Thomson Licensing

Xiao Dong Gu

Zhi Chen

Qu Qing Chen

Zhibo Chen

De Bing Liu

Kai Xie

Li Zhu

Feng Xu

Ning Liao

Fan Zhang

Charles Chunaming Wang

Zhi Bo Chen

In video quality control and estimation, the joint evaluation of compression artifacts and channel artifacts is a problem. The invention considers the joint perception of both a compression artifact level D(V) and a channel artifact level D(V) in a method for calculating overall distortion in a video being affected by compression artifacts and channel artifacts. The method comprises a step of adding a compression artifact level D(V) and a summand S that is derived from log (D(V)) multiplied with a factor that decreases with increasing compression artifact level D, such as D(V)=D(V)+c&#xb7;(K&#x2212;D(V))&#xb7;log(D(V)). The result obtained is a measure for the overall distortion.

Method and device for calculating distortion of a video being affected by compression artifacts and channel artifacts

A method for estimating video quality on bit-stream level, wherein the video quality refers to a video after error concealment and the method is performed on bit-stream level before said error concealment, comprises extracting and/or calculating a plurality of global condition features from a video bit-stream, extracting and/or calculating a plurality of local effectiveness features at least for a lost MB, calculating a numeric error concealment effectiveness level for each (or at least for each lost) MB by emulating an error concealment method that is used in said error concealment, and providing the calculated error concealment effectiveness level as an estimated visible artifacts level of video quality.

Method and device for estimating video quality on bitstream level

Blur is one of the most important features related to video quality. Accurate estimating the blur level of a video is a great help to accurately evaluate the video quality. An improved method is provided for estimating the blur level of videos that are compressed by a block based codec, such as H.264/AVC, MPEG2, etc. According to the invention, local blur detection is based on macroblock (MB) edges, a content dependent weighting scheme is employed to decrease the influence from texture and when detecting local blur, the spreading of detection will stop at local minimum and maximum luminance positions.

Blur measurement in a block-based compressed image

A user terminal device, a server device, a system and a method for assessing quality of media data are described. The user terminal device is used for extracting artifact features from the media data and for communicating the features to the server device which is then used for determining a quality score using the artifacts and an artifact/quality score database accessible by the server device. The score, transmitted to the user terminal device, is presented to a user from which a subjective quality score and a request for re-determination are received which the user terminal device communicates to the server device. This in turn is used for re-determining the quality score and for transmitting back the re-determined quality score wherein the quality score is re-determined using the received artifacts, the received subjective quality score and the artifact/quality score database.

User terminal device, server device, system and method for assessing quality of media data

A method and apparatus for measuring the quality of a video is provided. The method comprises: generating a frame loss pattern of the video by indicating whether each frame in the video is lost or successfully transmitted; and evaluating the quality of the video as a function of the generated t came loss pattern.

Method and apparatus for measuring quality of video based on frame loss pattern

Accurately estimating the image quality of video is still difficult, especially when there is no reference video available. A method for determining a quality measure for a video image comprises selecting a measuring point, such as a MB, determining a context area around the measuring point, calculating a variance of pixel values in the context area, calculating a variance of pixel values in the measuring point, calculating a relation between the two variances of pixel values, and averaging said relations for a plurality of measuring points, wherein a quality measure for a video image is obtained.

Method for determining a quality measure for a video image and apparatus for determining a quality measure for a video image

An adaptive video presentation method for automatically presenting a video with stream-embed information based on content analysis of the video on a smaller display with a limited screen size is provided. The method comprises steps of determining a salient object group containing at least one salient object based on perceptual interest value of macroblocks for each frame of said video, extracting a window having a minimum size containing the salient object group for a scene of the video, characterized in that it further comprises steps of comparing size of the extracted window with the smaller display size; and presenting at least a selected area of the extracted window containing at least a part of the salient object group for the scene on the smaller display in different operation modes based on the result of the comparison steps for different motion mode for the scene of the video.

Method and device for adaptive video presentation

When for video coding Intra refresh is used, which inserts Intra coded blocks into previously Inter coded pictures, an efficiently adapted rate control method is required for error resilient video coding. A method for adaptively determining a bit budget for encoding video pictures comprises pre-analyzing each of the pictures of a group of pictures, wherein a relative complexity index is calculated for each picture, allocating bits to the pictures based on their relative complexity index and encoding each of the pictures with the allocated number of bits. The pre-analysis comprises selecting pictures for Intra refresh coding, extracting attention area information from the selected pictures, encoding at least the macroblocks of the attention area using Intra mode, calculating for each picture a complexity index, and calculating from the complexity indices of the pictures of the group a relative complexity index for each picture. Thus, a subjectively better video quality is achieved.

Method and apparatus for adaptively determining a bit budget for encoding video pictures

When video sequences are obtained from e.g. news, interviews, conferences and sports matches, flashlight often appears in the video due to photographing. When encoding the video sequence, the intensity changes a lot so that the motion estimation can not find a well-matching block in a previous picture. Accordingly, the video encoder will encode in intra mode and thereby generate much more bits than for the neighboring non-flash pictures. According to the invention, not the real flash picture is encoded in the video sequence but an artificial non-flash or de-flashed picture, and some indications and parameters are inserted into the bit stream to model the flash effect. The decoder can regenerate the flash picture by reconstructing the non-flash picture and then adding the flash effect. The number of bits required for coding flash pictures is thereby significantly reduced.

Method and apparatus for encoding a flash picture occurring in a video sequence, and for decoding corresponding data for a flash picture

The invention concerns a method for embedding video annotation data into a coded video stream. The method comprises the step of &#x2014;encapsulating said video annotation data into a unit, so-called video annotation unit, of the coded video data stream which format corresponds to at least one format used for sending the associated video data, &#x2014;inserting an identifiable synchronizing code enabling the identification of said video annotation unit into the video data stream.

Method for embedding video annotation data into a coded video stream and video recording device

International image or video coding standards uses hybrid coding, wherein a picture is separated into pixel blocks on which predictive coding, transform coding and entropy coding is employed. The transform coding is effective because the prediction error samples are correlated in the frequency domain. However, when the prediction quality is getting better and better, spatial domain coding becomes more effective than transform coding. According to the invention, it is first determined in which corner of a current block the first non-zero amplitude value is located. Based on the related zeros run length value in that block, a pre-defined scan path is selected, i.e. a context-based adaptive scan mode is used.

Method and apparatus for selecting a scan path for the elements of a block in spatial domain picture encoding and decoding

The present invention provides a salience estimation method for object-based visual attention model. The method comprises steps of segmenting the image into a plurality of objects to be estimated, extracting feature maps for each segmented object, calculating the saliences of each segmented object in a set of circles defined around a center pixel of the object based on the extracted feature maps, and integrating the saliences of each segmented object in all circles in order to achieve an overall salience estimation for each segmented object. The present invention is much more human vision inosculated and of low computing complexity.

Salience estimation for object-based visual attention model

In known video coding standards there are basically three types of pictures: I, P and B. Video sequences are usually coded in a group of picture structure wherein several P or B pictures are coded following one I picture. However, this GOP structure has some disadvantages with respect to error resilience and storage medium recording. If a P picture is lost e.g. due to transmission channel error, then the subsequent P pictures can not be reconstructed correctly, and the error will propagate temporally and cause unpleasing artifacts. This GOP structure is designed for forward play only and makes complicated a reverse play operation. According to the invention, a reversible GOP structure is used for the video encoding and decoding. The RGOP structure contains both, a forward encoding chain and a backward encoding chain. Each picture in the RGOP structure is assigned to only one of these chains and the video pictures of adjacent RGOP chains are interleaved.

Method and apparatus for encoding groups of pictures of a video sequence, each of said groups including an intra encoded picture and more than two encoded pictures

The frame following a scene cut is usually coded as an I picture. In CBR encoding, the encoder will try to keep the bit rate constant, which will often cause serious picture quality degradation at scene changes. In VBR encoding, more bits will be allocated to the first frame of the new scene and the bit rate will increase significantly for a short time. Therefore subsequent frames must be coded in 'skipped' mode, which will often cause jerk artifacts. According to the invention, in each frame belonging to a scene change period, areas are determined that have different human attention levels. In the frames (n&#x2212;1, n&#x2212;2, n&#x2212;3) located prior to the first new scene frame, to the areas having a lower attention level less bits are assigned than in the default encoding, and in the frames (n, n+1, n+2) located at and after the scene cut the thus saved bits are additionally assigned to the areas having a higher attention level.

Method and apparatus for adapting a default encoding of a digital video signal during a scene change period

Optimised bit allocation is important in video compression to increase the coding efficiency, i.e. to make optimum use of the available data rate. In view of the human visual system, a human usually pays more attention to some part of a picture rather than to other parts of that picture. Therefore the bit allocation should be optimised for different-attention picture areas (GOB). The inventive distortion-driven bit allocation scheme allocates the coding/decoding error distortion to picture areas consistently with the human visual system, and satisfies the constraint of bit rate as well. The invention uses a distortion/bitrate/rhoquantization parameter histogram analysis. Based on corresponding tables (D[QP], R[QP] and &#x3c1;[QP]), the relationships between quantization parameter, rate, distortion and percentage of non-zero coefficients for the different-attention areas are determined (PREALUTI, DISALL, RALL). Thereafter a rho-domain bit rate control is used (RDBALL) for calculating the bit allocation inside each group of macroblocks.

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Beijing, China

Xiao Dong Gu