Hierarchical fast selection of intraframe prediction mode in HEVC

In the new HEVC standard, there are 35 intraframe prediction modes. Therefore, real-time implementations need fast mode pre-selection to reduce the computational load of cost comparison for individual modes. In this paper, a simple technique is proposed to reduce the complexity of the Unified Intra Prediction by decreasing the mode candidate number evaluated in the Rough Mode Decision step. We call this approach hierarchical as we decrease stepwise the angles between the directions of the prediction modes that are tested. Obviously, the fast mode selection results in significant complexity reduction obtained at the cost of choosing a sub-optimum mode related to slightly reduced compression performance. In the paper, it is proposed how to calculate the trade-off between encoder complexity and compression performance, using the ratio of relative coding time reduction and average bitrate increase estimated for constant decoded video quality. Extensive experiments prove that this ratio is much higher for the proposed technique than for many other techniques from the references

Efficient coding unit size selection based on texture analysis for HEVC intra prediction

Determining the best partitioning structure for a given Coding Tree Unit (CTU) is one of the most time consuming operations within the HEVC encoder. The brute force search through quadtree hierarchy has a significant impact on the encoding time of high definition (HD) videos. This paper presents a fast coding unit size decision-taking algorithm for intra prediction in HEVC. The proposed algorithm utilizes a low complex texture analysis technique based on the local range property of a pixel in a given neighborhood. Simulation results show that the proposed algorithm achieves an average of 72.24% encoding time efficiency improvement with similar rate distortion performance compared to HEVC reference software HM12.0 for HD videos

Quality of Experience (QoE)-Aware Fast Coding Unit Size Selection for HEVC Intra-prediction

The exorbitant increase in the computational complexity of modern video coding standards, such as High Efficiency Video Coding (HEVC), is a compelling challenge for resource-constrained consumer electronic devices. For instance, the brute force evaluation of all possible combinations of available coding modes and quadtree-based coding structure in HEVC to determine the optimum set of coding parameters for a given content demand a substantial amount of computational and energy resources. Thus, the resource requirements for real time operation of HEVC has become a contributing factor towards the Quality of Experience (QoE) of the end users of emerging multimedia and future internet applications. In this context, this paper proposes a content-adaptive Coding Unit (CU) size selection algorithm for HEVC intra-prediction. The proposed algorithm builds content-specific weighted Support Vector Machine (SVM) models in real time during the encoding process, to provide an early estimate of CU size for a given content, avoiding the brute force evaluation of all possible coding mode combinations in HEVC. The experimental results demonstrate an average encoding time reduction of 52.38%, with an average Bjøntegaard Delta Bit Rate (BDBR) increase of 1.19% compared to the HM16.1 reference encoder. Furthermore, the perceptual visual quality assessments conducted through Video Quality Metric (VQM) show minimal visual quality impact on the reconstructed videos of the proposed algorithm compared to state-of-the-art approaches

Diseño de un sistema de reducción de complejidad para codificación de vídeo

Actualmente, la gran popularidad alcanzada por las aplicaciones que emplean servicios de vídeo, como las videoconferencias, o la creciente demanda de la alta definición, ya sea para la televisión o para dispositivos móviles, ha producido que la codificación de vídeo se convierta en una herramienta vital en el desarrollo de las nuevas tecnologías con el objetivo de transmitir y almacenar de forma eficiente secuencias de vídeo digital. Desde la década de los años 90, los organismos de estandarización se han encargado de desarrollar diferentes estándares de codificación de vídeo, el último de ellos se denomina HEVC. Este estándar alcanza una capacidad de compresión superior a todos los estándares previos gracias al uso de un conjunto de técnicas novedosas. No obstante, la utilización de dichas técnicas tiene como inconveniente un incremento relevante de la carga computacional producida en el proceso de codificación. En relación con este hándicap, en los últimos años se han elaborado numerosos métodos con el fin de reducir la complejidad en el proceso de codificación sin que esto implique un decremento significativo de la calidad visual o la eficiencia de compresión. En este trabajo se propone un algoritmo cuyo objetivo es reducir la complejidad asociada al estándar HEVC. El método propuesto se basa en dividir el cuadro en diferentes regiones independientes y, tras analizar las propiedades estadísticas específicas de cada región, aplicar un test de hipótesis que nos permitirá decidir el número de recursos de codificación a utilizar en cada una de ellas. Una característica esencial de nuestra propuesta será su capacidad de adaptación a lo largo del proceso de codificación a las características intrínsecamente variables de las secuencias de vídeos, teniendo en cuenta la variedad de contenido que podremos encontrar en secuencias diferentes e, incluso, los cambios habituales de contenido a lo largo de una misma secuencia. Con todo ello, puede reducirse la complejidad del codificador de vídeo de forma notable, sin producir grandes pérdidas de eficiencia de compresión. El método propuesto ha sido examinado de manera exhaustiva y se ha comparado con otros sistemas del estado del arte, empleando para ello un conjunto formado por una gran cantidad de secuencias de contenido diverso y diferentes resoluciones, comprobando que obtiene mejores resultados que los métodos comparados.Currently, the great popularity of applications employing video services such as video conferencing, or the increasing demand for high definition, either for television or for mobile devices, has produced the video encoding becomes a tool essential in the development of new technologies to transmit and efficiently store digital video sequences. Since the early 90s, standardization organizations have been commissioned to develop different video coding standards, the last one is called HEVC. This standard achieves higher compression capacity above all previous standards through the use of a set of novel techniques. However, the use of these techniques has the drawback a relevant increase in the computational load produced in the encoding process. In connection with this issue, in recent years numerous methods have been developed in order to reduce complexity in the encoding process without implying a significant decrease in visual quality and compression efficiency. This paper presents an algorithm which aims to reduce the complexity associated with HEVC standard. The proposed method is based on dividing the frame into several independent regions and, after analyzing the specific statistical properties of each region, apply a hypothesis test that will allow us to decide the number of coding resources to use in each region. An essential feature of our proposal will be its ability to adapt along the coding process to the inherently variable characteristics of video sequences, taking into account the variety of content that can be found in different sequences and even the usual changes included along one sequence. With all of this, the complexity of the video encoder can be reduce significantly, without causing great loss of compression efficiency. The proposed method has been examined thoroughly and compared with other systems of the state of the art, employing a set consisting of a large number of sequences of different contents and different resolutions, ensuring that outperforms the methods compared.Ingeniería de Sistemas Audiovisuale

Методы и алгоритмы адаптивного разбиения видеокадров на блоки кодирования в системеН.265/HEVC

Целью данной работы является разработка методов и алгоритмов, обеспечивающих существенное снижение вычислительных затрат при кодировании видеоданных в системах кодирования нового стандарта H.265/HEVC. В результате исследования разработаны новые алгоритмы быстрого разбиения видеокадра на блоки кодирования в системе видеокодирования H.265/HEVC, позволяющие снизить вычислительную сложность процесса сжатия видеоизображений более чем в 2 раза. Разработанные методы доведены до алгоритмической и программной реализации в виде библиотеки классов на языке C и включены в коммерчески распространяемый группой компаний Элекард программный продукт "Elecard Codec SDK"The goal of the work is development of methods and algorithm which provides significant reduction of computational complexity of video coding process in encoding systems under standard of video compression H.265/HEVC. As a result of this work new algorithms of frame fast splitting into coding units under standard H.265/HEVC are developed. These algorithms provides 2 times computing complexity reduction of encoding process. The results of research and development is presented as the C class library. This library is included into commercially distributed product of Elecard company "Elecard Codec SDK"