The amount of data is a measure of the amount of data. The basic unit of data amount is the bit. Data are used for storing and transmitting information, bearing in mind that the information content of a message is not equal to the amount of data, even if is often used in this context, the word information when data are meant. The information content, in contrast to the amount of data can not be read immediately, and there are different approaches to determine him. The amount of data that is stored in a file is referred to as file size. For storage media, the amount of data to indicate the free and the maximum storable data volume (capacity) is used. Wikipedia
Useful informatoin for dataset / data volume of a live stream can be found in Video-Compression.