# Framework for Video Steganography Using Integer Wavelet Transform and JPEG Compression
## 2 Literature Review  
In this section, some of the existing steganography techniques are reviewed. These techniques include text, audio, image, and video steganography. A lot of work has been done on steganography techniques by researchers and academicians. However, there are some issues with these techniques and these issues need to be resolved to enhance the security of the communication system. Some of the techniques are explored with their pros and cons as follows:  
Using text has some advantages, like requiring less memory space, less processing time, and less cost for printing. Along with that, the growth of the internet in almost every field of life also supports text documents. In text steganography, it is very difficult to use secret keys, although secret keys improved the security level. During the embedding of secret information rewriting, spacing, modifying line height, addition, and removal of words may result in the detection of secret information. It does not work properly on public carrier files [7]. A long time ago, text steganography was widely used by many researchers. Numerous text steganography techniques have already existed. In [8], authors proposed a novel text steganography technique in Persian and Arabic texts. A vertical displacement of points in Persian and Arabic phrases has been calculated by authors for concealing secret information. Implementation of work was done in Java language. Persian and Arabic phrases have many points in them so there exist a large number of options for concealing secret information. By doing so, the concealing capacity was improved. It was very difficult to detect hidden secret information because of the lack of availability of modern OCR (Optical Character Recognition) programs for these languages. However, secret information may get lost because of the retyping of text [9]. In this work, the Least Significant Bit Matching (LSBM) technique has been proposed for greyscale images in the spatial domain. Whenever the secret information bit does not match the Least Significant Bit (LSB) of the carrier image, then +1 or \(-1\) is arbitrarily added to the resultant pixel value [10]. The irregularity effect is avoided due to the possibility of increasing or decreasing every altered pixel value being identical. LSBM works by matching the bits of the secret information and the carrier file, whereas LSB substitution works by substituting the LSB of the carrier file with secret data. This technique provides a large capacity as compared to the LSB technique. The visual quality of the stego file and robustness against image processing attacks is good in comparison with LSB. The LSB matching technique is more robust than the LSB substitution technique. LSB substitution technique just replaces the LSB bit of the carrier file with the secret information bit, while the LSB matching technique matches bits of carrier and secret file. Steganalysis of the LSB matching technique is very challenging and related to LSB substitution. In the silent part of speech, secret information can be concealed which is known as the audio steganography technique. It is the simplest technique for concealing secret information with a low capacity. In this proposed work, to find the capacity of the technique, silent intervals of speech are determined and their respective length also. Determined values are reduced by x, where \(0<x<2\)n bits and n bits represent the size of secret information that is to be concealed. During retrieval of secret information, x is calculated as mod (NewIntervalLength, 2n bits). An example is given below to understand the process of information concealing and retrieval. If value 5 is to be concealed inside the silent part of speech having size = 108, there is a need to remove 6 samples from this silent part of speech, resulting in a new length of 102 samples. For retrieving concealed information from the silent part in stego speech, a need to find mod (102, 8) = 6. These silent parts of speech remain unchanged as they generally happen in continuous sentences.