Patent Publication Number: US-2013229575-A1

Title: Digital TV Data Processing Method and System Thereof

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
     This patent application is based on Taiwan, R.O.C. patent application No. 101106913 filed on Mar. 2, 2012. 
     FIELD OF THE INVENTION 
     The present invention relates to a digital TV data processing method and a system thereof, and more particularly, to a digital TV data processing method for increasing display fluency during a channel switch and a system thereof. 
     BACKGROUND OF THE INVENTION 
     As technology develops, analog TV systems are gradually replaced by digital TV systems since digital TV data, compared to analog TV data, are advantageous in easy record and control, higher interference resistance ability, and higher frequency resource utilization rate, in addition to higher definition and better color display. 
       FIG. 1  shows a schematic diagram of a digital TV system  100  according to the prior art. The digital TV system  100  comprises an antenna  101 , a tuner  103 , a demodulator  105  and a decoder  109 . After processed by the tuner  103  and the decoder  105 , a processed result is recorded in a storage device  107 . Alternatively, the processed result may be further decoded by the decoder  109  to video data and audio data, and be real-time displayed. The foregoing operations are controlled by a control unit  106 . Except for the elements shown in  FIG. 1 , a person having ordinary skills in the art should know other elements (e.g., a filter) in the digital TV system  100  and other detailed operations, which shall not be described for brevity. 
     However, when the digital TV program is displayed in real time and a channel is switched to another channel, since a period of time is needed for decoding and demodulating the digital TV data to be displayed, the display of the program seems not fluent to a user while no frame is displayed for a period of time when the channel is switched to the new channel. 
     SUMMARY OF THE INVENTION 
     Therefore, one object of the present invention is to provide a method for increasing display fluency during a channel switch and a system thereof. 
     According to an embodiment of the present invention, a digital TV data processing method applied to a TV display system simultaneously receiving digital TV data associated with a plurality of channels is provided. The method comprises: (a) when first channel digital TV data corresponding to a first channel are displayed, storing second channel digital TV data corresponding to a second channel, the second channel digital TV data comprising audio data and video data; (b) when the first channel is switched to the second channel, decoding from the video data of the stored second channel digital TV data at a first rate; and (c) when the decoding catches up real-time second channel digital TV data corresponding to the second channel, decoding video data of subsequent second channel digital TV data corresponding to the second channel at a second rate and displaying a corresponding real-time decoding result, wherein the first rate is higher than the second rate. 
     According to another embodiment of the present invention, a digital TV system comprises a video decoder, a control unit and a storage device. The control unit stores second channel digital TV data into the storage device when first channel digital TV data corresponding to a first channel are displayed, and the second channel digital TV data comprise audio data and video data. When the first channel is switched to the second channel, the video decoder decodes from the video data of the stored second channel digital TV data at a first rate, and decodes video data of subsequent second channel digital TV data corresponding to the second channel at a second rate when the foregoing decoding catches up real-time second channel digital TV data corresponding to the second channel. The control unit controls the digital TV system to display a corresponding real-time decoding result. The first rate is higher than the second rate. 
     Accordingly, a predetermined recorded video is rapidly decoded and displayed during a time period for processing digital TV data corresponding to a to-be-switched channel, and a digital TV program corresponding to the to-be-switched channel is then normally displayed to decrease switching disfluency. 
     The advantages and spirit related to the present invention can be further understood via the following detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a digital TV system in the prior art. 
         FIG. 2  is a schematic diagram of a digital TV data processing method in accordance with an embodiment of the present invention. 
         FIG. 3  is a schematic diagram of a remote controller of a digital TV system in accordance with an embodiment of the present invention. 
         FIG. 4  is a flow chart of a digital TV data processing method in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Some words referring to practical elements are applied in the specification and subsequent claims. A person having ordinary skills in the art shall comprehend, and a hardware manufacturer may use different terms to name the same elements. Functions, rather than names, of the elements are used to distinguish the elements in the specification and the subsequent claims. Moreover, the word “comprise” has an open-ended meaning as “including but not limited to” in the specification and the subsequent claims. 
       FIG. 2  shows a digital TV data processing method in accordance with an embodiment of the present invention. The first channel being currently displayed and the second channel to be displayed correspond to a same frequency point. Generally, data of a plurality of channels correspond to the same frequency point are simultaneously received. According to this embodiment, digital TV data of at least one of the other channels corresponding to the same frequency point as the current channel are stored. For example, TV data of the second channel is stored when a TV program of the first channel is displayed. The method shown in  FIG. 2  is also applied to any other channels corresponding to the same frequency point as the first channel and the second channel. However, in another embodiment, the first channel and the second channel are not limited to the two channels corresponding to the same frequency point. In addition, the stored channel digital TV data are not limited to the channels corresponding to the same frequency point. In another embodiment, not all TV data of a plurality of channels corresponding to the same frequency point are stored. Since most tuners can only receive and decode digital TV data of channels corresponding to the same frequency point, at least two tuners  103  are needed to receive TV data of a channel corresponding to a different frequency point from that of the currently-displayed channel. There are different manners to select a predetermined channel to store the TV data thereof. In one embodiment, the predetermined channel may be defined by a user. In another embodiment, the frequency and total watch time of a channel is automatically recorded to generate a usage parameter to determine the predetermined channel. For example, when it is determined that the most watched channels are 5, 20 and 58 according to the frequency and total watch time of the channel, it means the user often switches between the channels. Therefore, when a TV program is currently displayed on the channel 5, TV data of the channels 20 and 58 are stored to facilitate the digital TV data processing method according to the present invention. Alternatively, the TV data of the three channels may also be stored even if other channels except for the channels 5, 20 and 58 are currently displayed. 
     Referring to  FIG. 2 , when the first channel is switched to the second channel, the decoder  109  begins to decode the stored digital TV data of the second channel in the storage device  107 . The digital TV data can be divided into video data and audio data, and the digital TV system has two different sets of hardware for respectively decoding the video data and the audio data. In this embodiment, the video data of the second channel digital TV data recorded in the storage device  107  comprises a first predetermined type of frame, e.g., a start frame (frame I). In an embodiment, the digital TV system decodes and displays the first frame I (i.e., a decoding result). In another embodiment, the digital TV system does not immediately display the corresponding decoded frame I. In practical applications, when the video data of the second channel digital TV data corresponding to a time period around the frame I have high similarity, i.e., when the videos are relatively static, the user can obtain video information as soon as the frame I is displayed, so as to alleviate the disfluency in the prior art that the user has to wait for a period of time to see the frame. However, when the video data of the second channel digital TV data corresponding to the time period are greatly different, the user may feel obvious visual discontinuousness when the frame I is immediately displayed. After that, when the decoder  109  completes decoding subsequent real-time second channel digital TV data, the digital TV system switch to normally display the real-time second channel digital TV data. Specifically, during a time period T 2  after the digital TV system is switched to the second channel, the second channel digital TV data stored during a time period T 1  are first accessed and decoded, and subsequently received second channel digital TV data are then decoded. In this embodiment, the second channel digital TV data stored during the time period T 1  comprises the first frame I. During the time period T 2 , the front processing units, i.e., the tuner  103  and the decoder  105 , have switched to process the subsequently received second channel digital TV data comprising a second frame I, for example. After the first frame I is decoded, the digital TV system continues to decode the subsequently received second channel digital TV data with information of the first frame I. Subsequently, when a presentation time stamp (PTS) corresponding to a decoding result of a video data of the subsequently-received second channel digital TV data shows that the decoding result is synchronous with a live stream of the received TV data, that is, when the decoding result of the video data of the digital TV system catches up with the received live stream, the process enters a time period T 3 . During the time period T 3 , synchronization associated with the second channel digital TV data is performed, and the decoding result (comprising the decoding result of the video data and the decoding result of the audio data) of the real-time second channel digital TV data is normally displayed. A decoding rate of the digital TV system during the time period T 2  is raised, so that the decoding rate during the time period T 2  is faster than the decoding rate for processing the subsequent real-time second channel digital TV during the time period T 3 . 
     In an embodiment, during the time period T 2 , the synchronization mechanism is paused, i.e., an audio-visual synchronization (AV Sync) signal is in OFF status. The AV Sync signal is for synchronizing the audio data of the digital TV data with the video data. When the AV Sync signal is in ON status, the decoding rate cannot be raised to synchronize the decoding result of the audio data with that of the video data, so that the AV Sync is temporarily changed to the OFF status to decode the stored digital TV data at a maximum rate. In practical applications, the decoding rate is greatly raised to a maximum decoding rate due to pause of the synchronization mechanism, and generally, the maximum decoding rate can be up to three to four times of the general decoding rate, so that the decoding result of the digital TV system can catch up the received live stream in an extreme short time. When the decoding result of the digital TV system catches up the received live stream, i.e., during the time period T 3 , the AV Sync signal is in the ON status to complete the decoding result for normally displaying the second channel digital TV data. 
     In an embodiment, the second channel digital TV data stored in the storage device  107  during a predetermined time period is processed at the beginning of the time period T 2 . According to digital TV specification, the digital TV data comprises at least one frame I within every 0.5 second, so that the predetermined time period can be designed as 0.5 second; however, it shall not be construed as limiting the present invention. 
     The second channel in  FIG. 2  may also correspond to channel information associated with a remote controller of the digital TV system, e.g., channel information associated with a predetermined button. Taking the remote controller  300  in  FIG. 3  as an example, when the first channel is displayed, once a channel up button  301  or a channel down button  303  of the control remoter  300  is pressed, the digital TV system switches the first channel to the second channel. The user may define which channel corresponds to the channel up button  301  or the channel down button  303 . In another embodiment, the first channel and the second channel may both correspond to a predetermined button of a remote controller of the digital TV system. For example, the first channel and the second channel both correspond to a return button  305  of the remote controller  300  that the user may switch between the first channel and the second channel by pressing the return button  305 . 
     According to an embodiment of the present invention, a digital TV data processing method is provided.  FIG. 4  shows a flowchart of the digital TV data processing method in accordance with an embodiment of the present invention. The flow comprises steps below. In Step  401 , a channel is switched (the first channel is switched to the second channel as shown in  FIG. 2 ). In Step  403 , an AV Sync signal is in OFF status. In Step  405 , a video data of a stored digital TV data is processed at a maximum rate (a video data of the second channel digital data stored in the storage device  107  during the time period T 1  is decoded at a high rate during the time period T 2  as shown in  FIG. 2 ). In Step  407 , a video decoding result is generated when a video data of a subsequently received digital TV data is processed at the maximum rate. In Step  409 , it is determined whether the video decoding result catches up a live stream. The flow proceeds to Step  411  in which the decoding is performed at a normal rate when a determination result in Step  409  is yes; otherwise, the flow returns to Step  407 . In Step  413 , The AV Sync signal is in ON status, and synchronization of an audio data begins. In Step  415 , a digital TV program comprising video and audio information is normally displayed. 
     The foregoing digital TV data processing method is also applied to the digital TV system shown in  FIG. 1 ; however, it shall not be construed as limiting the present invention. 
     According to the present invention, a predetermined recorded video is rapidly decoded and displayed during a time period for processing a digital TV data corresponding to a to-be-switched channel, and a digital TV program corresponding to the to-be-switched channel is then normally displayed to decrease switching disfluency. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not to be limited to the above embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.