26-04-2012, 12:03 PM
Robust Video Data Hiding Using Forbidden Zone Data Hiding and Selective Embedding
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Introduction
DATA HIDING is the process of embedding information
into a host medium. In general, visual and arual media
are preferred due to their wide presence and the tolerance
of human perceptual systems involved. Although the general
structure of data hiding process does not depend on the host
media type, the methods vary depending on the nature of such
media. For instance, image and video data hiding share many
common points; however video data hiding necessitates more
complex designs [6], [7] as a result of the additional temporal
dimension. Therefore, video data hiding continues to constitute
an active research area.
Forbidden Zone Data Hiding
Forbidden zone data hiding (FZDH) is introduced in [8].
The method depends on the forbidden zone (FZ) concept,
which is defined as the host signal range where no alteration
is allowed during data hiding process. FZDH makes use of FZ
to adjust the robustness-invisibility tradeoff.
Framework
The embedding operation for a single frame is . Y-channel is utilized for data embedding. In the first
step, frame selection is performed and the selected frames
are processed block-wise. For each block, only a single bit
is hidden. After obtaining 8 × 8 DCT of the block, energy
check is performed on the coefficients that are predefined
in a mask. Selected coefficients of variable length are used
to hide data bit m. m is a member of message bits or
frame synchronization markers. Message sequence of each
group is obtained by using RA codes for T consecutive
frames. Each block is assigned to one of these groups at
the beginning. After the inverse transform host frame is
obtained.
Block Partitioning
Two disjoint data sets are embedded: message bits (m1) and
frame synchronization markers (m2). The block locations of
m2 are determined randomly depending on a random key. The
rest of the blocks are reserved for m1. The same partitioning is
used for all frames. A typical partitioning is shown in Fig. 5.
m2 is embedded frame by frame. On the other hand, m1 is
dispersed to T consecutive frames. Both of them are obtained
as the outcomes of the RA encoder.
Erasure Handling
Due to adaptive block selection, de-synchronization occurs
between embedder and decoder. As a result of attacks or even
embedding operation decoder may not perfectly determine the
selected blocks at the embedder. In order to overcome this
problem, error correction codes resilient to erasures, such as
RA codes are used in image [3] and video [2] data hiding in
previous efforts.
Conclusion
In this paper, we proposed a new video data hiding framework
that makes use of erasure correction capability of RA
codes and superiority of FZDH. The method is also robust to
frame manipulation attacks via frame synchronization markers.
First, we compared FZDH and QIM as the data hiding
method of the proposed framework. We observed that FZDH
is superior to QIM, especially for low embedding distortion
levels.