JP2005072708A - Apparatus and method for frame format conversion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frame format converting apparatus and a frame converting method which convert a frame including a sound encoding bit encoded by a voice encoding system, such as AMR (Adaptive Multi-Rate) for switching an encoded bit rate per frame into another frame of the voice encoding system. <P>SOLUTION: This frame format converting apparatus 100 is provided with: a frame extracter 102 for extracting continuously inputted frames per frame; an FT detecting/storing section 103 for detecting a frame type bit from among the extracted frames; an unnecessary bit deleting section 104 for deleting the frame type bit and an additional information bit from among the extracted frames; a bit shift 105 and a bit reverting section 106 for changing the voice encoded bit into the predetermined position of the extracted frame; and an FT positioning section 107 for positioning the frame type bit to the predetermined position of the extracted frame. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a frame including audio encoded bits encoded based on a predetermined audio compression encoding method capable of switching an encoding bit rate in units of frames, for example, Adaptive Multi-Rate (AMR). The present invention relates to a frame configuration conversion apparatus and a frame configuration conversion method.
[0002]
[Prior art]
Conventionally, Adaptive Multi-Rate (AMR), which is capable of switching the coding bit rate in units of frames, is a standard speech coding method used in the third generation mobile communication system, 3GPP (3rd Generation Partnership) (See, for example, Non-Patent Document 1).
[0003]
AMR is used in the third generation mobile communication system when encoding audio content distributed together with video by a video distribution service, or encoding audio transmitted in a TV phone service.
[0004]
AMR has also become widespread as an audio encoding method for encoding audio content distributed as streaming data using RTP (Real-time Transport Protocol) on the Internet and the like.
[0005]
[Non-Patent Document 1]
“Mandatory spec code spec processing functions; Adaptive Multi-Rate (AMR) spec code frame structure − TS26.101 release 5 Prot.
[0006]
[Problems to be solved by the invention]
However, AMR has a plurality of frame configurations (frame formats) depending on its use, that is, a communication protocol to be used, and each frame format is not compatible with other frame formats. was there.
[0007]
For example, the frame structure (RTP Payload Format) when distributing AMR data encoded by AMR using RTP is AMR using the TV telephone communication protocol (3G-324M) in the third generation mobile communication system. Since the frame configuration (Interface Format 2) for data distribution is not compatible, AMR data having RTP Payload Format can be directly distributed to mobile phone terminals used in the third generation mobile communication system. There was a problem that I could not.
[0008]
Therefore, the present invention has been made to solve the above-described problems, and includes speech encoded bits encoded by a speech encoding method in which the encoding bit rate can be switched on a frame basis, such as AMR. It is an object of the present invention to provide a frame configuration conversion apparatus and a frame configuration conversion method that can convert a frame to be converted into another frame of the speech encoding method.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a voice coding encoded based on a predetermined voice compression coding method capable of switching a coding bit rate in units of frames, for example, Adaptive Multi-Rate (AMR). A first frame (for example, RTP Payload) in which a bit, a frame type bit (Frame Type) indicating a frame type, and an additional information bit (Change mode Request bit, frame quality indicator, etc.) are arranged in a predetermined order A frame configuration conversion device for converting (Format) into a second frame (for example, Interface Format 2), wherein a frame extraction unit (frame extraction) extracts the first frame that is continuously input in units of frames. Part 102) and extracted Based on the configuration of the frame type detection unit (FT detection / storage unit 103) that detects the frame type bit from the outgoing frame and the second frame, the speech code included in the extracted frame Based on the configuration of the processing unit (unnecessary bit deletion unit 104, bit shift unit 105, and bit inversion unit 106) that changes the digitized bit to a predetermined position on the extracted frame, and the frame type, The gist of the present invention is to include a frame type bit arrangement unit (FT arrangement unit 107) that arranges the frame type bit detected by the detection unit at a predetermined position on the extracted frame.
[0010]
According to this feature, the processing unit changes the speech encoded bit to a predetermined position of the extracted frame extracted by the frame extracting unit based on the second frame configuration, and the frame type bit arrangement unit In order to arrange the frame type bit at a predetermined position on the extracted frame, the encoded bit rate includes audio encoded bits encoded based on a predetermined audio compression encoding method that can be switched in units of frames. The structure of the frame can be converted.
[0011]
According to a second feature of the present invention, in the first feature of the present invention, the processing unit deletes the frame type bit and the additional information bit included in the extracted frame, and extracts the extracted information. The gist is to change the speech coding bits to the predetermined position by shifting the position of the speech coding bits on the frame.
[0012]
A third feature of the present invention is that, in the second feature of the present invention, the processing unit reverses the order of the speech encoded bits having a predetermined number of bits sequentially arranged on the extracted frame. The gist of the present invention is to change the speech coding bit to the predetermined position.
[0013]
According to such a feature, the bit shift unit shifts the position of the speech encoded bits on the extracted frame, and the bit inversion unit stores the speech encoded bits of a predetermined number of bits sequentially arranged on the extracted frame. Since the order is reversed, the frame configuration can be converted with a smaller number of processing steps.
[0014]
That is, according to this feature, by registering in advance the contents of processing necessary for conversion from the first frame configuration to the second frame configuration in the bit deletion unit, the bit shift unit, and the bit inversion unit. The frame configuration can be converted with a small number of processing steps, and the processing speed related to the frame configuration conversion can be improved.
[0015]
According to a fourth aspect of the present invention, in the first to third aspects of the present invention, as the predetermined audio compression encoding method, a frame including the audio encoded bits encoded by Adaptive Multi-Rate is included. The gist is to convert the configuration.
[0016]
According to this feature, AMR data encoded by AMR can be converted from, for example, RTP Payload Format to Interface Format 2. As a result, by using the frame configuration conversion apparatus according to the present invention, for example, AMR data having RTP Payload Format published on the Internet is distributed to mobile telephone terminals used in the third generation mobile communication system. It becomes possible to do.
[0017]
A fifth feature of the present invention is that a speech coding bit that is coded based on a predetermined speech compression coding method that can switch a coding bit rate in units of frames, a frame type bit that indicates a frame type, A frame configuration conversion method for converting a first frame in which additional information bits are arranged in a predetermined order into a second frame, wherein the first frame that is continuously input is converted into a frame unit. The speech encoding included in the extracted frame based on the step of extracting, the step of detecting the frame type bit from the extracted extracted frame, and the configuration of the second frame A step of changing a bit to a predetermined position on the extracted frame, and a step of detecting the frame type bit based on the configuration of the second frame. And summarized in that comprises the steps of placing the frame type bit is detected in a predetermined position on said extraction frames by.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
(Configuration of frame configuration conversion device)
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a logical block configuration of the frame configuration conversion apparatus according to the present embodiment.
[0019]
As shown in the figure, the frame configuration conversion apparatus 100 includes a data input unit 101, a frame extraction unit 102, an FT detection / storage unit 103, an unnecessary bit deletion unit 104, a bit shift unit 105, and a bit inversion. Unit 106, FT placement unit 107, and data output unit 108.
[0020]
The data input unit 101 sends AMR data input from the outside to the frame extraction unit 102. In the present embodiment, the data input unit 101 is encoded by AMR (Adaptive Multi-Rate) and is defined by IETF RFC3267. AMR data having a Payload Format (first frame) configuration is input to the data input unit 101.
[0021]
The data input unit 101 includes an input interface such as a LAN card such as 100BASE-TX that acquires AMR data via a communication network, or an AMR stored in an external storage medium such as a CD-ROM or DVD-ROM. An external storage medium access device that reads data can be used.
[0022]
The frame extraction unit 102 extracts an AMR data frame having an RTP payload format continuously input to the data input unit 101 in units of frames.
[0023]
Specifically, the frame extraction unit 102 uses AMR data having an RTP payload format sent from the data input unit 101 as a frame with the CMR (Change Mode Request) bit as the most significant bit (MSB: Most Significant Bit). The AMR data frame extracted in units is sent to the FT detection / storage unit 103.
[0024]
Here, FIG. 2 shows a frame configuration of AMR data having the RTP payload format extracted by the frame extraction unit 102.
[0025]
As shown in the figure, the AMR data having the RTP Payload Format includes voice encoded bits (D) encoded by the AMR, frame type bits indicating the frame type, that is, information indicating the encoding bit rate ( FT: frame type) and additional information bits such as a CMR bit (CMR) used when changing the encoding bit rate and a confirmation bit (F) indicating the presence or absence of a subsequent frame.
[0026]
The FT detection / storage unit 103 detects a frame type bit (FT) from the AMR data frame extracted by the frame extraction unit 102. In this embodiment, the FT detection / storage unit 103 constitutes a frame type detection unit. To do.
[0027]
Specifically, the FT detection / storage unit 103 detects the frame type bit (FT) located in the second to fifth bits of Octet 1 shown in FIG. 2 and the contents of the detected frame type bit (FT). And the contents are transferred to the FT placement unit 107.
[0028]
Further, after detecting the frame type bit (FT), the FT detection / storage unit 103 sends the AMR data frame sent from the frame extraction unit 102 to the unnecessary bit deletion unit 104.
[0029]
The unnecessary bit deletion unit 104 selects a frame type bit (FT) from the AMR data frame sent from the FT detection / storage unit 103 based on the Interface Format 2 (second frame) to be output. ) And additional information bits such as a CMR bit and a confirmation bit (F).
[0030]
Specifically, the unnecessary bit deletion unit 104 deletes information located in Octet 0 and Octet 1 shown in FIG.
[0031]
Unnecessary bit deletion section 104 sends an AMR data frame from which frame type bits (FT) and additional information bits such as CMR bits and confirmation bits (F) are deleted to bit shift section 105.
[0032]
The bit shift unit 105 shifts the position of the speech encoded bit (D) on the AMR data frame sent from the unnecessary bit deletion unit 104 based on the configuration of the RTP Payload Format and the configuration of the Interface Format 2. Is.
[0033]
Specifically, the bit shift unit 105 shifts the speech encoded bit (D) by 4 bits to the LSB side. Further, the bit shift unit 105 deletes the padding bit (P) included in the last octet where the speech encoded bit (D) is located.
[0034]
Also, the bit shift unit 105 shifts the speech coding bit (D) and sends the AMR data frame from which the padding bit (P) is deleted to the bit inverting unit 106.
[0035]
Based on the configuration of RTP Payload Format and the configuration of Interface Format 2, the bit inverting unit 106 has a predetermined number of audio encoded bits sequentially arranged on the AMR data frame sent from the bit shift unit 105 The order of (D) is reversed.
[0036]
Specifically, the bit reversing unit 106 inverts the order of speech coding bits (D) on an octet basis, that is, in units of 8 bits on the AMR data frame sent from the bit shift unit 105.
[0037]
For example, an octet on an AMR data frame can be represented by D (236) -D (237) -D (238) -D (239) -D (240) -D (241) -D (242) -D (243 ) And the coded speech bits are sequentially arranged from the MSB side to the LSB (Least Significant Bit) side, the arrangement of the coded speech bits on the octet is represented by D (243) -D (242) -D ( 241) -D (240) -D (239) -D (238) -D (237) -D (236). That is, the bit inverting unit 106 changes the speech coding bit (D) from MSB first to LSB first in units of octets (8 bits).
[0038]
In addition, the bit inversion unit 106 sends the AMR data frame in which the order of the audio encoded bits (D) is inverted to the FT arrangement unit 107.
[0039]
In the present embodiment, the unnecessary bit deletion unit 104, the bit shift unit 105, and the bit inversion unit 106 constitute a processing unit. A more specific frame configuration conversion method by the unnecessary bit deleting unit 104, the bit shift unit 105, and the bit inversion unit 106 will be described later.
[0040]
Based on the configuration of Interface Format 2, the FT placement unit 107 sets the frame type bit (FT) detected by the FT detection / storage unit 103 to a predetermined position on the AMR data frame transmitted from the bit inversion unit 106. In this embodiment, a frame type bit arrangement unit is configured.
[0041]
Specifically, the FT placement unit 107 converts the frame type bit (FT) transferred from the FT detection / storage unit 103 from the fifth bit of Octet 0 of the AMR data frame sent from the bit inversion unit 106. Sequentially arranged on the LSB side, that is, MSB first.
[0042]
Also, the FT placement unit 107 sends the AMR data frame in which the frame type bit (FT) is placed to the data output unit 108.
[0043]
The data output unit 108 outputs the AMR data processed by the unnecessary bit deletion unit 104, the bit shift unit 105, the bit inversion unit 106, and the FT placement unit 107 as AMR data having the Interface Format 2. In the present embodiment, an output unit is configured.
[0044]
Specifically, the data output unit 108 outputs AMR data sent from the FT placement unit 107 to the outside as AMR data having Interface Format 2. Here, FIG. 3 shows a configuration of an AMR data frame having Interface Format 2 output from the data output unit 108.
[0045]
As shown in the figure, AMR data having Interface Format 2 is composed of speech coding bits (D) encoded by AMR and frame type bits (FT) indicating the frame type.
[0046]
Further, compared with the AMR data having the RTP Payload Format shown in FIG. 2, the speech coding bits (D) are sequentially arranged from the LSB to the MSB side for each octet, that is, LSB first.
[0047]
As an output interface provided in the data output unit 108, a LAN card such as 100BASE-TX that outputs AMR data via a communication network can be used. In such a case, the data input unit 101 and the data output unit 108 can of course be configured by the same LAN card.
[0048]
(Frame structure conversion method)
Next, a method for converting the frame configuration of AMR data using the above-described frame configuration conversion apparatus according to the present embodiment will be described.
[0049]
FIG. 4 shows a processing flow of the frame configuration conversion apparatus 100 when converting the AMR data frame from the RTP Payload Format to the Interface Format 2.
[0050]
As shown in the figure, in step S10, the frame configuration conversion apparatus 100 extracts AMR data having the input RTP payload format in units of frames. As described above, the AMR data frame extracted in step S10 has the frame configuration shown in FIG.
[0051]
In step S20, the frame configuration conversion apparatus 100 detects the frame type bit (FT) from the AMR data frame extracted in step S10, and stores the content of the detected frame type bit (FT).
[0052]
Here, FIG. 5 shows the position of the frame type bit (FT) detected in step S20 on the AMR data frame. As shown in the figure, in the RTP Payload Format, the frame type bit (FT) is arranged in the second to fifth bits of Octet 1.
[0053]
In step S30, the frame configuration conversion apparatus 100 deletes the frame type bit (FT) and the additional information bits such as the CMR bit and the confirmation bit (F) from the AMR data frame extracted in step S10. To do.
[0054]
Here, FIG. 6 shows the positions on the AMR data frame of the frame type bits (FT) and additional information bits such as CMR bits and confirmation bits (F) to be deleted in step S30. As shown in the figure, the frame configuration conversion apparatus 100 includes a frame type bit (FT), a CMR bit, and a confirmation bit located in Octet 0 and Octet 1 from the AMR data frame extracted in step S10. An additional information bit such as (F) is deleted.
[0055]
In step S40, the frame configuration conversion apparatus 100 shifts the speech coding bits (D) included in the AMR data frame by 4 bits to the LSB side.
[0056]
In step S50, the frame configuration conversion apparatus 100 deletes the padding bit (P) included in the last octet in which the speech encoded bit (D) is located.
[0057]
Here, FIG. 7A shows the configuration of the AMR data frame before the bit shift processing of the speech encoded bit (D) in step S40 is executed. FIG. 7B shows the structure of the AMR data frame after the processing in steps S40 and S50, that is, the speech encoded bit (D) is shifted by 4 bits to the LSB side and the padding bit (P) is deleted. Show. As shown in FIG. 4B, the 4 bits from the MSB of Octet 0 are in a state where no information is arranged as a result of the bit shift process.
[0058]
In step S60, the frame configuration conversion apparatus 100 inverts the order of speech coding bits (D) in units of octets (8 bits) on the AMR data frame on which the processing in steps S40 and S50 has been performed, that is, The speech coding bit (D) is changed from MSB first to LSB first in octets.
[0059]
Here, FIG. 8A shows the structure of the AMR data frame before the order of the speech coding bits (D) is reversed. FIG. 8B shows the structure of the AMR data frame after the order of the speech coding bits (D) is reversed.
[0060]
For example, D (236) located in the MSB of Octet 30 before inversion is inverted by the processing of Step S60, and is arranged in LSB of Octet 30, that is, placed in the position of D (242) before inversion. . Hereinafter, as indicated by the arrows in FIG. 5A, the positions of D (237) to D (242) are reversed, and the other speech coded bits (D) are similarly ordered in octets. Inverted.
[0061]
In step S70, the frame configuration conversion apparatus 100 arranges the frame type bit (FT) detected in step S20 at a predetermined position on the AMR data frame.
[0062]
Here, FIG. 9 shows the position where the frame type bit (FT) is arranged in step S70. As shown in the figure, the frame configuration conversion apparatus 100 sequentially arranges the frame type bits (FT) from the fifth bit of Octet 0 of the AMR data frame in the LSB direction, that is, MSB first.
[0063]
In step S80, the frame configuration conversion apparatus 100 outputs the AMR data in which the frame type bit (FT) is arranged in step S70 as AMR data having the Interface Format 2.
[0064]
(Action / Effect)
According to the present embodiment, the unnecessary bit deletion unit 104, the bit shift unit 105, and the bit inversion unit 106 have the speech extraction bit (D) generated by the frame extraction unit 102 based on the configuration of Interface Format 2. To change to a predetermined position of the extracted AMR data frame, the FT placement unit 107 places the frame type bit (FT) at a predetermined position on the extracted AMR data frame. It is possible to convert the configuration of a frame including audio encoded bits encoded based on a predetermined audio compression encoding method in which the encoding bit rate can be switched in units of frames.
[0065]
According to the present embodiment, the bit shift unit 105 shifts the position of the speech coding bit (D) on the AMR data frame, and the bit inversion unit 106 has the predetermined number of bits sequentially arranged on the frame. Therefore, the RTP Payload Format can be converted to the Interface Format 2 with a smaller number of processing steps.
[0066]
That is, according to the present embodiment, the contents of processing necessary for conversion from RTP Payload Format to Interface Format 2 are registered in advance in the unnecessary bit deletion unit 104, the bit shift unit 105, and the bit inversion unit 106. Thus, the frame configuration can be converted with a small number of processing steps, and the processing speed related to the frame configuration conversion can be improved.
[0067]
Furthermore, according to the present embodiment, by using the frame configuration conversion apparatus 100, for example, AMR data having RTP Payload Format published on the Internet is used as a mobile telephone terminal used in the third generation mobile communication system. It becomes possible to deliver to.
[0068]
(Example of change)
In the embodiment of the present invention described above, an example in which AMR data having RTP Payload Format is converted to AMR data having Interface Format 2 has been described. However, output from the configuration of a frame input to frame configuration conversion apparatus 100 is described. The present invention can be applied to other frame configurations by pre-registering the contents of the processing for converting into the configuration of the frame to be performed in the unnecessary bit deletion unit 104, the bit shift unit 105, the bit inversion unit 106, and the like. be able to.
[0069]
【The invention's effect】
As described above, according to the present invention, a frame including speech encoded bits encoded by a speech encoding method in which the encoding bit rate can be switched on a frame basis, such as AMR (Adaptive Multi-Rate). In addition, it is possible to provide a frame configuration conversion apparatus and a frame configuration conversion method that can convert the speech encoding scheme into another frame.
[Brief description of the drawings]
FIG. 1 is a diagram showing a logical block configuration of a frame configuration conversion apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a frame configuration of data input to the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram showing a frame configuration of data output from the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating a frame configuration conversion method by the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 5 is a diagram showing an arrangement state of data on a frame in the middle of frame configuration conversion by the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 6 is a diagram showing an arrangement state of data on a frame in the middle of frame configuration conversion by the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 7 is a diagram showing an arrangement state of data on a frame in the middle of frame configuration conversion by the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 8 is a diagram showing an arrangement state of data on a frame in the middle of frame configuration conversion by the frame configuration conversion apparatus according to the embodiment of the present invention.
FIG. 9 is a diagram showing an arrangement state of data on a frame in the middle of frame configuration conversion by the frame configuration conversion apparatus according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Frame structure conversion apparatus, 101 ... Data input part, 102 ... Frame extraction part, 103 ... FT detection / storage part, 104 ... Unnecessary bit deletion part, 105 ... Bit shift part, 106 ... Bit inversion part, 107 ... FT Arrangement unit 108: Data output unit

Claims (5)

An audio encoding bit encoded based on a predetermined audio compression encoding method in which an encoding bit rate can be switched in units of frames, a frame type bit indicating a frame type, and an additional information bit are predetermined A frame configuration conversion device that converts first frames arranged in order into second frames,
A frame extraction unit for extracting the first frame continuously input in units of frames;
A frame type detection unit for detecting the frame type bit from the extracted extracted frame;
Based on the configuration of the second frame, a processing unit that changes the speech encoded bits included in the extracted frame to a predetermined position on the extracted frame;
And a frame type bit arrangement unit that arranges the frame type bits detected by the frame type detection unit at a predetermined position on the extracted frame based on the configuration of the second frame. Frame configuration conversion device. The processor is
Deleting the frame type bit and the additional information bit included in the extracted frame;
2. The frame configuration conversion device according to claim 1, wherein the speech coding bit is changed to the predetermined position by shifting the position of the speech coding bit on the extracted frame. The processing unit changes the speech coding bits to the predetermined position by inverting the order of the speech coding bits of a predetermined number of bits sequentially arranged on the extracted frame. The frame configuration conversion apparatus according to claim 2. 4. The structure of claim 1, wherein as the predetermined audio compression encoding method, a configuration of a frame including the audio encoded bits encoded by Adaptive Multi-Rate is converted. 5. Frame configuration conversion device. An audio encoding bit encoded based on a predetermined audio compression encoding method in which an encoding bit rate can be switched in units of frames, a frame type bit indicating a frame type, and an additional information bit are predetermined A frame configuration conversion method for converting a first frame arranged in order into a second frame,
Extracting the first frames input consecutively in units of frames;
Detecting the frame type bit from the extracted extracted frame;
Based on the configuration of the second frame, the step of changing the speech coding bits included in the extracted frame to a predetermined position on the extracted frame; and the configuration of the second frame And a step of arranging the frame type bit detected by the step of detecting the frame type bit at a predetermined position on the extracted frame.

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