JP2002135123A - Information data processor, its processing method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect errors within an AAU stream. SOLUTION: A stream-disassembling circuit 24 outputs the AAU stream from an input buffer 22 to an expansion processing circuit 28 as it is, and outputs allocation information and scale factor selection information, which are included in the AAU stream, to an allocation arithmetic circuit 26. The arithmetic circuit 26 calculates the number of effective data included in the AAU, by using the allocation information and the scale factor selection information, and determines whether the value of the number is appropriate. The expansion processing circuit 28 is expanded, in other words restores AAU stream data from the disassembling circuit 24 into a digital audio signal, and supplies the restored digital audio signal to an interpolation data buffer 30 and an interpolation selection circuit 32. The data buffer 30 updates storage data into the latest digital audio signal, when an error is mixed. According to the result of the arithmetic circuit 26, the selection circuit 32 selects the digital audio signal, output from the expansion processing circuit 28 when there is no error mixed, the data stored in the data buffer 30, when there is an error mixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information data processing apparatus and method for decompressing compressed information data and a storage medium storing the data processing program.

[0002]

2. Description of the Related Art A method for compressing a digital audio signal includes an MP / MP described in ISO / IEC 11172-3.
There is an EG audio compression system. FIG. 4 is a block diagram showing a schematic configuration of a conventional decompression device for decompressing an audio access unit (hereinafter, abbreviated as AAU), which is an MPEG audio compressed stream, into a digital audio signal.

In FIG. 4, reference numeral 10 denotes an AAU input unit;
Is an input buffer for adjusting the input timing of the AAU stream from the AAU input unit 10, and 14 is the input buffer 1
1 AA stream whose timing has been adjusted by 2
A decompression processing circuit for reading out only the AU and decompressing the digital audio signal, and a digital audio output unit 16 for outputting the digital audio signal restored by the decompression processing circuit 14.

[0004] The extension operation of the conventional example shown in FIG. 4 will be described.
The AAU stream is input from the AAU input unit 10 to the input buffer 12. The input buffer 12 outputs the AAU stream to the decompression processing circuit 14 at a constant rate in units of 1 AAU compression cycle. The expansion processing circuit 14 restores the digital audio signal from the AAU stream input from the input buffer 12 according to a predetermined expansion algorithm. The restored digital audio signal is output from the digital audio output unit 16 to the outside.

[0005]

In the conventional example, if an error is mixed in an input AAU stream due to a transmission path or the like, the error cannot be detected and decompression processing is performed. Therefore, when an error is included in a field that greatly affects the output level of the digital audio signal, such as an allocation and a scale factor, a problem occurs in that a large volume of noise is output. As a countermeasure, a method of judging an error by detecting a specific pattern has been proposed (Japanese Patent Application Laid-Open No. 8-328599). However, this is a muting technique in a limited situation, and the error detection omission is prevented. Many.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an information data processing apparatus and method for detecting an error with high accuracy and expanding information data, and a storage medium storing the data processing program.

[0007]

According to the present invention, there is provided an information data processing apparatus comprising: an effective data comprising information data compressed by using a predetermined period as a compression unit and compression attribute data indicating an attribute of the entire compression unit; Input means for inputting an information data stream in units of an information data unit of a predetermined data amount constituted by stuffing data for adjusting the amount, and the information data based on the compressed attribute data input by the input means Calculating means for predicting the data amount of the effective data of the unit, decompressing means for decompressing the compressed information data, and whether or not the data amount predicted by the calculating means is an allowable data amount in the information data unit Determining means for determining
Processing means for modifying the information data decompressed by the decompression means in accordance with the result of the determination by the determination means.

Further, the information data processing apparatus according to the present invention is characterized in that valid data comprising information data compressed by using a predetermined period as a compression unit and compression attribute data indicating an attribute of the entire compression unit; Input means for inputting an information data stream in units of an information data unit of a predetermined data amount constituted by data amount information on the amount and stuffing data for adjusting the data amount, and a compression attribute input by the input means Calculating means for predicting the data amount of the valid data of the information data unit based on data; decompressing means for decompressing the compressed information data; and a data amount calculated by the calculating means and the information data unit Comparison means for comparing the data amount obtained from the data amount information, and a comparison result of the comparison means Depending characterized by having a processing means for modification processing the decompressed information data by the decompression means.

Further, the information data processing method according to the present invention provides a method for adjusting effective data consisting of information data compressed using a predetermined period as a compression unit and compression attribute data indicating attributes of the entire compression unit. Inputting an information data stream in units of an information data unit having a predetermined data amount constituted by the stuffing data of the above, and a data amount of the effective data of the information data unit based on the input compression attribute data A computing step of predicting the compressed information data; a decompressing step of decompressing the compressed information data; a determining step of determining whether the predicted data amount is an allowable data amount in the information data unit; Modifying the expanded information data according to the result.

Further, the information data processing method according to the present invention is characterized in that valid data composed of information data compressed by using a predetermined period as a compression unit and compression attribute data indicating an attribute of the entire compression unit; Inputting an information data stream in units of an information data unit of a predetermined data amount composed of data amount information relating to the amount and stuffing data for adjusting the data amount, based on the input compressed attribute data Calculating the data amount of the effective data of the information data unit, decompressing the compressed information data, and obtaining the calculated data amount and the data amount information of the information data unit. A comparing step of comparing the data amount with the data amount, and modifying the expanded information data according to the comparison result And having a treatment step of.

Further, a storage medium according to the present invention stores a processing program of the above information data processing method.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of the present invention. In this embodiment, an AAU stream (see FIG. 3), which is a stream compressed by MPEG audio, is expanded into a digital audio signal.

Reference numeral 20 denotes an AAU input unit, 22 denotes an input buffer for adjusting the timing of an AAU stream from the AAU input unit 20, and 24 denotes an AA stored in the input buffer 22.
The stream decomposing circuit 26 reads out the U stream in units of 1 AAU and separates each information set in the AAU such as the allocation information and the scale factor information from the allocation information decomposed by the stream decomposing circuit 24. An allocation operation circuit 28 for calculating the number of valid data included in the stream data is a decompression processing circuit for restoring a digital audio signal from the AAU data decomposed by the stream decomposing circuit 24.

Reference numeral 30 denotes an interpolation data buffer for holding the digital audio signal restored by the decompression processing circuit 28 at least until the next AAU is decompressed by the decompression processing circuit 28; , An interpolation selection circuit for selecting the output of the expansion processing circuit 28 or the output of the interpolation data buffer 30 in accordance with the output of
Is a digital audio output unit for outputting the digital audio signal selected by the interpolation selection circuit 32 to the outside.

In the MPEG audio compression, 0 to 24
The kHz band is divided into 750 Hz units, and information on 32 subbands per channel is compressed. The compression is performed on the sub-bands with audible data, and the sub-bands without audible data are not transmitted.

The allocation is a parameter indicating the resolution of the sample data allocated to each sub-band. If the value is "0" (although it is tabulated by parameters such as the compression rate and frequency), it is in principle. 0
If the bit is "16", a resolution of 16 bits is given.

The scale factor is a parameter for normalizing the sample data to be compressed for each sub-band to 2 (the sample value becomes a number of 2 or less in absolute value in the process of compression. The scale factor is the reciprocal of the coefficient given so that the value becomes 2 (it is assumed that the product of the allocation value and the sample value is taken by the decoder so that the data can be restored, so that the reciprocal is used). is there).

In the MPEG audio layer 1, 6 bits are assigned to each sub-band for the scale factor. Therefore, sub-bands whose allocation is other than 0 always require 6 bits for scale factor transmission (there is no concept of scale factor selection information in layer 1).

In the MPEG audio layer 2, three scale factors are required for each subband (the access unit is 8 ms in the layer 1 but is 3 ms in the layer 2 in order to increase the compression efficiency.
Because the access unit is configured twice as long.)

The scale factor selection information compresses the above three scale factors (for coefficients having similar values, 3
All are not transmitted) and give information such as how many scale factors are in the subband.

The operation of this embodiment will be described. The AAU stream input from the transmission path at the timing of the transmission path is AA stream.
The data is input to the input buffer 22 via the U input unit 20. The input buffer 22 converts the input AAU stream into a constant rate in units of 24 ms of the compression cycle and outputs the stream to the stream decomposition circuit 24. For example, MPEG audio layer 2
, The input buffer 22 converts the AAU stream to 1A
The data is supplied to the stream decomposition circuit 24 at a constant rate in units of 24 ms, which is the AU compression cycle.

The stream decomposing circuit 24 decomposes the AAU stream from the input buffer 22 into allocation, scale factor selection information, scale factor, audio data, etc., and supplies them all to the decompression processing circuit 28. The factor selection information is output to the allocation operation circuit 26. In other words, the stream decomposition circuit 24
Decompression processing circuit 28 converts the AAU stream from
And the allocation information and the scale factor selection information included in the AAU stream are supplied to the allocation arithmetic circuit 26.

The allocation calculation circuit 26 calculates the number of valid data included in the AAU from the allocation information and the scale factor selection information input from the stream decomposition circuit 24, determines whether the value is a valid number of data, The determination result is supplied to the interpolation selection circuit 32 as a selection signal. For example, in the case of an AAU stream encoded with layer 2 and having a transmission rate of 384 kbps,
The AU can accommodate up to 1152 bytes (including the header) in one unit. In this case, if the calculation result of the number of valid data exceeds the maximum data number of 1152 bytes, the allocation arithmetic circuit 26 determines that the allocation information and the scale factor selection information contain an error.

The method of calculating the number of valid data by the allocation operation circuit 26 is performed by the following equation. That is, the number of valid data = (the number of fixed header information) + A + ancillary where A is represented by the following equation. A = (sample resolution derived from allocation × 3)
6 + 2) + 6 × (the number of coded scale factors derived from the allocation selection information).

The fixed header information used in the above equation indicates the number of data required for fixing such as synchronization signal, compression mode information, allocation, etc., and A indicates the number of data calculated for the subband included in the access unit. Show,
Ancillary indicates the number of ancillary data (ancillary data is any data other than MPEG audio, and the number of ancillary data must be assigned in advance by an encoder and decoder), and 36 is a sample per access unit. 2 indicates the number of bits of the scale factor selection information, and 6 indicates the number of bits per scale factor.

The decompression processing circuit 28 decompresses the AAU stream data input from the stream decomposition circuit 24 according to a predetermined decompression algorithm, and restores a digital audio signal. The restored digital audio signal is applied to the interpolation data buffer 30 and the interpolation selection circuit 32. The interpolation data buffer 30 updates the stored data with the latest digital audio signal according to the determination result of the allocation arithmetic circuit 26 and only when no error is mixed. The data stored in the interpolation data buffer 30 is read out to the interpolation selection circuit 32.

According to the determination result (selection signal) of the allocation operation circuit 26, the interpolation selection circuit 32 outputs the digital audio signal output from the decompression processing circuit 28 when no error is mixed and an interpolation data buffer when an error is mixed. The digital audio signal (interpolated signal) stored in the memory 30 is selected and supplied to the digital audio output unit 34.

With this configuration, in this embodiment, M
Even if CRC parity is not added to the PEG audio stream, it is possible to detect the presence or absence of an error.

FIG. 2 is a schematic block diagram of a second embodiment of the present invention. In the second embodiment, as shown in FIG. 3, an ancillary data area is secured in advance in the AAU data format, and the number of valid data other than the stuffing data in the decompression process is stored together with the identification signal and the like. Keep it. The second embodiment uses this value to determine whether an error has occurred.

The configuration of the embodiment shown in FIG. 2 will be described. 40
Is the AAU input unit, and 42 is the AA from the AAU input unit 40.
Input buffer for timing adjustment of U stream, 44
Is an ancillary data extraction circuit for extracting ancillary data from the stream stored in the input buffer 42;
Reference numeral denotes an ancillary data processing circuit for searching the ancillary data extracted by the ancillary data extraction circuit 44 for valid data number information.

Reference numeral 48 denotes A stored in the input buffer 42.
A stream decomposing circuit that reads an AU stream in units of 1 AAU and classifies each information set in the AAU such as allocation information and scale factor information into a AAU from the allocation information decomposed by the stream decomposing circuit 48 An allocation operation circuit 52 for calculating the number of valid data included and comparing with the valid data number information from the ancillary data processing circuit 46;
Is a decompression processing circuit for restoring a digital audio signal from the AAU data decomposed by the stream decomposing circuit 48.

Numeral 54 denotes an interpolation data buffer for holding the digital audio signal restored by the decompression circuit 52 at least until the next AAU is decompressed by the decompression circuit 48. Reference numeral 56 denotes an allocation operation circuit 50. , An interpolation selection circuit for selecting the output of the decompression processing circuit 52 or the output of the interpolation data buffer 54,
Is a digital audio output section for outputting the digital audio signal selected by the interpolation selection circuit 56 to the outside.

The operation of the embodiment shown in FIG. 2 will be described. The operations of the AAU input unit 40, the input buffer 42, the stream decomposing circuit 48, the decompression processing circuit 52, the interpolation data buffer 52, the interpolation selection circuit 56, and the digital audio output unit 58 are respectively performed by the AAU in the embodiment shown in FIG. Input unit 20, input buffer 22, stream decomposition circuit 24, decompression processing circuit 28, interpolation data buffer 3
0 is the same as the operation of the interpolation selection circuit 32 and the digital audio output unit 34.

The stream decomposing circuit 48 decomposes the AAU stream from the input buffer 42 into allocation, scale factor selection information, scale factor, audio data, etc., as in the case of the stream decomposing circuit 24, At the same time, the allocation information and the scale factor selection information are output to the allocation arithmetic circuit 50.

The ancillary data extraction circuit 44 extracts ancillary data from the data stored in the input buffer 42 and supplies it to the ancillary data processing circuit 46. The ancillary data processing circuit 46 searches the input ancillary data from the circuit 44 for data number information effective at the time of decompression processing. The search method is not limited to a specific method. As an example, there is a method in which a bit pattern is determined in advance as header information with a compression device, and the decompression device searches for the determined pattern. When there is valid data number information as a search result, the ancillary data processing circuit 46 applies the value to the allocation arithmetic circuit 50.

The allocation operation circuit 50 calculates the number of valid data included in the AAU from the allocation information and the scale factor selection information input from the stream decomposition circuit 48, and calculates the calculation result and the valid data from the ancillary data processing circuit 46. The numbers are compared, and if they match, it is determined that there is no error; if they do not match, it is determined that there is an error, and the result of the determination is applied to the interpolation selection circuit 56 as a selection signal.

The expansion processing circuit 52 expands the AAU stream data input from the stream decomposition circuit 48 according to a predetermined expansion algorithm, and restores a digital audio signal. The restored digital audio signal is applied to the interpolation data buffer 54 and the interpolation selection circuit 56. The interpolation data buffer 54 updates the stored data with the latest digital audio signal according to the determination result of the allocation arithmetic circuit 50 and only when no error is mixed. The data stored in the interpolation data buffer 54 is read out to the interpolation selection circuit 56.

According to the determination result (selection signal) of the allocation operation circuit 50, the interpolation selection circuit 56 outputs the digital audio signal output from the decompression processing circuit 52 when no error is mixed and an interpolation data buffer when an error is mixed. The digital audio signal (interpolated signal) stored in 54 is selected and supplied to the digital audio output unit 58.

In the above example, a countermeasure against an error is taken by outputting interpolation data. For example, silent data is previously written in the interpolation data buffer 54, and writing of digital audio signals is prohibited. Thus, a modification process such as a mute process when an error is mixed may be performed.

In the second embodiment, the number of valid data calculated from the allocation information and the like can be compared with the number of transmitted valid data, and the mixture of errors can be detected with high accuracy.

An object of the present invention is to supply a storage medium storing program codes of software for realizing the functions of the host and the terminal of the first and second embodiments to a system or an apparatus, and to provide the system or the apparatus with the storage medium. It is needless to say that the present invention is also achieved when a computer (or a CPU or an MPU) reads and executes a program code stored in a storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the first and second embodiments, and the storage medium storing the program code constitutes the present invention.

As storage media for supplying the program code, ROM, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, C
A D-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, or the like can be used.

Further, the functions of the first and second embodiments are realized by executing the program code read by the computer, and the computer operates on the computer based on the instruction of the program code. It goes without saying that the OS or the like performs a part or all of the actual processing, and the processing realizes the functions of the first and second embodiments.

Further, after the program code read from the storage medium is written into a memory provided in an extension function board inserted into the computer or a function extension unit connected to the computer, based on the instructions of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the functions of the first and second embodiments are realized by the processing is also included.

[0047]

As can be easily understood from the above description, according to the present invention, a data error in an input information data unit can be detected easily and accurately, so that an information data error can be detected. Information degradation due to contamination can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a first embodiment of the present invention.

FIG. 2 is a schematic configuration block diagram of a second embodiment of the present invention.

FIG. 3 is an example of an AAU format according to a second embodiment.

FIG. 4 is a schematic block diagram of a conventional example.

[Explanation of symbols]

 10: AAU input unit 12: Input buffer 14: Decompression processing circuit 16: Digital audio output unit 20: AAU input unit 22: Input buffer 24: Stream decomposition circuit 26: Allocation calculation circuit 28: Decompression processing circuit 30: Interpolated data buffer 32 : Interpolation selection circuit 34: Digital audio output unit 40: AAU input unit 42: Input buffer 44: Ancillary data extraction circuit 46: Ancillary data processing circuit 48: Stream decomposition circuit 50: Allocation operation circuit 52: Decompression processing circuit 54: Interpolation data buffer 56: Interpolation selection circuit 58: Digital audio output unit

Claims (12)

[Claims] 1. Predetermined data composed of valid data composed of information data compressed using a predetermined period as a compression unit, compression attribute data indicating attributes of the entire compression unit, and stuffing data for adjusting the data amount. Input means for inputting an information data stream in units of an amount of information data units, and calculating means for predicting the data amount of the valid data of the information data unit based on the compressed attribute data input by the input means Decompression means for decompressing the compressed information data; determination means for determining whether or not the data amount predicted by the calculation means is an allowable data amount for the information data unit; Processing means for modifying the information data decompressed by the decompression means accordingly. Information data processing device. 2. Effective data comprising information data compressed in a predetermined period as a compression unit and compression attribute data indicating attributes of the entire compression unit, data amount information on the data amount of the effective data, and data amount adjustment. Input means for inputting an information data stream in units of an information data unit of a predetermined data amount constituted by stuffing data for; and the information data unit of the information data unit based on compressed attribute data input by the input means. Calculating means for predicting the data amount of valid data; decompressing means for decompressing the compressed information data; and calculating the data amount calculated by the calculating means and the data amount obtained from the data amount information of the information data unit. Comparing means for comparing, expanded by the expanding means according to the comparison result of the comparing means Information data processing apparatus characterized by having processing means for modification processing the broadcast data. 3. The information data processing apparatus according to claim 1, wherein the information data is audio data. 4. The information data stream is an MPEG data stream.
The information data processing device according to claim 1, wherein the information data processing device is an audio bit stream. 5. The information data processing device according to claim 4, wherein the information data unit is an AAU (Audio Access Unit) of MPEG audio. 6. The compression attribute data is allocation and scale factor selection information defined by MPEG audio layer 2.
An information data processing device according to claim 1. 7. The information data processing apparatus according to claim 3, wherein the processing unit mutes the audio data. 8. The information data processing apparatus according to claim 3, wherein said processing means interpolates the audio data into other audio data. 9. The information data is audio data, the information data stream is an MPEG audio bit stream, and the data number information is arranged in an ancillary data area defined by MPEG audio. The information data processing device according to claim 2, wherein 10. Predetermined data composed of valid data composed of information data compressed using a predetermined period as a compression unit, compression attribute data indicating the attributes of the entire compression unit, and stuffing data for adjusting the data amount. An input step of inputting an information data stream in units of an amount of information data units; an operation step of predicting a data amount of the valid data of the information data unit based on the input compressed attribute data; A decompressing step of decompressing the information data, a judging step of judging whether the predicted data amount is an allowable data amount in the information data unit, and the decompressed information data according to the judgment result. And a processing step of modifying the data. 11. Valid data including information data compressed using a predetermined period as a compression unit and compression attribute data indicating attributes of the entire compression unit, data amount information on the data amount of the valid data, and data amount adjustment. Inputting an information data stream in units of an information data unit having a predetermined data amount constituted by stuffing data for; and inputting the valid data of the information data unit based on the input compression attribute data. A calculating step of predicting a data amount; an expanding step of expanding the compressed information data; a comparing step of comparing the calculated data amount with a data amount obtained from data amount information of the information data unit; Modifying the expanded information data according to the comparison result. Information data processing method. 12. A storage medium storing a program for a processing step of the information data processing method according to claim 10 so as to be readable by a computer.