Abstract: Methods and systems for rate-constrained search ordering algorithms for reducing computational cost of motion estimation in video coding have been provided. Conventional search orderings, such as spiral search, can weaken the filtering criterion of rate-constrained successive elimination algorithms. Simulation results provided herein above demonstrate that, on average, the amount of SAD (sum of absolute differences) operations required to encode the tested sequences, is reduced using embodiments of the invention, when compared to the conventional implementations of spiral search for example. Advantageously, for sequences with unpredictable motion, this reduction may be greater than 5%, and may even exceed 10% when smaller block partitions are evaluated.

Abstract: Methods and systems for parallel rate-constrained motion estimation in a video encoder are provided. Embodiments of the present invention provide a solution for the problem of the reliance upon spatial dependencies when processing parallel RCME on a frame. In order to solve this problem, embodiments of the present invention determine a list of at least two Motion Vector Predictor Candidates (MVPC), determine, in parallel for at least two of said at least two MVPCs, corresponding Motion Vector Candidates (MVC) using Rate-Constrained Motion Estimation (RCME) and determine the optimal Motion Vector (MV) among the determined MVCs based on rate distortion optimization.

Abstract: Methods of optimal encoding of signals to be compatible with characteristics of target receivers while meeting constraints pertinent to sizes of encoded signals or capacities of paths communicating signals to the target receivers are disclosed. The methods are based on analytical modeling of the encoding process guided by experimental data relating measured performance indicators of encoded signals of diverse classifications to respective encoding parameters. A computationally-efficient technique is devised to determine optimal encoding parameters based on pre-processed data derived from the analytical models. The methods may be implemented at an encoder of original signals or a transcoder of pre-encoded signals.

Abstract: In real-time video applications, where unreliable networks are commonplace, corrupted video packets can affect adversely the visual quality. In this patent application, we present an improved method and system for video error correction based on maximum likelihood. Rather than discarding corrupted video packets, the method estimates the likeliest syntactically valid video slice content based on these packets. We present two embodiments, which permits solving the problem at the slice-level, and a simplified solution operating at the syntax element-level. The performance of the method is evaluated using the H.264 baseline profile. Unlike existing video error concealment methods, we correct errors in the bitstream instead of reconstructing missing pixels. Simulation results show that the proposed method yields improved visual quality, and is also computationally simpler than existing state-of-the-art error concealment methods. A corresponding system for video error correction is also provided.

Abstract: Methods and apparatus for determining encoding parameters of an encoder or a transcoder which yield an encoded signal of optimal measurable properties are disclosed. For a video signal, the encoding parameters may include quantization granularity, a measure of display resolution, and a frame rate. The measurable properties of an encoded signal may include a fidelity index, a relative size, and a relative flow rate. Reference data records quantifying properties of sample signals encoded according to experimental sets of encoding parameters are used to define parameters of conjectured analytical functions characterizing the encoding or transcoding functions. The analytical functions are then used to generate granular tables of estimated measures of encoded-signal properties. A fast search mechanism relies on the granular tables, together with sorted arrangements of the granular tables, to determine, in real-time, preferred encoding parameters for multimedia data streams received at an encoder or a transcoder.

Abstract: System and method for optimizing a transcoding session between multiple terminals are disclosed. The method determines properties of the transcoding session, including a number of terminals participating in the transcoding session, media characteristics supported by each terminal, a measure of performance of the transcoding session to be optimized, and optionally a proportion of time involved in the transcoding session for each terminal. Then a cost function characterizing the measure of performance of the transcoding session and depending on the above properties of the transcoding session is built, followed by optimizing the cost function with respect to said measure of performance to determine an optimal measure of performance for the transcoding session and optimal values for the media characteristics for each terminal. In one embodiment, codecs used by multiple terminals and computational complexity of the transcoding session are optimized.

Abstract: Methods and apparatus for determining encoding parameters of an encoder or a transcoder which yield an encoded signal of optimal measurable properties are disclosed. For a video signal, the encoding parameters may include quantization granularity, a measure of display resolution, and a frame rate. The measurable properties of an encoded signal may include a fidelity index, a relative size, and a relative flow rate. Reference data records quantifying properties of sample signals encoded according to experimental sets of encoding parameters are used to define parameters of conjectured analytical functions characterizing the encoding or transcoding functions. The analytical functions are then used to generate granular tables of estimated measures of encoded-signal properties. A fast search mechanism relies on the granular tables, together with sorted arrangements of the granular tables, to determine, in real-time, preferred encoding parameters for multimedia data streams received at an encoder or a transcoder.

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: Methods and systems for determining motion vectors in a motion estimation process of a video encoder are provided. Embodiments of the present invention provide a solution for the problem of unnecessary cost function evaluations, found when combining the successive elimination method with a predetermined list of candidate motion vectors search ordering. In order to solve this problem, embodiments of the present invention provide an adaptive scan ordering of block matching candidates within a search area. Advantageously, embodiments of the present invention will only evaluate necessary cost functions, without impacting rate-distortion.

Abstract: A video intermodal transcoder converts a compressed bitstream formulated according a type-1 compression scheme to a type-2 compressed bitstream formulated according to a type-2 compression scheme. The transcoder includes an augmented type-1 decoder, a transcoder kernel, and an augmented type-2 encoder. The transcoder kernel performs processes of creating motion-vector candidates and pre-computing prediction errors for each cell of a predefined image coding block and for each candidate motion vector for repetitive use in evaluating various image partitions. In an implementation where the type-1 compression scheme follows the H.264 standard and the type-2 compression scheme follows the HEVC standard, the transcoder exploits the flexibility of the coding-tree structure and other HEVC features to significantly reduce the bit rate of the compressed bit stream. The pre-computation of prediction errors significantly reduces the processing effort, hence increases the throughput of the transcoder.

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: System and method for optimizing a transcoding session between multiple terminals are disclosed. The method determines properties of the transcoding session, including a number of terminals participating in the transcoding session, media characteristics supported by each terminal, a measure of performance of the transcoding session to be optimized, and optionally a proportion of time involved in the transcoding session for each terminal. Then a cost function characterizing the measure of performance of the transcoding session and depending on the above properties of the transcoding session is built, followed by optimizing the cost function with respect to said measure of performance to determine an optimal measure of performance for the transcoding session and optimal values for the media characteristics for each terminal. In one embodiment, codecs used by multiple terminals and computational complexity of the transcoding session are optimized.

Abstract: Methods and apparatus for determining encoding parameters of an encoder or a transcoder which yield an encoded signal of optimal measurable properties are disclosed. For a video signal, the encoding parameters may include quantization granularity, a measure of display resolution, and a frame rate. The measurable properties of an encoded signal may include a fidelity index, a relative size, and a relative flow rate. Reference data records quantifying properties of sample signals encoded according to experimental sets of encoding parameters are used to define parameters of conjectured analytical functions characterizing the encoding or transcoding functions. The analytical functions are then used to generate granular tables of estimated measures of encoded-signal properties. A fast search mechanism relies on the granular tables, together with sorted arrangements of the granular tables, to determine, in real-time, preferred encoding parameters for multimedia data streams received at an encoder or a transcoder.

Abstract: In real-time video applications, where unreliable networks are commonplace, corrupted video packets can affect adversely the visual quality. In this patent application, we present an improved method and system for video error correction based on maximum likelihood. Rather than discarding corrupted video packets, the method estimates the likeliest syntactically valid video slice content based on these packets. We present two embodiments, which permits solving the problem at the slice-level, and a simplified solution operating at the syntax element-level. The performance of the method is evaluated using the H.264 baseline profile. Unlike existing video error concealment methods, we correct errors in the bitstream instead of reconstructing missing pixels. Simulation results show that the proposed method yields improved visual quality, and is also computationally simpler than existing state-of-the-art error concealment methods. A corresponding system for video error correction is also provided.

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: 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: Methods and systems for rate-constrained search ordering algorithms for reducing computational cost of motion estimation in video coding have been provided. Conventional search orderings, such as spiral search, can weaken the filtering criterion of rate-constrained successive elimination algorithms. Simulation results provided herein above demonstrate that, on average, the amount of SAD (sum of absolute differences) operations required to encode the tested sequences, is reduced using embodiments of the invention, when compared to the conventional implementations of spiral search for example. Advantageously, for sequences with unpredictable motion, this reduction may be greater than 5%, and may even exceed 10% when smaller block partitions are evaluated.

Abstract: Methods of optimal encoding of signals to be compatible with characteristics of target receivers while meeting constraints pertinent to sizes of encoded signals or capacities of paths communicating signals to the target receivers are disclosed. The methods are based on analytical modeling of the encoding process guided by experimental data relating measured performance indicators of encoded signals of diverse classifications to respective encoding parameters. A computationally-efficient technique is devised to determine optimal encoding parameters based on pre-processed data derived from the analytical models. The methods may be implemented at an encoder of original signals or a transcoder of pre-encoded signals.

Abstract: A method (and corresponding equipment) by which a multimedia message is sent from a sending terminal (21) via a messaging server (22)—such as a MMS Proxy-Relay in MMS or a SIP proxy server in SIP IM—to a receiving terminal (25) having limited multimedia capabilities, with the sending terminal (21) adapted to include a user agent (21a) for inserting, into the message, media characteristics of the message sufficient in detail to enable the messaging server (22) to determine whether the message should be transcoded based on actual or assumed multimedia capabilities of the receiving terminal (25), and with the messaging server (22) configured to read the media characteristics and decide whether the message should be transcoded based only on the inserted media characteristics and on actual or assumed multimedia capabilities of the receiving terminal (25). The media characteristics are advantageously inserted into the header of the message.

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.