JP3768008B2 - Image signal reproduction device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image signal reproducing apparatus that performs synchronous reproduction of a data sequence in which digitally encoded audio, video, caption data, and the like are multiplexed, and more particularly to a packet identifier, packet length, and header length of a multiplexed encoded signal. It is related to the thing which made error processing based on.
[0002]
[Prior art]
In recent years, as seen in DVD, digital CS broadcasting, and the like, media in which additional information signals such as image signals, audio signals, and caption information are digitally encoded and multiplexed are rapidly spreading.
[0003]
In the multiplexed digital signal reproducing apparatus as described above, errors may be mixed in the encoded digital data at the time of encoding or on the transmission path. Even in such a case, reproduction of reproduced images, sounds, etc. Therefore, it is desired to provide an apparatus that can perform a reproduction operation that is smooth and has little deterioration.
[0004]
In the digital media, encoding defined by the MPEG standard is generally used for video signals. For audio, an encoding method other than MPEG may be employed. For multiplexing audio and video encoded data, multiplexing is performed by a multiplexing method defined in the MPEG system standard.
[0005]
FIG. 8 shows an example of audio, video, and additional information encoded data multiplexed by packets. The multiplexed and encoded data is byte aligned. In the figure, PSP is a packet start code prefix code, PID is a packet identifier, PKC is packet length information, PI is reproduction information, VCD is video encoded data, SCD is audio encoded data, and ACD is a code of additional information. Encoded data, PKT is a packet, and any one of these packet identifier PID, packet length information PKC, reproduction information PI, encoded video data VCD, encoded audio data SCD, encoded data ACD of additional information Data. PKH is a pack header. PCK is a pack, and consists of a pack header PKH and a packet PKT.
[0006]
The audio and video signals are digitally encoded by a dedicated encoding device, and are multiplexed on a packet basis by a multiplexing device. At the beginning of the packet, a packet start code prefix code PSP as a synchronization signal indicating the beginning of the packet and a packet header such as a packet identifier PID for distinguishing between voice and image packets, packet length information PKC, image and audio synchronous reproduction information, etc. PKH is added. The packet start code prefix code PSP is a unique pattern in the multiplexed data. In video signal encoding, hierarchical encoding is performed, and a code string indicating the start of the hierarchy and a code string indicating the hierarchy name are used. The code string indicating the start of the hierarchy and the start code prefix code indicating the packet head are the same code string.
[0007]
Normally, a packet start code prefix code appears in a multiplexed data sequence for each data unit indicated by the packet length included in the header information of the packet, so that confusion with the hierarchical start code of the video encoded data does not occur.
[0008]
Usually, in storage media, packets are managed in units of sectors, a pack start code is added to the head of the packet, and one pack is composed of a pack start code, a header portion following the start code, and the packet. Usually, one pack has a fixed length and a packet has a variable length.
[0009]
FIG. 9 shows an example of the configuration of an image signal separation device in a conventional image signal reproduction device. In the figure, reference numeral 1 denotes a multiplex encoded signal supply unit for supplying a multiplex data string to the image signal reproducing apparatus, and accumulates data after error correction such as ECC is performed. 2s1 is an input buffer for temporarily storing the multiplexed data sequence supplied from the multiplexed encoded signal supply unit 1, and 2s2 is a data changeover switch for switching the multiplexed data sequence output from the input buffer 2s1 to the terminals a, b, and c for output. It is. 2s3 is a unique pattern detector that detects a unique pattern from the data output from the terminal a of the data selector switch 2s2. 2s4 is a header analysis unit that analyzes the header of the data output from the terminal b of the data changeover switch 2s2. Reference numeral 2s5 denotes buffer transfer control means for performing buffer transfer control of data output from the terminal c of the data changeover switch 2s2. Reference numeral 2s6 denotes input processing control means for performing switching control of the data selector switch 2s2 based on the detection result of the unique pattern detector 2s3.
[0010]
Reference numeral 2 denotes a multiple signal demultiplexing unit including the input buffer 2s1, the data changeover switch 2s2, the unique pattern detector 2s3, the header analysis unit 2s4, the buffer transfer control unit 2s5, and the input processing control unit 2s6.
[0011]
Reference numeral 2s7 denotes reproduction time information storage means for storing reproduction time information analyzed by the header analysis unit 2s4. Reference numeral 2s10 denotes a decoded data buffer for storing data to be decoded obtained by the buffer transfer control means 2s5. Reference numeral 2s8 denotes reproduction time information reading control means for performing reproduction time information reading control. Reference numeral 2s11 denotes decoded data read control means for performing read control of the decoded data stored in the decoded data buffer 2s10. Reference numeral 2s14 denotes a reproduction time reference counter that counts a reproduction reference time serving as a reference for the reproduction time. Reference numeral 3 denotes a decoding unit that compares the reproduction reference time counted by the reproduction time reference counter 2s14 with the reproduction time information obtained by the reproduction time information read control means 2s8 and decodes the decoded data at a timing when these coincide with each other.
[0012]
6 is an image signal reproduction unit comprising the multiple signal separation unit 2, reproduction time information storage unit 2s7, reproduction time information read control unit 2s8, decoded data buffer 2s10, decoded data read control unit 2s11, reproduction time reference counter 2s14, and decoding unit 3. Device.
[0013]
A host CPU 4 controls the image signal reproducing device 6. A host bus 5 connects the host CPU 4 and the image signal reproducing device 6.
[0014]
Next, the operation will be described. The multiplexed data sequence supplied from the multiplexed encoded signal supply unit 1 is temporarily stored in the input buffer 2s1. First, the data changeover switch 2s2 is connected to the terminal a. The multiplexed data sequence stored in the input buffer 2s1 is input to the unique pattern detector 2s3 via the data changeover switch 2s2, and the operation shifts to the operation of detecting a unique pattern indicating the multiplexed data pack and packet delimiter.
[0015]
When the unique pattern detector 2s3 detects a unique pattern representing the head of a pack or packet, the unique pattern detector 2s3 notifies the input processing control means 2s6 that the head of the pack or packet has been detected and packs, video, audio, subtitles, etc. Of which packet is detected.
[0016]
The input processing control means 2s6 switches the data changeover switch 2s2 to the terminal b in response to the detection of the head of the pack or packet and activates the header analysis unit 2s4.
[0017]
In the input processing control means 2s6, the identifier of the packet to be decoded after being stored in the decoded data buffer 2s10 in the subsequent stage is set in advance by the external host CPU 4, and a packet with an identifier that does not match the valid packet identifier is received. If detected, the code data in the packet is transferred to the decoded data buffer 2s10.
[0018]
The header analysis unit 2s4 extracts the packet length, header length, reproduction time information, and the like necessary for multiplexing of the multiplexed signal included in the header of the multiplexed data sequence. The packet length or header length is used to separate the decoded data contained in the packet into a decoded data buffer. When the packet is a valid packet, the reproduction time information is stored in the reproduction time information storage unit 2s7 every time it is extracted. In the reproduction time information storage means 2s7, the storage area is managed in the form of a ring buffer, and the input data is delayed for a time corresponding to one round of the input data going around the ring.
[0019]
The reproduction time management information accumulated by the header analysis unit 2s4 is appropriately used as the most recent time information storage unit 2s7 as control information when the decoding unit 3 in the subsequent stage completes and outputs the reproduction unit.FromIt is read by the reproduction time information read control means 2s8. The decoded data included in the packet is buffered in the decoded data buffer 2s10 based on the transfer control information for each encoded data type such as video, audio, and subtitle using the packet identifier indicating the type of the packet, the header length, and the packet length. It is transferred by the transfer control means 2s5. The decoding unit 3 decodes encoded data such as audio, video, and caption included in the decoded data buffer 2s10, and synchronizes data such as audio, video, and caption using the reproduction management information and the reproduction time reference counter. Perform playback.
[0020]
[Problems to be solved by the invention]
The conventional image signal reproduction apparatus is configured as described above, and can be reproduced without any trouble if the packet identifier, packet length, header length, etc. required for data separation are accurately given. .
[0021]
However, for example, some storage media and the like are manufactured without complying with the standard, and when such media is reproduced, an error may be mixed in the packet identifier, packet length, header length, etc. at the time of decoding. Also, if an error occurs beyond the error correction capability even on the transmission path, the error may be mixed into the packet identifier, packet length, header length, and the like.
[0022]
  FIG. 10 shows such error locations of the pack and packet layer. In the figure, E1 is a packet identifier error, E2 is a packet length error, E3 is a flag error, and E4 is a header length error.,E5 is reproduction time information and marker error.
[0023]
Thus, when an error is mixed in the packet identifier, the packet length, the header length, etc., the conventional image signal reproduction apparatus described above has a problem that the following malfunction occurs. That is,
(1) When an error occurs in the packet identifier, and an identifier that cannot originally exist is detected, this does not match the identifier of the valid packet. Therefore, the input processing control means 2s6 performs the same processing as the processing of the invalid packet. I do.
[0024]
That is, the input processing control means 2s6 controls the buffer transfer control means 2s5 so as to skip data reading up to the end of the error packet using the header length and packet length included in the header information following the packet identifier, After the buffer transfer control means 2s5 completes skipping of invalid data, the unique pattern detector 2s3 is activated to shift to a mode for detecting the head of a new pack packet.
[0025]
As described above, when an error occurs in the packet identifier, and this is changed to a packet identifier that cannot originally exist, in the conventional image signal reproduction device, the end of the packet having the packet identifier that cannot be present is reached. Since the data is skipped, even if the head of the new pack or packet exists in the middle of the data to be skipped in the error packet, this is ignored and the return point to the original data is delayed. There was a problem that.
[0026]
(2) When an error is mixed in the header length or packet length of the packet and the packet length becomes smaller than the header length, the head of the decoded data part is detected based on the header length information, and based on the packet length information Thus, the data transfer of the decoded data to the decoded data buffer is attempted.
[0027]
In this case, there is a high possibility that all of the header information has been destroyed by an error. Therefore, the playback time information that has been destroyed or the playback time information that originally does not have the header error pattern causes emulation due to an error, and header analysis. The unit 2s4 stores the reproduction time information by the emulation caused by this error in the reproduction time information storage means 2s7, so that the synchronous reproduction information including the error is stored in the reproduction time information storage means 2s7 and the reproduction time information read control means 2s8. Since the decoding unit 3 is used for reading and synchronous reproduction via the receiver, there is a problem that errors are likely to occur in synchronous reproduction.
[0028]
Also, when the packet length is larger than the original value, if the buffer transfer control means 2s5 uses an error value, a considerable number of packets are erroneously skipped, or the decoded data buffer 2s10 different from the target is read. Since different pieces of decoded data are stored, there is a problem that a large amount of error data is stored in the decoded data buffer 2s10.
[0029]
This state will be described with reference to FIG.
In FIG. 11, the input data is supplied from the multiple encoded signal in FIG.Part1 is input from the left side of FIG. In FIG. 11, when a packet is skipped by using the wrong packet length information due to an error, the wrong packet length information is, for example, 1000, and one packet length is 100. About 10 packets are skipped, and the return point from the error is delayed on the time axis.
[0030]
(3) In addition, as shown in FIG. 12, due to destruction due to an error in the header information, reproduction time information larger than a value that can be originally generated is generated and stored in the reproduction time information storage unit 2s7 by the header analysis unit 2s4. Since the decoding unit 3 compares the error reproduction time information with the count value of the reproduction time reference counter 2s14 to perform output control, the decoding operation is temporarily performed until the reproduction time reference counter 2s14 matches the reproduction time information. May stop.
[0031]
The time during which the decoding operation is temporarily stopped may reach several hours depending on the degree of error in the reproduction time information.
[0032]
In addition, the decoding unit 3 or the external host CPU 4 determines whether the playback apparatus is performing a playback operation of a sequence in which this state is simply displayed intermittently with a large playback time interval as in a slide show or the like. There has been a problem that it is difficult to accurately determine whether the suspension is caused by the display time information error as described above.
[0033]
The present invention has been made to solve the above-described problems of the prior art. Even if an error may be mixed in the encoded digital data, an error of the input encoded data can be prevented. An object of the present invention is to provide an image signal reproducing apparatus that can improve the accuracy of quicker recovery from an error and determination of a synchronous reproduction error, and has higher error tolerance.
[0034]
[Means for Solving the Problems]
  In order to solve the problems of the conventional example, the present invention has been solved by newly providing the following means and control.
  That is, according to the first aspect of the present invention, in an image signal reproducing apparatus that performs synchronous reproduction of a data sequence in which digitally encoded audio, video, and caption data are multiplexed, an error in encoding or on a transmission path is present. A unique pattern detector for identifying a unique pattern representing the distinction between each encoded data sequence included in a multiplexed data sequence when reproducing the included data sequenceWhen,Header analyzer for analyzing information contained in headers starting with the unique patternAnd the unique pattern extracted by the unique pattern detector and the header analyzerError determination of packet format information is performed based on at least one parameter of packet identifier, packet length, and header length to be extracted.Packet format informationError detectorA header information error determiner that compares the packet length extracted by the header analyzer with the header length, and determines that the packet is an error packet if the header length is greater than the packet length; and the unique A control unit for controlling the pattern detector;WithThe control unit, when the header information error determiner determines that the packet to be determined is an error packet, controls the unique pattern detector to transition to a new unique pattern detection operation.As a result, the return point from the occurrence of an error is accelerated.At the same time, the possibility of synchronized playback using incorrect playback time information is reduced, enabling smoother synchronized playback..
[0035]
  Further, the invention of claim 2 of the present application is the image signal reproducing apparatus of claim 1,When a multiplexed data string has a fixed pack length and a packet is stored in the pack, an error packet and the error determiner determine if the packet length extracted by the header analyzer is larger than the pack length. And replace the packet length with the maximum packet length that can be included in the pack.I did soThe possibility of synchronized playback using incorrect playback time information is reduced, and smoother synchronized playback is possible..
[0036]
  According to a third aspect of the present invention, in the image signal reproducing device according to the first aspect,The header analyzer for extracting reproduction time information included for synchronous reproduction of a multiplexed data string included in a packet header in multiplexed data includes reproduction time information storage means for writing the header information, and includes audio, video, and caption data The decoding unit reads out the reproduction time information stored in the reproduction time information storage unit and manages the reproduction time, and also manages the writing and reading of the reproduction time information storage unit managed by the header analyzer and the decoding unit. In addition, the decoding unit includes reproduction time information reading control means for freely reading reproduction time information stored in the reproduction time information storage means without depending on the read / write management information.As a result, the possibility of performing synchronized playback using incorrect playback time information is reduced, and smoother synchronized playback is possible.
[0037]
  The invention of claim 4 of the present application3In the described image signal reproduction device,When the difference between the reproduction time information used for the synchronous reproduction and the reproduction reference counter used for the synchronous reproduction is larger than a predetermined error determination value, the decoding unit tries to execute the synchronous reproduction by the reproduction time information read control means. It is determined that an error occurs when the playback time information of a playback unit is smaller than the playback time information of the next playback unit, and synchronous playback using the error playback time information is not performed.Therefore, the possibility of performing synchronized playback using incorrect playback time information is reduced, and smoother synchronized playback is possible.
[0038]
  The invention of claim 5 of the present application4In the described image signal reproduction device,Since the external host CPU rewrites the reproduction time information determined to be error, and the decoding unit performs synchronous reproduction based on the rewritten reproduction time information, any area of the synchronous reproduction time information storage means is stored. By providing a readable interface, the accuracy of the error determination of the synchronous reproduction information is improved.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an image signal reproducing apparatus according to Embodiment 1 of the present invention. FIG. 1 also shows components newly added in the image signal reproduction apparatus according to Embodiments 2 to 4 described later. In addition, components having the same functions as those of the conventional example are denoted by the same reference numerals, and detailed description thereof is omitted.
[0045]
  In FIG. 1, 2s12 isAs a parameter of packet format informationThis is a packet identifier error determiner that determines the type of error that has occurred in the packet identifier. In the first embodiment, only the packet identifier error determiner 2s12 is added to the conventional example of FIG.
  FIG. 2 is a flowchart showing the control operation of the image signal reproducing apparatus according to Embodiment 1 of the present invention.
[0046]
Next, the operation of the first embodiment will be described with reference to FIGS. When the multiplex data is read from the input buffer 2s1 and the unique pattern detector 2s3 detects the unique pattern representing the head of the pack or packet, it notifies the input processing control means 2s6 that the unique pattern has been detected (step of FIG. 2). s11). The input processing control means 2s6 activates the header analysis unit 2s4 (see steps s12 and s13 in FIG. 2), analyzes the pack and packet identifier following the unique pattern (see step s14 in FIG. 2), and extracts the extracted packet identifier. The packet identifier error determination unit 2s12 is notified. If the combination of the unique pattern and the packet identifier cannot originally exist in the multiplexed data (see steps s15 and s16 in FIG. 2), the packet identifier error determiner 2s12 determines that this is an error and indicates that it is an error. Simultaneously with the input processing control means 2s6, the header analysis unit 2s4 is notified of the stop of header analysis (see steps s17 and s18 in FIG. 2). On the other hand, when the packet identifier error determination unit 2s12 determines that the combination of the unique pattern and the packet identifier exists in the multiplexed data, the pack and packet processing is terminated (see step s20 in FIG. 2) and input. The unique pattern detector is activated by the processing control means 2s6 to search for a start code (see step s11 in FIG. 2).
[0047]
On the other hand, after the header analysis unit 2s4 is stopped by the input processing control means 2s6 (see step s18 in FIG. 2), a new pattern and a unique pattern detection mode indicating the head of the packet for the unique pattern detector 2s3 are detected. (See step s19 in FIG. 2).
[0048]
As described above, the error determination by the packet identifier error determination unit 2s12 makes it possible to perform a quicker process by performing control such that the header processing of the error packet is not performed and the skipping of the error packet is not performed based on the header information. It is possible to perform a recovery operation from an error.
[0049]
Here, in normal synchronous reproduction, a reproduction reference counter serving as a reference is compared with reproduction time information, and if the difference is within a predetermined threshold, the reproduction unit of the reproduction time information is output. If the playback time information is smaller than the playback reference counter, the output of the corresponding playback unit is canceled and playback of the next playback unit is started. Conversely, when the reproduction time information is large, reproduction unit output is not performed.
[0050]
As described above, according to the first embodiment, when there is a packet identifier that cannot originally exist in the multiplexed stream, the header information of the packet following the packet identifier is ignored, and the data of the header length and the packet length is ignored. Since the input processing control means controls the unique pattern detector so that it can immediately enter the detection of a new pack and a unique pattern representing the head of the beginning of the packet without skipping the reading. It has the effect of becoming faster.
[0051]
(Embodiment 2)
  Next, a second embodiment of the present invention will be described with reference to FIG.
  In FIG. 1, 2s13 is a header information error determiner for determining an error that has occurred in header information.9Only the header information error determination unit 2s13 is added to the conventional example.
  Also figure3 isIt is a flowchart which shows the control operation of the image signal reproducing | regenerating apparatus by Embodiment 2 of this invention.
[0052]
  Next, the operation of the second embodiment will be described with reference to FIGS. First, the input pattern control means 2s6 activates the unique pattern detector 2s3 to detect a start code (see steps s21 and s22 in FIG. 3). When the start code is detected, the input processing control means 2s6 activates the header analysis unit 2s4 (see step s23 in FIG. 3), and when the packet length is acquired, the header information error determination unit 2s13As a parameter of packet format informationThe header length is checked (see step s24 in FIG. 3). When it is determined that the packet length does not exceed the maximum packet length that can be originally taken (see step s25 in FIG. 3), normal processing is performed (see step s27 in FIG. 3), and pack and packet processing is performed. After completion (see step s28 in FIG. 3), the process returns to the first process.As a parameter of packet format informationWhen it is determined that the packet length exceeds the maximum packet length that can be originally taken (see step s25 in FIG. 3), the packet length of the corresponding several packets is set to the packet length threshold, that is, the maximum packet that can be taken by the input stream. In addition to the replacement by the length (see step s26 in FIG. 3), the process returns to the first process, the unique pattern detector 2s3 is activated by the input process control means 2s6, and the process proceeds to the detection of the start code of the next packet.
[0053]
  For this reason, as shown in FIG. 4, if there is an error in the packet length but no error processing is performed, will the entire range of packet data specified by this incorrect packet length be skipped? Or stored in the decoded data buffer 2s10, according to the second embodiment, even if there is an error in the packet length, the range of the packet data is essentially the maximum packet that one packet can take. Since it is limited by the length, data is not skipped over a plurality of packets and is not stored in the decoded data buffer 2s10. Therefore, accurate data cannot be reproduced. .
  As described above, according to the second embodiment, when an error is mixed in the packet header length and the packet length and the packet length is larger than the maximum packet length, the error determination unit determines that the packet is an error packet. When the input processing control means is notified and the playback time information is included, the input processing control means controls the header analyzer so as not to store the playback time information in the playback time information storage means. Thus, the possibility of performing synchronized playback using the playback time information is reduced, and smoother synchronized playback is possible.
[0054]
(Embodiment 3)
  Next, Embodiment 3 of the present invention will be described with reference to FIG.
  In FIG. 1, 2s13 is a header information error determiner for determining an error occurring in the header information, and the third embodiment is similar to the second embodiment in comparison with the conventional example of FIG. Only 2s13 is added.
  FIG. 5 is a flowchart showing the control operation of the image signal reproducing apparatus according to the third embodiment of the present invention.
  Next, this embodiment3Will be described with reference to FIGS. First, the input pattern control means 2s6 activates the unique pattern detector 2s3 to detect a start code (see steps s31 and s32 in FIG. 5). When the start code is detected, the input processing control means 2s6 activates the header analysis unit 2s4 (see step s33 in FIG. 5), and the header length and packet length extracted by the header analysis unit 2s4 are the header information error determiner. 2s13 is notified and the check is performed (see step s34 in FIG. 5). When it is determined that the packet length is smaller than the packet header length (see step s35 in FIG. 5), the header information error determination unit 2s13 determines that the header information of the packet is destroyed by an error, and the packet An information error is notified to the input processing control means 2s6 (see step s36 in FIG. 5). When the playback time information exists in the header, the input processing control means 2s6 invalidates the playback time information and controls the header analysis unit 2s4 so as not to store it in the playback time information storage means 2s7 (steps s37, FIG. 5). s38). The input processing control means 2s6 controls not to activate the buffer transfer control means 2s5 for transferring the decoded data to the decoded data buffer 2s10. In addition, the input processing control means 2s6 activates the unique pattern detector 2s3 to control to detect new packs and packets, and to control to enter new packs and packet processing (step of FIG. 5). s39).
[0055]
When the header information error determiner 2s13 determines that the packet length is greater than the packet header length (see step s35 in FIG. 5), the pack and packet processing is completed (see step s40 in FIG. 5). ), Control to enter new pack and packet processing.
[0056]
By the above control, in the case of the error pattern, the reproduction time information including the error is not used for the synchronous reproduction in the decoding unit 3, and the synchronous reproduction with high error tolerance can be realized.
[0057]
In the case of storage media, the pack length is fixed, and when the header information error determination unit 2s13 determines that an error is recognized in the packet length, the packet length is the maximum length that can be taken by the fixed-length packet. The input processing control means 2s6 notifies the input processing control means 2s6, and the input processing control means 2s6 transfers or reads the encoded data included in the packet in the decoding buffer 2s10 with the packet length reset by the header information error determination unit 2s13. The buffer transfer control means 2s5 is controlled so as to skip.
[0058]
The header information error determination unit 2s13 determines that an error has occurred even when the marker added to the reproduction time information is valid at an illegal position, and does not store the reproduction time information in the reproduction time information storage unit 2s7. .
[0059]
  Thus, the present embodiment3According to the above, errors are mixed in the packet header length and packet length., PaWhen the header length is larger than the packet length, the error determination unit determines that the packet is an error packet and notifies the input processing control means. When the reproduction time information is included, the reproduction time information is stored in the reproduction time information storage means. Since the input processing control means controls the header analyzer so that it is not stored in the memory, the possibility of performing synchronized playback using incorrect playback time information is reduced, and smoother synchronized playback is possible. effective.
[0060]
(Embodiment4)
  Next, an embodiment of the present invention4Will be described with reference to FIG.
  In FIG. 1, 2s9 is reproduction time information reading means for reading time information from the reproduction time information storage means 2s7.4Is a figure9Only the reproduction time information reading means 2s9 is added to the conventional example.
  FIG. 6 shows an embodiment of the present invention.45 is a flowchart showing a control operation of the image signal reproduction device according to the above.
[0061]
  Next, the operation will be described. The decoding unit 3 decodes the encoded data existing in the decoded data buffer 2s10 (see step s41 in FIG. 6), and obtains the first reproduction time information corresponding to the reproduction unit entered in the reproduction time information storage means 2s7. Obtained via the reproduction time information read control means 2s8 (see step s42 in FIG. 6), compares the reproduction time reference counter with 2s14 (see step s43 in FIG. 6), and controls the output timing. When the reproduction time information 1 read via the reproduction time information read control means 2s8 has a value larger than the assumed reproduction time (see step s44 in FIG. 6), the decoding unit 3 reproduces the reproduction time information read control means 2s9. And the second reproduction time information registered next to the reproduction time information is read (see step s45 in FIG. 6), and the first reproduction time information and the second reproduction time information are The values are compared (see step s46 in FIG. 6), and the second reproduction time information is greater than the first reproduction time information.SmallIf this is the case (see step s47 in FIG. 6), this is determined to be an error, and control is performed so as not to use the first reproduction time information (see step s48 in FIG. 6).
[0062]
Then, the playback time reference counter 2s14 and the first playback time information are compared, the output timing of the playback image is determined and output (see step s49 in FIG. 6), and the decoding of the decoding unit is performed as the next playback unit. Control to shift to the operation is performed (see step s50 in FIG. 6), and the decoding unit 3 returns to the decoding operation.
[0063]
By providing the reproduction time information read control means 2s9 as described above, it is possible to determine an error in the reproduction time information and perform smoother synchronous reproduction.
[0064]
In particular, in the case of encoded data of video information by MPEG, the order of reproduction signals in input encoded data and the order of reproduction units at the time of output are different. The order of output of the input encoded data is changed according to the encoding method in the reproduction output process. Therefore, the second reproduction time information read for comparison with the first reproduction time information is not necessarily the value of the next entry stored in the reproduction time information storage means. An entry of a reproduction unit whose reproduction unit order at the time of output reproduction is temporally next to the first reproduction unit is read from the reproduction time information storage means, and is used as second reproduction time information.
[0065]
  Thus, the present embodiment4According to the above, in addition to the reproduction time information read control means 2s8 for reading the reproduction time information storage means 2s7 having a ring buffer structure, the reproduction time information different from the read pointer 1 managed by the reproduction time information read control means 2s8. Reproduction time reading means 2s9 having a second read pointer capable of freely reading any area of reproduction time information in the storage means 2s7 is newly provided, and the reproduction time information read control means 2s8 can be controlled by the decoding unit 3. Therefore, an interface capable of reading an arbitrary area of the synchronous reproduction time information storage means is provided, and there is an effect that the accuracy of determining the error of the synchronous reproduction information can be improved.
[0066]
(Embodiment5)
  Next, an embodiment of the present invention5Will be described with reference to FIG.
  In FIG. 1, 2s15 is a data bus that enables the external host CPU 4 to read the reproduction time information entered in the reproduction time information storage means 2s7, and 7 is a reproduction time register that holds the reproduction time of the decoding unit 3. This embodiment5Is a figure9The data bus 2s15, the reproduction time register 7 and the reproduction time information read control means 2s9 are added to the conventional example.
  FIG. 7 shows an embodiment of the present invention.55 is a flowchart showing a control operation of the image signal reproduction device according to the above.
[0067]
Next, the operation will be described. When decoding of the decoded data included in the decoded data buffer 2s10 is completed, the decoding unit 3 reads the first reproduction time information entered in the reproduction time information storage unit 2s7 through the reproduction time information read control unit 2s8, and The reproduction time information is compared with the count value of the reproduction time reference counter 2s14, and output control is performed. At this time, the first reproduction time information can be read from the external host CPU 4 and monitored. The external host CPU 4 monitors the reproduction time register 7 in which the first reproduction time information is stored every predetermined period (see step s51 in FIG. 7), and the reproduction time register 7 and the reproduction time reference counter 2s14. (See step s52 in FIG. 7), if the reproduction time information stored in the reproduction time register 7 is not updated for a predetermined time (see step s53 in FIG. 7), the decoding unit 3 stops due to the occurrence of an error. The playback time information reading control means 2s9 is activated, and the second playback time information entered next to the first playback time information is read via the data bus 2s12 (see FIG. 7). In step s54, the reproduction time register 7 is compared with the second reproduction time information (see step s55 in FIG. 7), and the first reproduction time information and the second reproduction time information are compared. When the relationship with the reproduction time information is greatly deviated from the relationship assumed from the decoding sequence, that is, when the reproduction time register 7 is larger than the second reproduction time information (see step s56 in FIG. 7). It is determined that there is an error, and the external host CPU 4 rewrites the reproduction time register 7 (see step s57 in FIG. 7), and shifts to normal processing (see step s58 in FIG. 7).
[0068]
As described above, by providing the reproduction time information read control means 2s9, which is an interface capable of reading the reproduction time information from the external host CPU 4, and the data bus 2s15 connected to the host bus 5, more accurate error determination is possible. Can be performed.
[0069]
In addition, the aboveFirstPlayback time informationNewsWhen write access from the host CPU 4 is permitted to the stored reproduction time register 7, the external host CPU 4 rewrites the reproduction time register 7 with an appropriate value, thereby matching the reproduction time reference counter 2s14. It is possible to cancel the stop of the decoding operation of the decoding unit 3 by generating the establishment of the above. Further, by releasing the reproduction time information storage unit 2s7 to the external host CPU 4, it becomes possible to realize more flexible and accurate reproduction apparatus synchronization processing.
[0070]
  Thus, the present embodiment5According to the present invention, since it is configured to be able to read from the host CPU 4 via the host bus 5 connected to the external host CPU 4, an interface capable of reading an arbitrary area of the synchronous reproduction time information storage means Thus, there is an effect that the accuracy of the error determination of the synchronous reproduction information can be improved.
[0071]
  In the first embodiment, only the packet identifier error determiner 2s12 is replaced with the second embodiment., 3Then, only the header information error determination unit 2s13 is used in the embodiment.4Then, only the reproduction time information reading means 2s9 is used in the embodiment.5Then, the data bus 2s15, the reproduction time register 7, and the reproduction time information read control means 2s9 are provided. However, two or more of these embodiments may be combined, and the effects of the embodiments are combined. It is possible to get things.
[0072]
【The invention's effect】
  As described above, according to the image signal reproduction device of the first aspect of the present invention, in the image signal reproduction device that performs synchronous reproduction of a data sequence in which digitally encoded audio, video, and caption data are multiplexed. A unique pattern detector for identifying a unique pattern representing a distinction between each encoded data sequence included in a multiplexed data sequence when encoding or reproducing a data sequence including an error in a transmission pathWhen,Header analyzer for analyzing information contained in headers starting with the unique patternAnd a unique pattern extracted by the unique pattern detector,Header analyzerButError determination of packet format information is performed based on at least one parameter of packet identifier, packet length, and header length to be extracted.Packet format informationError detectorA header information error determiner that compares the packet length extracted by the header analyzer with the header length, and determines that the packet is an error packet if the header length is greater than the packet length; and the unique A control unit for controlling the pattern detector;WithThe control unit, when the header information error determiner determines that the packet to be determined is an error packet, controls the unique pattern detector to transition to a new unique pattern detection operation.As a result, the error return point becomes faster when reproducing multi-encoded data including errors.At the same time, the possibility of synchronized playback using incorrect playback time information is reduced, enabling smoother synchronized playback.effective.
[0073]
  According to the image signal reproducing device of the present invention, the image signal reproducing device according to claim 1,When a multiplexed data string has a fixed pack length and a packet is stored in the pack, an error packet and the error determiner determine if the packet length extracted by the header analyzer is larger than the pack length. In addition, since the packet length is replaced with the maximum packet length that can be included in the pack, the possibility of performing synchronized playback using incorrect playback time information is reduced, and smoother synchronized playback is possible.effective.
[0074]
  According to the image signal reproduction device of the invention of claim 3 of the present application, in the image signal reproduction device of claim 1,The header analyzer for extracting reproduction time information included for synchronous reproduction of a multiplexed data string included in a packet header in multiplexed data includes reproduction time information storage means for writing the header information, and includes audio, video, and caption data The decoding unit reads out the reproduction time information stored in the reproduction time information storage unit and manages the reproduction time, and also manages the writing and reading of the reproduction time information storage unit managed by the header analyzer and the decoding unit. In addition, the decoding unit includes reproduction time information reading control means for freely reading reproduction time information stored in the reproduction time information storage means without depending on the read / write management information.So that incorrect playback time informationIs less likely to use synchronized playback,This has the effect of enabling smoother synchronized playback.
[0075]
  According to the image signal reproducing device of the invention of claim 4 of the present application,3In the described image signal reproduction device,When the difference between the reproduction time information used for the synchronous reproduction and the reproduction reference counter used for the synchronous reproduction is larger than a predetermined error determination value, the decoding unit tries to execute the synchronous reproduction by the reproduction time information read control means. It is determined that an error occurs when the playback time information of a playback unit is smaller than the playback time information of the next playback unit, and synchronous playback using the error playback time information is not performed.Incorrect playback time informationIs less likely to use synchronized playbackThus, there is an effect that smoother synchronized playback is possible.
[0076]
  AlsoAccording to the image signal reproducing device of the invention of claim 5 of the present application,4In the described image signal reproduction device,Since the external host CPU rewrites the reproduction time information determined to be error, and the decoding unit performs synchronous reproduction based on the rewritten reproduction time information, any area of the synchronous reproduction time information storage means is stored. By providing a readable interface, the accuracy of error determination in synchronized playback information is improved.effective.
[Brief description of the drawings]
FIG. 1 is a first embodiment of the present invention.5FIG. 2 is a block diagram showing an image signal reproduction device according to FIG.
FIG. 2 is a flowchart showing a control operation of the image signal reproduction device according to the first embodiment of the present invention.
FIG. 3 is a flowchart showing a control operation of an image signal reproduction apparatus according to Embodiment 2 of the present invention.
FIG. 4 is a data format diagram for explaining the effect of the image signal reproduction device according to the second embodiment of the present invention when an error exists in the packet length.
FIG. 5 shows an embodiment of the present invention.3The flowchart figure which shows the control operation | movement of the image signal reproducing | regenerating apparatus by.
FIG. 6 shows an embodiment of the present invention.4The flowchart figure which shows the control operation | movement of the image signal reproducing | regenerating apparatus by.
FIG. 7 shows an embodiment of the present invention.5The flowchart figure which shows the control operation | movement of the image signal reproducing | regenerating apparatus by.
FIG. 8 is an explanatory diagram of multiplex encoded data.
FIG. 9 is a block diagram showing a conventional image signal reproduction apparatus.
FIG. 10 is a data format diagram showing an error location in a packet.
FIG. 11 is a diagram for explaining the operation of the conventional image signal reproducing apparatus when there is an error in the packet length.
FIG. 12 is a diagram for explaining the operation of the conventional image signal reproducing apparatus when there is an error in the reproduction time information.
[Explanation of symbols]
  2s1 input buffer
  2s2 data selector switch
  2s3 unique pattern detector
  2s4 header analysis unit
  2s5 buffer transfer control means
  2s6 input processing control means
  2s7 playback time information storage means
  2s8 Playback time information read control means
  2s9 Playback time information read control means
  2s10 decoded data buffer
  2s11 Decoded data read control means
  2s12 packet identifier error determiner
  2s13 Header information error determiner
  2s14 Playback time reference counter
  2s15 data bus
  1 Multiple encoded signal supply unit
  2 Multiplex signal separator
  3 Decryption unit
  4 Host CPU
  5 Host bus
  6 Image signal playback device
  7 Playback time register

Claims (5)

In an image signal reproduction device that performs synchronous reproduction of a data sequence in which digitally encoded audio, video, and caption data are multiplexed,
A unique pattern detector for identifying a unique pattern representing a distinction between each encoded data sequence included in a multiplexed data sequence when encoding or reproducing a data sequence including an error in a transmission path ;
A header analyzer that analyzes information included in the header starting with the unique pattern;
A unique pattern of the unique pattern detector extracts, before Kihe Dda packet identifier analyzer extracts, packet length, packet format information errors for which the error determination packet format information based on the at least one parameter of the header length A determiner ;
A header information error determiner that compares the packet length extracted by the header analyzer with a header length, and determines that the packet is an error packet if the header length is greater than the packet length;
A controller for controlling the unique pattern detector ,
The control unit, when the header information error determiner determines that the packet to be determined is an error packet, controls the unique pattern detector to transition to a new unique pattern detection operation.
An image signal reproducing apparatus characterized by that. The image signal reproducing apparatus according to claim 1, wherein
When a multiplexed data string has a fixed pack length and a packet is stored in the pack, an error packet and the error determiner determine if the packet length extracted by the header analyzer is larger than the pack length. An image signal reproducing apparatus that replaces the packet length with a maximum packet length that can be included in the pack. The image signal reproducing apparatus according to claim 1, wherein
The header analyzer for extracting reproduction time information included for synchronous reproduction of a multiplexed data string included in a packet header in multiplexed data includes reproduction time information storage means for writing the header information, and includes audio, video, and caption data The decoding unit reads out the reproduction time information stored in the reproduction time information storage means and manages the reproduction time,
In addition to write / read management of playback time information storage means managed by the header analyzer and the decoding unit,
Image signal reproduction characterized in that the decoding unit comprises reproduction time information read control means for freely reading reproduction time information stored in the reproduction time information storage means without depending on the read / write management information apparatus. The image signal reproducing apparatus according to claim 3 , wherein
When the difference between the reproduction time information used for the synchronous reproduction and the reproduction reference counter used for the synchronous reproduction is larger than a predetermined error determination value, the decoding unit tries to execute the synchronous reproduction by the reproduction time information read control means. An image signal reproduction apparatus characterized in that an error is determined when reproduction time information of a given reproduction unit is smaller than reproduction time information of a next reproduction unit, and synchronous reproduction using the error reproduction time information is not performed. The image signal reproducing apparatus according to claim 4 , wherein
An image signal reproducing apparatus, wherein an external host CPU rewrites reproduction time information determined to have an error, and a decoding unit performs synchronous reproduction based on the rewritten reproduction time information.

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