Video quality

About: Video quality is a research topic. Over the lifetime, 13143 publications have been published within this topic receiving 178307 citations.

Transform domain transcoding from MPEG-2 to H.264 with interpolation drift-error compensation

Abstract: With the increasingly extensive applications of the new emerging video coding standard H.264, it inspires an urgent need to transcode the widely available MPEG-2 compressed video to H.264 format. In this paper, we investigate the issues on transcoding MPEG-2 into H.264 in transform domain with consideration of drift error due to the mismatch of motion compensation, and propose a transform domain solution to transcode MPEG-2 into H.264. We first analyze two major kinds of drifting error resulting from the mismatch of motion compensation: interpolation error and quantization error. The former is caused by the difference between the interpolation filters adopted in these two standards, thus very unique to the transform domain transcoding from MPEG-2 to H.264. Furthermore, it is identified as the dominant factor of the video quality degradation, especially in the case of small quantization parameter at high bit-rate, by extensive experimental results. As a major contribution of this paper, the close form of interpolation error is derived from transform domain. We then proposed the transcoding scheme based on quantization error drifting compensation and Interpolation error drifting compensation. Experimental results show that the proposed transform domain transcoding scheme achieves very promising performance in terms of low computational complexity and high transcoded video quality. Most importantly, its peak signal-to-noise ratio is very close to the cascaded transcoding architecture with time-consuming decoding and recoding process in pixel domain.

Efficient information hiding in H.264/AVC video coding

Abstract: This paper proposes a new real-time information hiding algorithm on latest H.264/AVC video coding standard. The information is embedded into the Trailing Ones of 4×4 blocks during the Context-based Adaptive Variable Length Coding (CAVLC) process. This algorithm is efficient with low computational complexity. The simulation results show that the degradation of video quality is negligible, and the same overall bit-stream length is maintained. Based on this information hiding method, a video subtitle transmission scheme is proposed. Under the simulation of different RTP packet loss channels, the embedded information can be well recovered. The comparison with other algorithms shows the superiority of our proposed method.

Codec and GOP Identification in Double Compressed Videos

Abstract: Video content is routinely acquired and distributed in a digital compressed format. In many cases, the same video content is encoded multiple times. This is the typical scenario that arises when a video, originally encoded directly by the acquisition device, is then re-encoded, either after an editing operation, or when uploaded to a sharing website. The analysis of the bitstream reveals details of the last compression step (i.e., the codec adopted and the corresponding encoding parameters), while masking the previous compression history. Therefore, in this paper, we consider a processing chain of two coding steps, and we propose a method that exploits coding-based footprints to identify both the codec and the size of the group of pictures (GOPs) used in the first coding step. This sort of analysis is useful in video forensics, when the analyst is interested in determining the characteristics of the originating source device, and in video quality assessment, since quality is determined by the whole compression history. The proposed method relies on the fact that lossy coding is an (almost) idempotent operation. That is, re-encoding a video sequence with the same codec and coding parameters produces a sequence that is similar to the former. As a consequence, if the second codec in the chain does not significantly alter the sequence, it is possible to analyze this sort of similarity to identify the first codec and the adopted GOP size. The method was extensively validated on a very large data set of video sequences generated by encoding content with a diversity of codecs (MPEG-2, MPEG-4, H.264/AVC, and DIRAC) and different encoding parameters. In addition, a proof of concept showing that the proposed method can also be used on videos downloaded from YouTube is reported.

Network Coding with Multi-Generation Mixing: Analysis and Applications for Video Communication

Abstract: Network Coding (NC) is an emerging networking approach that improves overall throughput over packet networks. Meanwhile, traditional NC approaches have limited advantages under certain network conditions, such as sparse connectivity and high losses; this is especially true for real-time applications. In this paper, we propose and analyze a generalized approach of network coding, which is based on Multi-Generation Mixing (MGM). As we demonstrate in this paper, MGM-based NC improves the performance of real-time data communications under scenarios of sparse connectivity and high loss rates. Under such scenarios, practical network coding not only fail to achieve any improvements; on the contrary it may lead to performance degradations. The analytical as well as the simulation studies we present in this paper show major improvements that can be achieved in situations where practical network coding is not a viable option. In particular, we demonstrate major gains in PSNR video quality under MGM-based network coding.

Adaptive disabling of deblock filtering based on a content characteristic of video information

Abstract: A method of adaptively disabling deblock filtering of video information including determining a content characteristic of the video information, and adaptively disabling deblock filtering of the video information based on the content characteristic. The content characteristic may be a content complexity, such as an average of minimum sums of absolute differences of pixel values determined during motion estimation, or the mean square error of the video information, or the number of bits used for coding the video content. The content characteristic may be other than complexity, such as motion vector information. A video information processing system including a video processing circuit which processes video information and which determines a content characteristic of the video information, and a deblocking filter circuit which adaptively disables deblock filtering of the video information based on the content characteristic.