Steganography. What can be hidden in images, audio recordings and video recordings other than text?

Everything can be hidden. But depending on what you mean by the word спрятать ?

1. Например, как спрятать картинку (первой изображение) в другой картинке (во втором изображении)? We take the second image of a sufficiently large size (meaning not meters, but pixels) with respect to the first (the larger, the better). It is desirable that the second image was not monophonic, but was as variegated as possible. Let the first image be, for example, 100x100px in size. And the second image, for example, 5000х5000px. Разбиваем first image by pixels. Each pixel of the first image is placed instead of every 50th pixel of the second image. As a result, we have one image - the second. But you will never “collect” the first image with your eyes and you will not say that the second is somehow strange. Hid? Hid.

2. Как спрятать картинку (изображение) в видеозаписи? Video recording is nothing more than a set of images shown to us alternately with very high speed. Due to the inertia of vision, each frame separately merges with the similar and is not distinguished by man. Therefore, it will be enough to replace any one separate frame in the video with your own picture. Of course, it is desirable that the colors, tonality, etc. it coincided with the same parameters of the frame being replaced. And, it is desirable that it replaces the frame in a dynamic video. Think you will notice such a picture? Hardly. So they hid it.

3. Ну и как спрятать видеозапись в видеозаписи? Use one of the above methods. Video recording is nothing more than a collection of images. It is possible to hide individual images of a single video in separate images of the second (see point 1). Or, insert separate images of a single video between separate images of a second video (see point 2). Success will depend on the size of the frames, the length of the video, their quality, dynamism, etc. etc.

You can hide any sequence of bytes. The size of the sequence depends only on the concealment algorithm and the size of the container.

Most of the steganographic algorithms (except the most primitive ones) do not depend on how you interpret the sequence of bytes you are trying to hide.