Although many data hiding methods are proposed in the literature, all of them distort the quality of the host content during data embedding. In this paper, we propose a novel data hiding method in the compressed video domain that completely preserves the image quality of the host video while embedding information into it. Information is embedded into a compressed video by simultaneously manipulating Mquant and quantized discrete cosine transform coefficients, which are the significant parts of MPEG and H.26x-based compression standards. To the best of our knowledge, this data hiding method is the first attempt of its kind. When fed into an ordinary video decoder, the modified video completely reconstructs the original video even compared at the bit-to-bit level. Our method is also reversible, where the embedded information could be removed to obtain the original video. A new data representation scheme called reverse zerorun length (RZL) is proposed to exploit the statistics of macroblock for achieving high embedding efficiency while trading off with payload. It is theoretically and experimentally verified that RZL outperforms matrix encoding in terms of payload and embedding efficiency for this particular data hiding method. The problem of video bitstream size increment caused by data embedding is also addressed, and two independent solutions are proposed to suppress this increment. Basic performance of this data hiding method is verified through experiments on various existing MPEG-1 encoded videos. In the best case scenario, an average increase of four bits in the video bitstream size is observed for every message bit embedded.

This paper proposes an efficient data representation scheme to improve the performance of a data hiding method [1] in MPEG compressed domain. Even though [1] completely preserves the quality of the modified video to that of the original (compressed) video and [1] is reversible, [1] suffers from consistent filesize increase caused by data embedding. To suppress filesize increase, reverse zerorun length (RZL) is proposed to efficiently encode the message. RZL utilizes the statistics of the macroblocks with respect to [1], and the distance between two excited macroblocks is considered to encode a message segment. RZL simultaneously achieves high payload and high embedding efficiency, thus RZL is able to suppress the filesize increase caused by data embedding. We theoretically analyzed that RZL outperformsmatrix encoding for both payload and embedding efficiency for this particular data hiding method. Experiments are also carried out to verify the theoretically deduced results, and the observed results agree with the expected outcomes.

We propose a fast transcoder from digital video (DV) to MPEG-4 in the coded domain. Since DV is interlaced sequence whereas MPEG-4 (SIF) is progressive sequence and different discrete cosine transform (DCT) mode $({\hbox {2}}\ast{\hbox {4}}\ast{\hbox {8}}{\hbox {DCT}})$ is used in DV, different compressed domain transcoding method from that of MPEG to MPEG conversion is required. We have exploited matrix conversion reflecting these properties and introduce approximation and integration of resolution conversion and quantization process. Simulation results of DV to MPEG-4 conversion show that the proposed method can achieve very fast conversion while maintaining high transcoding performance when compared with base-band transcoding and siginificant improvement over conventional method is also realized.

This paper proposes a new architecture for VASA, a single-chip MPEG-2 422P@HL CODEC LSI with multichip configuration for large scale processing beyond the HDTV level, and demonstrates its flexibility and usefulness. VASA is the world's first single-chip full-specs MPEG-2 422P@HL CODEC LSI with a multichip configuration. An LSI was successfully fabricated using the 0.13-mum eight-metal CMOS process. The architecture not only provides an MPEG-2 422P@HL CODEC but also large scale processing beyond the HDTV level for digital cinema and multiview/-angled live TV applications with a multichip configuration. The VASA implementations will lead to a new dimension in future high-quality, high-resolution digital multimedia entertainment.

In IP-based TV distribution, coding degradation is sometimes evident in critical scenes because the bit rate for compression is rather low. Prefiltering is an effective countermeasure since it replaces the coding noise with the degradation more difficult to detect visually, though it has the drawback that excessive smoothing might occur. This paper proposes a scene-adaptive method to control a prefilter separate from the encoder. By calculating block-wise motion-compensated predictive error variances and correlation coefficients, it estimates the coding noise as well as the potential improvement by prefiltering each frame, realizing a control scheme which performs prefiltering only when effective

In this work, we propose a data embedding scheme in MPEG-1/audio layer II compressed domain. Data embedding is conducted every AAU by using side information (location of sub-band allocated audio signal) as a data carrier. In general, non-zero signals concentrates in low and middle frequency bands. Therefore we utilize sub-bands that are not allocated audio signal in high frequency bands to embed information. The proposed scheme can increase payload while achieving rewritable (reversible) data, embedding by choosing appropriate parameter. We verify the basic performance of our scheme through computer simulation by using some voice and music signals

Recently, several scrambling techniques have been proposed for video digitally archived. These methods realize efficient processing by partial encryption on MPEG compressed data while keeping compatibility to MPEG format. However, they have common drawbacks expanding the entire code. Also, they have not reported on local shuffling in a frame. In this work, we propose a new video scrambling scheme on MPEG compressed domain, which shuffles a part of DC and AC coefficients by DCT in a frame. Our scheme is applicable to local region without data expansion from the original MPEG file

A novel video watermarking method is proposed, which can directly embed a watermark into a bit stream generated by an H.264 video encoder. Watermarking to encoded data provides a content provider of flexible capability to attach secret information; however it brings a drift problem. A drift compensation method has been proposed, however it requires many computations such as DCT and motion compensation. Therefore a new drift compensation method with spatiotemporal watermarking is proposed that only cancels the effect of the embedding on blocks with little motion. It achieves great reduction of computation and realizes fast and high picture quality watermarking. The computer simulation shows that degradation of picture quality is negligible compared to noises due to H.264 compression, and that the proposed method is highly resilient to frequency domain attacks

In this paper, we propose a rewritable data embedding scheme on MPEG coded data domain for content managements including DRM, content controlling and indexing. Data embedding is performed in a block by block basis, where the length of zero run and the value of dummy AC component of quantized DCT coefficients are used as a data carrier. In the detection process, we can reconstruct the MPEG coded data that is very close to the original one, which enables us not only to rewrite embedded data but also retain the original MPEG video quality. In the experiment, we show that up to a few kbits/frame data embedding without any large PSNR penalty and data recovery can be realized using typical MPEG-1 coded stream.

H.264/MPEG-4 AVC has become widely used in various applications and services because of its high coding efficiency. With the spread of H.264/MPEG-4 AVC contents, it has been strongly required to edit the H.264/MPEG-4 AVC coded contents with less computational complexity since the compression of H.264/MPEG-4 AVC requires far more processing power than other existing formats such as MPEG-4, MPEG-2. In this paper, we propose a fast frame-accurate editing method for H.264/MPEG-4 AVC contents. In the proposed method, we employed "adaptive bit allocation and GOP-length modification" and "Re-quantization scheme with drift noise management" The proposed editing method can realize frame-accurate cut and splice editing regardless of picture coding types I, P, and B. In the experiment, we could also confirm the effectiveness of the proposed method in terms of processing power and the picture quality of the edited contents when compared with conventional editing

Multimedia contents transmission and management system "VAST-web" is proposed. It employs store-and-forward transmission technique to maintain the contents quality. It also has a central management function of contents stored at remote locations so that contents query and contents pull model as well as contents push model are supported. A novel transmission protocol "SVFTP" is also introduced, which is a core technique in VAST-web. Its throughput performance is evaluated theoretically and experimentally to show it is well-suited to large volume multimedia contents transmission. Besides, its pipeline transmission capability provides VAST-web system with great flexibility for media playback.

H.264/MPEG-4 AVC (ISO/IEC 14496-10) adopted the weighted prediction which is particularly useful for coding the fade/dissolve transition scenes. This paper proposes a determination method of weighting factors for the weighted prediction. The simulation results show that over 30% bitrate savings can be achieved when compared with the conventional methods.

This paper proposes shot genre classification from MPEG compressed movies, as one of the high-level indexing methods for audio-visual contents. Through statistical analysis of low-level and mid-level audio-visual features on compressed domain, the proposed method can achieve subjectively accurate shot classification within the movies into predefined genre set, which can be applied to various content handling applications, such as summarization, navigation, editing, filtering, and so on. By feeding subjectively evaluated feature set for each shot genre into the linear machine decision tree classifier, each shot is classified at very low cost. The experimental results show that most of the shots in the movies can be classified into subjectively accurate genres, and also the dominant shot genre can correctly resolve each movie genre.

The paper proposes a novel method for automatically summarizing MPEG coded audio-video content in the compressed domain, and describing audio-video summaries in the MPEG-7 standard format. Semantically important features for summary generation are carefully analyzed, and two types of summaries, digest and highlight, are extracted. A digest extraction is based on an audio level estimation and visual features analysis, where digest shots are adaptively determined for user-specified duration by utilizing the MPEG-7 based motion features. A highlight-based summarization from TV broadcast sports programmes is achieved by analyzing audio class and audio level. The extracted summaries and related features are described by the MPEG-7 description tools. Experimental results show that the digests and highlights can be successfully extracted in various kinds of contents without a priori knowledge of content characteristics.

This paper proposes the tile size conversion method for the wavelet image transcoding gateway and a set of methods to reduce the tile boundary artifacts caused by the conversion.In the wavelet image coding system represented by JPEG2000, pictures are usually divided into one or more tiles and each tile then transformed separately. On low memory terminals such as mobile terminals, some decoders are likely to have limits on what tile sizes they can decode. Assuming a system using these limited decoders, methods were investigated for converting the tile size quickly and automatically at the gateway when image data with a non-decodable tile size is received at the gateway from another system. Furthermore, tile boundary artifacts reduction methods are investigated. This paper proposes a basic method, which creates a tiled wavelet coefficient sequence from a non-tiled wavelet coefficient sequence. This paper also verifies the validity of the proposed scheme by implementing it with a 5x3 reversible filter and a 9x7 irreversible filter.

This paper proposes a fast and efficient transcoding algorithm from MPEG-2 video to MPEG-1 video where spatial resolution reduction is involved. We use quantization parameters along with motion information of the incoming MPEG-2 video bitstream to estimate the motion vectors for MPEG-1 transcoding without any additional motion estimation process. Since such information can be directly extracted from the original MPEG-2 video bitstream, very fast transcoding can be achieved. In addition, since the proposed method is not restricted to a specific coding structure, it can be applied to various types of GOP structures. The experimental results show that the proposed method can provide approximate motion vectors to that of full range motion estimation. therefore transcoding efficiency can be increased and picture quality is enhanced when compared with the conventional fast transcoding methods.

Although NLE (nonlinear editing) becomes widely used for multimedia contents creation, its deployment for MPEG has not been exploited much due to the inter-frame coding structure of MPEG. We propose two fast algorithms in order to realize dissolve operation of MPEG coded data. One is based on the baseband method (BBM) where dissolving is performed in the pixel domain. The other uses the transformed domain method (TDM). Since motion estimation is altered due to the transition and its re-calculation process greatly increases the computational complexity, we use texture information to determine dominant motion during dissolving and avoid the motion estimation calculation. In the experiment, it is observed that fast dissolve processing using BBM can be achieved at less than half of the conventional BBM with at most 1 dB penalty. As for TDM, although it achieves the same processing speed of that of the proposed BBM, larger degradation is found due to the restricted motion accuracy.

Audio information classification becomes a very important task for such purposes as automatic keyword spotting and other content-based audio-visual query systems. In this paper, we describe a fast and accurate audio data classification method on the MPEG coded data domain. Firstly silent segments are detected using a robust approach for different recording conditions. Then the non-silent segments are classified into three types, music, speech, and applause using temporal density, bandwidth and center frequency of subband energy. In order to be robust for a variety of audio sources as much as possible, we use Bayes discriminant function for multivariate Gaussian distribution instead of manually adjusting a threshold for each discriminator. In the experiment, every one-second of MPEG audio data is classified and about 90% of audio and speech segments have been successfully detected. As for the detection speed, less than 20% of MPEG audio decoding processing power is required.

Moving object detection is a useful tool for such purposes as intelligent video browsing/analysis and video surveillance systems. Previously several algorithms have been reported on moving object detection from compressed video data. However, in these algorithms, flat regions are often falsely detected. In addition if multiple moving objects are involved, each moving object may not be identified and therefore object tracking becomes very difficult. We describe a fast moving detection and identification method from MPEG coded data. The experimental results show that each moving object is successfully identified for several surveillance sequences.

Although a GOP (group of picture) length is often fixed in MPEG, this may not guarantee the best picture quality from the point of view of coding efficiency. Furthermore, it is also well known that P-picture interval M=3 does not provide the best quality for all sequences. We propose an MPEG encoding algorithm with scene adaptive dynamic GOP structure to enhance the picture quality in the cases mentioned above. Using macroblock characteristics such as luminance activity and simple motion compensation on the activity domain, N and M values are dynamically determined.

Formerly, once the audio data is compressed, transcoding is used to scale the bit rate, where decoding and re-encoding are taking place. Therefore, data manipulation of coded data has been very complex and time consuming work. We describe three algorithms for bit rate scaling in the coded MPEG data domain. One is a bandwidth limitation method cutting higher frequency components until the target data rate is satisfied. The other two use a re-quantization process where a quantization step in each subband is modified. One of them reflects the psychoacoustic model from bit allocation information obtained in the bitstream in order to improve the bit rate scaling efficiency. The simulation results show that the re-quantization process provides a very high conversion efficiency and a nearly equal sound quality can be obtained as directly coding from PCM by reflecting the psychoacoustic model. It is also shown that a very fast scaling (factor of six) have been achieved when compared with the transcoding method.

This paper proposes a very fast and accurate scene change detection algorithm on MPEG coding parameter domain. The fast operation can be obtained by spatio-temporally subsampling coding information and by exploiting only coding parameters extracted in variable length decoding (VLD) stage, while the accurate detection is accomplished by examining the statistical characteristics of various scene changes on the coding parameter domain. The computer simulation shows that the proposed algorithm can accomplish detection more than 5 times faster than that of real-time playback for MPEG-2 video sequences using a standard workstation. It is also shown that most of abrupt scene changes, dissolve transitions, and wipe transitions have been successfully detected.

We propose rate conversion method by re-quantization in which MPEG coded video at high bit rate is converted into the MPEG bitstream at a lower bit rate without decoding to obtain the reconstructed picture. The quantization step required for re-quantization is determined by the local and global quantization steps which are closely related to the activities in the pixel domain. The simulation results show that very similar rate distortion curves to those of transcoding have been obtained, and the difference in SNR is relatively small, about 0.4 dB at 1 Mbit/s in MPEG1 using a master bitstream at 4 Mbit/s, and 1 dB at 3 Mbit/s in MPEG2 using a master at 9 Mbit/s. Since the proposed method is very simple and requires much less hardware implementation cost than transcoding, it has a significant advantage as a rate conversion tool.

Proposes a pel adaptive image restoration algorithm for coded video signals, where ringing effects near sharp edges are smoothed out and blocking effects are removed without blurring edges at the decoder. The basic idea in this algorithm is that noise in block coded images is estimated from local statistics of image and quantization information and that each pixel data is estimated adaptively using linear least mean square error method. Since local mean and local variance for each pixel are the main calculation in the proposed algorithm, it is readily adaptable to real-time image processing. The simulation examples of processed images coded by MPEG are presented to demonstrate that a significant improvement in subjective quality has been achieved.>