Experiments with digital video playback

Digital video playback on mobile devices is fast becoming widespread and popular. Since mobile devices are typically resource constrained in terms of network bandwidth, battery power and available screen resolution, it is often necessary to formulate special encoding techniques in order to optimize power consumption during video streaming and playback. The existing H.264 standard is popular for video encoding on mobile devices, since it results in a low-bitrate video with visual clarity that is adequate for video playback on mobile devices. However, due to the complexity of the H.264 representation, the video decoding procedure is typically computationally intensive. In this paper, we propose a novel lossy video representation termed as Ligne-Claire (LC) video. LC videos are obtained via graphics overlay of outlines or silhouettes of objects in the video over an approximated texture video. Since the playback of LC video is typically meant for mobile devices, the visual quality of video is adequate for most mobile applications wherein the semantic content of the video can be characterized by object shapes and approximate texture information. Experimental results presented in the paper demonstrate that the proposed lossy LC video encoding scheme results in power savings of 50% or more during video playback compared to standard H.264-encoded videos, of similar video file size. In order to evaluate the visual quality of the LC video, we compare the performance of LC videos with H.264-encoded videos in the context of some typical computer vision tasks. Our results indicate that the performance of the computer vision algorithms on these videos is similar. This fact, coupled with subjective evaluation, and the resulting significant power savings, indicates that the proposed LC representation can be used effectively to encode video for power-constrained mobile devices.

This paper describes the architecture, functionality, and design of HDVO-a high definition video co-processor from Philips Semiconductors. The coprocessor design is modular and functionally complete, and is intended to be a part of and function as the primary picture/video composition hardware in any media-processor chip targeted at Digital Television (DTV) applications. Essentially a screen-refresh engine, HDVO can mix multiple video and graphics planes and is capable of scaling vertically and horizontally pictures of the highest resolution (1920/spl times/1080) specified in the DTV standard prescribed by the United States Advanced Television Systems Committee (ATSC). HDVO can efficiently process all (eighteen) ATSC video formats, including video generation for picture-in-picture display, and is currently being wed as an on-chip video coprocessor in the TM-2700 digital television chip. TM-8700 is the second generation of an architectural family of programmable multimedia processors from Philips Semiconductors and it not only supports all ATSC formats, from standard-definition to wide-angle high-definition video, but has also the power to handle High-Definition Television (HDTV) video and audio source decoding (high-level MPEG-2, AC-3 and ProLogic audio, closed captioning, etc.) as well as the flexibility to process advanced interactive services.

T In today's television competitive environment, quality of service is critical. For network providers, the delivered quality of service (QoS) is usually a matter of technical signal quality. However, with the current development of digital broadcasting, the quality of service that is provided to the end-user is one of the most important performance criterion. Thus, perceived image and sound quality are important and must be monitored. This paper addresses the issue of video quality monitoring in digital television networks. Many approaches to objective video quality assessment have been proposed and are being evaluated by normalization bodies. In order to build and apply in-service measurement, we propose a global model describing the whole approach and the different technical solution. Our technical solution is a double-ended with reduced reference method. Video quality assessment of digital television signals in a broadcasting network sets strong technical constraints. The reduced reference, a comparative approach, is well adapted since it has a moderate technical complexity and because it informs on any distortion in the network. The proposed method has been implemented and tested in a range of situations on simulated and real DVB networks. Three main applications are presented, network monitoring, DVB-T coverage area determination, and laboratory tests. This allows concluding that in-service measurements are the only valid measurements for end-to-end transmissions.

The H.264 video compression standard provides tools for coding improvements of at least 2 dB, in terms of PSNR, and at least 50% in bit rate savings as compared with MPEG-2 video compression standard. It is expected that the H.264/MPEG-4 AVC will take over the digital video market, replacing the use of MPEG-2 in most digital video applications. The complete migration to the new video-coding algorithm will take several years given the wide scale use of MPEG-2 in the market place today. This creates an important need for transcoding technologies for converting the large volume of existent video material from the MPEG-2 into the H.264 format and vice versa. However, given the significant differences between the MPEG-2 and the H.264 encoding algorithms, the transcoding process of such systems is much more complex to other heterogeneous video transcoding processes. In this paper, we introduce and evaluate two versions of a fast intra-frame mode decision algorithm to be used as part of a high-efficient MPEG-2 to H.264 transcoder. In this work, we utilize an architecture of pixel domain video transcoding but we use the DC coefficient of the MPEG-2 DCT 8x8 blocks. Our evaluation results show that the proposed algorithm considerably reduces the complexity involved in the intra-frame prediction.

Colour image variations produced by the change of video acquisition devices strongly affect colour appearance based recognition tasks in digital video applications. Up to date, many algorithms have been developed in order to achieve independence from different image formation factors like intensity, orientation and colour of the illumination source. We check the capability of three of these approaches to generate device independent colour representations in order to be used as a normalization step previous to the recognition process. Our previously developed color correction approach for video imagery based on Gaussian mixture models has also been tested. Experimental results show that a simple algorithm like the grayworld correction is enough for appearance based recognition under this particular kind of color variability. Similar recognition rates are obtained using our correction, with the advantage that the visual quality of normalized images is preserved. In digital video library applications, where not only recognition tasks are performed, this approach becomes much more useful.

An approach that has made possible the integration of video frequency continuous-time filters with wide dynamic range is discussed. The tuning scheme necessary to maintain the stable and accurate frequency response in the presence of temperature variations, process tolerance, and aging is described. Detailed design techniques specific to high-frequency operation are introduced to implement a 5-V, seventh-order elliptic analog magnitude filter for antialiasing in digital video applications. The filter, based on a G/sub m/-C technique, exhibits a dynamic range of 61 dB and dissipates a power of 75 mW. Ninety-two chips from various wafers and two different process runs were tested. Seventy-five percent of the fabricated chips were functional, and 63% of them met the commercial-grade specifications in spite of an error in the layout which forced the phase control circuitry to perform suboptimally.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Video parsing is a fundamental operation used in many digital video applications such as digital libraries and video servers. The accuracy and execution speed of the parsing algorithm is critical if large amounts of video data are to be processed, particularly in real-time. We present a new algorithm to reconstruct DC coefficient images of a DCT and motion compensation compressed video sequence, e.g. MPEG. The histograms of the DC coefficient images can be used to detect scene changes.

Real-time human eye recognition and tracking systems with human-computer interaction mechanism are being adopted to advance user experience in smart devices and consumer electronic systems. Eye tracking systems measure eye gaze and pupil response non-intrusively. This paper presents an analysis of pupil response to video structure and content. A consumer device that can assess user response to a video can provide better experiences with approaches such as real-time content adaptation. The first set of experiments involved presenting different video content to subjects and measuring eye response with an eye tracker. Results show that pupil constrictions and magnitude of constrictions vary with content. Significant changes in video and scene cuts led to sharp constrictions. User response to videos can provide insights that can improve subjective quality assessment metrics. This paper also presents an analysis of the pupillary response to quality changes in videos with the second set of experiments. The results of the tests show pupil constrictions for noticeable changes in perceived quality. Using real-time eye tracking systems for video analysis and quality evaluation can open a new class of applications for consumer electronic systems.

We derive a statistical graphical model of video scenes with multiple, possibly occluded objects that can be efficiently used for tasks related to video search, browsing and retrieval. The model is trained on query (target) clip selected by the user. Shot retrieval process is based on the likelihood of a video frame under generative model. Instead of using a combination of weighted Euclidean distances as a shot similarity measure, the likelihood model automatically separates and balances various causes of variability in video, including occlusion, appearance change and motion. Thus, we overcome tedious and complex user interventions required in previous studies. We use the model in the adaptive video forward application that adapts video playback speed to the likelihood of the data. The similarity measure of each candidate clip to the target clip defines the playback speed. Given a query, the video is played at a higher speed as long as video content has low likelihood, and when frames similar to the query clip start to come in, the video playback rate drops. Set of experiments o12n typical home videos demonstrate performance, easiness and utility of our application.

With the digital and networked development in information industry, people's requirements for video playback quality step up, and people put forward higher requirements to the regulatory work. After timely detecting factors which effect the quality of video playback, such as: mosaic, no sound, black field, supervision departments take corresponding measures to adjust the broadcast program which is beneficial to improve the playback quality. Among them, this article made some analysis on the static frame and black field which are important parts of the program content detection, and tells us the causes and characteristics of them. Then we design the detection method for these two kinds of phenomena by controlling the static frame and black field threshold size .Finally, we use the MATLAB program to realize the detection of the static frame and black field.

We discuss a novel approach for constructing deterministic reactive systems that revolves around a temporal model that incorporates a multiplicity of timelines. This model is central to Lingua Franca ( LF ), a polyglot coordination language and compiler toolchain we are developing for the definition and composition of concurrent components called reactors, which are objects that react to and emit discrete events. Our temporal model differs from existing models like the logical execution time (LET) paradigm and synchronous languages in that it reflects that there are always at least two distinct timelines involved in a reactive system; a logical one and a physical one—and possibly multiple of each kind. This article explains how the relationship between events across timelines facilitates reasoning about consistency and availability across components in cyber-physical systems (CPSs).

This paper presents results from a set of design sessions held in a broadcasting company. The aim of research was to find a user centered design method which includes the future users into the product development in the early stages of new product design. In this case, the products were interactive television programs and applications for digital television. The study also aims at creating a design method with the user study participants as equal research partners with the designers.

Panoramic, or 360° video streaming and playback are prime components of mixed-reality and panoramic movie-viewing experiences, they offer an immersive viewing experience, and they are becoming increasingly popular, albeit very resource-demanding. Caching of 360° video content at caches close to the user reduces content delivery delay and bandwidth consumption. In 360° video streaming, the recently proposed tiling approach allows the streaming of different parts (tiles) of the 360° content at different resolutions as opposed to monolithic single-stream transmission.We study the problem of optimal caching of 360° video streams. The difference from conventional video is that each tile may need to be cached simultaneously at multiple resolutions, since it may appear in different positions at different viewports, and the time proportions of these positions are dictated by users' viewing statistics. For example, a tile close to the center of a viewport must have high resolution, while the same tile close to the edge of another viewport can have low resolution. This leads us to a novel caching objective. Cached resolutions for each tile should be as close as possible to the required ones for each tile, according to tile viewing statistics. We study the cases of caching tile streams at different resolutions or in a layered encoding fashion. We seek to optimize an objective that combines (i) an error metric between requested and cached tile resolutions across viewports, and (ii) coverage of the tile set. For the case of multiple resolutions, we show that the problem of selecting the tile resolutions to cache so as to minimize the error metric above is equivalent to the K-Medoids problem. For layered encoding, the problem is to find the maximum-resolution layer to cache for each tile stream, and this is equivalent to a Multiple-Choice Knapsack problem. We present an implementation of the cache optimization scheme, we evaluate our model on a tiled 360° video distribution simulator and demonstrate a significant increase in cache hit ratio over conventional caching strategies.

In this paper, we propose design and implementation of a practical end-to-end system which implements multi-channel digital television (DTV) multicasting to the home over broadband community access network using sender-driven video rate adaptation and receiver-driven playback adjustment. For video rate adaptation, we employ Program Clock Reference (PCR) embedded in the MPEG-2 transport stream (TS) to enhance packet timing control precision and regulate the transmission rate in a refined way. At the same time, we integrate Traffic Control (TC) ingeniously to separate streams of multiple channels at the network card of DTV server and thus avoid bandwidth competition between them. For playback adjustment, we introduce control theory and over-boundary strategy to reduce buffer jitter and maximize the visual quality of displayed video according to the receiver buffer occupancy. We test our system with standard definition (SD) and high definition (HD) MPEG-2 streams and find that the proposed algorithms can reduce overflow and underflow of sender and receiver buffer, and achieve better video quality and more concurrent channels than traditional solutions.

MDVQM: A novel multidimensional no-reference video quality metric for video transcoding