Abstract: A video encoding method comprises encoding a series of images of original video data into an encoded video stream comprising key frames and delta frames, wherein the delta frames are organized in a hierarchical prediction pattern comprising a plurality of temporal layers. The video encoding method further comprises adding to the encoded video stream a hidden delta frame for at least some of the key frames. Each hidden delta frame corresponds to a key frame, is based on same original video data as the corresponding key frame and is referring to a previous key frame in the encoded video stream. Also, a method of reducing a file size of the video stream encoded according to the video encoding method is disclosed.

Abstract: A method for encoding and transmitting a plurality of image frames of a video stream includes: intra refresh encoding the plurality of image frames; encoding one image frame of the plurality of image frames to produce encoded image data of the one image frame, the encoded image data being organized in a plurality of data packets, wherein the encoding comprises intra frame encoding the one image frame; transmitting, over a time period, the intra refresh encoded image frames; transmitting the plurality of data packets, wherein the transmission of the plurality of data packets is distributed over the time period during which the intra refresh encoded image frames are transmitted. An interrelated method for receiving and storing the plurality of image frames, as well as devices and computer program products for performing the methods, are also provided.

Abstract: A method of providing an event-initiated video sequence, comprises a pre-event video sequence and a post-event video sequence. The pre-event image frames are stored in a non-processed format until such time that an event is taking place. By postponing the image processing of the pre-event video sequence, power savings are accomplished.

Abstract: A method of processing a video stream comprises receiving a first/second set of input image frames comprising image data originating from a first/second source of input image frames; encoding the sets of input image frames into first/second sets of encoded image frames, forming a combined video stream, wherein an encoded image frame of the first set of encoded image frames exclusively references one or more other encoded image frames of the first set of encoded image frames, and an encoded image frame of the second set of encoded image frames references both an encoded image frame of the first set of encoded image frames and another encoded image frame of the second set of encoded image frames; and signing, using a first/second key, a first/second signing group comprising one or more encoded image frames of the first/second set of encoded image frames, wherein each key pertains to the respective source.

Abstract: A method for forming a combined image frame of a combined video stream comprises: capturing image frames of first and second video streams; encoding image data of the image frames of the first and second video streams, wherein each image frame of the first and second video streams are respectively encoded into first and second encoded data comprising a plurality of rows wherein each row has a height of a single coding unit and a width equal to a width of the image frame and is encoded as one or more slices; and combining the first and second encoded data into combined encoded data by interleaving rows of the first and second encoded data. The combined encoded data representing the combined image frame of the combined video stream.

Abstract: A method for controlling video processing. A stream of images emanating from an image sensor is received. The contents of an image in the stream is evaluated. A part of the image stream, which part is antecedent the image being evaluated, is forwarded to a video encoder. Until the evaluation is complete, one or more empty frames are added at the end of an encoded image stream corresponding to the forwarded image stream.

Abstract: Methods and apparatus, including computer program products, for processing a stream of image frames captured by a camera system. When an image frame from the stream of image frames is dropped, a current camera movement is determined. A substitute image frame for the dropped image frame is generated. The substitute image frame comprises a reference to a previous image frame and includes one or more motion vectors estimated solely based on the determined current camera movement. Remaining image frames in the stream of image frames are encoded and the substitute image frame is inserted at the place of the dropped image frame in the stream of encoded image frames.

Abstract: Methods, systems and computer program products, for processing a stream of image frames captured by a camera system. A hardcoded alert image frame is generated in response to detecting an event. The hardcoded alert image frame includes motion deltas and/or color changes with respect to an event image frame. A stream of encoded image frames is generated, in which stream the hardcoded alert image frame is inserted in display order after the encoded event image frame.

Abstract: A method encodes an image of a video sequence by analyzing motion in the video sequence to identify a coherent region in the image that has moved with a distance vector which is longer than a threshold since a previously encoded image in the video sequence. A cost for inter-coding the block is calculated as a combination of a cost for encoding a motion vector and a residual. For at least one block of pixels in the coherent region, the cost for encoding the motion vector is calculated relative to the distance vector of the coherent region instead of being calculated relative to a motion vector of a neighbouring block of pixels in the image. The block is then inter-coded if the combined cost for encoding the motion vector and the cost for encoding the residual when combined are below a cost for intra-coding the block of pixels.

Abstract: A method of encoding a video sequence by an encoder supporting context-based adaptive binary arithmetic coding, CABAC is disclosed. The method comprises determining, by a rate controller, a compression parameter of the encoder based on a load parameter value, indicating a current actual load of the coding block, received from the coding block.

Abstract: A method of encoding a video stream for the provision of prunable video data, comprising: receiving, in an encoder, a video stream in which each image frame of the video stream is divided into a number of subviews, providing each subview with an assigned category based on a content of the particular subview, monitoring the evolution of category assigned for each subview, and encoding the video stream using a hierarchical P-frame encoding structure, in such manner that each change in category for a subview starts a new hierarchical P-frame structure.

Abstract: A method for encoding a video stream for the provision of prunable video data, comprising identifying, in the video stream, a first event-generating occurrence in one or more frames of the video stream, and, in an encoder, using the event-generating occurrence to initiate a hierarchical branch extending from a base-layer when encoding the video stream.

Abstract: A method for determining authenticity of a video in a surveillance system, whereby a sequence of image frames of a scene is captured, and an object is tracked. A current image quality measure in an image area corresponding to the tracked object is determined in at least a first and second image frame. chosen such that the object has moved at least a predetermined distance between the first and second image frames. A current image quality measure variation for the object is determined, the image quality measure variation describing the image quality measure as a function of position of the object in the image frames. The current image quality measure variation is compared to a known image quality measure variation. In response to the current image quality measure variation deviating from the known pixel density variation by less than a predetermined amount, it is determined that the video is authentic.

Abstract: Methods and apparatus, including computer program products, implementing and using techniques for encoding a video sequence comprising a plurality of image frames, by an encoder are described. An image frame is received from a video stream. An input is received, which indicates one or more regions in the received image frame for which a privacy mask should be applied. The one or more regions are represented by one or more coding units. The image frame is encoded into an output frame, wherein image data in the one or more regions is replaced by intra-predicted coding units with transformed coefficients set to zero, the intra-predicted coding units are obtained from a prediction stage in the encoder.

Abstract: A controller and a method for controlling output bitrate of a video encoder when encoding a video stream. The method for controlling output bitrate of a video encoder when encoding a video stream comprises: receiving weather forecast data for a location where the video stream is captured; predicting, based on the weather forecast data, a future increase in output bitrate of the video encoder due to weather affecting contents of the video stream; and reducing the output bitrate of the video encoder by increasing a compression level of the video stream so as to compensate for the future increase in output bitrate of the video encoder.

Abstract: A digital camera and a method for aligning digital images comprising: receiving images including first and second images depicting a first and a second region of a scene, the regions being overlapping and displaced along a first direction; aligning the images using a transformation; determining disparity values for an overlap between the images; identifying misalignments by identifying blocks of pixels in the first image having a same position along a second direction and having disparity values exhibiting a variability lower than a first threshold and exhibiting an average higher than a second threshold; adjusting the transformation for the identified blocks of pixels in the first image and their matching blocks of pixels in the second image; and realigning the images using the adjusted transformation.

Abstract: A method of controlling output bitrate of a video encoder encoding a video sequence comprises: setting an allowable average bitrate, gathering encoding data by encoding video during a first time period and for each of a plurality of time intervals, storing a respective output bitrate, and a quantisation parameter used for encoding during the respective time interval. For each time interval, the output bitrate is normalised by calculating a corresponding normalised bitrate estimated for a predetermined nominal quantisation parameter as a function of the output bitrate and the quantisation parameter. An average normalised bitrate is calculated by averaging the normalised bitrates of the plurality of time intervals. A new quantisation parameter is calculated based on a comparison of the average normalised bitrate and the allowable average bitrate. The video sequence is encoded using the new quantisation parameter during a second time period subsequent to the first time period.

Abstract: A video encoding method for encoding a series of images of original video data into an encoded video, comprises setting a periodic intra refresh pattern for the encoding of the series of images; setting a number of delta frames to be added between consecutive intra refresh frames of the periodic intra refresh pattern, thereby adjusting the intra refresh periodicity of the encoded video stream; and encoding the series of images of original video data into the encoded video stream using the set periodic intra refresh pattern and the set number of delta frames to be added between consecutive intra refresh frames. During the encoding, a current intra refresh frame is set to directly refer to a previous intra refresh frame and each delta frame added in between two consecutive intra refresh frames is set to only refer to a previous one of the two consecutive intra refresh frames.

Abstract: A method for encoding, using a block-based video encoding algorithm, a distorted image frame produced via at least one image sensor, comprising: determining a map of maximum pixel block sizes corresponding to the distorted image frame, wherein the map of maximum pixel block sizes is determined based on a spatial resolution distribution corresponding to a distribution of extents of the corresponding FOV, such that for a first portion of the distorted image frame having a first spatial resolution, the maximum pixel block size corresponding to the first portion is set to a first value, and for a second portion of the distorted image frame having a second spatial resolution being lower than the first spatial resolution, the maximum pixel block size corresponding to the second portion is set to a second value being lower than the first value; and encoding, using the block-based video encoding algorithm, the distorted image frame.

Abstract: A method and an apparatus for forming a video stream based on images of a scene captured by a camera. The method comprises: encoding image frames based on images captured by the camera, forming an encoded portion; determining a length of motion for a sample image frame, the length of motion being indicative of the amount of relative motion between the camera and the scene in the sample image frame relative a temporally preceding image frame; setting a motion length threshold based on a motion vector search range of the encoder; comparing the determined length of motion with the set motion length threshold; based on the outcome of the comparison, adjusting a chosen temporal frame distance of at least an adjustment portion (PA) of the video stream, wherein the adjustment portion is comprised in the encoded portion or in a temporally later encoded portion.