Spyridon K. Kapotas

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A new method for high capacity data hiding in H.264 streams is presented. The proposed method takes advantage of the different block sizes used by the H.264 encoder during the inter prediction stage in order to hide the desirable data. It is a blind data hiding scheme, i.e. the message can be extracted directly from the encoded stream without the need of(More)
A new method for data hiding in H.264/AVC streams is presented. The proposed method exploits the IPCM encoded macroblocks during the intra prediction stage in order to hide the desired data. It is a blind data hiding scheme, i.e. the message can be extracted directly from the encoded stream without the need of the original host video. Moreover, the method(More)
A new technique for controlling the bit-rate of H.264 encoded sequences is presented. The technique achieves bit-rate control by dropping frames directly in the compressed domain. The dropped frames are carefully selected so as to either eliminate or cause non perceptible drift errors in the decoder. The technique suits well for H.264 encoded sequences such(More)
A new data hiding scheme for scene change detection in H.264 streams is presented. The proposed scheme takes advantage of the different block sizes used by the H.264 encoder during the inter prediction stage in order to hide the scene change information inside the encoded sequence. This information enables real time scene change detection directly from the(More)
A new method for the automatic detection of moving objects directly in the H.264 compressed domain is proposed in this paper. The method takes advantage of the multiple block sizes, which are used during the inter-mode decision by the H.264 encoder. The different blocks/sub-blocks are combined with their associated motion vectors in order to denote a moving(More)
Nowadays, Data transmission over internet is not at all secure and they are vulnerable to various attacks. So in order to prevent our valuable information we require special security measures. One of the methods for secure data transmission is cryptography where the information is protected by transforming it into unintelligible format. But we can ensure(More)
The new JVT H.264 video coding standard is becoming the dominant standard, mainly due to its high coding efficiency. Among all modules in the encoder, motion estimation plays a key role since it can significantly affect the output quality of an encoded sequence. However, motion estimation requires a significant part of the encoding time. One reason is(More)
A new technique for controlling the bitrate of H.264 encoded sequences is presented. Bitrate control is achieved by dropping frames directly in the compressed domain. The dropped frames are carefully selected so as to either eliminate or cause non perceptible drift errors in the decoder. The technique suits well H.264 encoded sequences such as movies and tv(More)
The new JVT H.264 video coding standard is becoming the dominant standard, mainly due to its high coding efficiency. Among all modules in the encoder, motion estimation plays a key role since it can significantly affect the output quality of an encoded sequence. However, motion estimation requires a significant part of the encoding time. Thus, various fast(More)
—The new JVT H.264 video coding standard uses variable block sizes ranging from 16x16 to 4x4 in interframe coding. This new feature increases significantly the coding efficiency, but results in extremely high computational complexity. This paper proposes a new fast block size selection algorithm based on a frame projection approach. This is achieved by(More)
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