Abstract: In H.264/AVC video encoding, rate-distortion
optimization for mode selection plays a significant role to achieve
outstanding performance in compression efficiency and video quality.
However, this mode selection process also makes the encoding
process extremely complex, especially in the computation of the ratedistortion
cost function, which includes the computations of the sum
of squared difference (SSD) between the original and reconstructed
image blocks and context-based entropy coding of the block. In this
paper, a transform-domain rate-distortion optimization accelerator
based on fast SSD (FSSD) and VLC-based rate estimation algorithm
is proposed. This algorithm could significantly simplify the hardware
architecture for the rate-distortion cost computation with only
ignorable performance degradation. An efficient hardware structure
for implementing the proposed transform-domain rate-distortion
optimization accelerator is also proposed. Simulation results
demonstrated that the proposed algorithm reduces about 47% of total
encoding time with negligible degradation of coding performance.
The proposed method can be easily applied to many mobile video
application areas such as a digital camera and a DMB (Digital
Multimedia Broadcasting) phone.
Abstract: A simple but effective digital watermarking scheme
utilizing a context adaptive variable length coding (CAVLC) method
is presented for wireless communication system. In the proposed
approach, the watermark bits are embedded in the final non-zero
quantized coefficient of each DCT block, thereby yielding a potential
reduction in the length of the coded block. As a result, the
watermarking scheme not only provides the means to check the
authenticity and integrity of the video stream, but also improves the
compression ratio and therefore reduces both the transmission time
and the storage space requirements of the coded video sequence. The
results confirm that the proposed scheme enables the detection of
malicious tampering attacks and reduces the size of the coded H.264
file. Therefore, the current study is feasible to apply in the video
applications of wireless communication such as 3G system
Abstract: Multimedia information availability has increased
dramatically with the advent of video broadcasting on handheld
devices. But with this availability comes problems of maintaining the
security of information that is displayed in public. ISMA Encryption
and Authentication (ISMACryp) is one of the chosen technologies for
service protection in DVB-H (Digital Video Broadcasting-
Handheld), the TV system for portable handheld devices. The
ISMACryp is encoded with H.264/AVC (advanced video coding),
while leaving all structural data as it is. Two modes of ISMACryp are
available; the CTR mode (Counter type) and CBC mode (Cipher
Block Chaining) mode. Both modes of ISMACryp are based on 128-
bit AES algorithm. AES algorithms are more complex and require
larger time for execution which is not suitable for real time
application like live TV. The proposed system aims to gain a deep
understanding of video data security on multimedia technologies and
to provide security for real time video applications using selective
encryption for H.264/AVC. Five level of security proposed in this
paper based on the content of NAL unit in Baseline Constrain profile
of H.264/AVC. The selective encryption in different levels provides
encryption of intra-prediction mode, residue data, inter-prediction
mode or motion vectors only. Experimental results shown in this
paper described that fifth level which is ISMACryp provide higher
level of security with more encryption time and the one level provide
lower level of security by encrypting only motion vectors with lower
execution time without compromise on compression and quality of
visual content. This encryption scheme with compression process
with low cost, and keeps the file format unchanged with some direct
operations supported. Simulation was being carried out in Matlab.
Abstract: In this paper, we propose a reversible watermarking
scheme based on histogram shifting (HS) to embed watermark bits
into the H.264/AVC standard videos by modifying the last nonzero
level in the context adaptive variable length coding (CAVLC) domain.
The proposed method collects all of the last nonzero coefficients (or
called last level coefficient) of 4×4 sub-macro blocks in a macro
block and utilizes predictions for the current last level from the
neighbor block-s last levels to embed watermark bits. The feature of
the proposed method is low computational and has the ability of
reversible recovery. The experimental results have demonstrated that
our proposed scheme has acceptable degradation on video quality and
output bit-rate for most test videos.