Machine Learning based Efficient QT-MTT Partitioning Scheme for VVC Intra Encoders

The next-generation Versatile Video Coding (VVC) standard introduces a new Multi-Type Tree (MTT) block partitioning structure that supports Binary-Tree (BT) and Ternary-Tree (TT) splits in both vertical and horizontal directions. This new approach leads to five possible splits at each block depth and thereby improves the coding efficiency of VVC over that of the preceding High Efficiency Video Coding (HEVC) standard, which only supports Quad-Tree (QT) partitioning with a single split per block depth. However, MTT also has brought a considerable impact on encoder computational complexity. In this paper, a two-stage learning-based technique is proposed to tackle the complexity overhead of MTT in VVC intra encoders. In our scheme, the input block is first processed by a Convolutional Neural Network (CNN) to predict its spatial features through a vector of probabilities describing the partition at each 4x4 edge. Subsequently, a Decision Tree (DT) model leverages this vector of spatial features to predict the most likely splits at each block. Finally, based on this prediction, only the N most likely splits are processed by the Rate-Distortion (RD) process of the encoder. In order to train our CNN and DT models on a wide range of image contents, we also propose a public VVC frame partitioning dataset based on existing image dataset encoded with the VVC reference software encoder. Our proposal relying on the top-3 configuration reaches 46.6% complexity reduction for a negligible bitrate increase of 0.86%. A top-2 configuration enables a higher complexity reduction of 69.8% for 2.57% bitrate loss. These results emphasis a better trade-off between VTM intra coding efficiency and complexity reduction compared to the state-of-the-art solutions

Réduction de complexité de l’encodage vidéo VVC à l’aide de techniques d’apprentissage automatique

The video content visualization has been revolutionized in a decade with the emergence of new services like video on demand, video streaming, or video sharing platforms. The emerging video formats alongside with the explosion of IP video traffic require new video coding techniques that are even more efficient than existing ones. The organization JVET ISO/IEC, ITU-T standardized in July 2020 the video coding standard VVC ITU-T H.266 as a successor to HEVC. The new tools included in VVC provides almost 40% bitrate reduction but at the expense of a significant increase in encoder computational complexity estimated to 859%(x8) compared with HEVC. The research work objective is to propose complexity reduction techniques for VVC encoding while minimizing the coding quality degradation. The first contribution analyzes the possibilities of complexity reduction for the VVC encoding process depending on the encoding tools. The next contributions focus on reducing the complexity of the QT-MTT partitioning process using ML techniques. First, a CNN-based solution is developed to extract the partitioning probabilities associated with the different segments located within a CTU in the case of an AI configuration. A first complexity reduction technique exploiting this CNN and using a set of pre-computed thresholds for partitioning decisions has been defined. A second technique using a DT based ML approach for partitioning decisionmaking is proposed. Finally, a technique integrating a CNN and a DT-based ML approach is proposed in the case of an inter configuration.La visualisation de contenu vidéo a été révolutionnée en une décennie avecl’émergence de nouveaux services tels que la vidéo à la demande, le streaming vidéoou les plateformes de partage vidéo. Les nouveaux formats vidéo et l’explosion du traficvidéo IP nécessitent de nouvelles techniques de compression vidéo encore plus efficacesque les techniques existantes. L’organisation JVET ISO/IEC, ITU-T a standardiséen juillet 2020 la norme de codage vidéo VVC ITU-T H.266 comme successeur de HEVC.Les nouveaux outils inclus dans VVC permettent une réduction de près de 40% du débit mais au détriment d’une augmentation significative de la complexité de calcul de l’encodeur, estimée à 859% (x8) par rapport à HEVC.L’objectif de ce travail de recherche est de proposer des techniques de réduction de la complexité de l’encodage VVC tout en minimisant la perte de qualité du codage. La première contribution analyse les possibilités de réduction de complexité du processus d’encodage VVC en fonction des outils de codage. Les contributions suivantes se concentre sur la réduction de la complexité du processus de partitionnement en arbre QT-MTT à l’aide de techniques de ML. Tout d’abord, une solution basée sur un CNN est développée afin d’extraire les probabilités de partitionnement associées aux différents segments présents au sein d’un CTU dans le cas d’une configuration AI. Une première technique de réduction de complexité exploitant ce CNN et utilisant un ensemble de seuils pré-calculés pour les prises de décision de partitionnement a été définie. Une seconde technique utilisant une approche de ML basée sur des arbres de décision (DT) pour la prise de décision de partitionnement est proposée. Finalement, une technique intégrant un CNN et une approche de ML basée DT est proposée dans le cas d’uneconfiguration inter

A focus on the European hamster to illustrate how to monitor endangered species

International audienceAgriculture intensification, marked by the generalization of crop monoculture, by the increase in plot size and by the reduction of plant diversity, has led to huge decline in wildlife in European farmlands. In such habitat, research has long been biased towards birds and invertebrates, while very few studies have investigated the effect on small mammals. Considering the European hamster, Cricetus cricetus, we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals. We suggest that only a multidisciplinary approach will allow exploration of these effects, combining experimental laboratory work on captive-bred animals with the monitoring of wild individuals. In particular, individual energy balance has to be investigated and measured as accurately as possible, through either biochemical or bio-logging techniques. It is, indeed, the most affected physiological trait in a changing environment, as it determines both the reproductive output and the survival of the individual. We also discuss the inconvenience of capture-release approaches for such an endangered species and emphasize the disturbance that experimental protocols could impose on the hamster

Co-variations of cerebral blood volume and single neurons discharge during resting state and visual cognitive tasks in non-human primates

Summary: To better understand how the brain allows primates to perform various sets of tasks, the ability to simultaneously record neural activity at multiple spatiotemporal scales is challenging but necessary. However, the contribution of single-unit activities (SUAs) to neurovascular activity remains to be fully understood. Here, we combine functional ultrasound imaging of cerebral blood volume (CBV) and SUA recordings in visual and fronto-medial cortices of behaving macaques. We show that SUA provides a significant estimate of the neurovascular response below the typical fMRI spatial resolution of 2mm3. Furthermore, our results also show that SUAs and CBV activities are statistically uncorrelated during the resting state but correlate during tasks. These results have important implications for interpreting functional imaging findings while one constructs inferences of SUA during resting state or tasks

A 1-phytase type III effector interferes with plant hormone signaling

Plant pathogens translocate type III effector (T3E) proteins that may be recognized by plants to trigger immunity. Here, the authors show that the Xanthomonas T3E XopH possesses a novel 1-phytase activity that is required for XopH-mediated immunity of plants carrying the Bs7 resistance gene

MicroRNA-375/SEC23A as biomarkers of the <i>in vitro</i> efficacy of vandetanib

International audienc

Les résonances de 1905

Ce volume est consacré à la révolution russe de 1905-1907. Son histoire demeure encore mal connue, car elle fut souvent éclipsée par l’ombre rétrospective de celle de 1917 et son interprétation est loin d’être admise. Début d’agonie de l’autocratie, unique chance, rapidement manquée, d’une évolution vers l’État libéral, exemplaire révolution socialiste ou manifestation éclatante de l’arriération russe, la révolution de 1905 a servi sous tous les drapeaux, prophétisé tous les avenirs. Comme toutes les grandes révolutions, elle déroula des chaînes d’événements qui suivirent des rythmes différents mais qui convergèrent en un ébranlement général de l’ancien régime impérial russe.Révolution politique, sociale, nationale, elle fut, en effet, tout cela à la fois, de sorte qu’elle n’épargna aucun domaine. Aussi les travaux présentés ici s’attachent-ils avant tout à mesurer les profondes transformations qui en furent les effets directs. Mais les ondes de choc de la révolution ne s’arrêtèrent pas aux frontières de l’Empire, et c’est pourquoi l’ouvrage comporte aussi des études de la réception de l’événement à l’étranger. De même, la révolution de 1905 s’inscrivit d’emblée dans des filiations historiques européennes – mémoire de 1789, celle de 1848 – qui en firent un des grands événements fondateurs de l’Europe du XXe siècle

SDHB/SDHA immunohistochemistry in pheochromocytomas and paragangliomas : A multicenter interobserver variation analysis using virtual microscopy: A Multinational Study of the European Network for the Study of Adrenal Tumors (ENS@T)

Despite the established role of SDHB/SDHA immunohistochemistry as a valuable tool to identify patients at risk for familial succinate dehydrogenase-related pheochromocytoma/paraganglioma syndromes, the reproducibility of the assessment methods has not as yet been determined. The aim of this study was to investigate interobserver variability among seven expert endocrine pathologists using a web-based virtual microscopy approach in a large multicenter pheochromocytoma/paraganglioma cohort (n=351): (1) 73 SDH mutated, (2) 105 non-SDH mutated, (3) 128 samples without identified SDH-x mutations, and (4) 45 with incomplete SDH molecular genetic analysis. Substantial agreement among all the reviewers was observed either with a two-tiered classification (SDHB κ=0.7338; SDHA κ=0.6707) or a three-tiered classification approach (SDHB κ=0.6543; SDHA κ=0.7516). Consensus was achieved in 315 cases (89.74%) for SDHB immunohistochemistry and in 348 cases (99.15%) for SDHA immunohistochemistry. Among the concordant cases, 62 of 69 (∼90%) SDHB-/C-/D-/AF2-mutated cases displayed SDHB immunonegativity and SDHA immunopositivity, 3 of 4 (75%) with SDHA mutations showed loss of SDHA/SDHB protein expression, whereas 98 of 105 (93%) non-SDH-x-mutated counterparts demonstrated retention of SDHA/SDHB protein expression. Two SDHD-mutated extra-adrenal paragangliomas were scored as SDHB immunopositive, whereas 9 of 128 (7%) tumors without identified SDH-x mutations, 6 of 37 (∼16%) VHL-mutated, as well as 1 of 21 (∼5%) NF1-mutated tumors were evaluated as SDHB immunonegative. Although 14 out of those 16 SDHB-immunonegative cases were nonmetastatic, an overall significant correlation between SDHB immunonegativity and malignancy was observed (P=0.00019). We conclude that SDHB/SDHA immunohistochemistry is a reliable tool to identify patients with SDH-x mutations with an additional value in the assessment of genetic variants of unknown significance. If SDH molecular genetic analysis fails to detect a mutation in SDHB-immunonegative tumor, SDHC promoter methylation and/or VHL/NF1 testing with the use of targeted next-generation sequencing is advisable