Patent Publication Number: US-2010115558-A1

Title: Methods and devices for receiving and transmitting program listing data

Description:
FIELD OF THE INVENTION 
     The invention relates to a method of receiving program listing data. 
     The invention further relates to a method of transmitting program listing data. 
     The invention also relates to a device for receiving program listing data, the device comprising electronic circuitry. 
     The invention further relates to a device for transmitting program listing data, the device comprising electronic circuitry. 
     The invention also relates to computer program products enabling a programmable device to perform a method of receiving program listing data and transmitting program listing data, respectively. 
     BACKGROUND OF THE INVENTION 
     An example of a method of receiving program listing data is disclosed in EP 0880855. The method disclosed in EP0880855 manages the memory of an electronic program guide (EPG) by deleting less important unexpired program listings as soon as the memory is full. Although this ensures that the maximum capacity of the EPG memory can always be used, the removal of previously available program listing data can be confusing and annoying to users. 
     SUMMARY OF THE INVENTION 
     It is a first object of the invention to provide a method of receiving program listing data, which helps avoid removal of previously available program listing data. 
     It is a second object of the invention to provide a method of transmitting program listing data, which helps avoid removal of previously available program listing data. 
     It is a third object of the invention to provide a device for receiving program listing data, which helps avoid removal of previously available program listing data. 
     It is a fourth object of the invention to provide a device for transmitting program listing data, which helps avoid removal of previously available program listing data. 
     According to the invention, the first object is realized in that the method of receiving program listing data comprises the steps of receiving program listing data, determining whether the program listing data would fit into a certain memory when stored according to a first policy for storing program listing data, and selecting a second policy for storing program listing data if the program listing data would not fit into the certain memory when stored according to the first policy, a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy. An appropriate policy is selected based on the available (EPG) memory and (estimated) size of the program listing data. Omitting a certain field of information from a program listing is considered less annoying than omitting a whole channel or a whole day. Since the policy is selected before the program listing data is stored and the policy ensures that there is sufficient memory for the most important information, there is no need to remove previously available program listing data. 
     In an embodiment of the method, the at least part of the received program listing data describes programs belonging to a certain genre and/or programs being transmitted on a certain day. 
     The certain genre may include all genres except movies. For example, it may be desired to have extended description of movies, e.g. to enable a movie recommender, but this may not be necessary for all programs. 
     The certain field of information may comprise a description, an image, an audio segment and/or a video segment. The most interesting fields to omit are the fields that are relatively large. 
     The received program listing data may include a value for determining a size of at least part of the program listing data and determining whether the program listing data would fit into the certain memory comprises using the received value. To prevent the client device from having to analyze the size of the program listing data itself or basing its decisions only on averages only, a value received from a broadcaster can be used. 
     The value may comprise a variation in size of the at least a part of the program listing data with respect to a reference size. 
     Determining whether the program listing data would fit into the certain memory may comprise maintaining statistics and using the statistics to estimate the size of the program listing data when stored according to the first policy. This is advantageous when the broadcaster does not transmit any information about the size of the program listing data, but can also be advantageous in other cases. Since the broadcaster often does not know which technology is used to store the program listing data, e.g. which compression scheme is used, the size of the program listing data at the client device may be unknown. 
     The received program listing data may include a value for determining a size of at least part of the program listing data and determining whether the program listing data would fit into the certain memory may comprise maintaining statistics, using the statistics to estimate the size of the program listing data when stored according to the first policy, and correcting the estimated size with the received value. 
     According to the invention, the second object is realized in that the method of transmitting program listing data comprises the steps of determining a first value, the first value being useful for determining a first size of at least part of the program listing data when stored according to a first policy for storing program listing data, determining a second value, the second value being useful for determining a second size of at least part of the program listing data when stored according to a second policy for storing program listing data, but not useful for determining the first size, and a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy, and transmitting the first value and the second value along with the program listing data. To avoid the need for a client device to maintain statistics about the average size of (certain) program listing data, which requires more processing, the broadcaster may transmit all information that is necessary to determine the size of the program listing data when stored according to the different policies. 
     According to the invention, the third object is realized in that the electronic circuitry of the device for receiving program listing data is operative to receive program listing data, determine whether the program listing data would fit into a certain memory when stored according to a first policy for storing program listing data, and select a second policy for storing program listing data if the program listing data would not fit into the certain memory when stored according to the first policy, a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy. The device may be a TV or a set top box (e.g. a DVD/HD recorder or a digital satellite/cable/terrestrial receiver), for example. 
     According to the invention, the fourth object is realized in that the electronic circuitry of the device for transmitting program information is operative to determine a first value, the first value being useful for determining a first size of at least part of the program listing data when stored according to a first policy for storing program listing data, determine a second value, the second value being useful for determining a second size of at least part of the program listing data when stored according to a second policy for storing program listing data, but not useful for determining the first size, and a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy, and transmit the first value and the second value along with the program listing data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of the invention are apparent from and will be further elucidated, by way of example, with reference to the drawings, in which: 
         FIG. 1  is a flow chart of the method of receiving program listing data of the invention; 
         FIG. 2  is a flow chart of the method of transmitting program listing data of the invention; and 
         FIG. 3  is a block diagram of the devices of the invention. 
     
    
    
     Corresponding elements in the drawings are denoted by the same reference 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The method of receiving program listing data comprises three steps, see  FIG. 1 . A step  1  comprises receiving program listing data. A step  3  comprises determining whether the program listing data would fit into a certain memory when stored according to a first policy for storing program listing data. A step  5  comprises 
     selecting a second policy for storing program listing data if the program listing data would not fit into the certain memory when stored according to the first policy, a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy. 
     The method of transmitting program listing data comprises three steps, see  FIG. 2 . A step  11  comprises determining a first value, the first value being useful for determining a first size of at least part of the program listing data when stored according to a first policy for storing program listing data. A step  13  comprises determining a second value, the second value being useful for determining a second size of at least part of the program listing data when stored according to a second policy for storing program listing data, but not useful for determining the first size, and a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy. A step  15  comprises transmitting the first value and the second value along with the program listing data. 
     In an embodiment of the method, program listing data are available for 8 days and the following policies are defined: 
     Best Case Policy: 
     Complete data for 8 days will be available. 
     Policy A (Normal Field Expectation): 
     First day: Complete data for all channels 
     Remaining 7 days: All movies will have complete info. All other programs will have partial data (no long info). 
     Policy B (Worst Case): 
     First day: Complete data for all channels 
     Next day: All movies will have complete info. All other programs will have partial data (no long info). 
     Remaining 6 days: If memory is available, then all movies will have complete info. All other programs will have partial data (no long info). 
     In order to select one of the policies, the following information is collected:
     1) (Average) memory used per channel per day with complete data   2) (Average) memory used per channel per day with partial data (no long info)   3) (Average) memory used by one movie with complete data   4) (Average) Number of movies for 7 days per channel   

     The average memory used and the average number of movies can be updated at the client, i.e. at the program listing data receiver. To improve the information, the broadcaster of program listing data can broadcast the data variation as a percentage from a reference point (e.g. from a particular year), which can be used to correct the average memory and the average number of movies with information about the currently broadcast program listing data. Alternatively, the broadcaster can transmit all required information itself, e.g. the memory used per channel per day with complete data for the currently broadcast program listing data. In the latter case, the client does not need to maintain statistics. 
     From the above information, the following thresholds are calculated before initiating the download of the program listing data:
     1) Max Nr of channels up to which 8 day data can be supported as per policy A (N1)   2) Max Nr of channels up to which 2 day data can be supported as per policy B (N2)   3) Max Nr of days for which partial data can be supported as per policy B   4) Max Nr of days for which full data can be supported   5) Max Nr of channels that can be downloaded with full data (N3)   

     A policy is selected based on these thresholds and the following other information:
     1) Program listing data memory   2) Number of Host Mapped channels (HMC)   

     The following rules define which policy is selected: 
     If Host mapped channels are &lt;=N3, then complete data will be downloaded for all the host mapped channels (Best case policy is followed). 
     If Host mapped channels are &gt;N3, then the following rules will be followed. 
     If HMC&lt;N1, Policy A will be followed 
     If HMC&gt;N1 and &lt;N2, Policy B will be followed 
     If HMC&gt;N2, Policy B will be followed and all host mapped channels above N2 will be ignored 
     Hence in the worst case there will be one day of complete data and another day of partial data. Max number of channels will be reduced to the extent that the Policy B is always satisfied in any field condition. The channels that are ignored will be the ones that appear the last in the mapped channel list 
       FIG. 3  shows the electronic device  31  of the invention. The electronic device  31  comprises electronic circuitry  33 . At the client side, the electronic circuitry  33  is operative to receive program listing data, determine whether the program listing data would fit into a certain memory when stored according to a first policy for storing program listing data, and select a second policy for storing program listing data if the program listing data would not fit into the certain memory when stored according to the first policy, a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy. At the broadcaster side, the electronic circuitry  33  is operative to determine a first value, the first value being useful for determining a first size of at least part of the program listing data when stored according to a first policy for storing program listing data, determine a second value, the second value being useful for determining a second size of at least part of the program listing data when stored according to a second policy for storing program listing data, but not useful for determining the first size, and a certain field of information of at least part of the received program listing data being stored according the first policy, but not according to the second policy, and transmit the first value and the second value along with the program listing data. 
     The electronic device  31  may further comprise a storage means  35 , a reproduction means  37 , an input  39  and/or an output  41 . The electronic device  31  may be a stationary or a portable device. The electronic device  31  may be a consumer device, e.g. a TV or set top-box, or a professional device. The electronic circuitry  33  may be a general-purpose or an application-specific processor. The electronic circuitry  33  may be capable of executing a computer program. The program listing data may be DVB-SI data, for example. The program listing data may be transmitted using analog or digital broadcast or via the Internet, for example. 
     The storage means  35  may comprise, for example, a hard disk, solid-state memory, an optical disc reader or a holographic storage means. The reproduction means  37  may comprise, for example, a display and/or a loud speaker. The input  39  and output  41  may comprise, for example, a network connector, e.g. a USB connecter or an Ethernet connector, an analog audio and/or video connector, such as a cinch connector or a SCART connector, or a digital audio and/or video connector, such as an HDMI or SPDIF connector. The input  39  and output  41  may comprise a wireless receiver and/or transmitter. The input  39  may comprise a broadcast receiver. 
     While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art, and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications. The invention resides in each and every novel characteristic feature and each and every combination of characteristic features. Reference numerals in the claims do not limit their protective scope. Use of the verb “to comprise” and its conjugations does not exclude the presence of elements other than those stated in the claims. Use of the article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. 
     ‘Means’, as will be apparent to a person skilled in the art, are meant to include any hardware (such as separate or integrated circuits or electronic elements) or software (such as programs or parts of programs) which perform in operation or are designed to perform a specified function, be it solely or in conjunction with other functions, be it in isolation or in co-operation with other elements. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the apparatus claim enumerating several means, several of these means can be embodied by one and the same item of hardware. ‘Computer program product’ is to be understood to mean any software product stored on a computer-readable medium, such as a floppy disk, downloadable via a network, such as the Internet, or marketable in any other manner.