JP2004072360A - Digital voice processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive digital voice processor capable of allowing a digital voice signal inputted to the receiving side to surely coincide with a finally requested emphasis state while surely discriminating whether the format of the inputted digital voice signal is processed by preemphasis processing or not and capable of reducing the cost and the deterioration of characteristics. <P>SOLUTION: The digital voice processor is provided with a preemphasis information discrimination circuit 1 for detecting the preemphasis information of a digital voice signal and outputting an on or off signal as a discrimination signal in accordance with the detected information, a deemphasis filter 2 and an emphasis filter 3, an emphasis on/off setting switch 4 for setting the finally required emphasis ON/OFF state of the digital voice signal and outputting an on or off state signal as an instruction signal in accordance with the set state, and a selector 5 for outputting any one of output signals from filters 2, 3 and the through digital voice signal on the basis of the instruction signal and the discrimination signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital audio processing device for audio processing in television program production, and more particularly, to an audio processing device for automatically controlling digital audio de-emphasis processing and emphasis processing.
[0002]
[Prior art]
When a television program is produced, signals are transmitted between various devices. However, in the case of audio signals, the higher the frequency, the lower the level due to signal transmission. In some cases, the digital audio signal is transmitted after performing pre-emphasis processing for emphasizing the high frequency range of the digital audio signal.
[0003]
The signal subjected to the pre-emphasis processing is usually set to an emphasis OFF state in which the high-frequency side emphasized by the pre-emphasis processing is returned to the final sound in broadcasting. As desired, a de-emphasis process is performed on the signal receiving side. This is because, when the broadcast is performed as it is by the signal subjected to the pre-emphasis processing, the sound becomes uncomfortable floating on the high frequency side, and a large broadcast trouble may occur. It is important to perform processing properly.
[0004]
On the other hand, a signal may be transmitted without performing the pre-emphasis processing, and in this case, a broadcast may be performed using the transmitted signal without performing the de-emphasis processing. become.
[0005]
On the receiving side, whether or not to perform the above-described de-emphasis processing is conventionally determined by a voice technician confirming the state of the audio signal, determining whether or not the signal has been pre-emphasized, and When it is determined that the emphasis processing has been performed, the de-emphasis processing is manually performed. When it is determined that the emphasis processing has not been performed, the audio signal is directly output as it is. In this case, the analog output is recorded again via a device such as a digital mixer.
[0006]
On the other hand, the state of the signal required as the final output on the receiving side is often the emphasis OFF state as described above, but sometimes the signal in the emphasis ON state is required.
[0007]
As described above, even when it is required to set the emphasis ON state as the final output on the receiving side, the form of the input signal includes two types: a signal that has been subjected to pre-emphasis processing and a signal that has not been subjected to the pre-emphasis processing. Because of the type, the audio technician checks the state of the audio signal, determines whether the signal has been pre-emphasized, and if it determines that the signal has been pre-emphasized, If it is determined that the output is not the case, the user is forced to perform an emphasis process manually. More specifically, it is necessary to use a digital mixer having an emphasis function, or to once convert the signal to an analog signal, perform an emphasis process at that time, and then convert the signal to a digital signal again.
[0008]
[Problems to be solved by the invention]
As described above, there are two types of signals input to the receiving side: those subjected to pre-emphasis processing and those not subjected to pre-emphasis processing. The processing work to match the emphasis state required in the above is left to the voice technician's ability and manual work, and the burden on the voice technician becomes enormous. Was likely to occur.
[0009]
The digital mixer for performing the de-emphasis processing and the emphasis processing is an expensive device, and the process of performing the emphasis processing when the digital audio signal output is analog-recorded is performed by first converting the digital audio signal output into an analog signal and performing emphasis processing. Since the digital signal is converted again after the processing, the characteristics are deteriorated.
[0010]
The present invention has been made in view of the above circumstances, and while reliably identifying whether the form of a signal input to the receiving side has been subjected to pre-emphasis processing, the input signal is It is another object of the present invention to provide an inexpensive digital audio processing apparatus that can be surely matched with an finally required emphasis state and that has little deterioration in characteristics.
[0011]
[Means for Solving the Problems]
The digital audio processor of the present invention has a configuration for achieving the above object, detects pre-emphasis information of a digital audio signal input from an external device, and obtains the information and the finally obtained digital audio signal. A desired digital audio output is obtained by automatically controlling ON / OFF of an emphasis filter means and a de-emphasis filter means based on setting information of whether a signal is set to an emphasis ON state or an emphasis OFF state. It is.
[0012]
That is, the digital audio processing device of the present invention
Decoder means for decoding digital audio signals input from an external device;
Pre-emphasis information of the digital audio signal output from the decoder means is detected, and it is determined whether the pre-emphasis information of the digital audio signal is emphasis ON information or emphasis OFF information. Pre-emphasis information discriminating means for outputting an ON signal as the discrimination signal when the pre-emphasis information is discriminated as the emphasis OFF information,
De-emphasis filter means for receiving a digital audio signal from the decoder means and performing de-emphasis processing;
Emphasis filter means for receiving a digital audio signal from the decoder means and performing emphasis processing;
Whether the digital audio signal finally obtained is set to the emphasis ON state or the emphasis OFF state is set. If the digital audio signal is set to the emphasis ON state, the ON state signal is set. An emphasis ON / OFF setting switch means for outputting the OFF state signal as an instruction signal when the digital audio signal is set to the emphasis OFF state;
A determination signal from the pre-emphasis information determination means, an output signal from the de-emphasis filter means, an output signal from the emphasis filter means, an instruction signal from the emphasis ON / OFF setting switch means, When the instruction signal is an OFF state signal and the discrimination signal is an ON signal, an output signal from the de-emphasis filter means is selected and output, and the instruction signal is turned OFF. When the determination signal is an OFF signal in the state signal, and when the instruction signal is the ON state signal and the determination signal is the ON signal, the digital audio signal from the decoder means is selected and output, and the instruction signal is output. If the signal is an ON state signal and the determination signal is an OFF signal, the emphasis A signal selecting means for selecting an output signal from the filter means,
Encoder means for performing encoding processing on the signal output from the signal selection means and outputting the result;
It is characterized by having.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a digital audio processing device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the present embodiment.
[0014]
This device detects pre-emphasis information of a digital audio signal, determines whether the pre-emphasis information of the digital audio signal is emphasis ON information or emphasis OFF information, and the pre-emphasis information is emphasis ON information. When it is determined that the pre-emphasis information is emphasis OFF information, a pre-emphasis information determination circuit 1 that outputs each of the OFF signals as a determination signal, and a digital audio signal are input. A de-emphasis filter 2 for performing de-emphasis processing and an emphasis filter 3 for performing emphasis processing are provided.
[0015]
Further, whether the digital audio signal finally obtained is set to the emphasis ON state or the emphasis OFF state is set. If the digital audio signal is set to the emphasis ON state, the ON state signal is set. When the digital audio signal is set to the emphasis OFF state, an emphasis ON / OFF setting switch 4 for outputting the OFF state signal as an instruction signal is provided.
[0016]
Also, a discrimination signal from the pre-emphasis information discriminating circuit 1, an output signal from the de-emphasis filter 2, an output signal from the emphasis filter 3, an instruction signal from the emphasis ON / OFF setting switch 4, and a through digital voice And a selector 5 which receives a signal and functions so as to output a predetermined input signal based on the states of the instruction signal and the determination signal.
Further, a decoder 6 is arranged at a stage subsequent to the digital audio signal input unit, and an encoder 7 is arranged at a stage preceding the digital audio signal output unit.
[0017]
As described later, in the device of the present embodiment, the input digital signal is configured using the AES / EBU format, and the predetermined area including the pre-emphasis information is subjected to bi-phase modulation. In the decoder 6, the pre-emphasis information can be detected by the pre-emphasis information discriminating circuit 1 by performing a decoding process of performing a bi-phase demodulation on a predetermined area of the AES / EBU audio signal.
[0018]
Also, since the output from the device of this embodiment needs to be in the form of the AES / EBU audio signal when input to this device, the encoder 7 converts the output signal from the selector 5 An encoding process for returning to the AES / EBU audio signal at the time of input to the AES / EBU is performed.
[0019]
Hereinafter, the operation of the device of this embodiment will be described.
As described above, the digital audio signal input from the digital audio input unit is decoded by the decoder 6, and the pre-emphasis information (described later) of the digital audio signal output from the decoder 6 is detected by the pre-emphasis information discriminating circuit 1. Then, it is determined whether the emphasis information is ON or OFF. According to the discrimination result, if the emphasis information is ON, an ON signal is outputted to the selector 5 as a discrimination signal if the emphasis information is OFF.
[0020]
On the other hand, the emphasis ON / OFF setting switch 4 is set by the user. If no processing is performed, the emphasis OFF state is set. If the emphasis ON state is set, the ON state signal is set. If the emphasis OFF state is set, the OFF state signal is set to the selector 5 as an instruction signal. Output to
[0021]
The selector 5 selects and outputs an output signal from the de-emphasis filter 2 when the instruction signal is an OFF state signal and the determination signal is an ON signal, and outputs the determination signal when the instruction signal is an OFF state signal. When the signal is an OFF signal, or when the instruction signal is an ON state signal and the determination signal is an ON signal, a through digital audio signal is selected and output, and the instruction signal is determined by the ON state signal. When the signal is an OFF signal, the output signal from the emphasis filter 3 is selected and output.
[0022]
The signal output from the selector 5 is encoded by the encoder 7, converted into a digital audio signal in the same form as the input signal at the digital audio signal input unit in the AES / EBU format, and output from the digital audio signal output unit.
[0023]
As described above, in the present embodiment, the pre-emphasis information of the input digital audio signal is detected, and the emphasis filter 2 and the emphasis filter 2 are set based on the emphasis ON / OFF setting information indicating the final signal form desired by the user. Since the signal passage switching from the de-emphasis filter 3 is automatically controlled, a desired digital audio output can be stably and reliably obtained.
[0024]
FIG. 2A shows the emphasis characteristics of the digital audio signal that has been subjected to the pre-emphasis processing. As shown in FIG. 2A, the high frequency of the digital audio signal is enhanced by the pre-emphasis processing.
[0025]
FIG. 2B shows the de-emphasis characteristics of the de-emphasis filter 2 described above. As shown in FIG. 2B, the digital audio signal that has passed through the de-emphasis filter 2 has its high frequency band reduced.
[0026]
The emphasis characteristic of the above-mentioned emphasis filter 3 is set so as to have exactly the characteristic shown in FIG. 2A, and the digital audio signal that has passed through this emphasis filter 3 is emphasized in the high frequency range. Will be.
[0027]
Therefore, when the instruction signal is the OFF state signal and the discrimination signal is the ON signal, the output signal from the de-emphasis filter 2 is selected, so that the pre-emphasis processing as shown in FIG. 2A is performed. The digital audio signal is subjected to de-emphasis processing by a de-emphasis filter 2 having characteristics as shown in FIG. 2B, and the digital audio signal returned to a state before the pre-emphasis processing is performed is selected by a selector. 5 will be output.
[0028]
When the instruction signal is an ON state signal and the discrimination signal is an OFF signal, the output signal from the emphasis filter 2 is selected. The emphasis processing is performed by the emphasis filter 3 having the characteristic shown in FIG. 3A, and the digital audio signal in which the high frequency is emphasized is output from the selector 5.
[0029]
When the instruction signal is an OFF state signal and the determination signal is an OFF signal, and when the instruction signal is an ON state signal and the determination signal is an ON signal, a through digital audio signal is selected. , The output signal of the decoder 6 is output from the selector 5 as it is.
[0030]
Naturally, when the de-emphasis processing or the emphasis processing is performed based on the instruction signal or the like, the bits of the pre-emphasis information are reset in the encoder 7.
[0031]
FIG. 3 shows a channel status data format (FIG. 3 (B)) in which pre-emphasis information of a digital audio signal is stored, which is detected by the pre-emphasis information discriminating circuit 1 (FIG. 3B). 3 shows a frame format (FIG. 3A).
[0032]
In this embodiment, a digital audio signal is input in a form using the AES / EBU format described above, and the pre-emphasis information stored in this format is decoded by the decoder 6 to determine the pre-emphasis information. It can be detected in the circuit 1.
[0033]
That is, the AES / EBU format is composed of frames, and the frames are composed of subframes. As shown in FIG. 3A, the subframe format is divided into 32 time slots and numbered from 0 to 31 respectively. The preamble is assigned to slots 0 to 3, the auxiliary sample bits are assigned to slots 4 to 7, and the audio sample words (audio data) are assigned to slots 8 to 27. The slot 28 has a validity bit (V), the slot 29 has a user data bit (U), the slot 30 has a channel status bit (C) 10, and the slot 31 has a channel status bit (C) 10. Each slot is assigned a parity bit (P).
[0034]
The channel status bit (C) 10 allocated to the slot No. 30 transmits information corresponding to each audio signal. The information includes, for example, the word length of the audio channel, the number of audio channels, and the like. , Sampling frequency, and emphasis information of the audio signal, which is the point of the present embodiment, and has a block configuration of 192 bits in total.
[0035]
As shown in FIG. 3B, the emphasis information of the audio signal is allocated to the 2nd to 4th bits (c) 12 of the 0th byte of the channel status data format, and the 2nd to 4th bits are allocated to the emphasis information. , 000 indicates non-emphasis, receiver-side initialization, manual selection, 100 indicates non-emphasis, manual selection not possible, 110 indicates 50/15 microseconds, emphasis cannot be overlaid. Represents that.
[0036]
The pre-emphasis information discriminating circuit 1 detects emphasis information allocated to the second byte to the fourth bit (c) 12 of the 0th byte of the channel status data format, and if it is 000 or 100, it is emphasis OFF information. On the other hand, if it is 110, it is determined that it is emphasis ON information.
[0037]
As described above, it is possible to reliably determine whether or not pre-emphasis processing has been performed on the digital audio signal on the transmission side by detecting this emphasis information. It is possible to easily and reliably match the state.
[0038]
In practice, the data of the 4th to 31st slots is subjected to the above-described bi-phase demodulation process in the decoder 6, and the pre-emphasis information in that state is processed by the pre-emphasis information discriminating circuit 1. Information determination is performed.
[0039]
It should be noted that the digital audio processing device of the present invention is not limited to the above-described embodiment, and other various aspects can be changed. For example, in the above embodiment, the AES / EBU format having 20 audio data slots is used for transmitting the digital audio signal, but various known formats capable of transmitting the emphasis information of the digital audio signal are used. For example, an AES / EBU format having 24 audio data slots can be used.
[0040]
【The invention's effect】
According to the digital audio processing device of the present invention, the pre-emphasis information of the input digital audio signal is detected, and the information and the finally obtained digital audio signal are set to the emphasis ON state or the emphasis OFF state. Based on the setting information, the switching of the passage of the signals from the emphasis filter means and the de-emphasis filter means is automatically controlled, so that the desired digital audio output can be easily and reliably performed without deterioration of the characteristics. Can be obtained.
[0041]
Further, since the apparatus is specialized for emphasis signal processing, accurate processing can be realized at a small size and at low cost.
Further, it is possible to eliminate a broadcast trouble due to an artificial check error of the emphasis information.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a digital audio processing device according to an embodiment of the present invention; FIG. 2 is an emphasis characteristic (A) of a digital audio signal subjected to pre-emphasis processing, and a filter characteristic (B) of a de-emphasis filter; FIG. 3 is a conceptual diagram showing a subframe format (A) and a channel status data format (B) in which pre-emphasis information of a digital audio signal is stored.
1 Pre-emphasis information discriminating circuit 2 De-emphasis filter 3 Emphasis filter 4 Emphasis ON / OFF setting switch 5 Selector 6 Decoder 7 Encoder

Claims (1)

Decoder means for decoding digital audio signals input from an external device;
Pre-emphasis information of the digital audio signal output from the decoder means is detected, and it is determined whether the pre-emphasis information of the digital audio signal is emphasis ON information or emphasis OFF information. Pre-emphasis information discriminating means for outputting an ON signal as the discrimination signal when the pre-emphasis information is discriminated as the emphasis OFF information,
De-emphasis filter means for receiving a digital audio signal from the decoder means and performing de-emphasis processing;
Emphasis filter means for receiving a digital audio signal from the decoder means and performing emphasis processing;
Whether the digital audio signal finally obtained is set to the emphasis ON state or the emphasis OFF state is set. If the digital audio signal is set to the emphasis ON state, the ON state signal is set. An emphasis ON / OFF setting switch means for outputting the OFF state signal as an instruction signal when the digital audio signal is set to the emphasis OFF state;
A determination signal from the pre-emphasis information determination means, an output signal from the de-emphasis filter means, an output signal from the emphasis filter means, an instruction signal from the emphasis ON / OFF setting switch means, When the instruction signal is an OFF state signal and the discrimination signal is an ON signal, an output signal from the de-emphasis filter means is selected and output, and the instruction signal is turned OFF. When the determination signal is an OFF signal in the state signal, and when the instruction signal is the ON state signal and the determination signal is the ON signal, the digital audio signal from the decoder means is selected and output, and the instruction signal is output. If the signal is an ON state signal and the determination signal is an OFF signal, the emphasis A signal selecting means for selecting an output signal from the filter means,
Encoder means for performing encoding processing on the signal output from the signal selection means and outputting the result;
A digital audio processing device comprising:

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