H. Ghanei Yakhdan, M. Khademi, J. Chitizadeh,
Volume 5, Issue 1 (March 2009)
Abstract
The performance of video transmission over wireless channels is limited by the
channel noise. Thus many error resilience tools have been incorporated into the MPEG-4
video compression method. In addition to these tools, the unequal error protection (UEP)
technique has been proposed to protect the different parts in an MPEG-4 video packet with
different channel coding rates based on the rate compatible punctured convolutional
(RCPC) codes. However, it is still not powerful enough for the noisy channels. To provide
more robust MPEG-4 video transmission, this paper proposes a modified unequal error
protection technique based on the mutual information of two video frames. In the proposed
technique, the dynamic channel coder rates are determined online based on the mutual
information of two consecutive video frames. With this technique, irregular and high
motion areas that are more sensitive to errors can get more protection. Simulation results
show that the proposed technique enhances both subjective visual quality and average peak
signal to noise ratio (PSNR) about 2.5 dB, comparing to the traditional UEP method.
S. M. Marvasti Zadeh, H. Ghanei Yakhdan, Sh. Kasaei,
Volume 10, Issue 3 (September 2014)
Abstract
Sending compressed video data in error-prone environments (like the Internet and wireless networks) might cause data degradation. Error concealment techniques try to conceal the received data in the decoder side. In this paper, an adaptive boundary matching algorithm is presented for recovering the damaged motion vectors (MVs). This algorithm uses an outer boundary matching or directional temporal boundary matching method to compare every boundary of candidate macroblocks (MBs), adaptively. It gives a specific weight according to the accuracy of each boundary of the damaged MB. Moreover, if each of the adjacent MBs is already concealed, different weights are given to the boundaries. Finally, the MV with minimum adaptive boundary distortion is selected as the MV of the damaged MB. Experimental results show that the proposed algorithm can improve both objective and subjective quality of reconstructed frames without any considerable computational complexity The average PSNR in some frames of test sequences increases about 4.59, 4.44, 3.57, and 2.98 dB compared to classic boundary matching, directional boundary matching, directional temporal boundary matching, and outer boundary matching algorithm, respectively.
