JP2011164690A - Audio processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio processing device for reducing hardware cost or a burden of developing a control program, and minimizing the deterioration of performance in application processing requiring real time performance, and in which a signal processor keeps the track of the output status of data. <P>SOLUTION: The audio processing device 100 comprises: an additional information superimposition unit 113 which superimposes control information which is different from audio information as the additional information onto the audio data; and an additional information detection unit 150 connected to a data bus connecting a memory 120 and the audio data output circuit 140 and detecting the additional information 200 added to the audio data. The additional information detection unit 150 outputs the detected additional information 200 to an output control unit 111 of a signal processor 110 through an additional information detection state readout channel 117. The output control unit 111 controls the output of audio data on the basis of the additional information 200 detected by the additional information detection unit 150. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an audio processing apparatus that performs output processing of audio data, and more particularly, to an audio processing apparatus that realizes application processing that requires real-time performance such as audio and video.

  As application processing has become more complex and sophisticated in recent years, performance problems have become more prominent in signal processors that handle processing.

  One of the methods for reducing the processing performance of the processor is an automatic data transfer function using DMA (Direct Memory Access). For data transfer such as audio and video, DMA is used for the purpose of reducing the processing load on the processor. In the DMA transfer, data transfer between the main memory and the input / output device is executed at high speed without going through the CPU.

  In Patent Document 1, an information device capable of recording and reproducing audio data has a data transfer means by DMAC, and reads the transfer count value of DMAC at the time of data transfer to acquire the transfer size of the data, An audio information device is described that acquires the elapsed time during recording and playback from the sampling frequency during recording and playback.

  In Patent Document 2, data is output from a ring buffer including a plurality of buffers for temporarily storing audio data to be output to the outside, and a buffer in the ring buffer, and the buffer is in an empty state. And an interrupt signal generation unit that supplies the processor with the interrupt signal generated by thinning out the interrupt signal according to the sampling frequency of the audio data to be output to the outside, and when the processor receives the interrupt signal, the ring buffer An information processing apparatus that issues a data transfer command for writing audio data to an empty buffer is described.

JP 2005-182967 A JP 2008-77174 A

  However, such a conventional audio processing apparatus has the following problems.

  (1) In application processing that requires real-time performance such as audio and video, a signal processor that performs playback processing needs to know the output state of data. However, when data is output using the automatic data transfer function by DMA, the signal processor must always monitor the DMA transfer status in order to grasp the data output status, and accurately grasp it. It is difficult to do.

  (2) Further, in the prior art, there is a method of controlling data output using a dedicated control processor in order to monitor the data output state. According to this method, it is possible to monitor the output state of data. However, the mounting of the control processor has problems such as an increase in hardware cost and an increase in the burden of developing a program executed on the control processor. Another problem is a reduction in processing performance required for communication between a signal processor that performs reproduction processing and a control processor that performs output management.

  The present invention has been made in view of the above points, and in application processing that requires real-time performance such as audio and video, it is possible to reduce hardware costs and control program development burden, and to reduce processing performance. It is an object of the present invention to provide an audio processing apparatus in which a signal processor can grasp the output state of data.

  An audio processing apparatus according to the present invention includes a processor having a reproduction processing unit that performs reproduction processing of audio data and an output control unit that performs output control of the audio data, and an audio data output circuit that outputs audio data generated by the processor And a memory for temporarily storing audio data to be reproduced by the reproduction processing unit, a DMA controller for transferring data between the audio data output circuit and the memory without going through the processor, and control different from sound information Additional information superimposing means for superimposing information as additional information on the audio data of the reproduction processing unit and a data bus connecting the memory and the audio data output circuit are connected to detect additional information added to the audio data. An additional information detecting means and a configuration provided are employed.

  According to the present invention, in application processing that requires real-time performance such as audio and video, the hardware cost and the development burden of the control program are reduced, and the deterioration of the processing performance is minimized, so that the signal processing processor An audio processing apparatus that can grasp the output state can be realized.

The block diagram which shows the structure of the audio processing apparatus which concerns on Embodiment 1 of this invention. The figure explaining one format of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The figure explaining the other format of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The figure explaining the superimposition method and detection method of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The figure explaining the other superimposition method and detection method of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The figure explaining the other superimposition method and detection method of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The figure explaining the superimposition method of the additional information of the audio processing apparatus which concerns on the said Embodiment 1. FIG. The block diagram which shows the structure of the audio processing apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the audio processing apparatus which concerns on Embodiment 3 of this invention. The figure which compares and demonstrates the audio processing apparatus which concerns on the said Embodiment 3, and the output control of a prior art example. The figure explaining other output control of the audio processing apparatus which concerns on the said Embodiment 3. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an audio processing apparatus according to Embodiment 1 of the present invention. This embodiment is an example applied to a digital audio device.

  As shown in FIG. 1, the audio processing apparatus 100 includes a signal processor 110, a memory 120, a DMA controller 130, an audio data output circuit 140, and an additional information detection unit 150. Note that the audio processing apparatus 100 is supplied with reproduction data 101 read from the memory 10.

  The signal processor 110 includes an output control unit 111 that controls output of audio data, a reproduction processing unit 112 that performs reproduction processing of audio data, and an additional information superimposing unit 113.

  Here, the signal processor 110 generates audio data by cooperation of the reproduction processing of the audio data by the reproduction processing unit 112 and the output control of the audio data by the output control unit 111.

  The additional information superimposing unit 113 superimposes control information different from the sound information on the audio data 102 as additional information. Hereinafter, this control information is referred to as additional information 200 (see FIG. 2; the same applies hereinafter), and the audio data 102 to which the additional information 200 is added is referred to as audio data 103 with additional information.

  The memory 120 temporarily stores the audio data 103 with additional information.

  The DMA controller 130 performs data transfer between the audio data output circuit 140 and the memory 120 without going through the signal processor 110. When receiving a transfer start command from the signal processor 110, the DMA controller 130 reads data from a specified memory area and transfers the data to the audio data output circuit 140. The audio data 104 read to the DMA controller 130 is input to the audio data output circuit 140 and also input to the additional information detection unit 150.

  The audio data output circuit 140 outputs audio data generated by the signal processor 110. The audio data output circuit 140 changes the data transferred from the memory 120 to the audio transfer rate and outputs it.

  The additional information detection unit 150 is connected to a data bus connecting the memory 120 and the audio data output circuit 140, and detects the additional information 200 (see FIG. 2) superimposed on the audio data with additional information 103. The additional information detection unit 150 outputs the detected additional information 200 to the output control unit 111 of the signal processor 110 through the additional information detection state readout path 117. In the present embodiment, the additional information detection unit 150A-C is exemplified as the additional information detection unit 150.

  In the present embodiment, the output control unit 111 performs audio data output control based on the additional information 200 detected by the additional information detection unit 150.

  FIG. 2 is a diagram for explaining one format of the additional information 200, and is an example of the additional information 200A superimposed on the surplus bits in the existing transfer data bus width. 2A shows an example of the data bus width, and FIG. 2B shows sound output control using the additional information 200A.

  The additional information superimposing unit 113 (FIG. 1) superimposes the additional information 200A on surplus bits that are not used as the audio data 102 in the existing transfer data bus width without changing the conventional data bus width.

  As shown in FIG. 2A, when the data bus width is 32 bits and the audio data 102 is 24 bits, 8 bits can be used as the additional information 200A.

  When the quantization bit width of the audio data 102 is small, the number of bits that can be used for the additional information 200A increases. Further, the data bus width is not necessarily 32 bits.

  FIG. 3 is a diagram for explaining another format of the additional information 200. FIG. 3A shows an example in which there are no unused surplus bits, and FIG. 3B shows an example of the data bus width. 3 (c) shows sound output control using the additional information 200B. FIG. 3 is an example of additional information 200B applied to a system having an audio output channel that does not require a relatively high accuracy even in a high-precision audio system, although there are no unused surplus bits. .

  As shown in FIG. 3B, when the quantized bits of the audio data 102 match the data bus width, there are no unused surplus bits.

  As shown in FIG. 3B, in a system having an audio output channel that does not require relatively high accuracy even in a high-precision audio system, the additional information superimposing unit 113 (FIG. 1) By treating the lower bits of 102 as surplus bits, the additional information 200B is superimposed on the audio data 102.

  At this time, the audio data output circuit 140 masks and outputs the data so that the additional information superimposed on the audio data 102 is not output to the outside.

  For example, as shown in an example of the data width in FIG. 3A, when the data bus width is 32 bits and the audio data is 32 bits, there are no surplus bits that can be used for the additional information. By treating the audio data having little influence on the sound quality, for example, the lower 4 bits of the audio data of the subwoofer channel as extra bits, it is possible to superimpose additional information on these 4 bits.

  The operation of the audio processing device configured as described above will be described below.

  FIG. 4 is a diagram for explaining a method for superimposing and detecting the additional information 200.

  The additional information superimposing unit 113 adds the additional information 200A or 200B to the audio data 102. The audio data with additional information 103 (FIG. 1) on which the additional information is superimposed by the additional information superimposing unit 113A is output to the memory 120.

  The additional information detection unit 150A includes a register 155 that stores the superimposed additional information 200A or 200B read from the memory 120.

  The register 155 has a function of holding the detected additional information. The output control unit 111 acquires the detection result of the additional information through the additional information detection state reading path 117 (FIG. 1).

  FIG. 5 is a diagram for explaining another superposition method and detection method of the additional information 200. Here, a method of superimposing and detecting additional information when high-accuracy audio quality is required and surplus bits cannot be used will be described.

  As illustrated in FIG. 5, the additional information superimposing unit 113B includes a register 114 that stores audio data input from the reproduction processing unit 112, and an arithmetic processing unit 115 that performs arithmetic processing on each bit of the register 114. .

  The additional information superimposing unit 113B performs arithmetic processing using the audio data 102 (FIG. 1) of one sample or more. The additional information superimposing unit 113B outputs the audio data 102 on which the additional information is not superimposed to the memory 120. The additional information superimposing unit 113B outputs the result of the arithmetic processing performed by the arithmetic processing unit 115 to the additional information detecting unit 150B.

  The additional information detection unit 150B includes a register 151 that stores the audio data 102 read from the memory 120, and an arithmetic processing unit that performs the same arithmetic processing as the arithmetic processing unit 115 of the additional information superimposing unit 113B on each bit of the register 151. 152 and a comparator 153 that compares the calculation result of the calculation processing unit 152 and the calculation result notified from the additional information superimposing unit 113B.

  The additional information detection unit 150B compares the calculation result of the calculation processing unit 152 with the calculation result notified from the additional information superimposing unit 113B, and when the calculation result is the same result, the additional information superimposing unit 113B performs audio data The additional information is detected by determining that the additional information is superimposed on the.

  As described above, the signal processor 110 performs arithmetic processing using audio data of one sample or more, notifies the additional information detection unit 150B of the calculation result, and the additional information detection unit 150B performs calculation using the input audio data. It is detected as additional information that the result of the processing is the same as the calculation result.

  FIG. 6 is a diagram for explaining another superimposition method and detection method of the additional information 200. Here, another method of superimposing and detecting additional information when high-accuracy audio quality is required and surplus bits cannot be used will be described.

  As shown in FIG. 6, the additional information superimposing unit 113C includes a register 114 that stores audio data input from the reproduction processing unit 112, and a data processing unit 116 that processes audio data for each bit of the register 114. Have. The additional information superimposing unit 113C performs data processing using the audio data 102 of one sample or more and outputs the processed data to the memory 120. Examples of the audio data processing method include embedding discontinuous data by inverting upper bits of audio data. FIG. 6 shows data processing for embedding discontinuities by the data processing unit 116.

  The additional information detection unit 150 </ b> C includes a register 151 that stores processed audio data read from the memory 120, and a data reverse processing unit 154 that reverses data for each bit of the register 151. The data reverse processing is data processing reverse to the data processing by the data processing unit 116, and here is correction of discontinuous points.

  The audio data output circuit 140 does not output the processed audio data 104 (FIG. 1), but outputs the audio data 105 obtained by inversely processing the data by the additional information detection unit 150C. At this time, the audio data processed by the additional information superimposing unit 113C is a part of continuous audio data. The additional information detection unit 150 </ b> C determines that the additional information has been superimposed on the portion where this processing has been performed, and detects the additional information.

  As described above, the signal processor 110 processes the audio data of one sample or more as discontinuous data that can be reversibly converted, and the additional information detection unit 150C detects the detected discontinuous information as additional information and the discontinuous data. Is converted back to the original audio data and output. Since this method does not use surplus bits, highly accurate audio quality can be maintained.

  FIG. 7 is a diagram illustrating a method for superimposing additional information. The detection of additional information is the same as in FIG.

  The additional information superimposing unit 113C performs data processing by embedding discontinuous points in FIG. Further, the additional information detection unit 150C corrects the discontinuous points, which is the reverse processing of the data processing, and reconverts the discontinuous data into the original audio data and outputs it.

  As shown in FIG. 7, the audio data 104 input to the additional information superimposing unit 113C includes audio data 0, audio data 1 (processed) in which discontinuities are embedded, additional information, audio data 2,. N (N is an arbitrary natural number). That is, in the audio data 104, the audio data 1 is processed with respect to the audio data 0,..., The audio data N, and additional information is superimposed on the data immediately after that.

  The audio data 105 output from the additional information superimposing unit 113C includes audio data 0, audio data 1 (reverse processing) with corrected discontinuities, audio data 2,..., Audio data N (N is an arbitrary natural number). Have That is, the audio data 105 is obtained by performing reverse processing on the audio data 1 and extracting the additional information of the data immediately after that. As a result, the audio data 105 becomes continuous data such as the original audio data.

  As described above, in the additional information superimposing method of FIG. 7, the additional information is superimposed immediately after the processed data. The additional information detection unit 150C deletes the additional information from the audio data, and outputs the audio data 105 composed of the audio data and the reversely processed audio data.

  As described above in detail, the audio processing apparatus 100 according to the present embodiment includes the additional information superimposing unit 113 that superimposes control information different from the sound information on the audio data as additional information, the memory 120, and the audio data output circuit 140. And an additional information detection unit 150 that detects additional information 200 added to the audio data. The additional information detection unit 150 outputs the detected additional information 200 to the output control unit 111 of the signal processor 110 through the additional information detection state readout path 117. The output control unit 111 performs audio data output control based on the additional information 200 detected by the additional information detection unit 150.

  As described above, in an application process that requires real-time performance such as audio or video, the signal processor that performs the reproduction process needs to grasp the data output state.

  According to the present embodiment, the signal processor 110 accurately determines the audio data output state without constantly monitoring the DMA transfer state and without using a dedicated control processor to monitor the data output state. Can grasp. Further, it is possible to avoid a decrease in processing performance required for communication between a signal processor that performs reproduction processing and a control processor that performs output management.

  As a result, in application processing that requires real-time performance, such as audio and video, the signal processor can reduce the hardware cost and control program development burden while minimizing issues such as degradation in processing performance. The output state can be grasped.

(Embodiment 2)
FIG. 8 is a block diagram showing the configuration of the audio processing apparatus according to Embodiment 2 of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description of overlapping portions is omitted.

  As shown in FIG. 8, the audio processing device 300 includes the same circuit unit as the audio processing device 100 of FIG. However, the additional information detection unit 150 outputs the detected additional information to the reproduction processing unit 112 of the signal processor 110 by an interrupt notification 118. The additional information superimposing unit 113 superimposes additional information on the audio data 102 generated by the reproduction processing unit 112.

  The audio data with additional information 103 is stored in the memory 120 and read out to the DMA controller 130. The audio data 104 read to the DMA controller 130 is input to the audio data output circuit 140 and also input to the additional information detection unit 150.

  The additional information detector 150 detects additional information superimposed on the audio data 104 and notifies the signal processor 110 that the audio data 104 has reached the audio data output circuit 140 by an interrupt notification 118.

  Upon receiving the interrupt notification 118, the signal processor 110 performs fade-in / fade-out processing and sampling rate switching processing between songs.

  The method for detecting additional information according to the present embodiment is the same as the method for superimposing and detecting additional information 200 shown in FIGS.

  As described above, in the audio processing device 300 according to the present embodiment, the additional information detection unit 150 notifies the reproduction processing unit 112 of the signal processor 110 of the additional information detection by interruption, as in the first embodiment. The signal processor 110 can accurately grasp the audio data output state without constantly monitoring the transfer state of the DMA controller 130 and without using a dedicated control processor for monitoring the data output state. it can. Further, it is possible to avoid a decrease in processing performance required for communication between a signal processor that performs reproduction processing and a control processor that performs output management.

  By the way, in the first embodiment, the detected additional information is used by the output control unit 111, and in the second embodiment, the reproduction processing unit 112 is used. Differences between the first embodiment and the second embodiment will be described.

  In each of the first and second embodiments, the signal processor 110 performs processing according to the detected information. In the first embodiment, it is necessary to periodically read back the fed back information, and when the fed back information requires urgency, it becomes difficult to deal with it. However, there is an advantage that hardware resources can be reduced. In the second embodiment, the feedback information is notified of interruption in real time, so that the responsiveness is high. However, the interrupt processing places a load on the processor processing performance. In addition, hardware resources increase.

(Embodiment 3)
FIG. 9 is a block diagram showing a configuration of an audio processing apparatus according to Embodiment 3 of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description of overlapping portions is omitted.

  As shown in FIG. 9, the audio processing device 400 includes the same circuit unit as the audio processing device 100 of FIG.

  The audio data 103 on which the additional information is superimposed is stored in the memory 120 and read out to the DMA controller 130. The audio data 104 read to the DMA controller 130 is input to the audio data output circuit 140 and also input to the additional information detection unit 150.

  The additional information detection unit 150 detects additional information superimposed on the audio data 104 and activates the additional information detection control signal 119. The additional information detection control signal 119 is output to the audio data output circuit 140.

  The audio data output circuit 140 receives the additional information detection control signal 119 from the additional information detection unit 150 and switches output data and updates header information and footer information.

  The operation of the audio processing device configured as described above will be described below.

  FIG. 10 is a diagram for explaining and comparing the output control of the audio processing apparatus 400 of the present embodiment and the conventional example.

  As shown in FIG. 10A, in the conventional output control, it is necessary to input an audio data packet including invalid data in accordance with a certain header addition interval T. For example, FIG. -C. As shown, it is necessary to insert an output data packet corresponding to invalid data in accordance with the additional interval T. For this reason, in the conventional example, the signal processor (not shown) performs a control to superimpose invalid data after securing a memory area for storing data other than valid data and calculating how many invalid data sections exist. Was necessary.

  On the other hand, in the present embodiment, the additional information detection unit 150 detects the additional information 200 superimposed on the audio data 104, and the audio data output circuit 140 controls the additional information detection from the additional information detection unit 150. In response to the signal 119, output data is switched and header information and footer information are updated.

  As shown in FIG. 10B, the additional information 200 superimposed on the audio data with additional information 103 is detected by the additional information detection unit 150. The detected additional information 200 is notified to the audio data output circuit 140 as an additional information detection control signal 119, and output of audio data is started together with the header information. In the case of FIG. 10B, the additional information 200 is superimposed on the audio data 1, audio data 5, and audio data 9 of the audio data 103 with additional information. The additional information detection unit 150 detects the additional information 200 superimposed on the audio data 1, audio data 5, and audio data 9, and the audio data output circuit 140 performs switching of output data based on the additional information 200. Update header information and footer information.

  Therefore, as shown in FIG. 10B, the output of data is waited until a certain header addition interval T measured by the audio data output circuit 140, and the audio data can be output together with the header information.

  As described above, in this embodiment, the input data may be only valid data, and can be transferred in accordance with the audio output rate only by adding header information to the head of the data at regular intervals.

  FIG. 11 is a diagram illustrating another output control of the audio processing device 400 according to the present embodiment. FIG. 11 shows the operation when the additional information is not detected at the header output timing, that is, at the beginning of the fixed interval T.

  As shown in FIG. 11, the audio data output circuit 140 outputs auxiliary data designated in advance when the additional information detection control signal 119 is not inputted. When the additional information is detected by the additional information detection unit 150, the output of data is waited until a predetermined interval T measured by the audio data output circuit 140, and the audio data is output together with the header information.

  The method for detecting additional information according to the present embodiment is the same as the method for superimposing and detecting additional information 200 shown in FIGS.

  In the present embodiment, since all the processing is performed by hardware, there is an advantage that no load is imposed on the processor processing performance. Further, since it operates immediately after detecting feedback information, it is not necessary to consider responsiveness. However, it is conceivable that the processing contents cannot be widened as long as they are implemented by hardware (that is, only routine processing can be performed) and hardware resources are increased.

  The above embodiments are preferably used properly in the following cases.

Embodiment 1: When the processing itself has relatively time tolerance Embodiment 2: When responding in real time and there are a plurality of processing contents Embodiment 3: Processing according to the standard of the interface protocol Case

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this.

  In the above embodiments, the name of the audio processing apparatus is used. However, this is for convenience of explanation, and it is needless to say that the names of the audio signal reproducing apparatus and the audio system may be used.

  In the above-described embodiment, the signal processor is described as an example. However, any processor, such as a CPU or a DSP, may be used as long as it performs audio reproduction processing.

  Further, the type, number, connection method, and the like of each circuit unit constituting the audio processing apparatus are not limited to the above-described embodiments.

  The audio processing apparatus according to the present invention can be used for portable information devices, digital televisions, optical disk recorders, digital audio devices, and the like.

100, 300, 400 Audio processing device 110 Signal processor 111 Output control unit 112 Playback processing unit 113, 113A, 113B, 113C Additional information superimposing unit 120 Memory 130 DMA controller 140 Audio data output circuit 150, 150A, 150B, 150C Additional information Detection unit

Claims (9)

A processor having a reproduction processing unit that performs reproduction processing of audio data and an output control unit that performs output control of the audio data;
An audio data output circuit for outputting audio data generated by the processor;
A memory for temporarily storing audio data to be reproduced by the reproduction processing unit;
A DMA controller for transferring data between the audio data output circuit and the memory without going through the processor;
Additional information superimposing means for superimposing control information different from sound information as additional information on the audio data of the reproduction processing unit;
Connected to a data bus connecting the memory and the audio data output circuit, and additional information detecting means for detecting additional information added to the audio data;
An audio processing apparatus comprising:   The audio processing apparatus according to claim 1, wherein the output control unit performs output control of audio data based on the additional information detected by the additional information detection unit.   The audio processing apparatus according to claim 1, wherein the reproduction processing unit performs audio data reproduction processing based on the additional information detected by the additional information detection unit.   2. The audio processing apparatus according to claim 1, wherein the additional information superimposing unit superimposes the additional information on surplus bits within an existing transfer data bus width.   The audio processing apparatus according to claim 1, wherein the additional information superimposing unit superimposes the additional information on lower bits of audio data. The additional information superimposing means performs arithmetic processing using audio data of one sample or more, and notifies the additional information detecting means of the arithmetic result,
2. The audio according to claim 1, wherein the additional information detection unit detects the additional information by comparing the result of the arithmetic processing using the input audio data with the calculation result notified from the additional information superimposing unit. Processing equipment. The additional information superimposing means has data processing means for processing audio data of one sample or more as discontinuous information capable of reversible conversion,
2. The audio processing apparatus according to claim 1, wherein the additional information detecting means includes data reverse processing means for detecting the discontinuous information as additional information and reconverting and outputting the discontinuous audio data to the original audio data. . The additional information superimposing means superimposes the additional information on data immediately after the data processed by the data processing means as discontinuous data that can be reversibly converted into audio data of one sample or more,
2. The audio processing apparatus according to claim 1, wherein the additional information detecting means detects data next to the discontinuous information as additional information, and reconverts the discontinuous audio data into original audio data and outputs the data. The audio processing apparatus according to claim 1, wherein the additional information detection unit notifies the reproduction processing unit of detection of additional information by interruption.

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