Abstract: Method and system for determining a measure of quality for images by using multi-level decomposition are presented. Multi-level decomposition of images is performed in the wavelet domain producing subbands at each level of decomposition. Aggregation of subbands is performed across multiple levels to produce an accurate measure of image quality. By aggregating only selected subbands the computational complexity of the method is greatly reduced.

Abstract: Method and system for determining a measure of quality for images are presented. Multi-level decomposition of images in the wavelet domain using a variable number of levels of decomposition and aggregation of selected subbands is performed to obtain an accurate measure of quality. The processing time is reduced in comparison to that required by other methods for generating measures of quality.

Abstract: A method and system for an efficient transcoding of a sequence of input images in a first format to a sequence of output images in a second format are described. The method utilizes the encoding block mode, the motion vectors and the residual information extracted during the decoding of the input image that are effectively reused to select an optimal transcoding block mode and to perform selective refinement of motion vectors. A corresponding system for video transcoding is also provided.

Abstract: A method for quality-aware transcoding of an input image into an output image for display on a terminal having device file size and image size constraints are disclosed. The method extracts features of the input image including dimensions and file size of the input image, predicts a file size of the output image taking into account constraints of the terminal and extracted features, including selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal, determines quality metric values of the output image, characterizing a measure of distortion of the input image introduced by the transcoding, corresponding to the feasible transcoding parameters in the set of feasible transcoding parameters, and selects those transcoding parameters from the set of feasible transcoding parameters, which yield the highest quality metric value. A corresponding system is also provided.

Abstract: A method and system for generation of a block mode conversion table for use in online transcoding of a sequence of input images in a first format to a sequence of output images in a second format are described. The table is based on a sequence of training images and provides an effective mapping between the encoding block modes and respective candidate transcoding block modes used during the online transcoding. The method utilizes the encoding block mode, the motion vectors and the residual information extracted during the decoding of the training image to generate the block mode conversion table. A corresponding system is also provided.

Abstract: A method and device for improving rate controlling in video coding of sequences including a series of Inter frames separated by Intra frames, when a decoding delay is considered, comprise for each Inter frame of the series: computing a target frame size, computing a maximum buffer level related to a position of each Inter frame relative to a previous Intra frame and an upcoming Intra frame, and optimizing a transmission buffer level in response to the computed target frame size and the computed maximum buffer level.

Abstract: A system and method for predicting a file size of an image subject to transformation by scaling and a change of at least one quality-controlling parameter are described. The system receives the file size of the image before transformation, information about at least one quality-controlling parameter of the image before transformation, information about at least one quality-controlling parameter and a scaling factor to be applied to the image during transformation. A relative size prediction is calculated using the received quality-controlling parameters information and the scaling factor. The file size of the image after the transformation is finally calculated as a function of the file size of the image before the transformation and the calculated relative size prediction. Images are partitioned into classes of images, and for each class of images, an array of relative file size predictions, having at least two dimensions, is computed.

Abstract: Method and system for low complexity assessment of quality of an image are presented. By performing multiresolution decomposition of images using, for example, a discrete wavelet transform, and determining a metric based on a structural similarity index or a structural similarity map, a structural similarity score, characterizing similarity between images with a high degree of accuracy, is produced. The processing time is much smaller in comparison to that required by other methods producing image quality metrics of comparable accuracy.

Abstract: An improved MPEG-4 to H.264 transcoding algorithm is provided, exploiting residual, coding mode and motion vector information from the MPEG-4 stream. The use of the relative sum of absolute residuals (RSAR) to classify macroblocks (MB) leads to small sets of coding modes (CM) to test, and significantly reduces the computational complexity. In addition, RSAR is used to conditionally refine motion vectors (MV); only those MVs most likely to lead to quality improvements are refined. The average RSAR statistics are obtained from the transcoding of the previous Inter frame to provide adaptive thresholds for coding mode selection as well as conditional MV refinement. A corresponding video transcoder system is also provided.

Abstract: A visual quality assessment method and system are based on deriving a quality metric by comparing sub-band approximations of a distorted image and an undistorted version of the same image, providing a good compromise between computational complexity and accuracy. The sub-band approximations are derived from Discrete Wavelet (Haar) transforms of small image blocks of each image. Due to inherent symmetries, the wavelet transform is “blind” to certain types of distortions. But the accuracy of the method is enhanced, and the blindness of the transform is overcome, by computing quality metrics for the distorted image as well as computing quality metrics for a shifted version of the distorted image and combining the results.

Abstract: Method and system for low complexity transcoding of images with near optimal quality for display on a terminal are presented. Generating effective transcoding parameters prior to transcoding and retrieving the transcoding parameters based on the features of the input image and the characteristics of the terminal, an output image quality close to that produced by optimal quality transcoding is achieved. The processing time is much smaller in comparison to that required for optimal quality transcoding.

Abstract: Several quality-aware transcoding systems and methods are described, in which the impact of both quality factor (QF) and scaling parameter choices on the quality of transcoded images are considered in combination. A basic transcoding system is enhanced by the addition of a quality prediction look-up table, and a method of generating such a table is also shown.

Abstract: A method an system for establishing a multi-user communication session, having a session description, between terminals with incompatible media characteristics, in which users with terminals having incompatible media characteristics are invited to participate in the communication session. A transcoding session is set up for enabling transcoding between the incompatible media characteristics of the terminals based on information about the terminals of the users having accepted the invitation, this information comprising the media characteristics of the users' terminals. The session description is established according to the transcoding session and, during the communication session, media streams from the terminal of one user are transcoded according to the transcoding session and the transcoded media streams are transmitted according to the session description to the other users participating in the communication session, using the media characteristics of the terminals of those other users.

Abstract: A system and method for predicting a tile size of an image subject to transformation by scaling and a change about at least one quality-controlling parameter, in which an input receives the file size of the image before transformation, information about at least one quality-controlling parameter of the image before transformation, information about at least one quality- controlling parameter for application to the image during transformation, and a scaling factor for application to the image during transformation. A relative size prediction is calculated on the basis of the received quality-controlling parameters information and scaling factor. The file size of the image after transformation is finally calculated as a function of the file size of the image before transformation and the calculated relative size prediction. Images are partitioned into classes of images, and for each class of images, an array of relative file size predictions is computed, the array having at least two dimensions.

Abstract: Several quality-aware transcoding systems and methods are described, in which the impact of both quality factor (QF) and scaling parameter choices on the quality of transcoded images are considered in combination. A basic transcoding system is enhanced by the addition of a quality prediction look-up table, and a method of generating such a table is also shown.

Abstract: A system and method for predicting a file size of an image subject to transformation by scaling and a change about at least one quality-controlling parameter, in which an input receives (a) the file size of the image before transformation, (b) information about at least one quality-controlling parameter of the image before transformation, (c) information about at least one quality-controlling parameter for application to the image during transformation, and (d) a scaling factor for application to the image during transformation. A relative size prediction is calculated on the basis of the received quality-controlling parameters information and scaling factor. The file size of the image after transformation is finally calculated as a function of the file size of the image before transformation and the calculated relative size prediction.

Abstract: A method and system for parallel encoding of frames in a video are described, exploiting parallel processing at both frame and slice levels. One or more slices are processed in a preceding frame by one or more cores in a multi-core processor, and a slice is processed in a succeeding frame provided at least one of said one or more cores in the multi-core processor is available for processing; and the processing of a slice from said one or more slices at same physical location in the preceding input frame has been completed, the processing of frames and slices in the preceding and succeeding frames being performed at least partially in parallel. A significant speedup in comparison to the sequential encoding approach is achieved while maintaining high visual quality for the output video. A corresponding system for parallel encoding of a video is also provided.

Abstract: Method and system for transcoding a sequence of input images into a sequence of output images that can effectively handle one or more transcoding uses cases are presented. The embodiments of the invention exploit the incoming metadata retrieved from the decoding process to adapt the video content and to achieve a significant speed-up in comparison to the traditional cascaded approach while maintaining high quality for output images.

Abstract: A method an system for establishing a multi-user communication session, having a session description, between terminals with incompatible media characteristics, in which users with terminals having incompatible media characteristics are invited to participate in the communication session. A transcoding session is set up for enabling transcoding between the incompatible media characteristics of the terminals based on information about the terminals of the users having accepted the invitation, this information comprising the media characteristics of the users' terminals. The session description is established according to the transcoding session and, during the communication session, media streams from the terminal of one user are transcoded according to the transcoding session and the transcoded media streams are transmitted according to the session description to the other users participating in the communication session, using the media characteristics of the terminals of those other users.

Abstract: A method an system for establishing a multi-user communication session, having a session description, between terminals with incompatible media characteristics, in which users with terminals having incompatible media characteristics are invited to participate in the communication session. A transcoding session is set up for enabling transcoding between the incompatible media characteristics of the terminals based on information about the terminals of the users having accepted the invitation, this information comprising the media characteristics of the users' terminals. The session description is established according to the transcoding session and, during the communication session, media streams from the terminal of one user are transcoded according to the transcoding session and the transcoded media streams are transmitted according to the session description to the other users participating in the communication session, using the media characteristics of the terminals of those other users.