Advanced Design Space Exploration for Joint Energy and Quality Optimization for VVC

In recent studies, it could be shown that the energy demand of Versatile Video Coding (VVC) decoders can be twice as high as comparable High Efficiency Video Coding (HEVC) decoders. A significant part of this increase in complexity is attributed to the usage of new coding tools. By using a design space exploration algorithm, it was shown that the energy demand of VVC-coded sequences could be reduced if different coding tool profiles were used for the encoding process. This work extends the algorithm with several optimization strategies, methodological adjustments to optimize perceptual quality, and a new minimization criterion. As a result, we significantly improve the Pareto front, and the rate-distortion and energy efficiency of the state-of-the-art design space exploration. Therefore, we show an energy demand reduction of up to 47% with less than 30% additional bit rate, or a reduction of over 35% with approximately 6% additional bit rate.Comment: accepted as a conference paper for Picture Coding Symposium (PCS) 202

Sweet Streams are Made of This: The System Engineer's View on Energy Efficiency in Video Communications

In recent years, the global use of online video services has increased rapidly. Today, a manifold of applications, such as video streaming, video conferencing, live broadcasting, and social networks, make use of this technology. A recent study found that the development and the success of these services had as a consequence that, nowadays, more than 1% of the global greenhouse-gas emissions are related to online video, with growth rates close to 10% per year. This article reviews the latest findings concerning energy consumption of online video from the system engineer's perspective, where the system engineer is the designer and operator of a typical online video service. We discuss all relevant energy sinks, highlight dependencies with quality-of-service variables as well as video properties, review energy consumption models for different devices from the literature, and aggregate these existing models into a global model for the overall energy consumption of a generic online video service. Analyzing this model and its implications, we find that end-user devices and video encoding have the largest potential for energy savings. Finally, we provide an overview of recent advances in energy efficiency improvement for video streaming and propose future research directions for energy-efficient video streaming services.Comment: 16 pages, 5 figures, accepted for IEEE Circuits and Systems Magazin

Beyond Bj{\o}ntegaard: Limits of Video Compression Performance Comparisons

For 20 years, the gold standard to evaluate the performance of video codecs is to calculate average differences between ratedistortion curves, also called the "Bj{\o}ntegaard Delta". With the help of this tool, the compression performance of codecs can be compared. In the past years, we could observe that the calculus was also deployed for other metrics than bitrate and distortion in terms of peak signal-to-noise ratio, for example other quality metrics such as video multi-method assessment fusion or hardware-dependent metrics such as the decoding energy. However, it is unclear whether the Bj{\o}ntegaard Delta is a valid way to evaluate these metrics. To this end, this paper reviews several interpolation methods and evaluates their accuracy using different performancemetrics. As a result, we propose to use a novel approach based on Akima interpolation, which returns the most accurate results for a large variety of performance metrics. The approximation accuracy of this new method is determined to be below a bound of 1.5%.Comment: Including submission information. This work has been accepted for IEEE International Conference on Image Processing (ICIP) 2022. Copyright may be transferred without notice, after which this version may no longer be accessibl

Extended Signaling Methods for Reduced Video Decoder Power Consumption Using Green Metadata

In this paper, we discuss one aspect of the latest MPEG standard edition on energy-efficient media consumption, also known as Green Metadata (ISO/IEC 232001-11), which is the interactive signaling for remote decoder-power reduction for peer-to-peer video conferencing. In this scenario, the receiver of a video, e.g., a battery-driven portable device, can send a dedicated request to the sender which asks for a video bitstream representation that is less complex to decode and process. Consequently, the receiver saves energy and extends operating times. We provide an overview on latest studies from the literature dealing with energy-saving aspects, which motivate the extension of the legacy Green Metadata standard. Furthermore, we explain the newly introduced syntax elements and verify their effectiveness by performing dedicated experiments. We show that the integration of these syntax elements can lead to dynamic energy savings of up to 90% for software video decoding and 80% for hardware video decoding, respectively.Comment: 5 pages, 2 figure

Optimized Decoding-Energy-Aware Encoding in Practical VVC Implementations

The optimization of the energy demand is crucial for modern video codecs. Previous studies show that the energy demand of VVC decoders can be improved by more than 50% if specific coding tools are disabled in the encoder. However, those approaches increase the bit rate by over 20% if the concept is applied to practical encoder implementations such as VVenC. Therefore, in this work, we investigate VVenC and study possibilities to reduce the additional bit rate, while still achieving low-energy decoding at reasonable encoding times. We show that encoding using our proposed coding tool profiles, the decoding energy efficiency is improved by over 25% with a bit rate increase of less than 5% with respect to standard encoding. Furthermore, we propose a second coding tool profile targeting maximum energy savings, which achieves 34% of energy savings at bitrate increases below 15%

Identification and functional characterisation of transferrin receptor shedding proteases

0\. Titel und Inhaltsverzeichnis 1\. Zusammenfassung / Summary 1 2\. Einleitung 5 3\. Ergebnisse 20 4\. Diskussion 46 5\. Material 60 6\. Methoden 65 7\. Glossar 76 8\. Literaturverzeichnis 77 9\. Anhang 95Der Transferrinrezeptor (TfR) vermittelt die Aufnahme von Eisenionen in das Zellinnere. Die transferrinbindende Domäne des TfR kann im Bereich eines molekularen Abstandshalters (Stalk) zwischen Arg-100 / Leu-101 durch eine Protease von der Membran abgespalten und als so genannter löslicher (soluble) Transferrinrezeptor (sTfR101) freigesetzt werden. Obgleich die Serumkonzentration dieses sTfR101 bei bestimmten Erkrankungen verändert sein kann und als diagnostischer Parameter Verwendung findet, sind die molekularen Grundlagen dieses Prozesses noch weitestgehend unverstanden - insbesondere ist die Identität der beteiligten Sheddingprotease(n) unbekannt. In der vorliegenden Arbeit konnte gezeigt werden, dass zwei Serinproteasen den humanen TfR spezifisch an alternativen Schnittstellen im Stalk-Bereich schneiden: Neutrophile Elastase zwischen Val-108 / Arg-109 und Cathepsin G zwischen Lys-95 / Thr-96. Im Überstand von U937-Zellen wurden zudem zwei sTfR- Formen detektiert, die sich aufgrund ihrer molekularen Masse alternativen Formen des sTfR zuordnen lassen. Aus dem Kulturüberstand der leukozytären Zelllinie HL60 wurde dagegen ein sTfR isoliert, dessen N-Terminus mit Leu-101 beginnt. Die Freisetzung des sTfR101 aus isolierten Membranen wurde genutzt, um die bei Arg-100 spaltende TfR-Sheddingprotease erstmals näher zu charakterisieren: (i) Sie ist ein integrales Membranprotein. (ii) Der Sheddingprozess ist abhängig von einer intakten Membranstruktur. (iii) Sie ist inaktiv im sauren pH-Bereich und besitzt ein Optimum bei pH 7,5. (iv) Sie wird vermutlich durch Furin oder eine furinähnliche Protease aktiviert. (v) Sie zählt zu der Klasse der Metalloproteasen, vermutlich aus der Familie der ADAMs (a disintegrin and metalloprotease). (vi) TACE / ADAM-17 kann als TfR- Sheddingprotease ausgeschlossen werden, da die Protease durch TIMP-1 (tissue inhibitor of metalloproteinases), aber nicht TIMP-2 oder TIMP-3 inhibiert wurde. Zur Untersuchung des TfR-Sheddings im Zellsystem wurde ein ELISA optimiert, mit dessen Hilfe sTfR spezifisch im Kulturüberstand von leukozytären Zelllinien detektiert und quantifiziert wurde. Diese Ergebnisse bestätigten die Inhibitionsversuche, die mit Hilfe des Membranassays durchgeführt wurden. Weiterhin konnte festgestellt werden, dass der Freisetzungsprozess des sTfR101 in den Zellen konstitutiv abläuft, und als einziges, eindeutig das TfR-Shedding stimulierende Reagenz wurde der Tyrosinphosphataseinhibitor Pervanadat ermittelt. Biotinylierungsexperimente an leukozytären Zelllinien zeigten, dass der TfR zunächst auf der Zelloberfläche erscheinen muss, bevor er dem Sheddingprozess unterliegt - folglich nicht bereits auf dem Biosyntheseweg gespalten wird. Da PMA keinen reduzierenden Einfluss auf das Shedding der Zelllinien zeigte, kann die Plasmamembran der Zellen als Ort des Sheddings vermutlich ausgeschlossen werden. Auch der endosomale Recyclingweg erscheint aus den Ergebnissen dieser Arbeit unwahrscheinlich, da die TfR-Sheddingprotease nicht im sauren pH- Bereich aktiv ist.The transferrin receptor (TfR) mediates the cellular uptake of iron. The transferrin-binding extracellular domain of the receptor is cleaved in the stalk region between Arg-100 / Leu-101 by a protease and released as soluble TfR (sTfR101). Although the serum concentration of sTfR101 is altered in certain diseases and used as diagnostic parameter, the molecular basis of this process is largely unknown - in particular the identity of the protease involved is unknown. In the present work two proteases, which specifically cleave the human TfR in the stalk region were identified: neutrophil elastase between Val-108 / Arg-109 and cathepsin G between Lys-95 / Thr-96. These cleavage sites are in the near vicinity of the major cleavage site and have not been previously described. The assumption that alternative cleavage sites are present in vivo is supported by the observation in this work that two sTfR types occur in the supernatant of U937 cells. These sTfR types were classified as alternative sTfR because of their apparent molecular mass. In contrast the N-terminus of the sTfR isolated from HL60 cell culture supernatant was shown to start with Leu-101. After incubation of the membranes at 37 °C the sTfR101 was shed and used to establish an assay which would allow the involved protease to be characterised: (i) the protease is anchored to the membrane by an integral domain, (ii) TfR-shedding depends on an intact membrane structure, (iii) the protease is inactive at acidic pH with an optimum at pH 7.5, (iv) the protease is probably activated by furin or a furin-like pro-protein convertase, (v) the protease belongs to the metalloproteases, probably the ADAM-family (a disintegrin and metalloprotease) and (vi) TACE / ADAM-17 can be excluded, since the protease is inhibited by TIMP-1 (tissue inhibitor of metalloproteinases-1) but not TIMP-2 or TIMP-3. The TfR-shedding by leukocytic cell lines was determined in a specific ELISA optimised for quantifying sTfR in cell culture supernatant. The investigations revealed that the results of the inhibition experiments obtained by means of the membrane assay are in agreement with the cell system. Furthermore it was shown that the TfR-shedding process is mediated constitutively and the only reagent tested that stimulates TfR-shedding is the tyrosine phosphatase inhibitor pervandate. Since the localisation of TfR-shedding is unresolved, biotinylation experiments with leukocytic cell lines were performed. These experiments clearly show that the TfR must appear at the cell surface before it is shed - thus it is not cleaved during the biosynthetic pathway. The induced internalisation of the TfR by the phorbol ester PMA did not reduce TfR-shedding in the cell lines, the plasma- membrane can thus be excluded as the site of the TfR-shedding event. Furthermore the endosomal recycling pathway may also be excluded since the TfR-shedding protease is not active at acidic pH

Monoterpenes as novel substrates for oxidation and halo-hydroxylation with chloroperoxidase from Caldariomyces fumago

Chloroperoxidase (CPO) from Caldariomyces fumago was analysed for its ability to oxidize ten different monoterpenes with hydrogen peroxide as oxidant. In the absence of halide ions geraniol and, to a lesser extent, citronellol and nerol were converted into the corresponding aldehydes, whereas terpene hydrocarbons did not serve as substrates under these conditions. In the presence of chloride, bromide and iodide ions, every terpene tested was converted into one or more products. (1S)-(+)-3-carene was chosen as a model substrate for the CPO-catalysed conversion of terpenes in the presence of sodium halides. With chloride, bromide and iodide, the reaction products were the respective (1S,3R,4R,6R)-4-halo-3,7,7-trimethyl-bicyclo[4.1.0]-heptane-3-ols, as identified by 1H and 13C nuclear magnetic resonance. These product formations turned out to be strictly regio- and stereoselective and proceeded very rapidly and almost quantitatively. Initial specific activities of halohydrin formation increased from 4.22 U mg−1 with chloride to 12.22 U mg−1 with bromide and 37.11 U mg−1 with iodide as the respective halide ion. These results represent the first examples of the application of CPO as a highly efficient biocatalyst for monoterpene functionalization. This is a promising strategy for ‘green’ terpene chemistry overcoming drawbacks usually associated with cofactor-dependent oxygenases, whole-cell biocatalysts and conventional chemical methods used for terpene conversions