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Suche nach „[Y.] [Pitrey]“ hat 9 Publikationen gefunden
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    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, R. Pépion, P. Le Callet, Marcus Barkowsky

    Using overlapping subjective datasets to assess the performance of objective quality metrics on Scalable Video Coding and error concealment

    Proceedings of the 2012 Fourth International Workshop on Quality of Multimedia Experience (QoMEX), Melbourne, Australia

    2012

    Abstract anzeigen

    In this paper, four subjective video datasets are presented. The considered application is Scalable Video Coding used as an error-concealment mechanism. The presented datasets explore the relations between encoding parameters and perceived quality, under different network-impairment patterns and involve error-concealment on the decoder\textquoterights side, to simulate a complete distribution channel. The datasets share a part of common configurations which enables, in the first part of the paper, to compare the outcomes from several Single Stimulus experiments and draw interesting correspondances between different types of distortion. In the second part of the paper, we analyse the performance of three common objective quality metrics on each step of the distribution channel, to identify the possible directions to be followed in order to improve their accuracy in predicting the perceived quality.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, Marcus Barkowsky, R. Pépion, P. Le Callet, H. Hlavacs

    Influence of the source content and encoding configuration on the preceived quality for scalable video coding

    Proceedings of SPIE Vol. 8291: Human Vision and Electronic Imaging XVII, San Francisco, CA, USA, no. 54

    2012

    Abstract anzeigen

    In video coding, it is commonly accepted that the encoding paramaters such as the quantization step-size have an influence on the perceived quality. When dealing with Scalable Video Coding (SVC), the parameters used to encode each layer logically have an influence on the overall perceived quality. It is also commonly accepted that using given encoding parameters, the perceived quality does not change significantly according to the encoded source content. In this paper, we evaluate the impact of both SVC coding artifacts and source contents on the quality perceived by human observers. We exploit the outcomes of two subjective experiments designed and conducted under standard conditions in order to provide reliable results. The two experiments are aligned on a common scale using a set of shared processed video sequences, resulting in a database containing the subjective scores for 60 different sources combined with 20 SVC scenarios. We analyse the performance of several source descriptors in modeling the relative behaviour of a given source content when compared to the average of other source contents.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Marcus Barkowsky, M. Blestel, M. Carnec, A. Ksentini, P. Le Callet, G. Madec, R. Monnier, J. Nezan, R. Pepion, Y. Pitrey, J-F Travers, M. Raulet, A. Untersee

    An Overview of the SVC4QoE project

    Mobile Multimedia Communications, vol. 77

    2012

    ISBN: 978-3-642-35154-9

    Abstract anzeigen

    The aim of this paper is to give an overview of the SVC4QoE project which purpose is to use Scalable Video Coding (SVC) to optimize video transmission in terms of Quality of Experience over DVB-T2 channels. The originality of this project is to consider the influence of the whole chain of processing and delivery performed on the video data in terms of user-perceived quality. The encoding process, as well as transmission, decoding and display are included in the optimization process. Particularly, the multi-layer structure of SVC is to be exploited to circumvent alterations of the video related to transmission on error-prone networks. Combining SVC with QoE thus provides a way to reduce network operating costs, while increasing the quality from the user’s point of view. Several innovations are also to be mentioned, such as the use of a real-time open-source SVC decoder, evaluation of visual quality through subjective quality assessment tests, transmission and synchronization of SVC layers on the receiver’s side, and development and integration of an end-to-end DVB-T2 chain which implements the multi-PLP (Physical Layer Pipes) functionality in an SVC context.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, P. Hummelbrunner, B. Kitzinger, S. Buchinger, Marcus Barkowsky, P. Le Callet, R. Pepion

    Influence of Shooting Conditions, Re-Encoding and Viewing Conditions on the Perceived Quality of User-Generated Videos

    Sixth International Workshop on Video Processing and Quality Metrics for Consumer Electronics - VPQM 2012 (Jan 2012; Scottsdale, AZ, USA)

    2012

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, U. Engelke, Marcus Barkowsky, R. Pépion, P. Le Callet

    Aligning Subjective Tests using a Low Cost Common Set

    QoE for Multimedia Content Sharing, Lisbon, Portugal

    2011

    Abstract anzeigen

    In this paper we use a common set between three subjective tests to build a linear mapping of the results of two tests onto the scale of one test identi ed as the reference test. We present our low-cost approach for the design of the common set and discuss the choice of the reference test. The mapping is then used to merge the outcomes of the three tests and provide an interesting comparison of the impact of coding artifacts, transmission errors and error-concealment in the context of Scalable Video Coding.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, U. Engelke, P. Le Callet, Marcus Barkowsky, R. Pépion

    Subjective Quality of SVC-coded Videos with different Error-Patterns concealed using Spatial Scalability

    Proceedings of the 3rd European Workshop on Visual Information Processing (EUVIP) 2011, Paris, France

    2011

    Abstract anzeigen

    Degradation of network performance during video transmission may lead to disturbing visual artifacts. Some packets might be lost, corrupted or delayed, making it impossible to properly decode the video data on time at the receiver. The quality of the error-concealment technique, as well as the spatial and temporal position of the artifacts have a large impact on the perceived quality after decoding. In this paper, we use the spatial scalability feature of Scalable Video Coding (SVC) for error-concealment. This enables the transmission of a lower resolution video with a higher robustness, for example using unequal error protection. Under the assumption that only the higher resolution video would be affected, we evaluated the visual impact of packet losses in a large scale subjective video quality experiment using the Absolute Category Rating method. The number of impairments, the duration, and the interval between impairments as well the quality of the encoded lower resolution video are varied in a systematic evaluation. This allows for analyzing the influence of each factor both independently and jointly.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, Marcus Barkowsky, P. Le Callet, R. Pépion

    Subjective Quality Evaluation of H.264 High-Definition Video Coding versus Spatial Up-Scaling and Interlacing

    QoE for Multimedia Content Sharing, Tampere, Finlande

    2010

    Abstract anzeigen

    The upcoming High-De nition format for video display provides high-quality content, especially when displayed on adapted devices. When combined with video coding techniques such as MPEG-4 AVC/H.264, the transmission of High-De nition video content on broadcast networks becomes possible. Nonetheless, transmitting and decoding such video content is a real challenge. Therefore, intermediate formats based on lower frame resolutions or interlaced coding are still provided to address targets with limited resources. Using these formats, the nal video quality depends on the postprocessing tools employed at the receiver to upsample and de-interlace these streams. In this paper, we compare the full-HD format to three possible scenarios to generate a full-HD stream from intermediate formats. We present the results of subjective tests that compare the visual quality of each scenario when using the same bitrate. The results show that using the same bitrate, the videos generated from lower-resolution formats reach similar quality compared to the full-HD videos.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, Marcus Barkowsky, P. Le Callet, R. Pépion

    Subjective Quality Assessment Of MPEG-4 Scalable Video Coding In a Mobile Scenario

    European Workshop on Visual Information Processing (EUVIP) 2010, Paris, France

    2010

    Abstract anzeigen

    Scalable Video Coding provides several levels of video encapsulated in a single video stream. In a transmission scenario such as broadcasting, this structure is quite advantageous as it can be used to address heterogeneous decoding targets with variable needs and requirements. However, this adaptability comes at a slight cost in coding efficiency when compared to single-layer coding. Based on subjective experiments, this cost is evaluated in this paper by comparing the new MPEG-4 Scalable Video Coding (SVC) standard with the now-established MPEG-4 AVC standard. Two scenarios are analyzed in the context of mobile transmission applications. The first scenario uses the same bitrate for SVC and AVC, leading to a slightly lower PSNR for SVC. The second scenario uses the same PSNR for SVC and AVC, leading to a slightly lower bitrate for AVC. The results of the subjective tests illustrate several interesting aspects of the relation between the performance of the two standards. First, we observe that the offset between AVC and SVC is not severe, though statistically significant in terms of user Mean Opinion Score (MOS) in such a context. Second, while adding another layer to SVC always leads to a performance loss, the impact of this loss decreases when the number of layers increases.

    DigitalF: Angewandte Informatik

    Beitrag (Sammelband oder Tagungsband)

    Y. Pitrey, Marcus Barkowsky, P. Le Callet, R. Pépion

    Evaluation of MPEG4-SVC for QoE Protection in the Context of Transmission Errors

    Proceedings of SPIE Vol. 7798: Applications of Digital Image Processing XXXIII, San Diego, CA, USA

    2010

    Abstract anzeigen

    Scalable Video Coding (SVC) provides a way to encapsulate several video layers with increasing quality and resolution in a single bitstream. Thus it is particularly adapted to address heterogeneous networks and a wide variety of decoding devices. In this paper, we evaluate the interest of SVC in a different context, which is error concealment after transmission on networks subject to packet loss. The encoded scalable video streams contain two layers with different spatial and temporal resolutions designed for mobile video communications with medium size and average to low bitrates. The main idea is to use the base layer to conceal errors in the higher layers if they are corrupted or lost. The base layer is first upscaled either spatially or temporally to reach the same resolution as the layer to conceal. Two error-concealment techniques using the base layer are then proposed for the MPEG-4 SVC standard, involving frame-level concealment and pixel-level concealment. These techniques are compared to the upscaled base layer as well as to a classical single-layer MPEG- 4 AVC/H.264 error-concealment technique. The comparison is carried out through a subjective experiment, in order to evaluate the Quality-of-Experience of the proposed techniques. We study several scenarios involving various bitrates and resolutions for the base layer of the SVC streams. The results show that SVC-based error concealment can provide significantly higher visual quality than single-layer-based techniques. Moreover, we demonstrate that the resolution and bitrate of the base layer have a strong impact on the perceived quality of the concealment.