which start new GOPs, are aligned with scene changes. In a preprocessing stage (205, 210), the change in the sum of pixel differences between consecutive odd fields, or consecutive even fields, is calculated for every consecutive input field. A scene change is detected when a large positive value in the change of sum is followed by a large negative value therein. A decision of which picture type to use is not made until a final encoding stage (225, 235). I-frames can be inhibited when an encoder buffer level is too high. A counter resets the scene change indication to avoid a perpetual scene change state for transitions from still to motion. In film mode, the MPEG-recommended frame-based encoding is deactivated when a scene change occurred on a field boundary (e.g., when there is no redundant field in the picture).