About TV Stream Macro-Segmentation: Approaches and Results

International audienceIn the last few decades, digital TV broadcasting has witnessed a huge interest from users against the traditional analog transmission. Many facilities have been already provided for capturing, storing, and sharing digital video content. However, navigating within TV streams is still considered as an important challenge to be faced. From a user point of view, a TV stream is represented as a sequence of programs (P) and breaks (B). While from a signal point of view, this stream is seen as a continuous flow of video and audio frames, with no external markers of the start and the end points of the included programs and no apparent structure. Most TV streams have no associated metadata to describe their structure, except the program guides produced by the TV channels. These program guides lack precision, since the TV channels cannot predict the exact duration of live programs for example. In addition, they don't provide any information about breaks like commercials or trailers. To cope with this problem, TV stream macro-segmentation or structuring has been proposed as a promising solution in the domain of video indexing. TV stream macro-segmentation consists in precisely detecting the first and the last frames of all programs and breaks (commercials, trailers, station identification, bumpers…) of a given stream, and then in annotating all these segments with some metadata. This can be performed by (1) analyzing the metadata provided with the stream (EPG, EIT…), or (2) analyzing the audio-visual stream to detect the precise start and end of programs and breaks. In this chapter we aim at providing a survey of the existing approaches in this field. Then, we discuss and compare the results of the different approaches to see how to benefit from the advantages and to overcome the limitations of each of them