Researcher:
Özçelebi, Tanır

Profile Picture
ORCID

Job Title

PhD Student

First Name

Tanır

Last Name

Özçelebi

Name

Name Variants

Özçelebi, Tanır

Email Address

Birth Date

Filters

2004 - 200718

Advanced Search

Filter by

Settings

Researcher Of Publications: search.filters.isAuthorOfPublication.9ea56114-aaac-41c8-8c09-4cac8a31b0c0

Search Results

Now showing 1 - 10 of 18
  • Placeholder
    PublicationMetadata only
    Application QoS fairness in wireless video scheduling
    (Institute of Electrical and Electronics Engineers (IEEE), 2006) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; Sunay, Mehmet Oğuz; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; 26207; 16372; N/A
    The video pre-roll delay for filling up the client buffer can not be too long for user utility and buffer limitations in wireless point-to-multipoint streaming systems. Cross-layer design that deals with both physical and application layer aspects jointly is necessary for this purpose. We present a cross-layer optimized multiuser video adaptation and user scheduling framework for wireless video communication, where Quality-of-Service (QoS) fairness among users is provided with maximum video quality and video throughput. Both protocol layers are jointly optimized using a single Multi-Objective Optimization (MOO) framework that aims to schedule the user with the least remaining playback time and the highest video throughput (delivered video seconds per transmission slot) with maximum video quality. Experiments carried out in the IS-856 (1×EV-DO) standard and ITU pedestrian and vehicular environments demonstrate the improvements over the state-of-the-art schedulers in terms of video QoS fairness, video quality and throughput. / İstemci arabelleğini doldurmak için videodan önce gösterilen reklam gecikmesi, kablosuz noktadan çok noktaya akış sistemlerinde kullanıcı yardımcı programı ve arabellek sınırlamaları için çok uzun olamaz. Bu amaç için hem fiziksel hem de uygulama katmanı özelliklerini birlikte ele alan çapraz katman tasarımı gereklidir. Kablosuz video iletişimi için, kullanıcılar arasında Hizmet Kalitesi (QoS) adaletinin maksimum video kalitesi ve video çıkışı ile sağlandığı, katmanlar arası optimize edilmiş çok kullanıcılı bir video uyarlaması ve kullanıcı planlama çerçevesi sunuyoruz. Her iki protokol katmanı, kullanıcıyı maksimum video kalitesiyle en az kalan oynatma süresi ve en yüksek video verimi (iletim yuvası başına iletilen video saniyesi) ile programlamayı amaçlayan tek bir Çok Amaçlı Optimizasyon (MOO) çerçevesi kullanılarak ortaklaşa optimize edilmiştir. IS-856 (lxEV-DO) standardında ve ITU yaya ve araç ortamlarında gerçekleştirilen deneyler, video QoS adaleti, video kalitesi ve verim açısından en son teknoloji zamanlayıcılara göre iyileştirmeler göstermektedir.
  • Placeholder
    PublicationMetadata only
    Optimal rate and input format control for content and context adaptive video streaming
    (IEEE, 2004) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; Özçelebi, Tanır; Faculty Member; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26207; 16372; N/A
    A novel dynamic programming based technique for optimal selection of input video format and compression rate for video streaming based on "relevancy" of the content and user context is presented. The technique uses context dependent content analysis to divide the input video into temporal segments. User selected relevance levels assigned to these segments are used in formulating a constrained optimization problem, which is solved using dynamic programming. The technique minimizes a weighted distortion measure and the initial waiting time for continuous playback under maximum acceptable distortion constraints. Spatial resolution and frame rate of input video and the DCT quantization parameters are used as optimization variables. The technique is applied to encoding of soccer videos using an H.264 [1] encoder. The improvements obtained over a standard H.264 implementation are demonstrated by experimental results.
  • Placeholder
    PublicationMetadata only
    Per-GOP bitrate adaptation for H.264 compressed video sequences
    (Springer-Verlag Berlin, 2006) De Martin, Juan Carlos; Department of Computer Engineering; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; De Vito, Fabio; Özçelebi, Tanır; Civanlar, Mehmet Reha; Tekalp, Ahmet Murat; Other; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 16372; 26207
    In video transmission over packet data networks, it may be desirable to adapt the coding rate according to bandwidth availability. Classical approaches to rate adaptation are bitstream switching, requiring the storage of several pre-coded versions of a video, or layered (scalable) video coding, which has coding efficiency and/or complexity penalties. In this paper we propose a new GOP-level rate adaptation scheme for a single stream, variable target bitrate H.264 encoder; this allows each group of pictures (GOP) to be encoded at a specified bitrate. We first compare the performance of the standard H.264 rate control algorithm with the proposed one in the case of constant target bitrate. Then, we present results on how close the new technique can track a specified per-GOP target bitrate schedule. Results show that the proposed approach can obtain the desired target rates with less than 5% error.
  • Placeholder
    PublicationMetadata only
    Per-GOP bitrate adaptation for 11.264 compressed video sequences
    (Springer, 2006) De Martin, J.C.; Department of Computer Engineering; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; De Vito, Fabio; Özçelebi, Tanır; Civanlar, Mehmet Reha; Tekalp, Ahmet Murat; Other; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 16372; 26207
    In video transmission over packet data networks, it may be desirable to adapt the coding rate according to bandwidth availability. Classical approaches to rate adaptation are bitstream switching, requiring the storage of several pre-coded versions of a video, or layered (scalable) video coding, which has coding efficiency and/or complexity penalties. In this paper we propose a new GOP-level rate adaptation scheme for a single stream, variable target bitrate H.264 encoder; this allows each group of pictures (GOP) to be encoded at a specified bitrate. We first compare the performance of the standard H.264 rate control algorithm with the proposed one in the case of constant target bitrate. Then, we present results on how close the new technique can track a specified per-GOP target bitrate schedule. Results show that the proposed approach can obtain the desired target rates with less than 5% error.
  • Placeholder
    PublicationMetadata only
    Delay-distortion optimization for content-adaptive video streaming
    (Institute of Electrical and Electronics Engineers (IEEE), 2007) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 26207; 16372
    We propose a new pre-roll delay-distortion optimization (DDO) framework that allows determination of the minimum pre-roll delay and distortion while ensuring continuous playback for on-demand content-adaptive video streaming over limited bitrate networks. The input video is first divided into temporal segments, which are assigned a relevance weight and a maximum distortion level, called relevance-distortion policy, which may be specified by the user. The system then encodes the input video according to the specified relevance-distortion policy, whereby the optimal spatial and temporal resolutions and quantization parameters, also called encoding parameters, are selected for each temporal segment. The optimal encoding parameters are computed using a novel, multi-objective optimization formulation, where a relevance weighted distortion measure and pre-roll delay are jointly minimized under maximum allowable buffer size, continuous playback, and maximum allowable distortion constraints. The performance of the system has been demonstrated for on-demand streaming of soccer videos with substantial improvement in the weighted distortion without any increase in pre-roll delay over a very low-bitrate network using AVC/H.264 encoding.
  • Placeholder
    PublicationMetadata only
    An analysis of constant bitrate and constant PSNR video encoding for wireless networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2006) De Vito, F.; De Martin, J.C.; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; Sunay, Mehmet Oğuz; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; 26207; 16372; N/A
    In wireless networks, transmission of constant-quality, high bitrate video is a challenging task due to channel capacity and buffer limitations. Content adaptive rate control, is used as a solution to this problem. Instead of transmitting all of the video content at low quality, the most important content can be transmitted at high quality while still preserving an acceptable quality for the remaining segments. Furthermore, the rate control strategy inside the individual temporal segments plays a key role for the network performance and viewing quality. Although constant quality video encoding inside the temporal segments is preferable for the best viewing experience, it causes more network packet losses due to adverse bitrate fluctuations in the video stream. In cases when the network is too much loaded, it may be better to employ constant bitrate encoding for network friendliness. In this paper, a performance analysis of constant bitrate and constant peak signal-to-noise ratio encoding for content adaptive rate controlled video streaming over wireless networks is presented. Experimental results obtained using AVC/H.264 encoding in a CDMA/HDR multi-user environment with cross-layer optimized scheduling show performance comparisons of CBR and CPSNR encoding.
  • Placeholder
    PublicationMetadata only
    Cross-layer scheduling with content and packet priorities for optimal video streaming over 1xEV-DO
    (Springer-Verlag Berlin, 2006) De Martin, Juan Carlos; N/A; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; De Vito, Fabio; Sunay, Mehmet Oğuz; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; PhD Student; Other; Faculty Member; Faculty Member; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 26207; 16372
    Maximization of received video quality and application-level service fairness are the two principal objectives of multi-user wireless video streaming. The user and packet scheduling mechanisms employed are the determining factors on the communication system performance and must utilize multiple layers of the OSI protocol stack. The semantic and decodability (concealment related) importance and hence priorities of video packets can be considered at the application layer. In this paper, the use of video content and packet priorities for multi-objective optimized (MOO) scheduling in 1xEV-DO system is introduced. Rate adaptive AVC/H.264 encoding is used for content adaptation and a user with the least buffer fullness, best channel throughput and highest video packet importance is targeted for scheduling. Hence, losses are forced to occur at packets with low semantic/decodability importance. Results show that the proposed framework achieves 1-to-2 dB's better PSNR in high importance temporal regions compared to the state-of-the-art CBR encoding case.
  • Placeholder
    PublicationMetadata only
    A cross-layer approach for minimum delay content adaptive video streaming over variable bitrate channels
    (European Association for Signal Processing, 2005) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; Sunay, Mehmet Oğuz; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; 26207; 16372; N/A
    A novel cross-layer scheduling and stream switching algorithm for content and channel adaptive video streaming over 1xEV-DO (CDMA-HDR), where stream switching is done according to the receiver buffer level is presented. The instantaneous transmission rate to each user is determined by a multi-objective optimized scheduler, maximizing network throughput and individual receiver buffer levels simultaneously, while the instantaneous coding rate for each user is determined according to buffer status feedback. The transmitter always switches to the most suitable pre-optimized bitstream with minimum delay and visual distortion calculated for various channel capacity values and under constant bitrate assumption. The main target of the proposed framework is to guarantee continuous playout of the transmitted content at all user devices while providing maximum system throughput, minimum overall distortion and minimum pre-roll delay. Experimental results show that decoder buffer overflows and underflows that cause pauses in the playout are prevented as opposed to the case without stream switching.
  • Placeholder
    PublicationMetadata only
    Content and context adaptive video streaming over variable bit rate channels
    (Institute of Electrical and Electronics Engineers (IEEE), 2005) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 26207; 16372
    In this paper, a stream switching method for content and channel adaptive video streaming over variable bit rate (VBR) channels is presented. The best video coding strategy that gives minimum overall distortion and pre-roll delay at the decoder side is found by making use of semantic analysis and optimization via dynamic programming. Decoder violations originating from channel variations are dealt with by switching to the appropriate bit stream optimized for the current channel condition whenever it is necessary, providing continuous playback of the content. In this way, it is also possible to prevent the encoder side from unnecessarily congesting the network. Experimental results show that, significant improvements over the regular, single-bitstream transport (streaming) can be gained using this framework. / Bu makalede, değişken bit hızlı kanallarda içerik ve kanala göre uyarlanabilir duraksız video akımı için yeni bir teknik sunulmaktadır. Zamanda anlamsal parçalara bölünen videonun bozunumunun ve kesintisiz video oynatımını sağlayacak başlangıç bekleme süresinin, çeşitli kanal bit hızı seviyeleri esas alınarak enküçültüldüğü bu teknikte, video kodlama parametrelerinin en iyi seçimi için dinamik programlama kullanılmaktadır. Maksimum bozunum ve arabellek kısıtlamalarını dikkate alan metodumuz, kanalda oluşabilecek esaslı bit hızı değişimlerine ve bunların yol açacağı arabellek taşmaları ve bomboşalmalarına karşı uygun bit hızı için eniyilenmiş bit dizisine geçiş yapmak suretiyle videonun kodçözücü tarafında devamlı oynatılmasını sağlamaktadır. Bu şekilde kodlayıcının videoyu gereksizce yüksek bit hızında kodlayıp ağı meşgul etmesinin de önüne geçilmektedir. Deneysel sonuçlar makalenin basıma hazır uyarlamasında verilecektir.
  • Placeholder
    PublicationMetadata only
    Cross-layer design for real-time video streaming over 1xEV-DO using multiple objective optimization
    (Ieee, 2005) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Özçelebi, Tanır; Sunay, Mehmet Oğuz; Tekalp, Ahmet Murat; Civanlar, Mehmet Reha; PhD Student; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; 26207; 16372
    In wireless packet transmission systems, it is crucial to provide fairness in service while maximizing user utility and channel throughput. This is possible via intelligent allocation of system resources. For real time video applications, a pre-roll time for pre-fetching data at the client buffer is needed in order to compensate for channel variations that cause client buffer under/overflows, hence facilitating continuous playout of the video. In this paper, a novel multiple objective optimized (MOO) opportunistic multiple access scheme for optimal scheduling of users in a 1xEV-DO (IS-856) system is presented. At each time slot, the user that experiences the best compromise between the least buffer occupancy and the best channel condition is served. Experiments conducted in ITU Pedestrian A and Vehicular B environments show that our algorithm treats each user fairly while its channel throughput performance is very close to the ideal case, in which the user with the best channel characteristics is always served with no buffer constraints.