JP2005006288A - Radio communication apparatus, transmitter, receiver, radio communication system, wireless av system, radio transmitting method, operation control program, and recording medium recording program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus capable of performing data communication while preventing deterioration in the whole quality of videos and sounds to be transmitted by suppressing the deterioration in video and audio data to the minimum, even if a communication condition deteriorates. <P>SOLUTION: A radio communication system is provided with a video/audio transmitter 1 and a video/audio receiver 2 which transmit and receive data including video and audio data at a predetermined bit rate. The video/audio receiver 2 is provided with an error information generator 18 for detecting a communication condition on the basis of a signal from the video/audio transmitter 1, and the video/audio transmitter 1 is provided with a transmitter 6 for transmitting the data while variably controlling the bit rate on the basis of the communication condition detected by the video/audio receiver 2. If the communication condition does not meet a predetermined reference, the transmitter 6 temporarily lowers the bit rate and transmits the data to the video/audio receiver 2 with the lowered bit rate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication device, a wireless communication system, a wireless AV system, a wireless transmission method, an operation control program, and a recording medium on which the program is recorded.

  In recent years, with the explosive spread of the Internet, the number of cases in which a LAN (Local Area Network) is constructed in an office, a home, or the like is increasing. Thanks to the advancement of digital wireless communication technology, the need for so-called wireless LAN, which builds a wireless LAN due to the inconvenience of cabling, has increased greatly. In addition, the mobile environment represented by mobile terminals such as laptop computers It also helps us to use it below, and in the future, a considerable number of disseminated vehicles are expected.

  As a typical technology of this wireless LAN, there is IEEE 802.11 which has already been standardized by the Institute of Electrical and Electronics Engineers (IEEE). This standardized technology defines from the physical layer to the MAC (Media Access Control) layer, which is the lower layer of the data link, in the OSI model, and is a wired LAN transmission path, Ethernet ( In addition, it is a specification that can provide a roaming function as an additional function because it is wireless.

  Also in homes, the use of wireless transmission equipment has increased, and even video signal systems such as video and audio have been digitized and transmitted wirelessly from fixed transmitters to mobile receivers. And being watched more and more. On the other hand, since the frequency band that can be used without a license is limited, mutual interference between wireless devices or electromagnetic radiation devices is also increasing. It is important how to cope with interference from equipment or electromagnetic radiation equipment.

  As a countermeasure against interference, Patent Document 1 discloses a voice data communication apparatus that can reduce the probability of discarding received data due to a data error even if noise in the reception environment increases in compression at a variable bit rate of voice. Has been.

  FIG. 12 is a diagram illustrating a configuration of the voice data communication device described in Patent Document 1.

In FIG. 12, in the audio data receiving apparatus 201A that receives the audio data transmitted from the audio data transmitting apparatus 200, an error in the received data is detected by a CRC (Cyclic Redundancy Check) bit determining unit 201E, and the error rate determining unit 201F A message specifying the data compression rate and the number of retransmissions on the transmission side according to the determined error rate is generated by the retransmission instruction message generator 201G and transmitted to the voice data transmitting apparatus 200. In response to this, the encoder 213 compresses the data at the specified compression rate, and the CRC bit generator 214 adds CRC bits to generate a compressed data packet, which is stored in the data buffer. On the other hand, the retransmission counter 216 counts the number of times designated by the message, reads the compressed data packet of the data buffer 215 by that number, arranges it in one frame, and sends it out from the transmitter 219.
Japanese Patent Laid-Open No. 7-283757 (published on October 27, 1995) (FIG. 1)

  However, in such a conventional wireless communication device, since a variable bit rate is assumed as a compression method, it is necessary to change the compression rate and the number of retransmissions according to the error rate for each data packet transmission. is there. For this reason, when the communication state deteriorates, it is difficult to maintain the data quality constant, and as a result, the quality of the video and audio to be transmitted is lowered.

  The present invention has been made in view of the above problems, and its purpose is to minimize the deterioration of video and audio data even when the communication state deteriorates, and to transmit video and audio as a whole. It is an object of the present invention to provide a wireless communication apparatus that can perform data communication without lowering the quality of communication.

  The wireless communication device of the present invention is a wireless communication device that transmits data including video and audio data at a predetermined bit rate, and combines a communication state detection unit that detects a communication state, a plurality of transmission rates, and the number of retransmissions. Based on the detected communication state, the setting value storage means for storing the setting value, the setting value stored in the setting value storage means is selected, and the transmission rate and the number of retransmissions are set based on the selected setting value. And a transmission rate setting means.

  As a more preferred specific aspect, the communication state detecting means detects the communication state based on the electric field strength of the received radio wave, the error rate, or the number of retransmission requests based on the error rate.

  The communication state detection unit may detect a communication state between wireless communication devices with which communication links are established.

  Further, the video and audio data may be transmitted by an MPEG stream conforming to the MPEG encoding method.

  The transmitter according to the present invention is a transmitter for transmitting data including video and audio data at a predetermined bit rate, combining a receiving means for receiving error information from a data transmission destination, a plurality of transmission rates and the number of retransmissions. A setting value storage means for storing the set value, and a setting value stored in the setting value storage means based on the transmitted error information, and a transmission rate and the number of retransmissions are set based on the selected setting value. And transmission means for transmitting video and audio data at the transmission rate and the number of retransmissions based on the set value.

  The receiver of the present invention is a receiver for receiving video and audio data transmitted at a predetermined bit rate, receiving means for receiving video and audio data, error determining means for determining an error in received data, and determination Transmission means for transmitting the error information to the data transmission source.

  The error determination unit may determine the electric field strength of the received data, and the transmission unit may transmit the electric field strength determined by the error determination unit as error information.

  The wireless communication system of the present invention is a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate. The receiver transmits video and audio transmitted from the transmitter. A first receiving means for receiving data; an error determining means for determining an error in the received data; and a first transmitting means for transmitting the determined error information to the transmitter. Based on error information transmitted from the receiver, second receiving means for receiving error information transmitted from the receiver, setting value storage means for storing setting values combining a plurality of transmission rates and the number of retransmissions A transmission rate setting means for selecting a setting value stored in the setting value storage means and setting a transmission rate and the number of retransmissions based on the selected setting value; and It is characterized in that it comprises a second transmitting means for transmitting the video and audio data at the transmission rate and the number of retransmissions brute.

  The wireless communication system of the present invention is a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate. The receiver transmits video and audio transmitted from the transmitter. First transmission means for receiving data, electric field strength determination means for determining the electric field strength of the received data, and first transmission means for transmitting the determined electric field strength as error information to the transmitter. A second receiving means for receiving error information transmitted from the receiver, a setting value storing means for storing setting values combining a plurality of transmission rates and the number of retransmissions, and a transmission from the receiver. A transmission rate setting means for selecting a setting value stored in the setting value storage means based on the error information and setting a transmission rate and the number of retransmissions based on the selected setting value. When, and further comprising a second transmission means for transmitting the video and audio data at the transmission rate and the number of times of retransmission based on the set value.

  As a more preferred specific mode, the transmission rate setting means lowers the transmission rate and increases the number of retransmissions when the error is not corrected by retransmitting data at the maximum number of retransmissions.

  As a more preferred specific aspect, the transmission rate setting means reduces the transmission bit rate and sets the number of retransmissions when the electric field strength detected on the receiver side is below a predetermined level at which an error is likely to occur. It is to increase.

  As a more preferred specific aspect, the transmission rate setting means reduces the transmission rate and the number of retransmissions when the error rate of the data received on the receiver side is a predetermined level that affects video and audio. Is to increase.

  As a more preferred specific aspect, the transmission rate setting means may reduce the transmission rate to the lowest rank when the error rate detected on the receiver side increases rapidly and / or when the electric field strength decreases rapidly. To lower.

  As a more preferable specific aspect, the transmission rate setting means decreases the transmission rate by a predetermined rank when the error rate detected on the receiver side gradually increases and / or when the electric field strength gradually decreases. Is.

  As a more preferred specific aspect, the transmission rate setting means sets the transmission rate to the highest level when the error rate detected on the receiver side is at a level without interference and / or when the electric field strength is at a level without interference. Raise to rank.

  As a more preferred specific mode, the transmission rate setting means increases the transmission rate by a predetermined rank when the error rate detected at the receiver side gradually decreases and / or when the electric field strength gradually increases. Is.

  The wireless AV system of the present invention is a wireless AV system that connects a plurality of wireless communication devices through a wireless network, and the wireless communication device is the wireless communication system according to any one of claims 8 to 16. It is characterized by that.

  The wireless communication system may be a television receiver including a display device and a broadcast receiving tuner, and a center device that transmits video and audio data to the display device.

  In the wireless transmission method of transmitting data including video and audio data at a predetermined bit rate, the wireless transmission method of the present invention includes a step of detecting a communication state, and a set value combining a plurality of transmission rates and the number of retransmissions. And a step of selecting the setting value based on the detected communication state and setting a transmission rate and the number of retransmissions based on the selected setting value.

  In the wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, the present invention stores a setting value combining a step of detecting a communication state, and a plurality of transmission rates and the number of retransmissions. A program for causing a computer to execute a step process of selecting the set value based on a step and a detected communication state, and setting a transmission rate and the number of retransmissions based on the selected set value.

  Furthermore, the present invention stores a setting value combining a step of detecting a communication state and a plurality of transmission rates and the number of retransmissions in a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate. And a program for causing the computer to execute a step process of selecting the setting value based on the detected communication state and setting a transmission rate and the number of retransmissions based on the selected setting value. And a computer-readable recording medium.

  As described above in detail, according to the present invention, when an image or sound is transmitted due to interference from the surroundings during transmission of image or sound by fixed bit rate wireless transmission, the image or sound is disturbed. The error tolerance can be enhanced by temporarily lowering the transmission bit rate automatically and increasing the maximum number of retransmissions of error data.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a wireless communication device of the invention will be described in detail with reference to the accompanying drawings.

[Embodiment 1]
An embodiment of the present invention will be described as follows. FIG. 1 is a diagram illustrating an outline of operation of the wireless communication apparatus according to the first embodiment of this invention.

  As shown in FIG. 1, the wireless communication apparatus according to the present embodiment includes a video / audio transmitter 1 that transmits video / audio data, and a video / audio data that receives video / audio data from the video / audio transmitter 1. The receiver 2 includes a video source 3 that supplies video / audio data to be transmitted to the video / audio transmitter 1, and a monitor 4 that displays the transmitted video / audio data.

  In the video / audio wireless transmission, the video / audio transmitter 1 digitizes an input video signal in the case of analog, performs encoding, and sends the encoded video / audio data to the receiver side. Various error information is received from, and the bit rate and the number of retransmissions are specified.

  The video / audio receiver 2 receives encoded video / audio data in video / audio wireless transmission, and determines the level of error, error rate, and electric field strength given to the video / audio from the data. The determination result is transmitted to the transmitter side, and the received encoded video / audio data is decoded and output to the external monitor 4 or the like.

  FIG. 2 is a schematic block diagram illustrating a configuration of the wireless communication device.

  In FIG. 2, a video / audio transmitter 1 includes a video / audio input unit 5 input from a video source 3 and a transmission unit 6 (transmission) that wirelessly transmits encoded video / audio data to the receiver side. Means, second transmission means), encoding unit 7 that encodes the signal input to the input unit 5, and error information sent from the video / audio receiver 2 side, the bit rate and the maximum number of retransmissions. The bit rate / retransmission count setting unit 8 (setting value storage means, transmission rate setting means) for setting the data and the error data sent from the video / audio receiver 2 side when the data is transmitted Retransmission count unit 9 that counts whether or not retransmission has been performed, and reception unit 10 (reception unit, second reception unit) that receives error information transmitted from the video / audio receiver 2 side. .

  The bit rate / retransmission number setting unit 8 stores in advance a set value combining a plurality of transmission rates and the number of retransmissions in a table format, and is stored based on error information transmitted from the video / audio receiver 2. Then, the transmission rate and the number of retransmissions are set based on the selected setting value.

  The encoding unit 7, the bit rate / retransmission number setting unit 8, and the retransmission number counting unit 9 are configured by, for example, a microcomputer, and a data transmission function is realized by software. The encoding unit 7 may be configured as a separate electronic component such as an MPEG decoder.

  On the other hand, the video / audio receiver 2 includes a receiving unit 11 (receiving means, first receiving means) for receiving encoded video / audio data transmitted from the video / audio transmitter 1 side, An output unit 12 for outputting the video / audio signal transmitted from the audio transmitter 1 side to the outside, and a decoding unit for decoding the encoded video / audio signal transmitted from the video / audio transmitter 1 side 13, an error determination unit 14 (communication state detection means, error determination means) for determining whether or not there is an error in the video / audio data sent from the video / audio transmitter 1 side, and the video / audio transmitter 1 The error rate determination unit 15 (communication state detection means, error determination means) for determining the error rate of the video / audio data sent from the side, and the video / audio data sent from the video / audio transmitter 1 side Electric field to determine electric field strength Degree determination unit 16 (communication state detection unit, electric field strength determination unit) and video / audio data sent from video / audio transmitter 1 side, error determination unit 14, error rate determination unit 15, or electric field strength determination When the unit 16 needs to retransmit the video / audio data and needs to increase the maximum number of retransmissions, the error information is transmitted to the video / audio transmitter 1 side. Transmission means).

  The decoding unit 13, the error determination unit 14, the error rate determination unit 15, and the electric field strength determination unit 16 are configured by a microcomputer, for example, and a data transmission function is realized by software. Similarly to the encoding unit 7 of the video / audio transmitter 1, the decoding unit 13 may be configured as a separate electronic component such as an MPEG encoder.

  Hereinafter, an operation of the wireless communication apparatus configured as described above will be described.

  First, the overall operation of the wireless communication apparatus will be described.

  As shown in FIG. 1, the video / audio signal is input from the video source 3 to the video / audio transmitter 1, transmitted to the video / audio receiver 2 by wireless transmission, and output to the monitor 4.

  In the video / audio receiver 2, during transmission between the video / audio transmitter 1 and the video / audio receiver 2, when an error occurs in the data due to interference from the surrounding frequency band, and / or When the error rate is low enough to affect the image / sound, it is determined that the received electric field strength is low enough to affect the image / sound. Send the error information. The video / audio transmitter 1 receives error information from the video / audio receiver 2 side, lowers the bit rate, and increases the number of retransmissions, thereby enhancing error tolerance.

  Next, a specific operation of the wireless communication apparatus will be described.

  The video / audio signal input from the video source 3 to the video / audio transmitter 1 is input to the input unit 5 of the video / audio transmitter 1 as shown in FIG. It is encoded into a suitable digital compressed signal, sent to the transmission unit 6, and transmitted to the video / audio receiver 2 by wireless transmission. The transmitted video / audio signal is received by the receiving unit 11 of the video / audio receiver 2, decoded by the decoding unit 13, and then output from the output unit 12 to the monitor 4. Here, the encoded video / audio signal input to the receiving unit 11 on the receiver 2 side has an error determination unit 14, an error rate determination unit 15, and an electric field strength determination through a different path from the signal to be decoded. Sent to section 16.

  The error determination unit 14 determines an error in the received data. When the error is determined, it is necessary to retransmit the data with the error. Therefore, the transmission unit 17 of the video / audio receiver 2 sends a retransmission request to the video / audio receiver 2. The data is transmitted to the audio transmitter 1 side, and the number of retransmissions is counted by the retransmission number counting unit 9 on the video / audio transmitter 1 side, and the data in error is again transmitted from the transmission unit 6 to the video / audio receiver 2 side. Resent. If an error also occurs due to retransmission, this flow is repeated a predetermined number of times. The retransmission number counting unit 9 counts the number of retransmissions. If the error is not corrected even after performing the set maximum number of retransmissions, the bit rate / retransmission number setting unit 8 changes the bit rate to increase the maximum number of retransmissions so that no error occurs. .

  When the error rate determination unit 15 determines that the video and audio have an error level that is unbearable to see or hear, the information is sent to the transmission unit of the video / audio receiver 2. 17, the bit rate / retransmission count setting unit 8 of the video / audio transmitter 1 increases the error rate by changing the bit rate and increasing the maximum number of retransmissions. Avoid errors. Such an error that is unbearable to be seen or unbearable is determined by comparison with an error rate level calculated in advance through experiments or the like. There may be a plurality of error rate levels. Moreover, it is good also as a structure which can select a limit level by a user's instruction | indication.

  When the electric field strength determination unit 16 determines that the electric field strength is at a level that gives an error of a level that is unbearable to see or hear video and audio, the transmission unit of the video / audio receiver 2 17, the information is transmitted to the video / audio transmitter 1 side, and the bit rate / retransmission number setting unit 8 changes the bit rate and increases the maximum number of retransmissions, so that even when the electric field strength is low, Avoid errors. As in the case of the error rate, it is determined by comparison with the received electric field strength in advance by experiments or the like that the received signal is unbearable for viewing or unheard of.

  The error determination unit 14, error rate determination unit 15, and electric field strength determination unit 16 constitute an error information generation unit 18 that generates error information. If at least one of these three parts can be used as error information, it is preferable to generate error information using information of two parts or all three parts. Become.

  Also, when the error no longer occurs by reducing the bit rate and increasing the number of retransmissions, increase the bit rate at regular intervals to increase the maximum number of retransmissions in order to check whether the interference is still occurring. By increasing the number, check whether the error occurs again at the newly set maximum number of retransmissions, whether the error rate is not low, or the electric field strength is low. If there is no problem, the original bit rate and maximum retransmission are confirmed. Return to the number of times setting.

  By repeating this operation, even if there is interference from the surroundings in this wireless communication device, it can withstand viewing by smoothly reducing the bit rate and increasing the number of retransmissions without causing disturbance in the video and audio. It is possible to ensure transmission of image quality and sound.

  In other words, if the processing is such that the bit rate is temporarily lowered and the bit rate is increased again when there is no interference when the interference is a characteristic part of the present invention, the necessary minimum image degradation can be achieved. As a result, it is possible to receive high-quality video and audio data.

  3 to 5 are flowcharts showing the operation of the wireless communication apparatus described above. FIGS. 3 and 4 show the wireless transmission rate changing operation on the video / audio receiver 2 side, and FIG. The wireless transmission rate changing operation on the transmitter 1 side is shown. In the figure, S indicates each step of the flow.

  In the flow on the video / audio receiver 2 side in FIG. 3, the communication state between the video / audio transmitter 1 and the video / audio receiver 2 is first detected from the received data (step S1).

  Next, error information is created based on the detected communication state (step S2).

  Next, the created error information is transmitted to the video / audio transmitter 1 by the transmission unit 17, and this flow is finished (step S3).

  FIG. 4 is a communication state detection subroutine, which corresponds to the processing in step S1 in FIG.

  First, the error rate of the received data is determined by the error rate determination unit 15 (step S11).

  Next, the error determination unit 14 determines an error in the received data based on the retransmission count data (step S12).

  Next, the electric field intensity determination unit 16 determines the electric field intensity of the received signal (step S13), and the process returns to step S1 in FIG.

  If at least one of the above three steps S11 to S13 is executed, error information can be generated by the error information generation unit (error information generation means) 18 in step S2 shown in FIG. .

  For example, error information can be generated even with only the determined error rate, error information can be generated even with only the determined error, and only the electric field strength of the determined received signal can be generated. Can also create error information. Also, error information is a combination of error rate and error, error rate and received signal field strength, error and received signal field strength, error rate, error, and received signal field strength. Can be created.

  Further, the determinations in the above-described Steps S11 to S13 determine that the video and audio data are reproduced on the receiver 2 side, and the error is of a level that cannot be seen or heard. This determination may have a plurality of determination levels (for example, a first determination level and a second determination level) depending on the degree of error. Further, a difference may be provided for each error determination criterion, and a priority may be provided for the determination. In such a case, it is preferable that error information corresponding to the determination level is created and transmitted to the video / audio transmitter 1 side.

  FIG. 5 is a flowchart showing the flow of operations on the video / audio transmitter 1 side.

  First, error information transmitted from the video / audio receiver 2 side is received (step S21).

  Subsequently, it is determined from the received error information whether or not the error correction is impossible even by the maximum number of retransmissions (step S22). If it is determined that the error can be corrected, it is determined in step S23 whether the reception electric field strength on the video / audio receiver 2 side is at a low level.

  If it is determined in step S23 that the electric field strength is not at a low level, it is determined in step S24 whether or not the receiver 2 side reception error rate is at a high level.

  On the other hand, if it is determined in step S22 that error correction is impossible even by retransmission of the maximum number of retransmissions, if the received field strength is determined to be low in step S23, or if the reception error rate is determined in step S24. If it is determined that the level is high, the bit rate and the number of retransmissions are set based on the error information received in step S25.

  Here, it is a case where an error occurs during wireless transmission of images and sounds in an environment with a lot of interference, and normal data could not be transmitted even if data was retransmitted for the set maximum number of retransmissions. In this case, the bit rate / retransmission number setting unit 8 lowers the bit rate (transmission rate) and increases the number of retransmissions, thereby enhancing error tolerance.

  Therefore, the setting of the bit rate and the number of retransmissions in step S25 is a setting for decreasing the bit rate and increasing the number of retransmissions. Specific examples of setting the bit rate and the number of retransmissions based on this error information will be described later with reference to the second and third embodiments.

  If it is determined in step S24 that the reception error rate is not at a high level, in step S26, the original bit rate and the maximum number of retransmissions are returned to step S27.

  In step S27, data is transmitted to the video / audio receiver 2 at the set bit rate and the number of retransmissions, and this flow ends.

  In this way, in real-time transmission of moving images and audio, the video and audio can withstand viewing from the beginning, with the bit rate and the number of retransmissions that can decode beautiful video and video without interruption, and the low bit rate. Set several patterns such as level bit rate and number of retransmissions, perform constant bit rate transmission at the maximum bit rate during normal operation, and temporarily reduce the bit rate and increase the number of retransmissions only when interference occurs Control is performed.

  As described above, in the wireless communication apparatus according to the present embodiment, the video / audio receiver 2 receives the video / audio data, the reception unit 11, the error determination unit 14 that determines the video / audio data error, The video / audio transmitter 1 includes an error rate determination unit 15 that determines an error rate of video / audio data, an electric field strength determination unit 16 that determines electric field strength of video / audio data, and a transmission unit 17 that transmits error information. The transmission unit 6 transmits video / audio data, the bit rate / retransmission number setting unit 8 sets the bit rate and the maximum number of retransmissions according to error information, and the retransmission number counting unit 9 counts how many times the same data is retransmitted. And the receiving unit 10 for receiving error information, it is possible to set several kinds of preset bit rates and retransmission times when receiving interference from the surroundings. Within the scope of combinations set value, automatically lowering the bit rate, by increasing the number of retransmissions, increased resistance to interference, it is possible to realize a bit rate and the number of times of retransmission automatic change function.

  That is, in the transmission of video / audio, in an environment where there are many disturbances in the used frequency band, there is a problem that the video and audio are stopped due to the disturbance. Patent Document 1 discloses an apparatus that can reduce the probability of discarding received data due to a data error even if noise in the reception environment increases.

  However, the apparatus described in Patent Literature 1 changes the compression rate and the number of retransmissions according to the error rate for each data packet transmission, and requests that the compression rate and the number of retransmissions be increased as the error rate of the received data increases. Although the error is reduced, the video may be unbearable to see. On the other hand, in this embodiment, while realizing fixed bit rate transmission that always secures the bit rate necessary for video and audio transmission, an error due to disturbance is instantaneously judged only in the case of disturbance, and video and audio are transmitted. By reducing the bit rate temporarily and increasing the number of re-transmissions before giving visible interference, the video and audio are always reproduced clearly when there is no interference. By simply dropping it, it is possible to minimize overt interference.

[Embodiment 2]
Another embodiment of the present invention will be described as follows. In the present embodiment, a method for changing the bit rate and the number of retransmissions of the wireless communication apparatus will be described. Since the hardware configuration is the same as that in FIGS. 1 and 2 described in the first embodiment, detailed description thereof is omitted.

  FIG. 6 is a flowchart showing the wireless transmission rate changing operation on the video / audio transmitter 1 side of the wireless communication apparatus according to the present embodiment. It is executed by a microcomputer constituting the bit rate / retransmission number setting unit 8 and the retransmission number counting unit 9 of FIG. Steps that perform the same processing as in FIG. 5 are assigned the same step numbers, and descriptions of the overlapping parts are omitted.

  FIG. 7 is a diagram illustrating a configuration example of the bit rate and the maximum number of retransmissions referred to when transmitting video / audio data, and is an example of an MPEG rate for transmitting an MPEG stream.

  In FIG. 7, the MPEG rate (Mbps) and the maximum number of retransmissions are set for the MPEG rate, respectively. Each set value has a maximum / minimum transfer rate and an MPEG rate (Mbps). The maximum number of retransmissions is the number of times that the video / audio transmitter 1 retransmits when the communication state deteriorates.

  For example, in FIG. As shown in FIG. 4, when the communication state is the best, “0x21” is used as the setting value, the MPEG rate is 7.86 (Mbps), and the maximum number of retransmissions is “1”, but the communication state is deteriorated. Depending on the degree, for example, b. As shown in FIG. 7, the MPEG rate 7.18 (Mbps) with the set value “0x16” and the maximum number of retransmissions “2” are set. As shown, the MPEG rate 5.85 (Mbps) of the set value “0x0C” and the maximum number of retransmissions “4” are set. Note that the setting value and the MPEG rate are examples, and are not limited to these. Thus, the bit rate is made variable according to the communication state.

  An operation flow on the transmitter side in the wireless communication apparatus according to the present embodiment will be described with reference to the flowchart of FIG.

  First, when the bit rate and the number of retransmissions are set based on the error information received in step S25, or when the original bit rate and the maximum number of retransmissions are restored in step S26, the video / audio reception is performed in step S31. It is determined whether or not the machine 2 side reception error rate has increased rapidly.

  Here, the determination of whether or not the error rate has increased abruptly is made when the absolute value of the difference between the detected value and the previous value (including the past value before a certain time) exceeds a predetermined range. Determined to have increased. The determination method is an example, and an appropriate value is set in advance by simulation or the like, such as changing the threshold according to the error rate level.

  If the error rate has not increased sharply in step S31, it is determined in step S32 whether or not the video / audio receiver 2 side electric field strength has rapidly decreased. The determination as to whether or not the electric field strength has dropped sharply can be made by the same method as the determination process in step S31.

  When the reception error rate suddenly increases in step S31, or when the video / audio receiver 2 side electric field strength sharply decreases in step S32, it is determined that the communication state has deteriorated sharply for some reason. In S33, the bit rate is set to the lowest rank, and the process proceeds to Step S27.

  For example, in FIG. As shown in FIG. 7, when the MPEG rate 7.18 (Mbps) with the set value “0x16” is set, the d. As shown in FIG. 4, the bit rate is reduced to the lowest rank at a stroke instead of one step at a time. As a result, when the communication state such as communication interference is abruptly deteriorated, communication can be ensured by reducing the bit rate at once and increasing the number of retransmissions before the visible interference in video and audio becomes obvious. .

  Returning to the flowchart of FIG. 6, if the video / audio receiver 2 side electric field strength has not dropped sharply in step S32, whether or not the video / audio receiver 2 side reception error rate has gradually increased in step S34. Is determined.

  Here, the determination as to whether or not the error rate has gradually increased can be made, for example, by comparing the difference between the detected value and the previous value (including the past value before a certain time). If the error rate has not gradually increased, it is determined in step S35 whether or not the video / audio receiver 2 side electric field strength has gradually decreased. Whether or not the electric field intensity has gradually decreased can be determined by the same method as the determination process in step S34.

  When the reception error rate gradually increases in step S34 or when the video / audio receiver 2 side electric field strength gradually decreases in step S35, the bit rate is incremented in predetermined steps (for example, one rank) in step S36. Set to drop and proceed to step S27.

  For example, in FIG. 7 is lowered by one rank from the MPEG rate 7.86 (Mbps) of the set value shown in FIG. The MPEG rate is set to 7.81 (Mbps). Note that the setting value and the MPEG rate are examples, and are not limited to these. For example, in the above case, a. From the MPEG rate 7.86 (Mbps) of the set value shown in FIG. Alternatively, the MPEG rate may be set to 7.18 (Mbps).

  If the video / audio receiver 2 side electric field strength is not gradually decreased in step S35, the process proceeds to step S27. As a result, when the communication state gradually deteriorates, it is possible to reduce the bit rate stepwise to ensure communication, and to reduce the image quality / sound quality as much as possible.

[Embodiment 3]
The following will describe still another embodiment of the present invention. In the present embodiment, a method for changing the bit rate and the number of retransmissions of the wireless communication apparatus will be described. The hardware configuration is the same as that shown in FIGS. 1 and 2 described in the first embodiment, and a description thereof will be omitted.

  FIG. 8 is a flowchart showing the wireless transmission rate changing operation on the video / audio transmitter 1 side of the wireless communication apparatus. Steps that perform the same processing as in FIG. 5 are assigned the same step numbers, and descriptions of the overlapping parts are omitted.

  In the flowchart shown in FIG. 8, when the bit rate and the number of retransmissions are set based on the error information received in step S25, or when the original bit rate and the maximum number of retransmissions are returned to the set values in step S26, step In S41, it is determined whether or not the video / audio receiver 2 side reception error rate is at an appropriate level.

  Here, whether or not the error rate is at an appropriate level is determined based on whether or not the detected value is in a level range where there is no interference. The determination method is an example, and an appropriate value is set in advance by simulation or the like, such as changing the threshold according to the error rate level.

  If the error rate is not at the appropriate level in step S41, it is determined in step S42 whether the video / audio receiver 2 side electric field strength is at the appropriate level. As the threshold value indicating that the error rate or the electric field strength is at an appropriate level, an appropriate value is set in advance by simulation or the like.

  When the reception error rate is at an appropriate level in step S41, or when the video / audio receiver 2 side electric field strength is at an appropriate level in step S42, the error rate and / or electric field strength is restored to a level without interference. In step S43, the bit rate is set to the highest rank, and the process proceeds to step S27.

  For example, in FIG. As shown in FIG. 7, when the MPEG rate 7.18 (Mbps) with the set value “0x16” is set, the bit rate is not set by one step but a. Raise up to the highest rank shown in Thereby, when the communication state is recovered, the image quality / sound quality can be quickly improved. Here, in step S41 and step S42, the determination at an appropriate level of the error rate or the electric field strength may be made in a plurality of stages. For example, the first appropriate level and the second appropriate level lower than the first appropriate level are set in two stages, and when the first appropriate level is reached, the rank is raised to the highest rank at a stretch and the second appropriate level is reached. When the level is reached, it is possible to control the intermediate level of the highest rank.

  Returning to the flowchart of FIG. 8, if the video / audio receiver 2 side electric field strength is not at an appropriate level in step S42, whether or not the video / audio receiver 2 side reception error rate has gradually decreased in step S44. Determine. The determination as to whether or not the error rate has gradually decreased can be made, for example, by comparing the difference between the detected value and the previous value (including the past value before a certain time). If the error rate has not decreased gradually, it is determined in step S45 whether or not the video / audio receiver 2 side electric field strength has gradually increased. Whether or not the electric field intensity has gradually decreased can be determined by the same method as the determination process in step S44.

  When the reception error rate gradually decreases in step S44 or when the video / audio receiver 2 side electric field strength gradually increases in step S45, the bit rate is incremented in predetermined steps (for example, one rank) in step S46. Set to drop and proceed to step S27.

  For example, in FIG. Is raised by one rank to the MPEG rate 7.18 (Mbps) of the set value shown in FIG. The MPEG rate is set to 7.26 (Mbps). Note that the setting value and the MPEG rate are examples and are not limited to these. If the video / audio receiver 2 side electric field strength is not gradually decreased in step S45, the process proceeds to step S27.

  As a result, if the communication status returns to the level without interference, the bit rate is increased to the highest rank at a stretch to reproduce high image quality and high sound quality, and when the communication status gradually recovers, the bit rate is gradually increased. It is possible to gradually improve image quality and sound quality while ensuring communication.

  Here, since it is unlikely that an instantaneous return occurs once an interruption occurs, it may be possible to check the error rate and electric field strength every few times instead of every time. In this case, step S41 to step S46 may be executed every plural times.

[Embodiment 4]
The following will describe still another embodiment of the present invention.

  FIG. 9 is a block diagram illustrating a configuration of the wireless communication apparatus according to the present embodiment. As shown in FIG. 13, the wireless communication apparatus of this embodiment is an example applied to a display-separated wireless TV receiver.

  That is, the wireless AV system 101 includes a TV main unit 103 and a wireless center unit 102 as shown in FIG.

  The TV main unit 103 includes a wireless TV receiver with a built-in battery, and includes a remote controller (hereinafter referred to as a remote controller) 130 and is connected to the wireless center unit 102 via the TV main unit 103. Remote control operation of the video deck etc. that can be done.

  In FIG. 9, a wireless AV system 101 includes a wireless center unit (hereinafter referred to as a wireless center) 102 as a base device and a television (TV) main unit (hereinafter referred to as a TV main body) 103 as a portable terminal. The wireless center 102 (wireless communication device, transmitter, center device) and the TV body 103 (wireless communication device, receiver, display device) are paired to form a wireless transmission network.

  The wireless center 102 includes an BS terminal 111, a U / VHF antenna terminal 112, and a diversity terminal 113, a video 1 input terminal 114 with an S terminal for connecting devices such as a digital VTR and a DVD player, a decoder input / video 2 An input terminal 115, a monitor / BS output / video 3 input terminal 116, an AC power supply unit 117, and a Car-DC power supply unit 118 are provided.

  The TV main body 103 includes a TV output / video 4 input terminal 121 for connecting devices such as a digital VTR and a DVD (Digital Versatile Disc) player, an AC power supply unit 122, and a Car-DC power supply unit 123.

  The TV body 103 is a thin display device that is separable from the wireless center 102 and can be carried or carried with a built-in battery. For example, a liquid crystal television (hereinafter referred to as a liquid crystal television), an inorganic EL / organic EL display, a plasma display, or the like. These are wide concepts including various display devices, and are not limited by the display mechanism. Further, in this specification, the TV main body 103 mainly has a display function, an acoustic function, and the like, while the wireless center 102 mainly stores a control function and the like for controlling the tuner unit and the TV main body 103. The TV main body 103 according to the present embodiment will be described using a liquid crystal television as an example of a thin display device.

  Data is transmitted and received between the wireless center 102 and the TV main body 103 by an SS (Spread Spectrum) wireless system compliant with the IEEE 802.11b standard. Recently, the 5 GHz band is released as a frequency band, and a mode using the 5 GHz band instead of the 2.4 GHz band may be used. Data transmission from the wireless center 102 to the TV main body 103 uses moving picture expert group (MPEG) 2 video compression format to transmit moving image transmission, DVD-Video, and digital broadcasting over a communication line exceeding 10 Mbps. Further, command transmission between the wireless center 102 and the TV main body 103 is performed by the SS wireless method.

  When applying to an actual application including MPEG video and MPEG audio encoded streams (bit strings) and other encoded streams, the encoded streams are multiplexed and integrated into a single unit including synchronization. At the same time, it is necessary to make the stream a data format conforming to a specific physical format or protocol possessed by the storage medium or network.

  The MPEG2 system includes a program stream (MPEG2-PS, PS: Program Stream) that constitutes one program, and a transport stream (MPEG2-TS, TS: Transport Stream) that can constitute a plurality of programs, as in MPEG1. There is.

  The MPEG stream is a byte stream that is byte-aligned for each unit such as a header although there are many 1-bit flags. As a structure common to the entire MPEG system, the data portion that is not fixed length is preceded by information indicating the length. If unnecessary, that portion is skipped or the head of the next data group is confirmed and trusted. It has a data structure that enables highly-separated separation processing.

  An apparatus for receiving compressed video and audio signals in conformity with the MPEG2 encoding system is designed to receive video and audio sampling frequencies on the encoding side in order to prevent overflow and underflow of video and audio data on the decoding side. And the video, audio sampling frequency or STC (System Time Clock) on the decoding side must be matched.

  Therefore, the decoding apparatus uses PCR (Program Clock Reference) or SCR (System Clock Reference) defined by the MPEG2 system standard (ISO / IEC standard 13818-1). Thus, the video and audio sampling frequencies on the encoding side are matched with the video and audio sampling frequencies on the decoding side.

  FIG. 10 is a block diagram showing a configuration of the wireless center 102 of the wireless AV system.

  In FIG. 10, a wireless center 102 is connected to a BS terminal 111 and receives and selects a BS broadcast by a channel selection signal, and a U / VHF broadcast by a channel selection signal connected to a U / VHF antenna terminal 112. A U / VHF tuner 132 that receives and selects, a video / audio demodulator 133 that demodulates a video / audio (AV) signal received and selected by the BS tuner 131 or the U / VHF tuner 132, and an audio switching signal. An audio switching unit 134 that switches between received audio and information related to a program such as an EPG (Electrical Program Guide), video / audio information received by a source selection signal, information related to a program, video 1 input terminal 114, decoder External input information from input / video 2 input terminal 115 and monitor / BS output / video 3 input terminal 116 A first selector 135 that selects the TV, and an SS transmission unit 136 that transmits / receives a TV command, converts the data selected by the first selector 135 into an MPEG2 video compression format, and transmits the data to the TV main body 103 using the SS wireless method. (Transmission means, reception means, second transmission means, second reception means), the channel selection signal 141, the audio switching signal 142, the source selection signal 143, etc., and the TV command 144 are transmitted and received to transmit the entire apparatus. Stores a wireless center microcomputer (hereinafter referred to as a microcomputer) 137 (transmission rate setting means) for controlling the above, a control program for the wireless center microcomputer 137, communication control data, and various data of MPEG rates set for each content. EEPROM, an electrically rewritable non-volatile memory Constructed and a M (electrically erasable programmable ROM) 138 (setting value storage means).

  The wireless center 102 may include a plurality (two in this case) of broadcast receiving tuners, and at least one of the plurality of BS tuners 131 and U / VHF tuners may be a tuner capable of receiving terrestrial digital broadcasting.

  The SS transmission unit 136 includes an A / D converter 151 that converts the data selected by the first selector 135 into a digital signal, an MPEG2 encoder 152 that converts the data into an MPEG2 video compression format, and transmission data according to the SS radio system. The SS radio transmission engine 153 including an SS radio device and a radio control unit for transmission, and each part of the SS transmission unit are controlled, and a first SS-CPU 154 (communication state detection unit) for detecting a radio wave state is provided. .

  The EEPROM 138 stores the MPEG rate set for each content in a table as shown in FIG. Various specifications in the wireless center 102 and the TV main body 103 can be changed by changing a program written in the EEPROM 138. That is, recently, in order to avoid the time loss of changing the mask ROM for each debugging of the system development, the program ROM is a non-volatile memory, for example, EPROM, EEPROM, and the time for program development / modification time is greatly reduced. . Further, if the program is downloaded and the program contents of the EEPROM are rewritten, it is possible to easily upgrade functions or change functions.

  The SS wireless transmission engine 153 has a transmission function for transmitting an MPEG2 stream, a command, and the like to an SS reception unit 161 (described later in FIG. 11) of the TV main body 103, and a reception function for receiving a command and the like from the SS reception unit 161. Prepare.

  In particular, the first SS-CPU 154 detects a radio wave state detection that detects the communication state (the strength of the radio wave, the jamming of the communication path) between the wireless center 102 and the TV main body 103 by a retransmission request based on the electric field strength and error rate of the received radio wave. A function as a means is provided. Information indicating the detected radio wave state is sent to the wireless center microcomputer 137 as a TV command 144. In the present embodiment, the configuration in which the first SS-CPU 154 of the wireless center microcomputer 137 has the radio wave state detection function is shown, but the second SS-CPU 184 of the TV main body 103 has the same function and detects it. A mode in which information indicating the radio wave state is transmitted from the TV main body 103 to the wireless center 102 may be used. Alternatively, both the first SS-CPU 154 and the second SS-CPU 184 may have a radio wave state detection function. Furthermore, the aspect which the TV microcomputer 164 or the wireless center microcomputer 137 performs the said electromagnetic wave state detection function may be sufficient.

  The wireless center microcomputer 137 controls the entire apparatus and stores in advance a set value combining a plurality of transmission rates and the number of retransmissions as shown in FIG. Based on the information, the stored setting value is selected, and control is performed to set the transmission rate and the number of retransmissions based on the selected setting value.

  Here, as a technique for realizing a wireless AV system, for example, there is a standard specification called HAVi (Home Audio / Video Interoperability) Architecture that has been standardized in January 2000. As described in the HAVi V1.0 Specification version overview (1.1 General's 1.1 Scope), this specification connects home appliances and computers, and allows a user to use another device to connect another device. Provides an interface for operation. In the HAVi specification, as an example, it is assumed that a network is constructed by household appliances compliant with IEEE 1394 and IEC (International Electrotechnical Commission) 61883. Moreover, as in the same outline part of the specification, all users can freely use devices connected to the network realized by HAVi. In this way, by connecting AV devices in the home and constructing an AV network, the user can use any combination of devices in remote rooms.

  In addition to such a home AV network, the wireless center 102 as a transmitter and the TV main body 103 as a receiver include, for example, a mobile phone / PHS (Personal Handy-Phone System) (registered trademark) that performs wireless communication. Or a wireless communication terminal such as a portable information terminal (hereinafter referred to as PDA (Personal Digital Assistants)).

  FIG. 11 is a block diagram showing a configuration of the TV main body 103 of the wireless AV system.

  In FIG. 11, the TV main body 103 receives and transmits the TV command and receives the MPEG2 stream and command transmission data transmitted from the SS transmission unit 136 of the wireless center 102, and decodes (restores) the received MPEG2 stream and the like into the original data. ) SS receiving unit 161 (transmitting means, receiving means, first transmitting means, first receiving means), data restored by SS receiving unit 161 and external input via TV output / video 4 input terminal 121 A TV selector 171 that includes a second selector 162 that selects an AV signal to be transmitted, an LCD that displays a video signal and outputs an audio signal, and the TV command 171, and a source selection signal 172, OSD ( On-screen display) 173 etc. to send the whole device TV microcomputer 164 that performs control, EEPROM 165 that is an electrically rewritable nonvolatile memory that stores various data such as a control program of TV microcomputer 164, communication control data, and a communication channel change program, and a remote control (not shown) A remote control light receiving unit 166 that receives a control command from a device (hereinafter referred to as a remote control device), a battery 167, and a battery charger microcomputer 168 that controls charging / discharging of the battery 167 are configured.

  The SS reception unit 161 includes an SS radio reception engine 181 including an SS radio and a radio control unit for receiving data transmitted by the SS radio method, an MPEG2 decoder 182 for decoding the received MPEG2 stream, and an analog signal for the decoded data. A D / A conversion unit 183 that converts the signal to each other and each unit of the SS receiving unit and a second SS-CPU 184 (communication state detection unit, error determination unit, and electric field strength determination unit) that detect a radio wave state are configured. Is done.

  The SS radio reception engine 181 includes a reception function for receiving an MPEG2 stream, a command, and the like from the SS transmission unit 136 of the wireless center 102, and a transmission function for transmitting a command and the like from the SS reception unit 161.

  The TV microcomputer 164 has an OSD generation function unit therein, and displays information such as a channel, time, and volume on a screen of a television or the like. In an electronic apparatus such as a video apparatus such as a TV or a video conference system, information such as a channel, time, and volume is generally displayed on a TV screen. The OSD data is not an image, but is stored in a format called a bitmap. This bitmap is converted into YUV format pixel values represented by Y, Cb, and Cr, and the converted pixels are used for television broadcasting or the like. Is superimposed on the original image. Further, if an image playback device such as a DVD (not shown) is connected to the TV output / video 4 input terminal 121, OSD display is possible by superimposing the playback image on the display screen.

  Although not shown, the TV main body 103 includes a speaker, a key input unit, a slot for inserting / removing a card-type external expansion storage medium, and the like. It is good also as a structure which reads directly. The card-type external extended storage medium includes, for example, an SRAM (Static RAM) card that holds information written by power backup, a compact flash (registered trademark) (CF) including a flash memory that does not require power backup, smart media, memory It is a very small hard disk drive (HDD) or the like that can be mounted on a stick or a PC card Type II.

  The remote control light receiving unit 166 is an optical communication port unit that uses IR (Infrared Rays), and receives optical signals from a remote control device that performs various operations on the TV main body 103 or the wireless center 102. Specifically, it is a standard for transmitting data using infrared rays, an I / O port for performing optical communication in accordance with IrDA (Infrared Data Association), ASK, or the like, or a wireless communication port using radio waves. .

  The battery 167 supplies predetermined power to each part of the TV main body 103. When the battery 167 is ready to be charged, the battery charger microcomputer 168 detects that, for example, the TV main body 103 is mounted on the wireless center 102 or other cradle, and supplies a power supply terminal ( In either case, charging / discharging is controlled via a not shown). Specifically, the battery charger microcomputer 168 integrates the discharge current of the battery pack and starts charging when it is determined that the remaining capacity of the battery pack has become a predetermined value or less, and at the time of charging, the charging current to the battery pack is calculated. The charging is stopped when it is determined that the battery pack has been fully charged. The charged battery 167 becomes a main power source of the portable TV when the TV main body 103 is disconnected from the commercial power source, and supplies power to each part of the main body.

  As described above, the wireless AV system 101 according to the present embodiment includes the wireless center 102 and the TV main body 103 that transmit and receive video and audio data at a predetermined MPEG rate. A wireless center microcomputer 137 that performs control, an EEPROM 138 that stores a set MPEG rate, and a first SS that detects a communication state between the wireless center 102 and the TV main body 103 by a retransmission request based on the electric field strength and error rate of the received radio wave -The CPU 154 is provided, and the wireless center microcomputer 137 performs control to set the transmission rate of video and audio data to be transmitted based on the detected communication state, so that the communication state changes (especially when it deteriorates). As in the conventional example, the user manually By automatically setting the bit rate according to the AV data instead of lowering the video rate or fixing the bit rate, even if the communication status deteriorates, the degradation of video and audio data is minimized. The data transmission can be maintained as much as possible for data such as news programs that require information transmission.

  The wireless communication device, transmitter, receiver, wireless communication system, and wireless AV system of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. Of course, it can be added. For example, a portable TV is used as a wireless AV device, but the present invention is not limited to a TV receiver, and can be applied to a device having a wireless communication function or a combination thereof. For example, as an AV device, in addition to a VTR (Video Tape Recorder), a recording / reproducing apparatus for recording on an HDD or a DVD may be used. In addition, as a device that can transmit and receive data, a device that is integrated with an information device function represented by a personal computer may be used, and it can be applied to all systems. The contents of the transmitted / received data may be anything.

  In this embodiment, the TV receiver has been described. However, the present invention is not limited to this, and as described above, the present invention can be applied to a tuner, a personal computer, and other AV devices using the tuner.

  Further, the types of the processing units and the like, the type / format of the setting information, etc. constituting the wireless communication device, the transmitter, the receiver, and the wireless AV system are not limited to the above-described embodiments. In particular, it is suitable for application to a device that complies with HAVi.

  The AV data is transmitted by an MPEG stream conforming to the MPEG2 encoding system, but the data transmission can be similarly applied to data transmission other than an MPEG stream or an MPEG stream according to another MPEG system. Further, the content type and the MPEG rate shown in FIG. 6 are examples and are not limited to these.

  In this embodiment, the names wireless communication device, wireless communication system, wireless AV system, and wireless transmission method are used. However, this is for convenience of explanation, and a wireless transmission device, an AV data communication device, an information communication method, and the like. It may be.

  The wireless communication device, transmitter, receiver, and wireless AV system described above are also realized by a program for causing the wireless communication device, transmitter, receiver, and wireless AV system to function. This program is stored in a computer-readable recording medium. In the present invention, as the recording medium, the main memory itself may be a program medium, or a program reading device is provided as an external storage device and can be read by inserting the recording medium therein. May be. In either case, the stored program may be configured to be accessed and executed by the CPU, or in any case, the program is read and the read program is not shown in a program storage area. The program may be downloaded and executed by the program. It is assumed that this download program is stored in the main device in advance.

  Here, the program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (registered trademark) disk or a hard disk, or a CD-ROM / MO /. It may be a medium carrying a fixed program including a disk system of an optical disk such as MD / DVD, a card system such as an IC card / optical card, or a semiconductor memory such as a mask ROM, EPROM, EEPROM, flash ROM or the like. .

  Furthermore, although not shown in the figure, when a means capable of connection to an external communication network is provided, the program is fluidly supported so that the program is downloaded from the communication network via the communication connection means. It may be a medium. When the program is downloaded from the communication network in this way, the download program may be stored in the main device in advance, or may be installed from another recording medium. The content stored in the recording medium is not limited to a program, and may be data.

  As described above in detail, according to the present invention, when an image or sound is transmitted due to interference from the surroundings during transmission of image or sound by fixed bit rate wireless transmission, the image or sound is disturbed. The error tolerance can be enhanced by temporarily lowering the transmission bit rate automatically and increasing the maximum number of retransmissions of error data.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  Note that each unit and each processing step of the wireless communication apparatus according to the above embodiment is such that a calculation unit such as a CPU executes a program stored in a storage unit such as a ROM (Read Only Memory) or a RAM, and an input unit such as a keyboard. It can be realized by controlling output means such as a display or communication means such as an interface circuit. Therefore, the computer having these means can realize various functions and various processes of the wireless communication apparatus of the present embodiment simply by reading the recording medium storing the program and executing the program. In addition, by recording the program on a removable recording medium, the various functions and various processes described above can be realized on an arbitrary computer.

  As this recording medium, a program medium such as a memory (not shown) such as a ROM may be used for processing by the microcomputer, or a program reader is provided as an external storage device (not shown). It may be a program medium that can be read by inserting a recording medium therein.

  In any case, the stored program is preferably configured to be accessed and executed by the microprocessor. Furthermore, it is preferable that the program is read out, and the read program is downloaded to a program storage area of the microcomputer and the program is executed. It is assumed that this download program is stored in advance in the main unit.

  The program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, or a disk such as a CD / MO / MD / DVD. Fixed disk, IC card (including memory card), etc., or semiconductor ROM such as mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), flash ROM, etc. In particular, there are recording media that carry programs.

  In addition, if the system configuration is capable of connecting to a communication network including the Internet, the recording medium is preferably a recording medium that fluidly carries the program so as to download the program from the communication network.

  Further, when the program is downloaded from the communication network as described above, it is preferable that the download program is stored in the main device in advance or installed from another recording medium.

  Further, as conventional problems, there are the following, and the object of the present application is as follows.

  Since the conventional wireless communication device assumes a variable bit rate as a compression method, it is necessary to change the compression rate and the number of retransmissions depending on the error rate for each data packet transmission. Also, by requesting that the compression rate and the number of retransmissions be increased as the error rate of the received data increases, the compression rate may be increased too much, and the audio may become unbearable. There is also. Also, when applied to video transmission, the video may become unbearable.

  The present invention has been made in view of such a problem, and even when the communication state is deteriorated, wireless communication capable of minimizing the deterioration of video and audio data and enhancing error resistance. An object is to provide a communication device, a transmitter, a receiver, a wireless communication system, a wireless AV system, a wireless transmission method, an operation control program, and a recording medium on which the program is recorded.

  The wireless communication device of the present invention may have the following configuration.

  In a wireless communication apparatus that transmits data including video and audio data at a predetermined bit rate, a communication state detection unit that detects a communication state, and a setting value storage that stores a combination of a plurality of transmission rates and the number of retransmissions And a transmission rate setting means for selecting a setting value stored in the setting value storage means based on the detected communication state and setting a transmission rate and the number of retransmissions based on the selected setting value. A wireless communication apparatus.

  In addition, the communication state detection unit may detect the communication state based on the electric field strength of the received radio wave, the error rate, or the number of retransmission requests based on the error rate.

  The communication state detection unit may detect a communication state between wireless communication devices with which communication links are established.

  The video and audio data may be transmitted by an MPEG stream conforming to the MPEG encoding method.

  The transmitter of the present invention may have the following configuration.

  In a transmitter that transmits data including video and audio data at a predetermined bit rate, a receiving unit that receives error information from a data transmission destination, and a setting that stores a set value that combines a plurality of transmission rates and the number of retransmissions A value storage means, a transmission rate setting means for selecting a setting value stored in the setting value storage means based on the transmitted error information, and setting a transmission rate and the number of retransmissions based on the selected setting value; A transmitter comprising: transmission means for transmitting video and audio data at a transmission rate and the number of retransmissions based on the set value.

  The receiver of the present invention may have the following configuration.

  In a receiver that receives video and audio data transmitted at a predetermined bit rate, a receiving unit that receives video and audio data, an error determination unit that determines an error in the received data, and the error information that is determined as a data transmission source And a transmission means for transmitting to.

  The error determination unit may determine the electric field strength of the received data, and the transmission unit may transmit the electric field strength determined by the error determination unit as error information.

  The wireless communication system of the present invention may have the following configuration.

  In a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate, the receiver receives first video and audio data transmitted from the transmitter Means, error determination means for determining an error in received data, and first transmission means for transmitting the determined error information to the transmitter. The transmitter transmits error information transmitted from the receiver. Based on error information transmitted from the receiver, second setting means for receiving, setting value storage means for storing setting values combining a plurality of transmission rates and the number of retransmissions, the setting value storage means Transmission rate setting means for selecting a stored setting value and setting the transmission rate and the number of retransmissions based on the selected setting value; and the transmission rate and the number of retransmissions based on the setting value Wireless communication system characterized in that it comprises a second transmitting means for transmitting the video and audio data.

  In a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate, the receiver receives first video and audio data transmitted from the transmitter Means, field strength determination means for determining the field strength of received data, and first transmission means for transmitting the determined field strength as error information to the transmitter, wherein the transmitter transmits from the receiver. Based on error information transmitted from the receiver, second value receiving means for receiving error information, setting value storage means for storing setting values combining a plurality of transmission rates and the number of retransmissions, Transmission rate setting means for selecting a setting value stored in the setting value storage means and setting a transmission rate and the number of retransmissions based on the selected setting value; and transmission based on the setting value Wireless communication system characterized in that it comprises a second transmitting means for transmitting the video and audio data over preparative and retransmission count.

  The transmission rate setting means may reduce the transmission rate and increase the number of retransmissions when the error is not corrected by retransmitting the data at the maximum number of retransmissions.

  The transmission rate setting means may reduce the transmission bit rate and increase the number of retransmissions when the electric field strength detected on the receiver side is below a predetermined level at which errors are likely to occur.

  The transmission rate setting means may reduce the transmission rate and increase the number of retransmissions when the error rate of the data received on the receiver side is a predetermined level that affects video and audio.

  The transmission rate setting means may lower the transmission rate to the lowest rank when the error rate detected on the receiver side suddenly increases and / or when the electric field strength sharply decreases.

  The transmission rate setting means may decrease the transmission rate by a predetermined rank when the error rate detected on the receiver side gradually increases and / or when the electric field strength gradually decreases.

  The transmission rate setting means may increase the transmission rate to the highest rank when the error rate detected on the receiver side is at the level without interference and / or when the electric field strength is at the level without interference. .

  The transmission rate setting means may increase the transmission rate by a predetermined rank when the error rate detected on the receiver side gradually decreases and / or when the electric field strength gradually increases.

  The above wireless communication system may be applied to the following AV system.

  A wireless AV system for connecting a plurality of wireless communication devices through a wireless network, wherein the wireless communication device is a wireless communication system having the above-described configuration.

  The wireless communication system may be a television receiver including a display device and a broadcast receiving tuner, and a center device that transmits video and audio data to the display device.

  The wireless transmission method of the present invention may have the following configuration.

  In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and Selecting a set value based on a communication state, and setting a transmission rate and the number of retransmissions based on the selected set value.

  The control program of the present invention may have the following configuration.

  In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and A program for causing a computer to execute a step process of selecting the setting value based on a communication state and setting a transmission rate and the number of retransmissions based on the selected setting value.

  The recording medium of the present invention may have the following configuration.

  In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and A computer-readable program having recorded thereon a program for causing a computer to execute step processing for selecting the setting value based on a communication state and setting a transmission rate and the number of retransmissions based on the selected setting value recoding media.

  As described above in detail, according to the present invention, when an image or sound is transmitted due to interference from the surroundings during transmission of image or sound by fixed bit rate wireless transmission, the image or sound is disturbed. The error tolerance can be enhanced by temporarily lowering the transmission bit rate automatically and increasing the maximum number of retransmissions of error data.

  Further, the wireless communication device according to the present invention is a wireless communication device that transmits data including video and audio data at a predetermined bit rate, a communication state detection unit that detects a communication state based on a signal from a transmission partner, Data transmission means for transmitting the data while variably controlling the bit rate based on the communication state detected by the communication state detection means, wherein the data transmission means has the detected communication state as a predetermined reference When the above condition is not satisfied, the bit rate is temporarily reduced to transmit data.

  The data transmission means increases the bit rate to a predetermined level and transmits data if the communication state detected by the communication state detection means satisfies a predetermined standard when data transmission is performed at a reduced bit rate. You may make it transmit.

  Furthermore, a setting value storage means for storing a setting value combining a plurality of bit rates and the number of times of data retransmission is provided, and the data transmission means stores the setting value in the setting value storage means based on the detected communication state. The selected setting value may be selected, and data may be transmitted at a bit rate and the number of retransmissions corresponding to the selected setting value.

  The video and audio data may be transmitted by an MPEG stream conforming to the MPEG (Motion Picture Experts Group) encoding method.

  A wireless communication system according to the present invention is a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate. The receiver receives data received from the transmitter. Communication state detection means for determining an error and detecting a communication state based on the determination result, and error information transmission means for transmitting the communication state detected by the communication state detection means to the transmitter as error information The transmitter includes data transmission means for transmitting the data while variably controlling the bit rate based on the communication state detected by the communication state detection means, and the data transmission means includes the detected communication When the state does not satisfy a predetermined standard, the bit rate is temporarily lowered to transmit data.

  The wireless AV system according to the present invention is a wireless AV (audio visual) system in which a plurality of wireless communication devices are connected through a wireless network, wherein the wireless communication device is the wireless communication device according to claim 1. Yes.

  The wireless transmission method according to the present invention is a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, wherein a first step of detecting a communication state based on a signal from a transmission partner, A second step of transmitting the data while variably controlling the bit rate based on the communication state detected in the step, wherein the communication state does not satisfy a predetermined criterion in the second step. The bit rate is temporarily lowered to transmit data.

  The control program according to the present invention is a control program for operating the wireless communication apparatus having the above-described configuration, and may be a control program for causing a computer to function as each of the above-described means.

  The recording medium according to the present invention may be a computer-readable recording medium in which the control program having the above configuration is recorded.

  In order to solve the above problems, a wireless communication device according to the present invention detects a communication state based on a signal from a transmission partner in a wireless communication device that transmits data including video and audio data at a predetermined bit rate. And a data transmission means for transmitting the data while variably controlling the bit rate based on the communication status detected by the communication status detection means, wherein the data transmission means is detected. When the communication state does not satisfy a predetermined standard, the bit rate is temporarily reduced to transmit data.

  Here, the communication state does not satisfy a predetermined standard means a communication state that is difficult for most users to see if it is video data, and if it is audio data, a large number of users This refers to the communication status that is difficult to listen to.

  In addition, when the bit rate is lowered, the quality of video and audio will be reduced, but the bit rate is such that video and audio will not be produced as in the case where the communication state as described above does not meet the predetermined standard. Can be lowered.

  Therefore, when the data transmission means does not satisfy the predetermined criteria from the detected communication state, the data can be temporarily reduced to transmit the data, thereby minimizing the deterioration of the video and audio data. .

  As a result, even if the communication state deteriorates, deterioration of video and audio data is minimized, and as a result, data communication can be performed without reducing the quality of the entire video and audio to be transmitted. it can.

  In addition, when data transmission is performed at a reduced bit rate, if the communication state detected by the communication state detection means satisfies a predetermined standard, the bit rate is increased to a predetermined level and data is transmitted. It may be.

  This makes it possible to minimize the period during which video and audio data is degraded. In this case, the predetermined standard may be a standard for raising the bit rate at the beginning of communication, a standard for raising the bit rate to a value lower than the initial bit rate of communication, It may be a standard for raising the value to a value higher than the initial bit rate.

  Furthermore, a setting value storage means for storing a setting value combining a plurality of bit rates and the number of times of data retransmission is provided, and the data transmission means stores the setting value in the setting value storage means based on the detected communication state. The selected setting value may be selected, and data may be transmitted at a bit rate and the number of retransmissions corresponding to the selected setting value.

  In this case, even if the error rate of data transmission is high, such as when the communication state is very bad, data communication is possible if the bit rate is lowered and the number of times of data retransmission is increased. . That is, since the bit rate of data transmission and the number of times of data retransmission can be set according to the degree of communication state, error tolerance can be enhanced.

  The video and audio data may be transmitted by an MPEG stream conforming to the MPEG encoding method.

  In order to solve the above problems, a wireless communication system according to the present invention is a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate. Error determination means for determining an error in the data received from the transmitter; and error information transmission means for transmitting the error determined by the error determination means to the transmitter as error information. Based on the error information transmitted from the receiver, a communication state detection unit for detecting a communication state, and the bit rate is temporarily set when the communication state detected by the communication state detection unit does not satisfy a predetermined standard. And data transmission means for transmitting data to the receiver.

  According to the above configuration, even when the communication state deteriorates, it is possible to perform data communication while minimizing the deterioration of video and audio data without reducing the quality of video and audio to be transmitted. A system can be realized.

  Further, if the above-described wireless communication apparatus is applied to a wireless AV system in which a plurality of networks are connected, a wireless AV system in which deterioration of video and audio data is minimized can be realized.

  As described above, the wireless communication device according to the present invention includes a communication state detection unit that detects a communication state based on a signal from a transmission partner, and the bit based on the communication state detected by the communication state detection unit. Data transmission means for transmitting the data while variably controlling the rate, and the data transmission means temporarily lowers the bit rate when the detected communication state does not satisfy a predetermined standard. By transmitting, even if the communication status deteriorates, degradation of video and audio data is minimized, and as a result, data communication is performed without reducing the quality of the entire video and audio to be transmitted. There is an effect that can be.

  The wireless communication apparatus of the present invention is suitable for a home AV network system such as a display-separated type wireless TV receiver that wirelessly transmits video and / or audio data, but is not limited thereto. / PHS (registered trademark) (Personal Handy-Phone System) and personal digital assistants (PDA (Personal Digital Assistants)) and other wireless communication devices can be widely applied.

It is a figure which shows the operation | movement outline | summary of the radio | wireless communication apparatus of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication apparatus of this Embodiment. It is a flowchart which shows the radio | wireless transmission rate change operation | movement by the video / audio receiver side of the wireless communication apparatus of this Embodiment. It is a flowchart which shows the radio | wireless transmission rate change operation by the video / audio receiver side of the radio | wireless communication apparatus of this Embodiment. It is a flowchart which shows the radio | wireless transmission rate change operation | movement by the video / audio transmitter side of the wireless communication apparatus of this Embodiment. It is a flowchart which shows the radio | wireless transmission rate change operation | movement by the video / audio transmitter side of the radio | wireless communication apparatus of the 2nd Embodiment of this invention. It is a figure which shows the structural example of the bit rate referred to at the time of video / audio data transmission of the radio | wireless communication apparatus of this Embodiment, and the maximum number of resending. It is a flowchart which shows the radio | wireless transmission rate change operation by the video / audio transmitter side of the radio | wireless communication apparatus of the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication apparatus of the 4th Embodiment of this invention, a transmitter, a receiver, and a wireless AV system. It is a block diagram which shows the structure of the wireless center of the radio | wireless communication apparatus of this Embodiment, a transmitter, a receiver, and a wireless AV system. It is a block diagram which shows the structure of the TV main body of the radio | wireless communication apparatus of this Embodiment, a transmitter, a receiver, and a wireless AV system. It is a figure which shows the structure of the conventional audio | voice data communication apparatus. It is a block diagram which shows the principal part structure of the specific example of the wireless AV system using the radio | wireless communication apparatus of this invention.

Explanation of symbols

1 Video / audio transmitter (wireless communication device, transmitter)
2 Video / audio receiver (wireless communication device, receiver)
3 video source 4 external monitor 5 input unit 6 transmission unit (data transmission means)
7 Encoding section 8 Bit rate / retransmission count setting section (data transmission means)
DESCRIPTION OF SYMBOLS 9 Retransmission count part 10 Receiving part 11 Receiving part 12 Output part 13 Decoding part 14 Error determination part 15 Error rate determination part 16 Electric field strength determination part 17 Transmission part 18 Error information generation part (communication state detection means)
101 Wireless AV system (wireless communication system)
102 Wireless center (wireless communication device)
103 TV body (wireless communication device)
111 BS terminal 112 U / VHF antenna terminal 113 Diversity terminal 114 Video 1 input terminal 115 Decoder input / Video 2 input terminal 116 Monitor / BS output / Video 3 input terminal 117 AC power supply unit 118 Car-DC power supply unit 121 TV output / video 4-input terminal 122 AC power supply unit 123 Car-DC power supply unit 130 Remote control 131 BS tuner 132 U / VHF tuner 133 Video / audio demodulation unit 134 Audio switching unit 135 First selector 136 SS transmission / reception unit (data transmission means)
137 Wireless Center Microcomputer 138 EEPROM
141 Channel selection signal 142 Audio switching signal 143 Source selection signal 144 TV command 151 A / D converter 152 encoder 153 SS wireless transmission / reception engine 154 CPU
161 SS transmission / reception unit (data transmission means, communication state detection means)
162 Second selector 163 TV display unit 164 TV microcomputer 165 EEPROM
166 Remote control light receiving unit 167 Battery 168 Battery charger microcomputer 171 TV command 172 Source selection signal 173 OSD
181 SS wireless transmission / reception engine 182 coder 183 D / A conversion unit 184 CPU

Claims (21)

In a wireless communication apparatus that transmits data including video and audio data at a predetermined bit rate, a communication state detection unit that detects a communication state, and a setting value storage that stores a combination of a plurality of transmission rates and the number of retransmissions And a transmission rate setting means for selecting a setting value stored in the setting value storage means based on the detected communication state and setting a transmission rate and the number of retransmissions based on the selected setting value. A wireless communication apparatus. 2. The wireless communication apparatus according to claim 1, wherein the communication state detection unit detects a communication state based on a field intensity of a received radio wave, an error rate, or the number of retransmission requests based on the error rate. The wireless communication device according to claim 1, wherein the communication state detection unit detects a communication state between wireless communication devices with which a communication link is established. The wireless communication apparatus according to any one of claims 1 to 3, wherein the video and audio data are transmitted by an MPEG stream conforming to an MPEG encoding method. In a transmitter that transmits data including video and audio data at a predetermined bit rate, a receiving unit that receives error information from a data transmission destination, and a setting that stores a set value that combines a plurality of transmission rates and the number of retransmissions A value storage means, a transmission rate setting means for selecting a setting value stored in the setting value storage means based on the transmitted error information, and setting a transmission rate and the number of retransmissions based on the selected setting value; A transmitter comprising: transmission means for transmitting video and audio data at a transmission rate and the number of retransmissions based on the set value. In a receiver that receives video and audio data transmitted at a predetermined bit rate, a receiving unit that receives video and audio data, an error determination unit that determines an error in the received data, and the error information that is determined as a data transmission source A receiver for transmitting to the receiver. 7. The receiver according to claim 6, wherein the error determination unit determines the electric field strength of the received data, and the transmission unit transmits the electric field strength determined by the error determination unit as error information. In a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate, the receiver receives first video and audio data transmitted from the transmitter Means, error determination means for determining an error in received data, and first transmission means for transmitting the determined error information to the transmitter. The transmitter transmits error information transmitted from the receiver. Based on error information transmitted from the receiver, second setting means for receiving, setting value storage means for storing setting values combining a plurality of transmission rates and the number of retransmissions, the setting value storage means Transmission rate setting means for selecting a stored setting value and setting the transmission rate and the number of retransmissions based on the selected setting value; and the transmission rate and the number of retransmissions based on the setting value Wireless communication system characterized in that it comprises a second transmitting means for transmitting the video and audio data. In a wireless communication system including a transmitter and a receiver that transmit and receive data including video and audio data at a predetermined bit rate, the receiver receives first video and audio data transmitted from the transmitter Means, field strength determination means for determining the field strength of received data, and first transmission means for transmitting the determined field strength as error information to the transmitter, wherein the transmitter transmits from the receiver. Based on error information transmitted from the receiver, second value receiving means for receiving error information, setting value storage means for storing setting values combining a plurality of transmission rates and the number of retransmissions, Transmission rate setting means for selecting a setting value stored in the setting value storage means and setting a transmission rate and the number of retransmissions based on the selected setting value; and transmission based on the setting value Wireless communication system characterized in that it comprises a second transmitting means for transmitting the video and audio data over preparative and retransmission count. The wireless communication according to claim 8 or 9, wherein the transmission rate setting means reduces the transmission rate and increases the number of retransmissions when the error is not corrected by retransmitting data at the maximum number of retransmissions. system. The transmission rate setting means reduces the transmission bit rate and increases the number of retransmissions when the electric field strength detected on the receiver side is below a predetermined level at which an error is likely to occur. The wireless communication system according to any one of 8 to 10. The transmission rate setting means reduces the transmission rate and increases the number of retransmissions when the error rate of data received on the receiver side is a predetermined level that affects video and audio. Item 12. The wireless communication system according to any one of Items 8 to 11. The transmission rate setting means reduces the transmission rate to the lowest rank when the error rate detected on the receiver side suddenly increases and / or when the electric field strength sharply decreases. The wireless communication system according to any one of 8 to 12. The transmission rate setting means reduces the transmission rate by a predetermined rank when the error rate detected on the receiver side gradually increases and / or when the electric field strength gradually decreases. The radio | wireless communications system as described in any one of thru | or 13. The transmission rate setting means raises the transmission rate to the highest rank when the error rate detected at the receiver side is at a level without interference and / or when the electric field strength is at a level without interference. The wireless communication system according to any one of claims 8 to 14. 9. The transmission rate setting means increases the transmission rate by a predetermined rank when the error rate detected on the receiver side gradually decreases and / or when the electric field strength gradually increases. The radio | wireless communications system as described in any one of thru | or 15. A wireless AV system for connecting a plurality of wireless communication devices through a wireless network, wherein the wireless communication device is the wireless communication system according to any one of claims 8 to 16. . 18. The television receiver according to claim 17, wherein the wireless communication system is a television receiver including a display device and a broadcast receiving tuner and a center device that transmits video and audio data to the display device. Wireless AV system. In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and Selecting a set value based on a communication state, and setting a transmission rate and the number of retransmissions based on the selected set value. In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and A program for causing a computer to execute a step process of selecting the setting value based on a communication state and setting a transmission rate and the number of retransmissions based on the selected setting value. In a wireless transmission method for transmitting data including video and audio data at a predetermined bit rate, a step of detecting a communication state, a step of storing a set value combining a plurality of transmission rates and the number of retransmissions, and A computer-readable program having recorded thereon a program for causing a computer to execute step processing for selecting the setting value based on a communication state and setting a transmission rate and the number of retransmissions based on the selected setting value recoding media.

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