A comprehensive video codec comparison

In this paper, we compare the video codecs AV1 (version 1.0.0-2242 from August 2019), HEVC (HM and x265), AVC (x264), the exploration software JEM which is based on HEVC, and the VVC (successor of HEVC) test model VTM (version 4.0 from February 2019) under two fair and balanced configurations: All Intra for the assessment of intra coding and Maximum Coding Efficiency with all codecs being tuned for their best coding efficiency settings. VTM achieves the highest coding efficiency in both configurations, followed by JEM and AV1. The worst coding efficiency is achieved by x264 and x265, even in the placebo preset for highest coding efficiency. AV1 gained a lot in terms of coding efficiency compared to previous versions and now outperforms HM by 24% BD-Rate gains. VTM gains 5% over AV1 in terms of BD-Rates. By reporting separate numbers for JVET and AOM test sequences, it is ensured that no bias in the test sequences exists. When comparing only intra coding tools, it is observed that the complexity increases exponentially for linearly increasing coding efficiency

goDASH - GO accelerated HAS framework for rapid prototyping

In this short paper, we present goDASH, an infrastructure for headless streaming of HTTP adaptive streaming (HAS) video content, implemented in the language golang, an open-source programming language supported by Google. goDASHâ s main functionality is the ability to stream HAS content without decoding actual video (headless player). This results in low memory requirements and the ability to run multiple players in a large-scale-based evaluation setup. goDASH comes complete with numerous state-of-the-art HAS algorithms, and is fully written in the Google golang language, which simplifies the implementation of new adaptation algorithms and functions. goDASH supports two transportation protocols Transmission Control Protocol (TCP) and Quick UDP Internet Connections (QUIC). The QUIC protocol is a relatively new protocol with the promise of performance improvement over the widely used TCP. We believe that goDASH is the first emulation-based HAS player that supports QUIC. The main limitation in using QUIC protocol is the need for a security certificate setup on both ends (client and server) as QUIC demands an encrypted connection. This limitation is eased by providing our own testbed framework, known as goDASHbed. This framework uses a virtual environment to serve video content locally (which allows setting security certificates) through the Mininet virtual emulation tool. As part of Mininet, goDASH can be used in conjunction with other traffic generators

Video-assisted Overtaking System enabled by V2V Communications

V2X (Vehicle-to-Everything) is a promising technology to diminish road hazards and increase driving safety. This thesis focuses in the transmission of video between vehicles (V2V, Vehicle-to-Vehicle) in an overtaking situation, helping drivers to be more aware and less error-prone in these situations. In the implementation, the vehicle reads from vehicle's CAN and GPS data to setup the system, streams his Line of Sight to the overtaking vehicle and uses DSRC as the communication technology

Generalized Rate-Distortion Functions of Videos

Customers are consuming enormous digital videos every day via various kinds of video services through terrestrial, cable, and satellite communication systems or over-the-top Internet connections. To offer the best possible services using the limited capacity of video distribution systems, these video services desire precise understanding of the relationship between the perceptual quality of a video and its media attributes, for which we term it the GRD function. In this thesis, we focus on accurately estimating the generalized rate-distortion (GRD) function with a minimal number of measurement queries. We first explore the GRD behavior of compressed digital videos in a two-dimensional space of bitrate and resolution. Our analysis on real-world GRD data reveals that all GRD functions share similar regularities, but meanwhile exhibit considerable variations across different combinations of content and encoder types. Based on the analysis, we define the theoretical space of the GRD function, which not only constructs the groundwork of the form a GRD model should take, but also determines the constraints these functions must satisfy. We propose two computational GRD models. In the first model, we assume that the quality scores are precise, and develop a robust axial-monotonic Clough-Tocher (RAMCT) interpolation method to approximate the GRD function from a moderate number of measurements. In the second model, we show that the GRD function space is a convex set residing in a Hilbert space, and that a GRD function can be estimated by solving a projection problem onto the convex set. By analyzing GRD functions that arise in practice, we approximate the infinite-dimensional theoretical space by a low-dimensional one, based on which an empirical GRD model of few parameters is proposed. To further reduce the number of queries, we present a novel sampling scheme based on a probabilistic model and an information measure. The proposed sampling method generates a sequence of queries by minimizing the overall informativeness of the remaining samples. To evaluate the performance of the GRD estimation methods, we collect a large-scale database consisting of more than $4,000$ real-world GRD functions, namely the Waterloo generalized rate-distortion (Waterloo GRD) database. Extensive comparison experiments are carried out on the database. Superiority of the two proposed GRD models over state-of-the-art approaches are attested both quantitatively and visually. Meanwhile, it is also validated that the proposed sampling algorithm consistently reduces the number of queries needed by various GRD estimation algorithms. Finally, we show the broad application scope of the proposed GRD models by exemplifying three applications: rate-distortion curve prediction, per-title encoding profile generation, and video encoder comparison

Transcodificação em tempo real de vídeo digital H.264 para codecs de nova geração

A utilização do vídeo digital tem crescido bastante nos últimos anos em diversos dispositivos. A oferta e a procura de conteúdos audiovisuais com mais qualidade devem-se muito às melhorias significativas no poder de processamento nos diversos dispositivos e ao aumento da largura de banda na Internet. A utilização de codecs de vídeo torna-se inevitável para tornar a transmissão de vídeo digital mais eficiente. O codec de vídeo H.264 continua ainda hoje a ser utilizado em diversas plataformas relacionadas com o vídeo, sendo que em alguns casos é sacrificada a qualidade de vídeo para preservar a largura de banda utilizada. Novos codecs de vídeo surgiram após o H.264 para ultrapassarem problemas que este não consegue solucionar face às exigências atuais. Este trabalho analisa detalhadamente os codecs de vídeo H.265, VP9 e AV1 que visam substituir o H.264 no âmbito de transmissões televisivas através da implementação de um sistema apto para processar em tempo real as streams produzidas pelos estúdios de televisão, com o objetivo de reduzir a largura de banda necessária para a transmissão de conteúdos audiovisuais sem sacrificar a qualidade de vídeo. Propõe-se a implementação de um sistema que transcodifica as streams de vídeo enviadas pelos estúdios de televisão para codecs de vídeo mais recentes ao invés de substituir os equipamentos necessários em cada estação televisiva. Esta implementação detalha técnicas e ferramentas de software utilizadas num protótipo experimental, seguindo-se uma fase de testes realizados para validar o propósito da utilização deste tipo de sistema. No final, conclui-se que a utilização deste sistema permite em alguns casos reduzir o débito binário do mesmo vídeo de forma considerável, mantendo o mesmo nível de qualidade de imagem.The use of digital video has grown considerably in recent years in various devices. The supply and demand for higher-quality audiovisual content is due to significant improvements in the processing power of the various devices and the increase in bandwidth on the Internet. The use of video codecs becomes inevitable to make digital video transmission more efficient. The H.264 video codec is still used in several platforms related to the video, and in some cases the quality of video is sacrificed to preserve the bandwidth. New video codecs have emerged after H.264 to overcome problems that it can’t solve today. This work analyzes in detail the video codecs H.265, VP9 and AV1 that aim to replace the H.264 in the scope of television transmissions through the implementation of a system able to process in real time the streams produced by the television studios, with the objective to reduce the bandwidth required for the transmission of audiovisual content without sacrificing video quality. It is proposed to implement a system that transcodes video streams sent by video studios to newer video codecs instead of replacing the necessary equipment on each television station. This implementation details techniques and software tools used in an experimental prototype, followed by a phase of tests performed to validate the purpose of the use of this type of system. In the end, it is concluded that the use of this system allows in some cases to reduce the bitrate of the same video while maintaining the same level of image quality