Fahmi Kammoun

A Perceptual Measure of Blocking Artifact for No-reference Video Quality Evaluation of H.264 Codec

In this paper, we propose a new, perceptually significant video quality metric to estimate the blocking effect caused by the H.264/MPEG-4 Advanced Video Coding (AVC) standard. Our method operates in the spatial domain by taking into account the local variation inside each 16 by 16 block. The proposed approach does not require high computational complexity and can be suitable for real-time evaluation. We evaluate the performance of the proposed method by using three common intermediate format sequences at different compression rates. The comparison of the obtained results was made with Suthaharans technique using the IVP database. The performance metrics, Pearson and Spearman correlation coefficients, indicate that the proposed method outperformed the approach recommended in the literature for block-based compression, and the improvement was even better for the H.264/MPEG-4 AVC standard.

Motion vectors signs encryption for H.264/AVC

Currently, research is focused on selective encryption to protect movies against attacks transmitted over a public network. This choice is taken to ensure the security of compressed data without adding an important supplemental computational time for the encryption. So the encryption module is inserted into the video compression chain. In this paper we present an encryption method based chaos inserted in the H.264/AVC chain specially for the motion vectors signs. The results will be deducted according to the values of PSNR (Peak Signal to Noise Ratio), SSIM (Structural SIMilarity) and the encryption rate. Motion vectors signs encryption (MVSE) seems being interesting to lose the visual quality of the video for Inter predicted frames since movies are sensible to the motion sign.

A no reference quality metric to measure the blocking artefacts for video sequences

The need to measure video quality arises in the development of video equipment and in the delivery and storage of video and image information. In this paper, we propose a new perceptually significant video quality metric to estimate the effect of block coding for standards H.264 AVC and MPEG2. Our method operates in the spatial domain and does not require a high complexity of computation. We evaluate the performance of the proposed method by using three sequences CIF ‘common intermediate file’ with different compression rate. We compare it with Suthaharan’s and MSU’s techniques by using ‘LIVE’ and ‘IVP’ databases. Results indicate that the proposed method outperforms Suthaharan’s and MSU techniques in H264 coder. They also indicate that our method is more effective than MSU’s and Suthaharan’s techniques for the H.264 AVC standards with the Spearman Rank Order Correlation Coefficient.

A reduced reference video quality assessment of H.264 and mpeg2 codec based on sharpness metric

In this paper, we propose a new perceptually significant video quality metric for the H.264/Motion Picture Expert Group (MPEG)-4 Advanced Video Coding (AVC) and MPEG2 standard. Ourmethod operates in the spatial domain by using the Sobel filter. The proposed approach does notrequire a high computational complexity and can be suitable for real-time evaluation. We evaluatethe performance of the proposed method by using three Common Intermediate Format sequences at dif-ferent compression rates. The comparison of the obtained results is made with some video qualitymodels using “LIVE”, “IVP” and “IRCCyN/IVC 1080i” databases. The performance metrics, i.e. Pearson and Spearman correlation coefficients, indicate that the proposed method gives a good performance inH264 and MPEG2 codec distortions with the three databases comparing with other models.

Selective encryption of CAVLC for H.264/AVC

From years ago, encryption became a necessity to transmit data securely. Like message written, fixed images or movies should be encrypted also while transmitted over a public channel. Currently, the literature is pointed to selective encryption for those types of data against attacks. Thats to say, the encryption module is inserted into the chain of video compression to reduce the computational time, ensure the security and the reduction of the amount of video data. This paper presents one method of selective encryption based on chaos for H.264/AVC video compression. It consists of the insertion of the encryption part in the entropy coding module (CAVLC: Context Adaptive Variable Length Coding). The results will be deducted according to the values of PSNR (Peak Signal to Noise Ratio), SSIM (Structural SIMilarity) and the rate of encryption. Selective Encryption CAVLC (SE-CAVLC) is interesting since it consider both Intra and Inter frame.

Joint Selective Encryption of CAVLC and Signs of Motion Vectors for H.264/AVC

Currently, researchers are orienting their effort to selective encryption in order to protect video sequences against attacks during their transmission over a public channel. The reasons for this trend are of great importance. To reduce video data amount, the video compression chain is essential and to ensure their security, while in transmission, an encryption algorithm is evident. Thus, inserting the encryption module in the video compression chain is better than applying compression and encryption separately in terms of computing time. This paper presents a chaos based encryption method inserted in the H.264 Advanced Video Coding (AVC) used for video conferencing applications. The selective encryption was applied on context adaptive variable length coding (CAVLC) and on the signs of motion vectors. The results were deducted according to the values of peak signal to noise ratio (PSNR), structural similarity (SSIM) and the encryption rate (ER). Combining selective encryption of CAVLC (SE-CAVLC) and motion vector sign encryption (MVSE) are interesting in terms of enhancing the encryption and to damage the visual quality of the decoded video for both Intra and Inter predicted frames.

Improved hierarchical lossless video coding

Lossy video coding can be achieved by using the H.264 Advanced Video Coding. Some methods have been proposed to transform this coder into a lossless one. The hierarchical lossless video coding structure with new intra algorithm prediction was proposed to reach this goal. In this paper we proposed some enhancements of this method to improve the coding efficiency. The simulation results show that the proposed enhancements reduce the total bit of the coded sequence and the execution time.

A very efficient encryption scheme for the H.264/AVC CODEC adopted in Intra prediction mode

The concept of data compression in CODECs is based on pixel prediction to avoid redundancy. For the security of data compressed with the H.264/AVC CODEC, researchers are thinking to selective encryption. This paper presents a chaos based encryption method inserted in the H.264/AVC used for video conferencing application. It consists of the encryption of Intra prediction mode. The results show that the proposed method preserves format compliance of the H.264/AVC and has a low impact on the compression ratio. It is secure and very efficient. Moreover it can be realized in real time application. The metrics used to evaluate our scheme are Peak Signal to Noise Ratio (PSNR), Structural SIMilarity (SSIM) and the Encryption Rate (ER). We also discuss the key sensitivity of our algorithm and histograms of encrypted videos.

A quality evaluation model for calculating block and blur effects generated by H.264 and MPEG2 codecs

Abstract Many factors can affect and/or compromise the quality of visual media. Most video compression standards use motion compensation and block-based encoding scheme for compression. As a result, the decoded video is altered by one or more compression artifacts, such as block effect, blur, color bleeds, buzzing, false edges, jagged motion and flickering chrominance. In this framework, we present in this paper a quality prediction model for video encoders. Our model is designed to calculate the distortions of blocking and blurring effects, which appeared from the coding operation. We also give an overall score of the two distortions. The validation of our model is done using the subjective video database “LIVE” to correlate with the judgment of the observers. Correlation indicators such as the Spearman rank correlation coefficient (SROCC) and the Pearson linear correlation coefficient (PLCC) indicate that our model gives good performance.

Improved performance of quality metrics using saliency map and CSF filter for standard coding H264/AVC

Despite the great evolution in the field of quality metrics, classical tools such as the PSNR remain useful in the field of evolution of video coding research. Our idea is to improve the limited performance of these tools using simple and well known techniques. In the quality measurement of images and video sequences, the use of the characteristics of human visual systems becomes a priority in order to have a better correlation between the objective measurement and the judgment of the observers. For this, we try to improve the performance of the two existing metrics (PSNR “Peak Signal / Noise Ratio”, DVQ “Digital Video Quality”) for the H.264 / MPEG-4 (Motion Picture Expert Group) AVC (Advanced Video Coding). This improvement is carried out by extracting the zones of interest using a saliency map and using a filtering by the contrast sensitivity function CSF. We did a study using two types of saliency map SURF (Speeded Up Robust Features) and HARRIS saliency map. We use the subjective video database “LIVE” to test the performance of our proposed idea. Performance indicators, namely Pearson (PLCC), the Spearman coefficient (SROCC) and mean squared prediction error (RMSE) indicate that SURF give best results for the distortion produced by H264 video encoding then HARRIS. Our idea is proven especially in short distances of observation.