This article presents a study on the impact of video frame losses on the quality perceived by users. Video compression standards, such as MPEG, use a sequence of frames called Group of Pictures (GOP), which is a video...This article presents a study on the impact of video frame losses on the quality perceived by users. Video compression standards, such as MPEG, use a sequence of frames called Group of Pictures (GOP), which is a video compression method which a frame is expressed in terms of one or more neighboring frames. This dependence between frames impacts directly in the quality because a loss of a reference frame prevents the decoding of other frames in GOP, thereby reducing the user-perceived quality. The assessment of quality in this article is estimated by Peak Signal Noise Ratio (PSNR), which compares the original and the received images. Computer simulations were used to show that the degradation on the quality may vary for different patterns of GOPs and type of lost frames.展开更多
Packet losses usually result in frame losses in low bit rate video streaming over error prone networks. The whole frame error concealment （EC） algorithm is then necessary for the decoder to improve the video quality...Packet losses usually result in frame losses in low bit rate video streaming over error prone networks. The whole frame error concealment （EC） algorithm is then necessary for the decoder to improve the video quality. A refined bidirectional motion vector extrapolation was developed to improve the motion vector estimation precision by alleviating the effect of overlapped and hole regions with an adaptive overlapped block motion compensation to reduce block artifacts. A prescription-based framework was then developed to improve the error concealment at the encoder side. Simulations show that the EC algorithm at the decoder side outperforms the existing methods by 2-8 dB. Moreover, the prescription-based framework at the encoder side provides further peak signal to noise ratio improvement.展开更多
文摘This article presents a study on the impact of video frame losses on the quality perceived by users. Video compression standards, such as MPEG, use a sequence of frames called Group of Pictures (GOP), which is a video compression method which a frame is expressed in terms of one or more neighboring frames. This dependence between frames impacts directly in the quality because a loss of a reference frame prevents the decoding of other frames in GOP, thereby reducing the user-perceived quality. The assessment of quality in this article is estimated by Peak Signal Noise Ratio (PSNR), which compares the original and the received images. Computer simulations were used to show that the degradation on the quality may vary for different patterns of GOPs and type of lost frames.
基金Supported by the National Natural Science Foundation of China (No.60572081)
文摘Packet losses usually result in frame losses in low bit rate video streaming over error prone networks. The whole frame error concealment （EC） algorithm is then necessary for the decoder to improve the video quality. A refined bidirectional motion vector extrapolation was developed to improve the motion vector estimation precision by alleviating the effect of overlapped and hole regions with an adaptive overlapped block motion compensation to reduce block artifacts. A prescription-based framework was then developed to improve the error concealment at the encoder side. Simulations show that the EC algorithm at the decoder side outperforms the existing methods by 2-8 dB. Moreover, the prescription-based framework at the encoder side provides further peak signal to noise ratio improvement.
