Automatic Detection of TV Commercial Blocks in Broadcast TV Content
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1 Automatic Detection of TV Commercial Blocks in Broadcast TV Content Alexandre Ferreira Gomes work is dated because some of the assumed commercial Abstract — This paper describes in detail an algorithm characteristics are no longer valid. In this context, the main proposed for detecting TV Commercial Blocks in Broadcast TV objective of this Thesis is to design, implement and assess an Content, based on the presence or absence, in the screen, of a TV improved solution for the detection of commercials when channel logo. No pre-built database is required, as the proposed operating with current TV commercial broadcasting content. solution sets up its own collection of logos and takes into account the different types of logos that are broadcasted in a regular TV This shall be done by implementing a mechanism allowing to transmission. By distinguishing a TV channel logo from a correctly detect the beginning and the end of each commercial commercial brand logo, a final classification is assigned for each block present in the provided TV content and to generate an video shot, differentiating regular programs from commercial events report identifying all the detected commercials and the blocks. For the used test video dataset, that resulted from respective occurrence times. In the following section an recordings of three different Portuguese TV channels, a overview of some proposed methods is presented. Section III minimum accuracy of 93,9% on commercials detection was achieved; furthermore, the measured and reported processing will discuss in detail the algorithm developed with an time suggests that the proposed solution could enable real time architecture and explanation of each module. In Section IV the (i.e., while recording) detection of commercial blocks. methodology, conditions and metrics will be discussed followed by the results obtained for the algorithm. Index Terms — TV advertising; commercial blocks; shot detection; Digital on-Screen Graphics; logos detection; video II. TV COMMERCIALS CHARACTERIZATION processing. In this Section the main characteristics of TV commercials I. INTRODUCTION are exposed. HIS paper will focus on the development of an algorithm A. Legal Framework T that aims to detect TV Commercial Blocks in Broadcast In 2010, the European Parliament and the Council of the TV, based on the presence or absence, in the screen, of a TV European Union (EU) established a Directive [1] gathering a channel logo. As the global economy evolves, companies need set of rules concerning TV broadcasting activities. The to improve their marketing solutions in order to get some relevant points are the required insertion of some video and/or advantage over competitors; TV advertising commercials have audio elements to distinguish TV advertising from editorial emerged as an essential tool for achieving this goal. Television content, the imposed limit of 20% of TV advertising spots per is an important publicity space for companies and the visibility hour and the obligation of keeping the audio volume the same achieved by using this remarkable communication medium is as the remaining programs. something for what most companies fight for. Also, as it intends to capture viewers’ attention, there is a critical artistic B. Typical Structure of a Commercial Block component related, not withstanding its fundamental The typical structure of a Commercial Block is composed marketing objective. Curiously, there are two different faces by the following elements: i) Initial commercial block of the same coin struggling in this business. In first place, the separator, containing the word “Publicidade” (the Portuguese advertisers who want to check if their contracts with the word for “Advertising”); ii) TV Commercials; iii) Broadcaster broadcasters have been fulfilled, i.e., guaranteeing clauses like self-promotion; iv) Institutional commercials (specific from “which”, “when” and “how many times” some commercials the public TV channels) and vi) Final commercial block shall be broadcasted. On the other hand, the viewers who separator. In Portuguese television near 100% of the typically wish to eliminate the transmitted commercials from commercials last between 5 and 60 seconds. The exceptions their recorded TV programs or even from real-time programs. present a duration of 120 seconds. From the video content point of view, TV commercials are a C. Intrinsic characteristics of TV commercials special type of content. Their characteristics can be considered Intrinsic characteristics are those specifically related to the as intrinsic - if associated to the advertising content itself - or the process of making a commercial, notably its content extrinsic - if external to the advertising - and have been used elements, in which several advertising and marketing to build several solutions. However, some of the published techniques are applied. Some features used to attract the viewers’ attention can be analyzed and used to detect the presence of commercials; for this, well defined mathematical 2 features with a high distinguishing power from regular concluded that 99.98% of the BF sequences identified as programs are measured. Examples of intrinsic characteristics potentially belonging to commercial blocks were indeed part are: i) high scene cut rates (including hard cuts, fades and of a commercial block. However, about 15% of the overall dissolves); ii) considerable text presence (providing some key commercial blocks length was missed, notably commercial information in a clear way and in a short time is a major goal); block introduction, broadcaster self-promotions, previews and iii) audio jingles and background music; iv) the audio level the first and last commercials, because these elements were (which uses to be higher than regular content’s, despite the not separated with BFs. Sadlier et al. [3][4] developed a fact that legal framework presented in II. A is not allowing this different method to detect BFs. This solution includes two difference in EU countries anymore). main stages, the first associated to BF detection and the second corresponding to silence detection. Using this method, D. Extrinsic characteristics of TV Commercials Sadlier et al. got a 100% precision and a recall of 89.3%. The extrinsic characteristics of a commercial are those not related to the commercials’ message and content, and also not 2) Going deeper – Cut Rates to the advertising techniques themselves. These characteristics In [2] Lienhart et al. improved the detection performance of are normally related to the structure and composition of the their first solution by also detecting the presence of hard cuts commercial block. Examples of extrinsic characteristics are: i) and fades. Chen et al. [5] and Colombo et al. [6] propose commercial block separator (which is a short audiovisual similar solutions, despite the method to detect transitions is sequence that introduces or finalizes a commercial block and not the same. Colombo et al. [6] and Feng and Neuman [7] is mandatory according to the European directives); ii) the introduce the detection of dissolves, the most difficult video presence or absence of the channel logo in one of the screen transition case to deal with. In [2], some results are presented corners (as it the channel logo is typically suppressed during based on the “Cuts per Minute” feature. A false positive the commercial block); iii) black frames and silence (a detection of commercials of 0.09% and a detection of about classical hint used to detect the limits of a single commercial, 96.14% of the total commercials in the video are reported. as this type of frames are sometimes inserted at the beginning and at the end of each commercial); iv) time duration (it is a 3) Motion Analysis feature difficult to guess a priori, as multiple values have been Some authors [2][6][7] have referred that a commercial can adopted, though most commercials in the Portuguese TV be distinguished from other video content by comparing not channels have a time duration in the range of 5 to 60 seconds: only the cut rate but also the action level within each is shot, v) commercials repetition (a single TV commercial may be which is in generally higher for advertising content. For broadcast several times in a single commercial block, during a motion analysis, the most referred feature is ECR, proposed by day, a week or a month, meaning that, in a broadcast video Zabih et al. [8]. stream with enough temporal duration, any TV commercial is inevitably repeated). 4) Logo Detection The absence of TV channel logos during the commercial III. OVERVIEW OF TV COMMERCIALS DETECTION SCHEMES blocks is another characteristic that can be exploited for the In this Section, the most relevant solutions in the literature automatic detection of commercials, and several methods have targeting the detection of TV commercials are presented. been developed with interesting results. In [9] Glasberg et al. There are two main different approaches, knowledge-based propose a Static Area Descriptor for logo detection. The tests detection and repetition-based detection, which will be performed by Glasberg et al. were able to detect 90 out of 98 presented and discussed in the following. commercials; the algorithm failed with commercials containing the company logo on the screen. In [10], Albiol et A. Knowledge-based Detection al. propose a Logo Mask Extraction scheme based on the idea The knowledge-based schemes for the detection of TV that a logo exists if there is, in the image, an area with stable commercials are those based on the a priori knowledge of contours. Esen et al. [11], Mikhail et al. [12] an Ozay et al. specific characteristics. In practice, these methods tend to use [13] present more works related to automatic TV logos simultaneously both intrinsic and extrinsic characteristics. detection and recognition. Several combinations of characteristics have been exploited with appropriately designed and tested algorithms, as 5) Others presented in the following. Some works rely on background music and speech analysis [14][15][16], text detection [17][18] and still images detection 1) The First Steps – Black Frames and Silence [15].