-
دسترسی آزاد مقاله
1 - الگوریتم جدید انتخاب مُد داخل فریمی سریع در استاندارد کدگذاری ویدیویی H.264/AVC
مهناز نژادعلی مهدی جعفری مجید محمدیبا افزایش روزافزون ارتباطات ویدیویی در دستگاه‌های قابل‌حمل و کاربردی، طراحی کدکننده‌ها با میزان پیچیدگی کم و عملکرد بالا موردنیاز است. استاندارد H.264/AVC کارایی فشرده‌سازی بالاتري را نسبت به استانداردهاي قبلي ارائه مي دهد. اما این استاندارد با بکارگیری چندین تکنیک ک چکیده کاملبا افزایش روزافزون ارتباطات ویدیویی در دستگاه‌های قابل‌حمل و کاربردی، طراحی کدکننده‌ها با میزان پیچیدگی کم و عملکرد بالا موردنیاز است. استاندارد H.264/AVC کارایی فشرده‌سازی بالاتري را نسبت به استانداردهاي قبلي ارائه مي دهد. اما این استاندارد با بکارگیری چندین تکنیک کدگذاری قدرتمند، پیچیدگی کدگذار را بطور قابل ملاحظه ای افزایش می دهد. این مقاله الگوریتم جدیدی برای کاهش پیچیدگی کدگذار H.264/AVC ارائه می دهد. روش پیشنهادی از ماسک های جهت دار ساده، مُد بلوک های همسایه و تشخیص مُد تخمین داخلی 4×4 و/يا16×16 با تعيين پارامترهاي كوانتيزه به منظور انتخاب سریع مُد در پیش‌بینی به روش داخل فریمی استفاده می کند. نتایج شبیه‌سازی نشان می‌دهد که روش پیشنهادی زمان کدگذاری را ماکزیمم 29% درصد کاهش می‌دهد در حالی که تاثیر ناچیزی در کیفیت تصویر و میزان PSNR دارد. پرونده مقاله -
دسترسی آزاد مقاله
2 - Digital Video Stabilization System by Adaptive Fuzzy Kalman Filtering
Mohammad javad Tanakian Mehdi Rezaei Farahnaz MohannaDigital video stabilization (DVS) allows acquiring video sequences without disturbing jerkiness, removing unwanted camera movements. A good DVS should remove the unwanted camera movements while maintains the intentional camera movements. In this article, we propose a no چکیده کاملDigital video stabilization (DVS) allows acquiring video sequences without disturbing jerkiness, removing unwanted camera movements. A good DVS should remove the unwanted camera movements while maintains the intentional camera movements. In this article, we propose a novel DVS algorithm that compensates the camera jitters applying an adaptive fuzzy filter on the global motion of video frames. The adaptive fuzzy filter is a Kalman filter which is tuned by a fuzzy system adaptively to the camera motion characteristics. The fuzzy system is also tuned during operation according to the amount of camera jitters. The fuzzy system uses two inputs which are quantitative representations of the unwanted and the intentional camera movements. Since motion estimation is a computation intensive operation, the global motion of video frames is estimated based on the block motion vectors which resulted by video encoder during motion estimation operation. Furthermore, the proposed method also utilizes an adaptive criterion for filtering and validation of motion vectors. Experimental results indicate a good performance for the proposed algorithm. پرونده مقاله -
دسترسی آزاد مقاله
3 - Joint Source and Channel Analysis for Scalable Video Coding Using Vector Quantization over OFDM System
Farid Jafarian Hassan FarsiConventional wireless video encoders employ variable-length entropy encoding and predictive coding to achieve high compression ratio but these techniques render the extremely sensitive encoded bit-stream to channel errors. To prevent error propagation, it is necessary t چکیده کاملConventional wireless video encoders employ variable-length entropy encoding and predictive coding to achieve high compression ratio but these techniques render the extremely sensitive encoded bit-stream to channel errors. To prevent error propagation, it is necessary to employ various additional error correction techniques. In contrast, alternative technique, vector quantization (VQ), which doesn’t use variable-length entropy encoding, have the ability to impede such an error through the use of fix-length code-words. In this paper, we address the problem of analysis of joint source and channel for VQ based scalable video coding (VQ-SVC). We introduce intra-mode VQ-SVC and VQ-3D-DCT SVC, which offer similar compression performance to intra-mode H.264 and 3D-DCT respectively, while offering inherent error resilience. In intra-mode VQ-SVC, 2D-DCT and in VQ-3D-DCT SVC, 3D-DCT is applied on video frames to exploit DCT coefficients then VQ is employed to prepare the codebook of DCT coefficients. In this low bitrate video codecs, high level robustness is needed against the wireless channel fluctuations. To achieve such robustness, we propose and calculate optimal codebook of VQ-SVC and optimal channel code rate using joint source and channel coding (JSCC) technique. Next, the analysis is developed for transmission of video using an OFDM system over multipath Rayleigh fading and AWGN channel. Finally, we report the performance of these schemes to minimize end-to-end distortion over the wireless channel. پرونده مقاله -
دسترسی آزاد مقاله
4 - SSIM-Based Fuzzy Video Rate Controller for Variable Bit Rate Applications of Scalable HEVC
Farhad Raufmehr Mehdi RezaeiScalable High Efficiency Video Coding (SHVC) is the scalable extension of the latest video coding standard H.265/HEVC. Video rate control algorithm is out of the scope of video coding standards. Appropriate rate control algorithms are designed for various applications t چکیده کاملScalable High Efficiency Video Coding (SHVC) is the scalable extension of the latest video coding standard H.265/HEVC. Video rate control algorithm is out of the scope of video coding standards. Appropriate rate control algorithms are designed for various applications to overcome practical constraints such as bandwidth and buffering constraints. In most of the scalable video applications, such as video on demand (VoD) and broadcasting applications, encoded bitstreams with variable bit rates are preferred to bitstreams with constant bit rates. In variable bit rate (VBR) applications, the tolerable delay is relatively high. Therefore, we utilize a larger buffer to allow more variations in bitrate to provide smooth and high visual quality of output video. In this paper, we propose a fuzzy video rate controller appropriate for VBR applications of SHVC. A fuzzy controller is used for each layer of scalable video to minimize the fluctuation of QP at the frame level while the buffering constraint is obeyed for any number of layers received by a decoder. The proposed rate controller utilizes the well-known structural similarity index (SSIM) as a quality metric to increase the visual quality of the output video. The proposed rate control algorithm is implemented in HEVC reference software and comprehensive experiments are executed to tune the fuzzy controllers and also to evaluate the performance of the algorithm. Experimental results show a high performance for the proposed algorithm in terms of rate control, visual quality, and rate-distortion performance. پرونده مقاله
رایمگ
سامانه رایمگ تمامی فرآیندهای دریافت، ارزیابی و داوری، ویراستاری، صفحه‌آرایی و انتشار الکترونیکی نشریات علمی را به انجام می‌رساند
پیوندهای سایت
مراکز مرتبط
پشتیبانی
صفحات رسمی
حقوق این وب‌سایت متعلق به سامانه مدیریت نشریات رایمگ است.
حق نشر © 1403-1396