JP4636121B2 - Video processing device - Google Patents

Description

  The present invention inputs at least a digital video signal or audio signal and performs predetermined processing. For example, a television receiver, a video recording device such as a VTR or DVD that records video or audio, and video and audio are reproduced. The present invention relates to a video processing device such as an output switcher or a video signal distribution device. In particular, the present invention relates to a video processing apparatus that has been improved to obtain an appropriate video signal according to the magnitude of the error rate of an input digital video signal or the input state thereof.

  In package media such as television broadcasting and movie software, digitization of video signals and audio signals is progressing. Accordingly, display devices such as broadcast receiving devices (hereinafter referred to as STB; set-top-box), digital recording / reproducing devices, and HD (High Definition) television receivers that receive television signals are also digital video. It has become possible to handle signals and audio signals.

  As is well known, information signals such as video signals and audio signals are subjected to processing such as data amount compression and time division multiplexing in the process of transmission or recording / reproduction. Returned. Therefore, at least video information is generally given to the display device in baseband even when digitally delivered.

  In the display device, a reproduction signal such as a television broadcast signal, a hard disk recorder, a DVD (Digital Versatile Disc), or a digital VTR is input via the STB. For this reason, a standard for passing these information signals to and from the STB must be determined.

  In North America, a standard called EIA / CEA861 was issued in January 2000 as a digital video baseband transmission standard for display devices for this purpose. Here, DVI 1.0 (Digital Visual Interface version 1.0), which is a connection standard between the main body of a PC (Personal Computer) and a display device, is used. As for the connection method between the main body of the PC and the display device, for example, as described in the following Patent Document 1, Non-Patent Document 1, and the like, the video information transmission method is mainly defined in detail. In this case, the voice information is sent through another connection line. The audio information may be in either analog or digital format, and the another connection line may be any one of an analog cable, a digital coaxial cable, a digital optical cable, and the like.

JP 61-290529 A Published by Japan Electronics Industry Promotion Association, digital monitor interface standard (JEIDA-59-1999)

  However, considering usability, it is better to be able to transmit both video and audio over a set of cables. For this purpose, various methods such as superimposing a digital audio signal during a vertical or horizontal blanking period of the video signal have been proposed.

  Digital video information has a high transmission rate, and the error rate is likely to increase due to a long cable connection. It is common to perform error correction in an environment where errors are inherently likely to occur, such as long-distance transmission such as broadcasting and recording / reproduction on a recording medium. However, in the case of short-distance transmission such as STB and display device, even if error correction is left in audio information with a low tolerance for errors compared to video, an error of video information that has a very large transmission information amount compared to audio Corrections are often not done due to cost issues. In reality, the occurrence of an error may be a problem depending on the usage environment, and some means to replace the error correction is required. In the above-mentioned known literature, there is no description regarding such means.

  In view of the above problems, an object of the present invention is to provide a video processing apparatus capable of obtaining an appropriate video signal (with a lower error rate) even when the error rate of input digital video information is large. There is.

  In order to achieve the above object, a video processing apparatus according to the present invention provides an error rate detection circuit for an input digital video signal from a signal generator such as an STB or a digital audio signal superimposed thereon, and copes with a user when the error rate deteriorates. Warning display means for indicating the method is provided. Further, a holding circuit that holds a plurality of signal format information including at least one of the number of scanning lines and the horizontal resolution of the digital video signal and at least one of the plurality of signal formats held in the holding circuit are selected. And a control circuit, wherein at least one of a plurality of signal formats held in the holding circuit is selected and transmitted to the signal generator.

  Specifically, when the error rate is higher than a predetermined threshold, a signal format having a smaller number of scanning lines and / or horizontal resolution than the digital video signal currently being received is selected.

  In addition, with the above-described configuration, a warning screen indicating that a video signal having a high error rate and a low quality is being input and a coping method thereof may be displayed on the screen of a television receiver, for example. . This warning screen displays a message prompting the user to replace the connection line for transmitting the digital video signal, and / or whether or not to execute the selection described later (select a low scanning line number and / or horizontal resolution signal format). It may include an option for allowing the user to determine. According to the user's instruction or automatically, when the error rate is large (noisy), the signal generator is instructed to output a digital video signal with a small number of scanning lines and / or horizontal resolution. An appropriate video signal with a low error rate can be obtained.

  When both the digital video / audio signal and the analog video / audio signal can be received, the analog video / audio signal may be selected when the error rate of the digital audio signal is large. Further, an analog signal may be selected when no digital video signal is received, and a digital video signal may be selected when no analog signal is received. Furthermore, a receiving circuit that receives a digital video signal shows a single color or single brightness still image (for example, an image of all black, all white, or an image such as snow noise that has a substantially single brightness on the screen average). When a signal is received, an analog video signal may be selected. Further, an energy saving effect can be expected by reducing or stopping the power supply to the circuit blocks that are not selected.

  In this way, when both the digital video / audio signal and the analog video / audio signal can be received, and the digital video signal cannot be satisfactorily received due to some trouble, an appropriate video signal can be obtained by switching to the analog video signal. Can be obtained.

  According to the present invention, it is possible to indicate a countermeasure method to a user with an appropriate warning display according to the state of an input video / audio signal, and to automatically obtain an appropriate video / audio signal. Therefore, there is an effect that usability is improved.

  Embodiments of the present invention will be described below with reference to the drawings. In the present invention, first, the error rate of the input digital video signal and / or digital audio signal (hereinafter collectively referred to as digital information, sometimes referred to as analog information in the case of analog format) is detected, and this is large. In this case, the signal source side is urged to switch so that the data is sent in a format with less influence of errors. The format having little influence refers to a format having a low data rate, for example, having a small horizontal resolution and the number of scanning lines. When analog information is given in parallel with digital information, the following is performed. That is, when the error rate of digital information is large, analog information is selected and signal processing is performed. Alternatively, the signal processing is performed by comparing both qualities and selecting the good side. When digital video information is not input, analog video information is selected and signal processing is performed. If necessary, contents related to these operations and switching may be displayed on the display unit to alert the user.

  With particular emphasis on the above items, the operation will be described first with reference to FIG. FIG. 1 is a block diagram showing a first embodiment of the present invention, which includes a signal generating device 1 such as an STB and a video processing device 2, for example. Here, an example in which the video processing device 2 is a display device such as a television receiver will be described. These are connected to each other by two interfaces (cables) 42 and 43. In this embodiment, the signal generating device 1 and the video processing device 2 are connected by two interfaces. However, if these communication functions can be performed by one interface, they may be connected by a single interface. .

  First, details of the signal generator 1 will be described. A digital video signal is generated from the video signal source 11 of the signal generator 1, and a digital audio signal is generated from the audio signal source 12. When the signal generator 1 is an STB, this is obtained by receiving a digital broadcast, for example, or may be information reproduced from a hard disk recorder built in the STB. If the signal generator 1 is a DVD, a digital VTR, or the like, it is information reproduced from an inserted or incorporated recording medium, and the inserted recording medium may be package software, for example.

  The output of the video signal source 11 is given to the scan converter 16. The scan converter 16 is controlled by the resolution control circuit 17, and based on this, the format of the video signal is converted as necessary as described later. The output of the scan converter 16 is given to the audio multiplexing circuit 13. Here, the digital audio signal from the audio signal source 12 is superimposed on the digital video signal. There are several possible methods. For example, there is a method of superimposing on a horizontal or vertical blanking period of an image. That is, since it is not necessary to transmit a video signal in the blanking period, a digital audio signal can be sent using the audio signal as an audio packet instead of the video signal during that period. The output of the audio superimposing circuit 13 is given to the data transmission circuit 14, code-converted as necessary, power amplified, and given to the display device 2 via the interface 42.

  Next, the operation of the video processing device 2 will be described. The digital video signal input through the interface 42 is supplied to the data receiving circuit 21 through the switch 34 if it is closed. If code conversion for transmission is applied to this, it is decoded here. The output signal of the data receiving circuit 21 is given to an audio separation circuit 22 where the digital audio signal is separated from the digital video signal and supplied to an audio processing circuit 25 incorporating a DAC (digital analog converter). Further, it is input to the switching control circuit 28 as necessary. Note that the audio separation circuit 22 and the audio switching control circuit 28 are not separated in circuit and may be integrated, but this case is also within the scope of the present invention.

  Naturally, the operation of the audio separation circuit 22 differs depending on the method of multiplexing digital audio signals. For example, if it is superimposed on the horizontal or vertical blanking of the video, the separation operation is performed according to the blanking timing. The audio processing circuit with DAC 25 performs various signal processing such as time axis conversion, error correction, and data expansion on the digital audio information separated by the audio separation circuit 22 as necessary, and an analog signal is provided by the built-in DAC. Returned to This analog audio signal is supplied to the speaker 27 to reproduce the audio. If the video processing device 2 includes the recording unit 36, the audio signal is recorded on the recording medium by the recording unit 36.

  On the other hand, the digital video signal separated by the audio separation circuit 21 is given to the scan converter 35, and after being converted as necessary, the format of the video signal is given to the adder circuit 23. The adder circuit 23 adds information from an OSD (On Screen Display) circuit 29 and then inputs the information to the display unit 24 to display an image. If the display output unit 242 is present, the video is further output to the outside. Furthermore, if there is a recording unit 36, the output of the scan converter 35 is recorded on the recording medium by the recording unit 36.

  The digital video or audio signal separated by the audio separation circuit 22 is also supplied to the switching control circuit 28. The switching control circuit detects the error rate from the digital video signal (or digital audio signal), performs switching control on the switch 33 according to the magnitude, and also displays a warning display on the OSD circuit 29. Send the command. The switch 33 is connected to a holding circuit that holds a plurality of signal formats of the digital video signal. The holding circuit includes a first EDID (Extended Display Identification Data; data indicating a compatible signal format) circuit 31 and a second EDID circuit 32, each of which is configured by a nonvolatile memory such as an EEPROM. . That is, the first and second EDID circuits 31 and 32 function as a memory for storing the signal format. A first EDID 31 is connected to one input terminal of the switch 33, and a second EDID circuit 32 is connected to the other input terminal. Therefore, the switching control circuit 28 has either the first EDID 31 in which the first signal format is held or the second EDID circuit in which the second signal format is held depending on the error rate of the digital video signal. At least one of 32 is selected via the switch 33. When one of the EDID circuits is selected by the switch 33, the signal format held in the EDID circuit is transmitted to the signal generator 1 via the interface unit 43. The signal generator 1 generates a digital video signal that matches the signal format transmitted via the interface unit 43 and supplies the digital video signal to the video processor 2.

  Next, the details of the operation of the switching control circuit 28 will be described with reference to the flowchart shown in FIG. In FIG. 2, a start 201 indicates a starting point of a series of operations. First, in the error rate determination step 202, the error rate of the input digital video signal is detected and its magnitude is determined. Here, the error rate is determined from the digital video signal, but this is not always necessary. In transmission over a relatively short distance, error correction may be performed only on audio information. Even here, the error rate can be determined using the error correction function of the digital audio signal superimposed on the digital video signal. Good. It would also be possible to determine the error rate not from the video signal itself but from control information attached thereto (for example, copy control information indicating whether recording of information on a recording medium is permitted) or the like. The copy control information is transmitted at a frequency of, for example, every 2 seconds in order to confirm that the connection destination device is a device that operates according to this. The error rate of the copy control information at that time may be determined.

  The error rate determination unit 202 compares the detected error rate with a predetermined first threshold value. In this step, if it is determined that the detected error rate is smaller than the threshold value, the process returns to the beginning, and the error rate determination is repeated while receiving the input of information as it is. If the detection error rate exceeds a second threshold value that is larger than the first threshold value, it is determined that noise is mixed and it is difficult to withstand viewing, and the process proceeds to step 231. In step 231, the signal generator 1 is instructed to reset the format of the digital video signal such as the horizontal resolution and the number of scanning lines, and the process proceeds to step 232. In step 232, after the characters are displayed on the screen so that the user can recognize that the format of the digital video signal from the signal generator 1 has been reset (changed), the error rate is determined again by returning to the beginning. Repeat.

  When the resetting of the signal format is instructed in step 231, the switch 33 is connected to the first EDID circuit 31 side holding the signal format having a high horizontal resolution / number of scanning lines as shown in FIG. Then, this is switched to the second EDID circuit 32 side holding the low signal format. If it is originally connected to the second EDID circuit 32 side, that state is maintained. Of course, if there are lower third and fourth formats, you may switch to these in stages. The signal format sent to the signal generator 1 via the interface unit 43 is given to the scan converter 16 via the resolution control circuit 17. Here, the format conversion process is performed so as to generate a digital video signal having a lower scanning line number and a horizontal resolution indicated by the transmitted signal format (than the video signal before the error rate is determined to be large).

  As described above, when the number of errors is extremely large, the switching control circuit 28 selects a signal format in which the data rate is low (resolution is low) and the error rate tends to be small even under the same transmission conditions. In this way, even if the resolution is low, an appropriate image with low noise and high quality is obtained.

  Further, when the format of the input digital video signal is changed, the display device 2 also needs to reset the resolution such as the number of scanning lines. Therefore, the output of the switching control circuit 28 is also given to the switch 34. The switch 34 is disconnected for a specified time, the supply of the input signal is cut off, and the resetting is performed during that time. Further, if a switch is provided in the main digital information path as shown in FIG. 1, loss may be a problem. In order to avoid this, instead of eliminating the switch 34, the potential of the hot plug terminal may be changed and set again.

  In FIG. 1, the output of the switching control circuit 28 is also given to the OSD circuit 29. When the format changes, the OSD circuit 29 generates character information indicating that fact and adds it to the video information displayed by the adder circuit 23. In addition, when the format is changed and the resolution is lowered, this may cause dissatisfaction of the user. Corresponding to this, the scan converter 35 in FIG. 1 may up-convert the number of scanning lines, and may be displayed in a state before apparently lowering the resolution.

  Returning to FIG. 2 again, the switching control circuit 28 will be described. In step 202 described above, although it is not necessarily necessary to take countermeasures, if it is determined that the error rate is large enough to recommend countermeasures, that is, the error rate is larger than the first threshold, If it is smaller than the threshold value, the process proceeds to step 203. In step 203, a warning image is displayed by OSD to alert the user. At this time, the switching control circuit 28 gives a command for displaying a warning image on the display unit 24 to the OSD circuit 29. In response to this command, the OSD circuit 29 supplies a video signal for forming a warning image as shown in FIG. The warning image shown in FIG. 3 indicates to the user that the cable for transmitting the digital video signal is not suitable for viewing an abnormal or good video, and is replaced with another cable and switched. The control circuit 28 includes an option for asking whether or not a format selection operation for reducing the video resolution may be executed. For example, three options are prepared as shown in FIG. 3, and the user selects one desired item from these options. If the user selects a desired one, the process proceeds to step 204. Step 204 determines which option 1 to 3 has been selected.

  If the user selects 1, that is, replace the cable with a short, good one, the process proceeds to step 205 and the OSD circuit 29 prompts the user to replace the cable, for example, “Please replace the cable”. indicate. Then, the process proceeds to step 206, and it is determined whether or not the cable is actually exchanged by monitoring the potential at the interface 42 with the switching control circuit 28, for example. This is continued until the cable is actually replaced. If the cable is replaced, the measured error rate improvement status is OSD-displayed at 207 and the error rate determination is continued again.

  If the user selects 2, that is, viewing without taking any countermeasures, the process proceeds to step 208 to increase the first threshold value for determining the error rate. As a result, the sensitivity of the error rate determination is reduced, and even if a certain error rate occurs, the warning image is not displayed as “low error rate”. Then, returning to the beginning, the determination of the error rate is repeated again.

  If the user selects 3, that is, attempts to stabilize by reducing the resolution or the like, the process proceeds to step 231 to perform the control for switching the format such as the number of scanning lines and the horizontal resolution as described above. For details, refer to the description of the processing when the error rate exceeds the second threshold.

  Further, if the user does not respond after a certain period of time has elapsed, it may be set so that it automatically operates assuming that either 2 or 3 is selected. Furthermore, the OSD display may be continued for a long time depending on the contents, and the warning image display performed in steps 207 and 232 of FIG. 2 may be continued for a predetermined time. After that, the determination of the error rate is made only once for the first time so that it can be dealt with even if the situation changes midway.

  In the determination of the error rate in step 202, when the detected error rate exceeds the first and second thresholds, the switching operation as described above is not performed immediately, but the duration of the state exceeding the threshold is set. It is preferable to switch in consideration. For example, when there is a moment when the error rate deteriorates only once in a long time, it is troublesome if the format switching process or the like is performed each time. Therefore, it is better to switch for the first time when the state where the detection error rate exceeds the threshold value continues for several seconds, for example.

  As described above, according to the error rate of the input information, it is possible to take measures corresponding to the degree. If necessary, the error rate can be improved by changing the format such as the number of scanning lines and horizontal resolution of the input video information. The countermeasure can be selected by the user's selection. Further, the user can know the operation state of the apparatus on the warning screen. Further, if the format switching control is performed for the first time when a state with a high error rate continues for a predetermined time, the troublesome switching between formats due to an instantaneous increase in errors can be eliminated.

  Although FIG. 1 shows a case where the EDID circuits 31 and 32 are provided on the display device side, and this is selected by the switch 33 and sent to the signal generating device 1, the present invention is not limited to this. In addition, when the error rate exceeds a threshold value, a control command itself for changing the signal format is generated and sent to the signal generator 1, or the measured error rate data itself is sent to the signal generator. 1 includes a method for determining a countermeasure method, and all of them are within the scope of the present invention.

  Here, an example of the entire system to which the present invention is applied will be described. FIG. 4 is a block diagram showing an embodiment of the entire system used in the present invention, and shows an example in which information is transmitted / received by broadcast and recorded / reproduced. This includes devices to which the present invention is applied. Note that the first recording / reproducing apparatus 1B in FIG. 4 is built in the broadcast receiving apparatus 1A here, and for example, a hard disk recorder or the like is often used. The second recording / reproducing apparatus 1C is externally attached to the broadcast receiving apparatus 1A, and a DVD recorder, a digital VTR, or the like is often used. Since 1B and 1C are recording / reproducing apparatuses, the present invention can be applied even if one or both of them are not present.

  The information providing station 3 such as a broadcasting station transmits a signal radio wave modulated by information via a relay station 4 such as a broadcasting satellite. Transmission using a cable, transmission using a telephone line, transmission using terrestrial broadcasting, or the like may be used. For example, this signal radio wave received by the receiving side broadcast receiving apparatus 1A, which is an STB, is demodulated into an information signal, and then, if necessary, sent to the first recording / reproducing apparatus 1B and the second recording / reproducing apparatus 1C. It is recorded as a signal suitable for recording. The demodulated information signal is also sent to the display device 2A. Information reproduced by the first recording / reproducing apparatus 1B and the second recording / reproducing apparatus 1C is given to the display device 2A via the broadcast receiving apparatus 1A. When the information is provided in a removable recording medium in which information is recorded in advance, for example, package software, the reproduction operation and the like in the second recording / reproducing apparatus 1C to which the information is attached is performed. When performing the above-described transmission, the data amount of the signal is often compressed, but this is decompressed immediately before the signal is given to the display device 2A and restored. When recording to the recording / reproducing apparatuses 1B and 1C, recording is generally performed in a compressed state. Accordingly, when reproducing information from these, the information is once expanded through the broadcast receiving apparatus 1A and then given to the display apparatus 2A. The portion of the signal that gives a signal from the broadcast receiving device 1A to the display device 2A is difficult to record because the compression is released and the amount of data is enormous.

  The video input processing device 2 previously shown in FIG. 1 corresponds to the display device 2A in FIG. The signal generator 1 in FIG. 1 corresponds to the broadcast receiver 1A alone in FIG. 3 or a combination of the broadcast receiver 1A and the second recording / reproducing device 1C. When viewing what is currently being broadcast on the display device 2A, the broadcast receiving device 1A other than the first recording / reproducing device 1B corresponds to the signal generating device 1. When displaying what is reproduced from the first recording / reproducing apparatus 1B, the entire broadcast receiving apparatus 1A including this corresponds to the signal generating apparatus 1. When displaying what is reproduced from the second recording / reproducing apparatus 1C, both the receiving apparatus 1A and the receiving apparatus 1A together correspond to the signal generating apparatus 1. A PC (Personal Computer) having a tuner board and a graphic board is also considered as an example of the signal generator 1. In this case, the first recording / reproducing apparatus 1B corresponds to a built-in hard disk drive and its periphery, and the display device 2A corresponds to a PC display.

  Next, a second embodiment of the present invention will be described using the block diagram of FIG. Here, the video information interface between the signal generating device 1 and the display device 2 is performed by two systems of digital and analog, and either one (in terms of image quality or the like) is selected and displayed.

  In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals. Further, the portion related to the transmission of the audio signal is omitted. In the signal generator 1, the video information signal generated by the digital video signal source 11 is separated into two systems, one of which passes through the first scan converter 161 and the digital transmission circuit 142, and passes through the interface 42 in the digital form. To the video processing device 2 as a display device. The other is converted into an analog video signal by passing through the second scan converter 162 and the DAC 151 and supplied to the video processing device 2 via the interface 41.

  The resolution control circuit 171 controls the operations of the scan converters 161 and 162 based on video attribute information from the digital video signal source 11. For highly confidential information, the number of scanning lines, the horizontal resolution, and the like are limited only for the analog output side or for both digital and analog output. In an environment where the error rate on the digital delivery side is high, an operation such as the same restriction on only the digital output side can be considered. Depending on the operation setting, the same scan converters 161 and 162 can be used.

  In the display device 2, the output of the digital reception circuit 211 is supplied to one input terminal of the switching control circuit 281 and the switch 38. The output of the analog reception circuit 212 is converted into a digital signal by an ADC (analog-digital converter) 37 and supplied to the other input terminal of the switching control circuit 281 and the switch 38. The switching control circuit 281 monitors the state of digital information and analog information, and controls the switch 38 so as to select either one which is desirable. The information selected by the switch 38 is subjected to up-conversion processing or the like by the scan converter 35 as necessary, and if there is a recording unit 36, it is recorded on the recording medium. In addition, information such as characters generated by the OSD circuit 29 is superimposed and displayed on the display unit 29 in accordance with an instruction from the switching control circuit 281 given to the addition circuit 23. Further, if there is a video output unit 242, a video signal is further output from here.

  The switching control circuit 281 determines which input of digital information or analog information is displayed as follows. One is to detect the error rate of the signal input to the digital receiving circuit 211. If the detected value is smaller than a predetermined threshold, the digital side is detected. It is a method of selecting. As in the above example, the error rate may be the error rate of the digital audio information superimposed on the video. There is also a method in which a physical quantity directly related to image quality such as noise is compared and judged without using an error rate, and one of the better image quality is output. If there is no input, the side on which the signal is actually input is selected regardless of the quality. In this way, a good input is automatically selected without bothering the user.

  If neither input is present or if the error rate is abnormally high even if there is a digital input, an instruction may be issued to the OSD circuit 29 to issue a warning message. Further, which input is selected may be displayed on the OSD.

  In any case, the determination may be performed not only at the start of the operation, but continuously so as to be able to cope with a change in the situation. When the situation changes, instead of switching immediately, for example, when the same situation continues for several seconds or more, switching for the first time eliminates the trouble of frequent switching due to instantaneous quality degradation.

  The second is a method of switching to analog information when digital information is not supplied. For example, when the resolution control circuit 171 of the signal generator 1 instructs the scan converter 161 to change the resolution, during the resolution change, the resolution control circuit 171 sends a command to the digital transmission circuit 142 to stop the digital output. In such a case, the switching control circuit 281 of the display device 2 detects that no digital information is supplied, controls the switch 38 to switch in the direction opposite to that shown in the figure, and processes the information on the analog input side. Like that. At this time, the OSD circuit 29 may display that the input has been switched to the analog side. Conversely, when analog information is not supplied, the switch 38 may select digital information.

  When the supply of digital information is stopped by the signal generator 1, for example, a single color or single brightness all black or all white, all blue image, sandstorm-like so-called snow noise image, or a telop or OSD indicating supply stop It is also conceivable to transmit the still image shown or the like only through the digital interface. Therefore, a third method is to detect that the digital information is a single color or single luminance still image by the switching control circuit 281 and switch the switch 38 to the analog side. If there is a risk of malfunction when there is little motion even in a normal image, if the information on the digital side input and the analog side input are the same, the processing at the digital side input is not performed. It is good to continue. Further, the above-described image of all black, all white, etc. can be output even when the digital video signal is copy protected. Even in this case, the configuration of this embodiment is applied.

  As described above, it is possible to automatically select and output a high-quality signal from the input digital video signal and the analog video signal input separately. In addition, when there is no information of either one, the other information is automatically selected, but when there is a problem with the quality, a warning can be displayed. In addition, it is possible to know which is selected on the display. There is an effect that the troublesomeness of frequent switching can be eliminated by increasing the error in a short time.

  Next, a third embodiment of the present invention will be described using the block diagram of FIG. Here, when two systems of digital sound and analog sound are sent, one of preferable sound quality is selected and reproduced.

  6 that have the same configuration as in FIG. 1 are denoted by the same reference numerals. In the signal generator 1, the digital audio signal generated by the digital audio signal source 12 is separated into two systems, one of which passes through the audio superimposing circuit 13 and the digital transmitting circuit 14 for superimposing the digital audio on the digital video signal, and through the interface 42. To the video processing device 2 as a display device. The other is converted to an analog audio signal by passing through the DAC and supplied to the video processing apparatus 2 via the interface 44.

  In the display device 2, the audio switching control circuit 282 determines whether the analog audio or digital audio is based on the evaluation result of the sub audio evaluation circuit 210 that evaluates the quality of the analog audio signal, the presence or absence of audio superimposition, and the error rate of the digital video or audio signal. The voice selection switch 26 is switched by deciding which one to select.

  In this embodiment, first, it is automatically determined whether or not a digital audio signal is superimposed on the video signal so that the user does not require a troublesome switching operation. In general, the quality of a digital signal transmitted is better than that transmitted in an analog format. If it is superimposed, the digital audio signal superimposed on the video signal is selected and output with priority. To do. Depending on the result of the determination, the unused audio signal processing circuit may be turned off to save power. However, it is continuously determined whether or not a digital signal is superimposed.

  Furthermore, even with a digital audio signal, the quality deteriorates abruptly when the error rate increases, and it is preferable to output the signal connected in an analog format. Accordingly, not only the presence / absence of the superimposition of the digital audio signal but also the presence of this may be selected and output depending on the error rate. Since the signal generator 1 and the display device 2 are assumed to be at a relatively short distance, it is normal that error correction is not performed on video information even when transmitted in a digital format. For voice information with strict specifications, error correction is often performed. Therefore, it is easy to realize the function of monitoring the error rate described above.

  In the future, more devices will be designed on the premise of superimposing digital audio signals on video signals. In this case as well, in order to maintain compatibility with conventional devices, Since the connection is considered to remain, the present invention can be applied.

  In addition, when the output audio signal is switched, or when the digital audio signal is superimposed, there are many errors and some abnormalities are considered, a message to that effect is given and there are multiple countermeasures. In some cases it is convenient to allow the user to select.

  The operation of FIG. 6 will be described in detail below with particular emphasis on the above matters. A digital video signal is generated from the video signal source 11, which is a component of the signal generator 1, and a digital audio signal is generated from the audio signal source 12. When the signal generator 1 is an STB, this is obtained, for example, by receiving a digital broadcast, and may be information reproduced from a hard disk recorder built in the STB. In the case of a DVD, digital VTR, etc., it is information reproduced from an attached recording medium, and the attached recording medium may be, for example, package software.

  The digital audio signal is superimposed on the digital video signal by the audio superimposing circuit 13. There are several possible methods. For example, there is a method of superimposing on a horizontal or vertical blanking period of an image. Since it is not necessary to transmit the video signal in the blanking period, it is conceivable to send a digital audio signal using the audio signal as an audio packet instead of the video signal during that period.

  The output of the audio superimposing circuit 13 is given to the data transmission circuit 14, code-converted as necessary, power amplified, and given to the display device 2 via the interface 42. Further, the output of the previous audio signal source 12 is also given to the DAC 15 to become an analog audio signal, and is given to the video / audio receiving device 2 via the interface 44.

  Next, the operation of the video / audio receiving apparatus 2 will be described using the flowchart of FIG. 7 as necessary. The digital video signal input via the interface 42 is given to the data receiving circuit 21. If code conversion for transmission is applied to this, it is decoded here. Further, the signal is supplied to the sound separation circuit 22 where the above-described digital sound signal is separated and input to the sound processing circuit 25 with DAC and the sound switching control circuit 28. When the audio signal is not superimposed, dummy data is given to the audio processing circuit 25 with DAC, and information that the audio is not superimposed is given to the audio switching control circuit 28. Note that the audio separation circuit 22 and the audio switching control circuit 28 are not separated in circuit and may be integrated, but this case is also within the scope of the present invention. On the other hand, the digital video information is given to the adder circuit 23, and after adding the information from the OSD circuit 29 as will be described later, it is inputted to the display unit 24 and displayed. If there is a display recording unit 241, video is recorded there, and if there is a display output unit 242, video is output. Naturally, the operation of the audio separation circuit 22 differs depending on the method of multiplexing digital audio signals. For example, if it is superimposed on the horizontal or vertical blanking of the video, it is separated by looking at the blanking timing.

  Next, the operation of the voice switching control circuit 282 will be described. FIG. 7 is a flowchart showing the operation of the voice switching control circuit 282, which is also used in the description together. In FIG. 7, start 101 indicates the starting point of a series of operations. First, the audio superimposition determination unit 102 determines whether or not a digital audio signal is superimposed on a video signal. Several methods are known, such as determining from the format information included in the received data, or determining whether the clock of the audio signal is reproduced from the information separated by the audio separation circuit 22. If there is no superimposition of the digital audio signal, it goes down in FIG. 7 as it is to reach 103 and issues a command to the switch 26 to switch the connection in the direction opposite to that shown in the figure. As a result, the audio signal input via the interface 44 without being superimposed on the video signal is supplied to the speaker 27 to reproduce the audio. If there is an audio recording unit 271, audio is recorded here, and if there is an audio output 272, audio is output there.

  At this time, as indicated by 104 in FIG. 7, power consumption may be reduced by not supplying power to circuit blocks that are not used, such as the audio processing circuit 25 with DAC. Furthermore, a command may be sent to the OSD circuit 29 to indicate that the audio signal supplied from the interface 41 side is output as a message on the display unit 24 as indicated by 105 in FIG. Of course, the display may be continued for a long time, or may be turned off after being displayed only for a short time. Not only a simple display but also countermeasures such as cable replacement or switching to analog audio may be selected. Thereafter, the process returns to the audio superimposition determination unit 102 to continue the determination. The discriminating operation is performed only once for the first time so that the situation can be changed during the process.

  In FIG. 6, the audio signal input via the interface 44 is described as an analog signal, but the present invention is not limited to this. The point is that it is sent by another interface without being superimposed on the video signal, including the case where the interface is a digital coaxial cable, digital optical cable, infrared or wireless, etc., and supplied as a digital audio signal. Yes. In that case, the DAC 15 of the signal generator 1 is removed, and the DAC is placed between the interface 44 and the switch 26, or the DAC of the audio processing circuit 25 with the DAC is separated, and between the switch 26 and the speaker 27. Placed.

  A case where the audio switching control circuit 282 determines that digital audio signals are superimposed will be described next. The process moves from 102 in FIG. 7 to 111 for determining the error rate. Here, the error rate of the digital audio signal input superimposed on the video signal is determined. Of course, when there are many errors, the quality may be inferior to that input in analog form. If the error rate is small and a certain level of quality can be expected, the process proceeds from the right side of 111 in FIG. If so, it performs decompression processing here to convert it to analog format. At 124, the switch 26 is also commanded and connected in the direction shown. Thus, the audio signal input in the digital format is given to the speaker 26 to reproduce the audio. Further, a command may be sent to the OSD circuit 29 in 125 to indicate that the audio signal supplied from the interface 42 is being output on the display unit 24 as a message. If there are components in the portion from the interface 44 to the switch 26 in addition to the sub voice evaluation circuit 210, the supply of these power sources may be stopped. Thereafter, the process returns to the sound superimposition determination unit 102 to continue the determination.

  A case where it is determined at 111 in FIG. 7 that the error rate is large will be described below. Starting from the left side of 111, it is first determined at 112 whether or not there is an audio signal from the interface 44. In FIG. 1, this is performed by the sub voice evaluation circuit 210. In many cases, this is given in analog form, but it may be a digital audio signal given without being superimposed on the video signal as described above. When there is an audio signal from the interface 44, the audio signal goes from 112 to the left side, and the audio signal given from the interface 44 side is supplied to the speaker 27 through the same process as described above. This is done particularly when the error rate on the interface 42 side is poor and the audio signal from the interface 44 side is of better quality. When there is no audio signal from the interface 44, the audio signal from the interface 42 is output regardless of the quality. From 112, the power is supplied to the audio processing circuit 25 with DAC at 113, and the separated audio signal is decompressed and converted to an analog format. At 114, the switch 26 is also commanded and connected in the direction shown. Thus, the audio signal input in the digital format is given to the speaker 26 to reproduce the audio. Further, in 115, a command is issued to the OSD circuit 29, and the audio signal supplied from the interface 42 side is output. However, there is a problem in quality, so check the looseness of the cable connection or replace the cable with a shorter one. The message may be displayed on the display unit 24 as a message. Also in this case, when there are components in the portion from the interface 44 to the switch 26 in addition to the sub voice evaluation circuit 210, the supply of these power sources may be stopped. Thereafter, the process returns to the sound superimposition determination unit 102 to continue the determination.

  The determination of the presence / absence of the voice in 112 of FIG. 7 is not only based on the presence / absence of the text, but also the sub voice evaluation circuit 210 evaluates the quality of the voice signal input from the interface 44, The determination may be made after confirming that the quality is better than the signal. Alternatively, a certain lower limit may be provided for the quality of the audio signal input from the interface 44, and the audio signal input from the interface 42 may be output even if the error rate is large.

  If it is determined at 111 that the error rate is large, the switching operation as described above is not performed immediately, but switching may be performed in consideration of the duration of the state. Even if there is a moment when the error rate deteriorates only once over a long period of time, it is troublesome to perform the format switching process each time. For example, it is better to switch for the first time when the same state continues for several seconds.

  As described above, it is possible to automatically select and output a digital audio signal that is superimposed on the video signal and a high-quality audio signal that is input separately from the digital audio signal. . When there is no audio signal, the other side is automatically selected. When there is a problem with the quality, a warning can be displayed. In addition, it is possible to know which is selected on the display. In addition, there is a method in which some countermeasure means are shown and the user is allowed to select. Furthermore, the power supply of circuit blocks that are not used can be cut off to save power. There is an effect that the troublesomeness of frequent switching can be eliminated by increasing the error in a short time.

  A system application example to which the present invention is applied will be described.

  FIG. 8 is a block diagram showing an example in which information obtained by transmitting / receiving a broadcast and information reproduced from package software are switched using a switcher as an example of a video / audio receiving apparatus of the present invention. 1D is a broadcast receiving apparatus and corresponds to STB. 1E is a playback device, 2B is a switcher, 5 is a display device, 42A and 42B are digital video signal line interfaces, and 44A is an audio-only interface.

  The switcher 2B switches between the video output of the broadcast receiving device 1D and the video output of the playback device 1E such as package software, and functions as the video / audio receiving device of the present invention, and can select good audio information for any input. By superimposing the audio information obtained in this manner on the video information again, there is an advantage that the video and audio information can be transmitted to the display device 5 connected to the output of the switcher 2B by connecting only the digital video interface 42C.

  The present invention is generally applicable to an apparatus that inputs and processes video information. Not only the display device described mainly, but also a recording device for recording video information, a distribution device for outputting and distributing input information again, and the scope of the present invention is in that case. Further, the present invention is not limited to the case where the wired interface as described above is used between the devices. In the future, not only devices related to information such as video but also home appliances including general electric appliances will be developed. In this case, it is expected that a wireless interface is often used between the home server and each personal terminal. In this case, the present invention can also be applied to distribution of video content between apparatuses.

  The warning OSD display when the wireless interface is used is replaced with a display for prompting the replacement of the cable at the wired interface, for example, “Please keep the signal source close to the antenna of the display device because the radio wave condition is not good” or “ Please consider using a wired cable. " Also, a method of reducing the error rate by sending a command to the transmission side to increase the transmission power can be considered.

1 is a circuit block diagram showing a first embodiment of the present invention. 2 is a flowchart for explaining the operation of a switching control circuit 28 in FIG. FIG. 3 is a diagram showing an example of display by an OSD circuit 29 in FIG. 1. 1 is a block diagram showing an example of a digital information transmission / reception recording system to which the present invention is applied. The circuit block diagram which shows the 2nd Example of this invention. The circuit block diagram which shows the 3rd Example of this invention. 7 is a flowchart for explaining the operation of the voice switching control circuit 282 in FIG. The system block diagram which used the switcher as an Example of the video / audio receiver of this invention.

Explanation of symbols

1. Signal generator 11 Video signal source 12 Audio signal source 13 Audio superposition circuit 14 Data transmission circuit 141 -Analog information transmission circuit 142-Digital information transmission circuit 15-DAC (Digital Analogue Converter)
151... DAC (Digital Analogue Converter)
16... Scan converters 161 and 162. Scan converter 17... Resolution control circuit 171... Resolution control circuit 1 A... Broadcast receiving device 1 B, 1 C. ... Video input processing device 21... Data reception circuit 211... Digital information reception circuit 212... Analog information reception circuit 22. ... Addition circuit 24 ... Video display unit 242, ... Display output 25 ... Audio processing circuit 27 with DAC 27 ... Speaker 28 ... Switch control circuit 281 ··· Switching control circuit 282 ··· Voice switching control 29 ··· OSD (On Screen Display) circuit 2A · · · Display device 31 · · · First EDID (Extended Display) Identification Data) circuit 32 ... ... second EDID circuits 33 · switch 35 ..... scan converter 36 ..... recording unit 37 ····· ADC (Analogue Digital Converter)
38 ... Switch 3 ... Broadcasting station 4 ... Relay station

Claims (1)

In a video processing device that inputs and processes a video signal from a signal generator,
A first video signal and a second video signal can be input from the signal generator , and a switch unit for selecting one of the first and second video signals;
Detecting an error rate of the first video signal input to the signal input unit, the detected error rate is greater is than the predetermined threshold value, with respect to the signal generator of the first video signal When the signal for changing the resolution is transmitted and the first video signal is not input due to the resolution change of the first video signal in the signal generator, the input video signal is converted to the first video signal. A control circuit for controlling the switch unit to switch from a signal to the second video signal ;
A video processing apparatus comprising:

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