JPH04261234A - Method and device for inserting identification signal to digital audio signal - Google Patents

Abstract

PURPOSE:To easily detect a signal source in a digital audio signal channel by inserting an audio sample data and an identification signal to the digital audio signal. CONSTITUTION:A digital audio signal received by an insertion circuit 50 is fed to a format decoding circuit 54 via an input connector 52, in which an identification signal of a narrow band width in the digital audio signal is separated and also an incoming identification audio signal is eliminated. A substituted signal is inputted to a microphone 44 and stored in a memory 20 and a format coding circuit 16 inserts a new audio signal in a proper timing. The incoming identification audio signal is stored in the memory 20 through signal path from the circuit 54 to a selector 18. Even without the circuit 54, the digital audio signal is fed directly to the circuit 16 via the connector 52. Thus, the signal source of the audio signal channel is easily detected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inserting an identification signal into a digital audio signal. This identification signal can be used to detect the signal source of the audio signal channel in multi-channel signal processing.

0002

BACKGROUND OF THE INVENTION When mixing digital audio signals, for example in digital audio studios for recording or broadcasting, it is common to use a number of microphones or other sound generating or storing devices. It may be difficult for an operator of an audio mixing control device to accurately identify the source of a particular signal among many signals. This problem arises when the signal source is in a remote location, such as in outdoor broadcasting, when the signal source is one of many microphones used by entertainers on stage, or when the signal source is a multichannel digital This is especially serious when it is one of many channels in an audio recording device. Various methods have been tried to solve this problem. This included color-coding the microphones (or other signal sources) and their connecting lines, as well as providing the same color-coding in the audio mixing controller. However, this method requires precise interconnection of all corresponding conductors,
The drawback is that this is not always guaranteed. especially,
This is the case when a long cable contains multiple conductors.

0003

SUMMARY OF THE INVENTION It is therefore an object of the present invention to facilitate the detection of the signal source of an audio signal channel in multichannel signal processing.

0004

[Means for Solving the Problems] A method according to the present invention includes audio sample data and an identification signal in a digital audio signal, and the format of the digital audio signal is not restricted (to a specific format) and has free bits. Then, the digitized identification voice signal is repeatedly inserted into the free bits of the digital voice signal.

The apparatus according to the present invention inserts an identification signal into a digital audio signal, and includes means for synthesizing the format of the digital audio signal into a format including free bits, and means for creating a digitalized identification audio signal. , comprising means for storing the digitized identification audio signal and means for repeatedly inserting the stored identification audio signal into free bits of the digital audio signal.

[0006]

[Operation] In the present invention, digital audio signal formats such as those proposed by AES (Audio Engineering Association) and EBU (European Broadcasting Union) can be used, and the format includes narrow (low) band identification audio signals. There is enough capacity to insert the width. The identification audio signal can be generated by speaking directly into a microphone, the signal is digitized and stored in memory, and then read from memory and repeated continuously to identify the source of the sound. The identification audio signal is separate from the audio sample data that is actually needed within the signal format, so it does not interfere with the audio sample data. However, if necessary,
It can be played back and listened to using an appropriate format decoding circuit. Audible identification signals are much faster to generate than digital lexical signals (generally taking about the same amount of time as it takes to speak the desired message), and require at most one small microphone and one piece of equipment rather than a computer-style keyboard. This signal identification method is very suitable for use in practical operations where speed is important, since it is not bulky at all and only includes the above switch (with appropriate circuitry).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically explained below with reference to the drawings. FIG. 1 is a diagram showing an example of the format of a digital audio signal. Before explaining the embodiments of the present invention, AES (
Speech Technology Association) Recommendation of the Actual Linear Representation of Digital Speech Technology Serial Transmission Format for Digital Speech Data,
AES3-1985 (ANS1 S4,40-198
The digital audio signal format according to 5) will be briefly described. The digital audio signal is divided into a plurality of frames, each frame consisting of two consecutive subframes, each subframe having audio sample data transmitted in one sample period for each of two channels. The audio sample data in the two channels can constitute a stereo signal or can be used for other purposes.

The format of each subframe is shown in FIG. 1, and each subframe has a length of 32 time slots. The first four time slots contain synchronization and identification pre-signals having one of a fixed number of types. These formats are
The start of a data block consisting of 192 signal source sample periods is identified as well as the channel of the audio signal. The 24 time slots following the prefix are occupied by audio sample data transmitted most significant bit (MSB) last. If the full 24 bits are not needed for the audio sample, the first 4 bits can be used as auxiliary sample data. The remaining 20-bit word is reserved for the actual audio sample data. The four auxiliary sample data bits can be used to accommodate the identification audio signal in a narrow bandwidth.

Following the 24 audio sample data time slots are an audio sample valid bit (ASVB), a user data bit (UDB), an audio channel status bit (ACSB), and a parity bit (PB). Since these are not related to the present invention, they will not be discussed further. However, the audio channel status bit is excluded. This bit spans a 192-bit data block and provides various data regarding the voice channel status. This determines whether all 24 bits are needed for the audio sample data or, as required by the present invention, only 20 bits are used for the audio sample data and the remaining 4 auxiliary sample data bits are used for the identifying audio signal. Contains instructions on whether to use it.

FIG. 2 is a block diagram showing a digital microphone circuit including means for generating an identification audio signal as a first embodiment of the present invention. In the figure, 10 indicates the digital microphone circuit as a whole. A microphone 12 that generates an analog signal is connected to an analog-to-digital (A/D) converter 14. A/D converter 1
The output of 4 is sent to a format encoding circuit 1 in order to arrange the digitized audio signal from the microphone 12 into a suitable format as shown in FIG.
Connect to 6. The output of the A/D converter 14 is also connected via a selector 18 to a memory 20 and via another selector 22 to an auxiliary input of a format encoding circuit 16. The selectors 18 and 22 are the "identification" switch 2, respectively.
4 and "direct" switch 26. There is also an identification burst generator 28 controlled by format encoding circuit 16 and a direct burst generator 30 controlled by direct switch 26. The outputs of these generators 28, 30 and memory 20 are also fed to auxiliary inputs of format encoding circuit 16.

The circuit of FIG. 2 has the function of not only generating a conventional digitized audio signal as a digital microphone, but also generating an identification audio signal on the same channel. The identification audio signal is generated by speaking directly into the microphone and then repeated continuously. This allows identification of microphones and channels in the field.

As described above, a required audio signal is supplied from the microphone 12, digitized by the A/D converter 14, and formatted by the format encoding circuit 16. When attempting to use the AES format as shown in Figure 1, all audio sample data is transmitted in a 20-bit location reserved for that purpose, so the 4-bit auxiliary sample data location is used for narrow-bandwidth identification audio. Can be used for signals. To insert an identification audio signal, the identification switch 24 is operated to blow the desired message (such as "violin left" or "lead vocal") into the microphone 12. Message length is typically several seconds. When a message is injected, the corresponding digital signal is sent via selector 18 (activated by identification switch 24) to memory 20, where it is stored and ready for repeated insertion into the digital audio signal. Immediately after the message ends, the identification switch 24
to release.

Immediately before each repetition of the identification voice signal message, a zero value sample (
Generate an identification burst signal (equivalent to digitally generated silence). This identification burst signal allows
A device for providing an identification audio signal to an operator is capable of detecting the start of an identification audio signal message. The identification burst signal is provided by an identification burst generator 28 which is responsive to an "end of message" signal from format encoding circuit 16. Thus, once an identification voice signal message is stored in memory 20, a periodically repeated identification burst signal from said generator 28 is followed by memory 20.
The identification audio signal message stored therein is applied to the auxiliary input of the format encoding circuit 16, where the repeat signal message described above is inserted with a narrow bandwidth into the 4-bit auxiliary sample data location shown in FIG. Once the identified audio signal message is stored, the format encoding circuit 16 can process the required audio sample data in the conventional manner to synthesize the format.

[0014] At any time during transmission, the repeating identification voice signal message may be replaced by a non-repeating (direct) message of any duration. Such direct messages are typically sent in approximately 50 ms by a direct switch 26 that operates a selector 22 and a direct burst generator 30.
For example, a direct burst signal of all 1's can be followed by a direct message. The direct message is applied to the auxiliary input of the format encoding circuit 16 following the direct burst signal and inserted at the location of the auxiliary sample data mentioned above. When the direct message ends, digital microphone circuit 10 resumes repeating the identification voice signal (each after an identification burst).

If it is necessary to change the identification voice signal message generated by the circuit 10, the message stored in the memory 20 can be easily superimposed by simply operating the identification switch 24 and blowing a new message into the microphone 12. can write.

[0016] According to the technique described above, therefore, a repeating identifying voice signal is present in the same channel as the desired voice data, and this identifying signal (which can be temporarily replaced by a direct message) is present in the same channel as the desired voice data. ) can be easily decoded and give accurate information about the audio channel being received and processed. Identification audio signal messages are generally short, on the order of two seconds, to allow the operator to quickly examine many channels and to reduce memory capacity.

An important advantage of this technique is that audible identification signals can be created and entered much faster than digital lexical signals that must be entered in a tedious manner such as typing on a keyboard (typically taking about 2 seconds). ). Also, the audible identification signal does not require bulky equipment to create. No keyboard required, just one small microphone and a switch. The microphone used for this purpose may be the same as that actually used for the audio channel, as described above, if appropriate. For these reasons,
Audible identification signals are suitable for use in practical situations where speed of operation is a priority. Furthermore, as another advantage, the audible identification signal can be examined using only the normally available audio monitoring equipment, and typically requires no additional readout such as a display outside of the control panel, which is already very elaborate and complex in layout. No need to add equipment.

The circuit shown in FIG. 2 was a digital microphone circuit in which the identification audio signal generation means could be incorporated into the microphone device itself. FIG. 3 shows a second embodiment of the present invention in which an analogue signal including identification audio signal insertion means is used.
FIG. 2 is a block diagram showing a digital (A/D) conversion circuit. In some situations, an A/D is used to input an analog microphone (or other signal source) signal into a digital audio device (or other digital audio device such as a synthesizer, music device, video tape recorder, etc.). A conversion circuit may also be provided. In such cases a different embodiment as shown in FIG. 3 can be used. In this figure, many parts are similar to those shown in FIG. 2, and therefore their explanations will be omitted. A/D conversion circuit 40 has a socket 42 for input analog signals, which socket is connected to A/D converter 14 . Small microphone 44 mounted on the panel
is sent to the memory 20 for insertion of the identification audio signal via another A/D converter 46 and the selector 18, and also to the selector 2.
2 to the memory for direct message signal insertion.

The operation of the circuit of FIG. 3 is similar to that of FIG. 2, except that in the latter the identification voice signal and the direct message signal are derived by blowing into the microphone 44.
The former differs in that the analog audio signal is directly supplied to the socket 42. If desired, the circuits of FIGS. 2 and 3 can be combined by suitable switches so that the analog audio signal can be supplied from an external source or derived directly from the microphone.

FIG. 4 is a block diagram showing a digital audio signal insertion circuit as a third embodiment of the present invention. In the figure, an identification audio signal may be added to the digital audio signal received by insertion circuit 50, or the current identification audio signal may be replaced with a different signal. A digital audio signal, such as the AES format signal shown in FIG. 1, is applied to format decoding circuit 54 via input socket 52. Format decoding circuit 54 is capable of separating the 4-bit auxiliary data portion of the signal, or in other words, the narrow bandwidth identification audio signal, and can also remove the incoming identification audio signal, if desired. An alternative identification audio signal can be input at microphone 44 and the message stored in memory 20. Thereafter, the format encoding circuit 16 inserts a new identification audio signal at an appropriate timing. The signal path from format decoding circuit 54 to selector 18 allows the incoming identification audio signal to be stored in memory 20 instead of using microphone 44. Format decoding circuit 54 may not be necessary in some situations, in which case the digital audio signal is provided directly from input connector 52 to format encoding circuit 16. Multi-channel digital audio signals can be processed with a circuit similar to that of FIG. 4 with the addition of a channel selection switch.

[0021] The identification audio signal can also be used for identification in a storage device, such as a recording media device. For example, the tracks of a digital tape recorder that records on multiple tracks can be created by adding an identifying audio signal to the recorded signal from the beginning, or by adding an identifying audio signal from a preprogrammed memory within the tape recorder. Identification is possible.

When the recorder is stopped or operating in a reciprocating, slowing, or winding mode, tracks can be identified efficiently by, for example, replaying the most recent signal read from the tape. An identification audio signal should be constantly available. FIG. 5 shows the fourth embodiment of the present invention.
1 is a block diagram illustrating a portion of an exemplary multi-track digital tape recorder capable of handling identified audio signals; FIG. To provide the above functionality, as shown in Figure 5,
A memory 60 is provided in the playback channel of the recorder. The memory 60 stores the signals recorded on the tape during the playback mode and operates to repeat the identifying audio signal during other modes. Thus, the operator can identify what recording he is trying to play without disturbing the cue position on the tape.

In FIG. 5, a plurality of multi-track playback heads 62 are connected to a playback circuit 64 capable of playing back one or more of the recorded signals picked up by the heads 62. In FIG. The mode setting circuit 66 includes a reproduction circuit 64, a memory 60,
A playback mode signal is supplied to the selector 68. Selector 6
8 connects the memory 60 and the format encoding circuit 70 to each other. In the normal reproduction mode, the selected reproduction signal is directly supplied to the format encoding circuit 70, synthesized into a format including the first identified audio signal, and supplied to the output terminal. At the same time, the memory 60 is constantly overwritten with identification audio signals and stores the most recently received identification audio signal. The playback mode changes, such as stopping, slowing down,
When the reciprocating or winding mode is entered, the mode setting circuit 66 activates the selector 68 to repeatedly read out the stored identification audio signal from the memory 60 to the format encoding circuit 70, and also prevents overwriting of the memory 60 in those modes. To prevent. Therefore, even if the identifying audio signal is not immediately available by direct playback from tape, it can be obtained repeatedly from memory 60.

When recording identification audio signals, each identification message may be stretched to twice or more of its normal length on the recording medium and recorded at a low rate. In this way, the space required within each sample data of the digital audio signal can be further reduced. If this is done instead of providing the identification audio signal directly with the main digital audio signal (as described above with respect to the normal playback mode), the identification audio signal is first reconstructed in memory 60 and then reconfigured at the correct data rate required. The data will be supplied from the memory.

When a digital audio signal that includes an identification audio signal is provided to a digital audio controller (eg, as generated by any of the circuits of FIGS. 2-5), the identification audio signal is generally similar to the primary audio signal itself. passes through the control device. Suitable means, such as a push-button switch, may be provided so that the operator can listen to the identifying audio signal at the location where he or she wishes to identify the signal source during the processing sequence. Figure 6
1 is a block diagram illustrating a portion of a digital audio control device that may monitor identification audio signals. FIG. This figure shows one channel portion of such a digital audio control device. The digital audio signal for that channel is supplied to an identification signal extraction circuit 80. The extracted identification audio signal is sent to a selector 82 operated by an identification monitor push button switch 84.
is sent to the audio monitor circuit 86 via. The audio monitor circuit 86 also receives the main audio signal, suitably mixed or otherwise processed, for monitoring by a speaker 88 or headphones. The extracted identification audio signal is also sent directly to the burst and signal extraction circuit 90, the output of which is sent to the audio monitor circuit 86. The main audio signal is sent from the identification signal extraction circuit 80 to the audio processing circuit 92, where necessary audio signal processing such as level setting and timbre control is performed before mixing with other channels.

In operation, the main audio signal is sent to audio processing circuit 92 and undergoes normal signal processing. However, if the operator wishes to identify the signal source, pressing the identification pushbutton switch 84 activates the selector 82 and sends an identification audio signal to the audio monitoring circuit 86, allowing auditory monitoring. If the identification voice signal is replaced by a direct message signal following a direct burst, the direct burst and signal extraction circuit 9
0 is activated to detect a direct burst (eg, a continuous signal of all ones as described above) and provide a direct message signal to the audio monitor circuit 86. Direct message signals, as opposed to identification voice signals, appear on the audible monitor automatically rather than at the request of an operator. Thereby, a message different from normal times, such as a malfunction warning, can be extremely efficiently conveyed to the operator of the digital voice control device.

In some cases, it may be desired to retain the identification audio signal within the main audio signal and pass it to the audio processing circuit 92. Furthermore, before mixing a plurality of different audio signals, when sending the main audio signal to the audio processing circuit 92, the identification signal extraction circuit 80 may remove the identification audio signal. After processing and mixing, it may be desired to insert a new identification audio signal, and for this purpose a circuit similar to that of FIG. 4 may be included.

The identification signal extraction circuit 80 preferably includes means for detecting an identification burst signal (eg, a continuous signal of all "0"s as described above). This allows the identification audio signal to be removed or replaced synchronously. It can also be used to signal the end of a direct message signal.

As an extension of the circuit shown in FIG.
2 can be replaced with a memory and selector device similar to the memory 60 and selector 68 of FIG. 5, and the identification audio signal and the memory can be continuously recorded in the memory. Then, by operating the switch 84, the user can reproduce the most recently stored identification voice signal from the memory. When the user operates switch 84 in this manner, the identification audio signal will be provided from the beginning of the digital audio signal (as it is read from memory) rather than from the current position in the digital audio signal. In this way, the user does not have to wait for the beginning of the identification message, and can therefore quickly identify the message. Such a device can be used whenever the user has the means to examine the identifying audio signal.

Although the circuit of FIG. 6 has been described in connection with a multi-channel digital audio control system, the circuit (and variations thereof described above) are equally applicable to other applications. For example, apart from the audio processing circuit 92, it may be desirable to incorporate the circuit into a small portable module with input and output sockets that listens to an identified audio signal in order to combine a particular signal source with other types of audio equipment. Can be used by sound engineers.

Although the above embodiments have been described in relation to the AES format shown in FIG. 1, other digital audio signal formats may also be used with sufficient capacity to transmit narrow bandwidth identification audio signals. The present invention can be applied as long as there is a margin.

[0032]

As explained above, the identified audio signal technique described above provides an extremely efficient and easy to implement means for marking digital audio signals with easy-to-decode and clearly indicating identity. It is something. The technique also has the advantage of requiring few additions to existing hardware and can be used with existing equipment with little or no modification.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the format of a digital audio signal (subframe).

FIG. 2 is a block diagram showing a first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing an example of a digital audio control device that can be used in the present invention.

[Explanation of symbols]

12, 14, 44, 46 Means for creating digital identification audio signal 20, 60 Means for storing digital identification audio signal 16, 70 Format synthesis means 18, 2
0, 24, 28, 60, 66, 68 Means for repeatedly inserting identification audio signals

Claims (2)

[Claims] 1. A method for including audio sample data and an identification signal in a digital audio signal, wherein the format of the digital audio signal has free bits that are not constrained, and the digital audio signal is digitized into free bits. 1. A method for inserting an identification signal into a digital audio signal, the method comprising repeatedly inserting an identification audio signal that has been identified. 2. Means for synthesizing the format of a digital audio signal into a format with unrestricted free bits, means for creating a digitized identification audio signal, and means for storing the digitized identification audio signal; and means for repeatedly inserting the stored identification audio signal into free bits of the digital audio signal.