JP3155283B2 - Method and apparatus for triggering a measurement method for evaluating the quality of audio and / or audio signals - Google Patents

Abstract

A process and device (24) for triggering a measurement process for evaluating the quality of audio and/or speech signals enable field measurements to be carried out to determine the quality of a digital transmission. During a first step, digital values of a reference signal underlying at least part of a test signal whose quality is to be evaluated are stored. Digital values of the test signals are also at least temporarily stored. The degree to which a section of the reference signal values coincides with the test signal values is determined to trigger the measurement process as soon as a predetermined degree of coincidence is exceeded, in order to compare a further section of the reference signal values to the test signal values in the relative position in time of the reference signal and test signal values at the moment when a predetermined degree of coincidence occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a data-reduced audio and / or speech signal.
signals) quality assessment
More particularly, the present invention relates to a method and apparatus for triggering measurements for evaluating the quality of audio and / or audio signals.

Modern methods for quality assessment of data-reduced audio and / or audio signals, such as NMR signals, PAQM signals, POM signals, etc., use specially synthetically generated measurement signals. Rather, pure audio and / or audio signals are used for measurement purposes. This means that the original signal and the signal to be evaluated must be available for the measurement, ie the quality evaluation of the audio and / or audio signal. The original signal is, for example, audio recorded in a sound studio and / or
Or, it is an audio signal that is to be transmitted to a receiver (receiver) via a cable connection or a radio wave path. For economic transmission, the original signal needs to be data reduced or encoded, and then the signal is sent to a digital transmitter as a bit stream. Digital transmitters perform, for example, pulse amplitude quadrature modulation, whereby a data reduced audio and / or audio signal, ie a bit stream, is modulated and placed on a carrier. To go. In the case of radio wave transmission, this carrier is radiated by an appropriate antenna and received and demodulated by an appropriate receiving antenna. After the bit stream modulated by the appropriate modulation method has been demodulated, apart from the effects of the radio path, the demodulated signal is similar to the bit stream that was present in the transmitter prior to modulation. After de-encoding or decoding and digital-to-analog conversion, the signal initially recorded in the sound studio is reproduced as audible sound.

The method for quality assessment of the data-reduced audio signal consists of the audio signal reproduced in the receiver and the recorded audio signal, in order to detect coding / decoding or bit errors introduced by the radio path. The signal, ie, in this example, the audio signal recorded in the sound studio, is compared to recognize any differences therein. A reference signal, a signal recorded in a sound studio, and a test signal, a signal reproduced in a receiver after digital-to-analog conversion, for the purpose of evaluating the quality of the encoding, radio path and decoding. Is compared with

In this specification, "data reduction" is used synonymously with encoding or data compression.

As described above, the measurement requires a reference signal and a test signal. The delay between these two signals
Must be less than 500 milliseconds (ms) in current measurement methods. This is due to laboratory conditions (laboratory
There is no problem in conditions). Therefore, the quality assessment of data-reduced audio and / or audio signals has already been performed in laboratory conditions.

However, if field measurements
, There is usually no reference signal available. This is because the signal source, ie the sound studio or the transmitting antenna, is physically far away from the measuring point.

Obviously, in evaluating the quality of an audio signal, it is necessary to know the reference signal on which the test signal is based.
Since the quality assessment does not require a continuous comparison between the test signal and the reference signal, the test signal based on the reference signal can be considered if the encoding or decoding and transmission do not change much over time. It is also possible to compare only one section of the reference signal with the reference signal. Here, it is clear that the section of the test signal based on these reference signals and the reference signal itself need to be present in the measuring device.

An audio signal of a radio program that is often repeated in the same format is, for example, well-known theme music (jingles) (hereinafter, referred to as “jingles”). It is advertised for a radio program and is very helpful for listeners to recognize that it is a radio program, so it is streamed in a form that does not change over time. Thus, once a jingle is flushed from the transmitter, it is possible to perform quality measurements on the received audio and / or audio signal at many different locations and at many different times.

Methods for recognizing jingles are already known. However, these methods only recognize certain special music, and simply determine whether certain special music has been played, for example, for research purposes or to oversee the correct transmission of radio transmitters. It's just about recognizing.
In these known methods for recognizing jingles, a measure of whether they agree with a particular signal is given only at the very end of the jingle. However, this method is useless for measurement methods for evaluating the quality of audio and / or audio signals. This is because the measurement time has already ended when the jingle is recognized. Furthermore, known methods for recognizing jingles do not allow for accurate correction of the delay between the test signal and the reference signal.

It is an object of the present invention to provide an accurate method of triggering a measurement for evaluating the quality of an audio and / or audio signal.

A method for triggering a measurement for qualifying an audio and / or audio signal according to claim 1 and a method for triggering a measurement for qualifying an audio and / or audio signal according to claim 9. Device.

The invention is based on the fact that jingles before radio transmission are particularly suitable for incorporation in the quality assessment of radio signals. Here, the precondition is that the jingle is transmitted during the measurement period. The reference signal, that is, the jingle before being encoded and transmitted, is recorded at the transmitter side prior to the measurement, and can be delivered to the receiver side by, for example, a modem or a magnetic tape. The jingle detector according to the invention continuously compares the received signal with a pre-given or stored reference signal, but during the comparison compares one small section of the reference signal and the test signal. And when a certain speed of agreement is achieved, the at least one other section of the reference signal is compared with the corresponding section of the test signal. As soon as a match is recognized, the sound of the jingle or reference signal is played simultaneously with the test signal based on the jingle. Because the start of the jingle was recognized. After that, for quality evaluation of encoding, decoding, transmission, etc.,
Any known measurement method that compares two signals can be used.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 shows a system configuration in which the present invention can be implemented, and FIG. 2 shows a schematic block circuit diagram of an apparatus for triggering a measurement for evaluating the quality of an audio and / or audio signal.

FIG. 1 shows a schematic system configuration in which the method and apparatus of the present invention can be implemented. An audio source 10, which may be a sound studio or a magnetic tape or the like recorded there, is connected to a transmitter 12, which comprises a transmitting antenna 14. Transmitter 12 may perform analog-to-digital conversion on audio and / or audio signals coming from audio source 10. Also, digital audio and / or audio signals are encoded in transmitter 12. That is, data is reduced as is known to those skilled in the art. Furthermore, this is also known to those skilled in the art, and is modulated onto a carrier by an appropriate modulation method. As a result, the encoded and modulated audio and / or audio signal is transmitted to the transmitting antenna.
14 can be radiated. The encoded and modulated audio and / or audio signals are transmitted over a radio path (ra
dio path) 16 and received by the receiving antenna 18. It will be apparent that wireless path 16 is merely exemplary for those skilled in the art. Because this path 16
This can be realized by a cable connection that can transmit, for example, a digital radio signal or a digital television signal, that is, a multimedia signal.

The encoded and modulated audio and / or audio signals are received by a receiving antenna 18 and received by a receiver 20.
Are demodulated and decoded by appropriate means, and further subjected to digital / analog conversion. Then, it is sent to the jingle detector 24 through the receiving line 22. The jingle detector 24 constitutes a component of a device for triggering measurements for evaluating the quality of audio and / or audio signals, and a detector connection 2
6 and connected to a measuring device 28 (see FIG. 2).
The measuring device 28 performs one of several measuring methods known to those skilled in the art for evaluating the quality of audio and / or audio signals.

A dotted line coming out of a connection line connecting the audio source 10 and the transmitter 12 to the jingle detector 24 indicates a reference signal line 30. The dashed line of reference signal line 30 symbolically means that this connection between audio source 10 and jingle detector 24 need not be a continuous connection. This is because, as already described above, the reference signal, that is, the audio signal of the jingle before encoding and modulation may be given to the jingle detector 24 once or several times in advance. Conversely, the connections shown in solid lines represent data connections that are continuously active, at least during the measurement process for evaluating the quality of the audio signal.

FIG. 2 shows the jingle detector 24 in detail. Jingle detector 24 may be a personal computer with suitable software and a suitable operating system in the preferred embodiment. The jingle detector 24 includes a storage device 242 for storing the reference signal and for storing the test signal. The test signal is supplied to the digital signal processor card 244 via the test signal input line 22. The test signal is supplied to the measurement device 28 via a first output line 26a as needed, while the reference signal is supplied to the measurement device 28 via a second output line 26b of a digital signal processor card 244 as needed. Is done. Communication line (communic
The ation line 26c is used for communication between the jingle detector 24 and the measuring device 28 regarding initialization tasks and measurement. The fact that this communication line 26c is shown in dashed lines, like the reference signal line 30 in FIG. 1, does not mean that this communication line 30 is continuously active, but merely for example the measurement by the measuring device 28. It indicates that only the start or end may be signaled.

In a preferred embodiment of the method according to the invention, the reference signal previously sent in an appropriate manner from the audio source 10 to the jingle detector 24 is stored in a storage device 242 such as a standard personal computer hard disk. It is remembered. This standard personal computer comprises, as additional hardware, a digital signal processor card 244 in the form of a plug-in card, which comprises an audio test signal input line 22 and a first output line 26a. A second output line 26b. Note that the three lines 26a-2
6c are included in the detection circuit 26 shown in FIG. 1, as can be seen from the reference numbers assigned to them. The test signal input line 22 of the signal processor card 244, which may include a plurality of signal processors, is connected to the receiver 20, as can be seen in FIG. The first output line 26a and the second output line 26b of the digital signal processor card 244
The corresponding inputs of the measuring instrument 28 are connected to the test signal input and the reference signal input, respectively.

According to a preferred embodiment of the method according to the invention, at the start of the measurement cycle, a first section of the values of the reference signal is read from the hard disk 242 and entered into the memory of the digital signal processor card 244.
This first section may be about 1.5 seconds long.
In the digital signal processor card 244, the first section of the reference signal value is filtered, undersampled, and then cross-correlated with a similarly processed section of the test signal. (Cross corelation) comparison is performed. This test signal has been supplied to the digital signal processor card 244 or the storage device 242 via the receiving line 22. The test signal is also filtered and sampled.

It is obvious to those skilled in the art that if the receiver
If 20 communicates an analog value, an analog-to-digital conversion of the test signal can be performed at the appropriate portion of the digital signal processor card 244 in the jingle detector 24. However, if the receiver 20 communicates the digital value of the test signal, no analog / digital conversion in the jingle detector 24 is necessary. It is also clear that,
The cross-correlation performed between the section of the reference signal value and the section of the test signal value is performed digitally. In the preferred embodiment, the algorithm for cross-correlation, i.e., determining the degree of match between the section of the reference signal value and the section of the test signal value, is performed by software. In another embodiment, to determine the degree of coincidence between the section of the reference signal value and the section of the test signal value, an exclusive OR function (exclusiv) is performed.
The appropriate shift register (sh
Hardware with ift registers and logic gates can also be used.

As mentioned above, the comparison between the section of the reference signal value and the section of the test signal value to be evaluated is performed on a section basis. In a preferred embodiment of the invention, a section consists of 512 sample values of the test signal, and this section is also called a "frame". If the section of the reference signal value is shorter, the comparison operation is performed faster. However, in this case, the possibility that an error occurs in the detection of a match between the test signal and the reference signal will increase. If the section of the reference signal value used to determine the degree of coincidence becomes longer, the time required for this comparison work becomes longer. However, in this case the likelihood of error in the match detection will be reduced.

If the degree of coincidence or cross-correlation exceeds a certain value,
Due to the way of triggering the measurement for qualifying the audio signal, the test signal value compared to the section of the reference signal value will represent the start of the jingle which is present as the reference signal in the original form. If a certain degree of agreement or a certain degree of cross-correlation is exceeded, a measurement for evaluating the quality of the audio signal is triggered. The jingle detector 24 notifies the start of measurement to the measuring device 28 via the communication line 26c. This causes the meter 28 to enter an active state, receiving a further section of the reference signal value via the first output line 26a of the jingle detector 24, and at about the same time determining the value of the corresponding test signal.
24 via a second output line 26b. After the measurement performed by the meter 28 is triggered, a further section of the reference signal is read from the hard disk 242 and output to the meter 28 along with the test signal received via the receive line 22. The first output line 26a and the second output line 26b may be a four-channel audio interface or, for stereo output, the left and right channels of a digital audio signal. In this case, the left channel can correspond to the output line 26b transmitting the test signal, while the right channel can correspond to the output line 26a transmitting the reference signal from the hard disk 242.

Through cross-correlation of the sections of the test signal value with the corresponding number of values of the reference signal value, the delay between the reference signal and the test signal is automatically eliminated. This is because the section of the reference signal value is compared to a continuous bit stream of the received test signal. The new section of the reference signal value transmitted from the jingle detector to the measuring device corresponds to the value of the test signal based on the reference signal. Because the jingle detector determines that the section of the test signal value just used to evaluate the cross-correlation is based on the section of the reference signal value used to determine the cross-correlation, This is because the transmission of a further section of the test signal to the instrument starts.

Unlike the jingle detector according to the prior art described above,
In an embodiment of the invention, the entire jingle, except for the first section of the reference signal value, would be applicable to the measuring instrument for quality assessment. In the prior art, the entire jingle would have to be played first to subsequently determine that the test signal involved was the jingle.

Given that the cross-correlation of two signals means that the delay between them is known, in the method of the present invention if the principle that the delay is shorter than the length of one section or the length of a frame, This delay can also be corrected at the same time. If both the reference signal and the test signal are output simultaneously by the digital signal processor card, the first section of the reference signal used to determine the match by the jingle detector 24 also evaluates the quality of the audio signal. Can be used for measurements to

In the embodiment described so far, the reference signal stored on the hard disk 242 is permanently stored, while the test signal for the cross-correlation is only temporarily stored. After a match between the reference signal value and the test signal value sections is confirmed, the further received value of the test signal is not temporarily stored in the jingle detector 24 and the second output line 26b is Output directly to the measuring instrument 28 via the If the first section of the reference signal value is also to be used for the measurement, it is possible if both the reference signal and the test signal are output simultaneously by the digital signal processor card 244. If the digital signal processor card 244 has enough main memory, longer sections of the test signal can also be stored and delayed in the memory. When the jingle is confirmed, the entire jingle can be measured, not just the part transmitted after confirmation.

As mentioned above, this phase constitutes the actual measuring phase and is performed in the measuring instrument 28. The only function performed by the jingle detector 24 in this measurement stage is
A further section of the reference signal value is transmitted to the measuring device 28 in synchronization with the received test signal value.
As will be apparent to those skilled in the art, the number of values in a section must be the same during the test phase of the test signal and the reference signal. Further, as will be apparent to those skilled in the art, the reference signal may be composed of any number of sections as desired by the user. However, the reference signal must be distinguished into at least two or more sections. The one section is used by the jingle detector 24 to verify the match between the first section of the reference signal and the corresponding section of the test signal. The other section, together with the corresponding section of the test signal, is used by the meter 28 for quality evaluation of the test signal. However, as described above, by temporarily storing a long section of the test signal, the first section of the reference signal and the corresponding section of the test signal can be used for quality evaluation in the meter 28. .

If the signal output before and after the measurement step, i.e. the step of transmitting the test signal and the reference signal via the output lines 26b, 26a, is zero or very small, the jingle detector 24 With the appropriate software, the measuring instrument 28 can be programmed in a manner known to those skilled in the art so that the start and end of the measuring phase are automatically recognized. The start and end of the measurement stage are transmitted from the jingle detector 24 to the measuring device 28 via the communication line 26c.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiel Michael Germany, D-90425 Nuremberg, Staffelsteiner Strasse No. 38 (72) Inventor Gerhuiser Heinz Germany, D-91344 Weischenfeld, Saugendorf No. 17 (72 Inventor Schmidtmer Christian, Germany, D-90768 Fuls Ats Enhofer Strasse, 49th b. Hei 1-162248 (JP, A) JP-A-60-116258 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 29/00 G10L 11/00

Claims (12)

(57) [Claims] 1. A method for triggering a measurement for qualifying an audio and / or audio signal, the method comprising: providing a digital value of a reference signal which is at least part of the test signal to be qualitatively evaluated. And at least temporarily storing a digital value of the test signal, wherein the digital value of the test signal is obtained without performing analog / digital conversion when the test signal is a digital signal; When the test signal is an analog signal, it is obtained by performing analog / digital conversion, and the degree of coincidence between one section of the digital value of the reference signal and the stored digital value of the test signal Determining the digital value of the reference signal and the stored digital value of the test signal. Triggering the measurement as soon as the measured value exceeds a predetermined degree of coincidence. 2. The triggering method according to claim 1, wherein the trigger of the measurement is executed as soon as the predetermined coincidence is exceeded, and the digital value of the reference signal and the digital signal when the predetermined coincidence occurs. A trigger method, comprising: comparing the next section of the digital value of the reference signal at a position temporally opposite to the digital value of the test signal with the digital value of the test signal. 3. The triggering method according to claim 1, wherein a part of the test signal to be evaluated for quality and based on the reference signal is regular or irregular in the test signal. A trigger method comprising a jingle that is repeated at regular intervals. 4. The triggering method according to claim 1, wherein the test signal is a digital radio signal after being encoded, transmitted, and decoded, and the reference signal is an encoded, transmitted signal. One of the digital radio signals before being transmitted and decoded
A trigger method characterized by being a section. 5. The triggering method according to claim 1, wherein the reference signal and the test signal are sampled and filtered to obtain their digital values before being stored. A trigger method characterized by being performed. 6. The triggering method according to claim 1, wherein a degree of coincidence between a section of the digital value of the reference signal and a stored digital value of the test signal is different from each other. A trigger method characterized by being determined by correlation. 7. The triggering method according to claim 1, wherein when a predetermined degree of coincidence occurs, one or more next sections of the digital value of the reference signal correspond to the test. A triggering method, which is compared with a stored digital value of a signal. 8. The triggering method according to claim 7, wherein a predetermined degree of coincidence occurs between a first section of the digital value of the reference signal and a corresponding stored digital value of the test signal. Generating respective signals indicating the start or end of a measurement for evaluating the quality of the audio and / or audio signal at a time and thereafter when a lower match than the match first occurs. And how to trigger. 9. Apparatus (24) for triggering a measuring instrument (28) for performing a measurement for evaluating the quality of an audio and / or audio signal, the reference being at least part of the test signal to be evaluated. First storage means (242) for storing the digital value of the reference signal, and second storage means (244) for at least temporarily storing the digital value of the test signal. Means for determining the degree of coincidence between the section of values and the stored digital value of the test signal; and as soon as the predetermined degree of coincidence exceeds the measurement performed in the measuring instrument (28). A trigger device comprising: trigger means for triggering. 10. The trigger device (24) according to claim 9, wherein the first storage means (242) is a hard disk, and the second storage means (244) is a main memory of a digital signal processor card. A trigger device. 11. The trigger device (24) according to claim 9 or 10, wherein said means for judging the degree of coincidence and said trigger means comprise: an input line (22) for said test signal; A digital signal processor card (244) having a first output line for signal (26a) and a second output line for test signal (26b), said first and second output lines (26a, 26b); ) Is a trigger device, which is connected to a measuring device (28) for evaluating the quality of the audio signal. 12. The trigger device (24) according to any of claims 9 to 11, wherein the trigger device (24) is repeated at regular or irregular intervals in the test signal. The trigger device (24) transmits the start or end of the measurement to the measuring device (28).
A trigger device having a communication line (26c) connected to the trigger device.