KR20000048615A - Triggering of a Measurement Method for the Quality Assessment of Audio and/or Speech Signals - Google Patents

Abstract

PURPOSE: A triggering measurement process for evaluating the quality of audio and/or speech signal is provided to trigger accurately measurement process for evaluating the quality of audio and/or speech signal. CONSTITUTION: A triggering measurement process for evaluating the quality of audio and/or speech signal is composed of storing digital values of a reference signal underlying at least part of a test signal whose quality is to be evaluated; storing digital values of a test signal at temporarily; determining the degree to which a section of the reference signal values coincides with the test signal values; triggering the measurement process as soon as a predetermined degree of coincidences is exceeded. A triggering device is composed of a first storage device storing the digital values of the reference signal underlying at least part of the test signal whose quality is to be evaluated and a second storage device determining the degree to which a section of the reference signal values coincides with the test signal values and a trigger device a triggering the measurement process as soon as a predetermined degree of coincidences is exceeded.

Description

Triggering of a Measurement Method for the Quality Assessment of Audio and / or Speech Signals}

Modern methods for quality assessment of data reduced audio and speech signals, such as NMR, PAQM or POM, use real audio and speech signals for measurement without using special or synthetically generated measurement signals. This means that the original signal and the signal under evaluation are valid for the measurement for quality evaluation of the audio and speech signals. The original signal is, for example, audio and speech signals to be recorded in a sound studio and transmitted to the receiver by cable connection or wireless telegraph. For economical transmission, the signal must be transmitted as a bit stream to a digital transmitter or after pulse amplitude quadrature modulation, then the signal must be data reduced or coded. The data reduced audio and speech signal, i.e. the bit stream, is modulated with a carrier. In the case of wireless telegraph transmission, this carrier is either launched by an appropriate antenna or received and demodulated by an appropriate antenna. After the bit stream modulated by the appropriate modulation method is demodulated, it resembles the bit stream that was in the transmitter before being modulated without being affected by telegraph. After inverse or inverse decoding, and after digital / analog conversion, the signal recorded in the sound studio can be audible again. In order to detect coding / decoding errors or bit errors caused by telegraphs, the method of evaluating the quality of data-reduced audio and speech signals, for example, compares the audio signal recorded in the sound studio with the audio signal that the receiver can hear. To see the difference. In order to assess the quality of coding, telegraph, and decoding, the reference signal, i.e. the signal recorded in the sound studio, is compared with the test signal, i.e. the signal that the receiver can hear after digital / analog conversion.

As already mentioned, the reference and test signals must be present for the measurement. For current measurements, the delay between these two signals must not exceed 500 ms. This causes no problem in laboratory situations. The reason for this is that quality assessment of the data-reduced audio and speech signals has already been done under laboratory conditions.

However, if field measurements are made, there is no valid reference signal since the signal source, ie the sound studio or the transmit antenna, is actually far from the measurement point.

For evaluating the quality of the audio signal, it is obvious that the reference signal on which the test signal is based is known. The quality assessment does not require the test signal to be continuously compared with the reference signal. Assuming that coding, decoding, and telegraph do not change too much over time, a section of the test signal based on the reference signal can be compared to the reference signal. It is clear that the section of the test signal and the reference signal itself are present in the measuring device.

A radio program audio signal that repeats several times and again in the same form can be called a jingles, for example, because it is a "listener" radio program that contributes to identifying the listener's identity. The program is exported and remains unchanged for a long time. This means that once a rhythm is supplied to the transmitter, it is possible to make quality measurements on audio and speech signals received at different times in different places.

Methods of recognizing melodies are also known. However, this method only recognizes certain music for questionnaire surveys or to monitor the radio transmitter for proper operation. These methods simply recognize whether or not a particular piece of music is playing. Known methods for recognizing rhythms only measure whether they match a particular signal at the end of the rhythm. However, this result is invalid for measuring methods for quality evaluation of audio and speech signals. This is because the measurement period is already over when rhythm is recognized. At the same time, it is impossible to accurately compensate for the delay between the test signal and the reference signal in the known method for rhythm recognition.

The present invention relates to quality assessment of data reduced audio and speech signals, and more particularly to a method and apparatus for triggering a measurement method for quality assessment of audio and speech signals.

Figure 1 illustrates a system device in which the present invention can be implemented.

2 is a schematic block diagram of an apparatus for triggering a measuring method for quality evaluation of audio and speech signals.

It is an object of the present invention to provide accurate triggering of a measurement method for quality assessment of audio and speech signals.

This object is achieved by an apparatus which triggers an accurate triggering method of the measuring method for the quality evaluation of audio and speech signals according to claim 1 and a measuring method for the quality evaluation of the audio and speech signals according to claim 9.

The present invention is based on the fact that one melody before radio transmission is well suited to join the quality assessment of radio signals. The requirement for this is that such rhythm is transmitted during the measurement period. Reference signals, or rhythms before coding and transmission, can be recorded at the transmitter before measurement and then passed to the receiver in various ways, such as modems or magnetic tapes. The rhythm detector according to the present invention continuously compares the received signal with the supplied or stored reference signal. In the continuous comparison, only a small section of the reference signal is compared with the test signal and, to some extent, at least one other section of the reference signal is compared with the section corresponding to the test signal. Since the start of the rhythm has been confirmed, the rhythm or reference signal is played in synchronization with the test signal based on the rhythm. Known technical measurement methods for comparing two signals can be used for quality evaluation of coding, decoding, transmission, and the like.

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

Figure 1 illustrates a system device in which the present invention can be implemented.

2 is a schematic block diagram of an apparatus for triggering a measuring method for quality evaluation of audio and speech signals.

Figure 1 illustrates a schematic system apparatus and apparatus of the present invention that may implement the present invention. Audio source 10, which can be a sound studio or a magnetic tape recorded in the sound studio, is connected to transmitter 12. Transmitter 12 is alternately assigned one transmit antenna 14. Transmitter 12 can perform analog / digital conversion on audio and speech signals from audio source 10. Digital audio and speech signals are also coded at transmitter 12. That is, it is data reduced and modulated into a carrier by an appropriate modulation method, as is known to those skilled in the art, in order to allow coded and modulated audio and speech signals to be emitted to the transmit antenna 14. The coded and modulated audio and speech signals are forwarded to the telegraph 16 to be received by the receive antenna 18. For the person skilled in the art, telegraph 16 is merely representative. The reason for this is that it is possible to implement the 16 as a whole by a cable connection capable of transmitting a digital radio signal or a digital television signal, that is, a multimedia signal.

The coded modulated audio and speech signals received by receive antenna 18 are demodulated and decoded by appropriate means, and are also analog-to-digital converted at receiver 20 and input to rhythm detector 24 via receive line 22. The rhythm detector 24 constitutes an apparatus that triggers a measurement method for the quality evaluation of audio and speech signals and is capable of performing one of a number of measurement methods for the quality evaluation of audio and speech signals known to those skilled in the art via detector connection 26. Can be connected to the measuring device 28 (Fig. 2).

The dotted line from the connection of audio source 10 and transmitter 12 to rhythm detector 24 represents reference signal line 30. The dotted line on reference signal line 30 means that the connection between the audio signal 10 and the rhythm detector 24 is not continuously connected, which, as already mentioned, means that the reference signal, i.e. one melody audio signal before coding and modulation This is because it needs to be detected by the rhythm detector 24 at the moment. Solid lines, on the other hand, indicate an active data connection that is continuously active, at least during the measurement process for quality assessment of the audio signal.

2 shows the rhythm detector 24 in detail. In a preferred embodiment, the rhythm detector 24 may be a personal computer with suitable software and a suitable operating system. The rhythm detector 24 has a storage device 242 for storing a reference signal and a test signal. The test signal is supplied to the digital signal processor card 244 through the test signal input 22. The test signal can be supplied to the measuring device via the first output 26a as required. The second output 26b of the digital signal processor card 244 will supply a reference signal to the measuring device 28 as required. Communication line 26c serves for initial mission and measurement communication between rhythm detector 24 and measurement device 28. The communication line 26c is indicated by a dotted line, similar to the reference signal line 30 of FIG. 1, the communication line 26c is not continuously active but merely informs the start or end of the measurement by the measuring device 28, for example.

According to a preferred embodiment of the present invention, the reference signal transmitted from the audio source 10 to the rhythm detector 24 by an appropriate method was recorded in the storage device 242 which is a hard disk of a standard personal computer. As with additional hardware, a standard personal computer includes a digital signal processor card 244 in the form of a plug-in card that provides an audio test signal 22 and a first output 26a and a second output 26b. It should be pointed out here that, as already seen from the reference numerals, three lines 26a to 26c are contained within the detector connection 26 of FIG. Test signal input 22 of signal processor card 244, which may include several signal processors, is suitably connected to receiver 20, as shown in FIG. The first output 26a and the second output 26b of the digital signal processor card 244 are connected to corresponding inputs of the respective measuring devices 28 for the test signal and the reference signal.

According to a preferred embodiment of the invention, the first section of the value of the reference signal is read from the hard disk 242 into the memory of the digital signal processor card 244 at the beginning of the measurement cycle. This first section is about 1.5 s long. In the digital signal processor card 244, this first section is compared by correlation with a section of the test signal that has been filtered, sampled and then processed in the same way, which test signal is received via the digital signal processor via receive line 22. It was supplied to card 244 or storage 242. This test signal is also filtered and sampled.

It is already known to those skilled in the art that if the receiver 20 carries an analog value, the analog / digital conversion of the test signal performed at the rhythm detector 24 is performed by the appropriate section of the digital signal processor card 244. However, if receiver 20 carries the digital value of the test signal, no analog / digital conversion at rhythm detector 24 is necessary. The correlation between one section of reference signal values and one section of test signal values is done digitally. In a preferred embodiment, the arrangement, which determines the degree to which the correlation, i.e., one section of the reference signal value, matches the test signal value, is executed by software. In addition to this embodiment, the arrangement that determines how one section of the reference signal value matches the test signal value is implemented by hardware using an appropriate shift register and a logic gate that basically performs an exclusive-or function.

As already mentioned, the comparison between one section of the reference signal value and the test signal value to be evaluated is made in sections. In a preferred embodiment of the present invention, one section constituting 512 sample values of the test signal is also named one "frame". If the section of the reference signal value is shorter, the comparison operation will be executed faster, even if the number of false detections of the mutual match between the test signal and the reference signal increases. If the section of the reference signal value used to determine how much matches is selected long, the time required for this operation is greatly increased. On the other hand, the chance of misdetecting a match will be reduced.

If the degree of match or the degree of correlation exceeds a certain value, the method for triggering the measurement method for the quality evaluation of the audio signal is that the value of the test signal compared to the section of the reference signal value is in the original form as the reference signal. Indicates the beginning of rhythm present. If a certain degree of agreement or a certain degree of correlation is excessive, then a measurement method for quality evaluation of the audio signal is triggered. Rhythm detector 24 signals the start of measurement of measuring device 28 via communication line 26c. Here, the measuring device 28 is activated to receive the next section of the reference signal value via the first output 26a of the rhythm detector 24, the corresponding value of the test signal being simultaneously transmitted to the measuring device via the second output 26b of the rhythm detector 24. After triggering the measuring device, the next section of the reference signal is read from the hard disk 242 and passed to the measuring device 28 along with the test signal received via the receiving line 22. The triggering is performed by the measuring device 28. The first output 26a and the second output 26b can be a four channel audio interface or, if a stereo output, can be the left and right channels of the digital audio signal. The left channel corresponding to the output 26b may carry a test signal, and the right channel, that is, the output 26a, may carry a reference signal output from the hard disk 242.

Through the correlation of the section of the test signal value and the corresponding number 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 with the continuous bit stream of the received test signal. A new section of the reference signal value transmitted from the rhythm detector to the measuring device corresponds to the value of the test signal based on the reference signal. After the rhythm detector estimates that the current section of the test signal value included in the correlation evaluation is a section based on the section of the reference signal value used to determine the correlation, the next section of the test signal is passed to the measuring device. do.

Unlike the rhythm detector according to the prior art described above, in one embodiment of the present invention, the entire rhythm from the first section of the reference signal value will be useful for measuring devices for quality evaluation purposes. According to the prior art, the entire rhythm must be played first. This is to allow later to establish that the associated test signal was a rhythm.

Since the correlation of the two signals means that there is a delay between the two, this delay can also be compensated for at the same time. The principle of the method is that the delay is smaller than the section length or frame length. If both signals are output simultaneously by the digital signal processor card, the first section of the reference signal used by the rhythm detector 24 to determine the degree of agreement may also be provided for the measurement method for the quality evaluation of the audio signal.

Note that in the embodiment described so far, the reference signal of the hard disk 242 is stored permanently, and the corresponding test signal is only stored temporarily. After a match between the section of the reference signal value and the test signal value is established, the next received test signal is output directly to the measuring device 28 via the second output 26b without being temporarily stored in the rhythm detector 24. If the first section of the reference signal value is used for the measurement, both signals can be output simultaneously by the digital signal processor card 244. If the digital signal processor card 244 has sufficient main memory, sections of longer test signals may also be stored in the memory and delayed. When a rhythm is recognized, the entire rhythm can be measured, not just the portion of the rhythm passed after recognition.

As already known, this step constitutes an actual measurement step and is performed in the measuring device 28. The sole function of the rhythm detector 24 in this measurement step is to transfer the next section of the reference signal value to the measuring device 28 in synchronization with the received test signal value. It is natural for a person skilled in the art that the numerical value of the section value should be the same in the test step for the test signal and the reference signal. It will also be apparent to those skilled in the art that the reference signal can be composed of sections having as many values as the user desires. However, the reference signal should be divided into at least two sections. One is used by the rhythm detector 24 to match that section of the test signal with the first section of the reference signal. The other section is used by the measuring device 28 together with the corresponding section of the test signal for quality assessment of the test signal. However, as described above, by temporarily storing a section of the longer test signal, the first section of the reference signal and the corresponding section of the test signal can be used for quality evaluation by the measuring device 28.

With the appropriate software in the rhythm detector 24, if a small signal or no signal is output before the start of the measuring step, i.e., the transfer of the test signal and the reference signal via the outputs 26b and 26a, it is possible to As is known, the measuring device 28 can be programmed to automatically recognize the beginning and end of the measuring step. The beginning and the end of the measuring step are transferred from the rhythm detector 24 to the measuring device 28 via transmission line 26c.

The present invention can trigger a measurement method for quality evaluation of audio and speech signals.

Claims (12)

In the method for triggering a measurement method for the quality evaluation of audio and speech signals, Providing a digital value of a reference signal forming a basis for at least a portion of a test signal to be evaluated for quality; At least temporarily storing the digital value of the test signal; Determining a degree of agreement between sections of the reference signal value and the test signal value; A triggering method comprising the steps of triggering a measurement method that exceeds a certain degree of match. The method according to claim 1, When a certain degree of match occurs, the triggering of the measurement method exceeds the specified degree of match so that the test signal value is compared with the next section of the reference signal value at a position where the reference signal value and the test signal value are temporarily correlated. Triggering method characterized in that performed. The method according to claim 1 or 2, A part of a test signal subject to quality evaluation and based on a reference signal is a rhythm that repeats itself at regular or irregular intervals within the test signal. The method of claim 1, wherein The test signal is a decoded digital radio signal and the reference signal is a section of the digital radio signal before being coded, transmitted and decoded. The method according to any of the preceding claims, Triggering method characterized in that the reference signal and the test signal is sampled and filtered before being stored to obtain a digital value of the test signal and the reference signal. The method according to any of the preceding claims, The degree of agreement between the section of the reference signal value and the test signal value is determined by the correlation. The method according to any of the preceding claims, Once a certain degree of match is calculated, the next section of the reference signal value is compared with the corresponding value of the test signal. The method according to claim 7, Before the degree of agreement between the first section value and the reference signal value is calculated, and when a degree of agreement smaller than the specified value is calculated, each signal is generated which indicates the beginning or end of the measurement method for the quality evaluation of the audio and speech signals. Triggering method characterized in that. In the device (24) for triggering a measuring device (28) for performing a measuring method for the quality evaluation of audio and speech signals, A first storage device 242 for storing a digital value of a reference signal forming a basis for at least a portion of a test signal to be evaluated for quality; A second storage device 244 for at least temporarily storing the digital value of the test signal; An apparatus 24 for determining a degree of agreement between sections of the reference signal value and the test signal value; A triggering device, characterized in that it consists of a triggering device 24 for triggering a measurement method performed in the measuring device 28 as soon as a certain degree of agreement is exceeded. The method according to claim 9, Triggering device, characterized in that the first storage device (242) is a hard disk and the second storage device (244) is the main memory of the digital signal processor card. The method according to claim 9 or 10, The device for determining the degree of agreement and the triggering device are in a digital signal processor card 244 having a first output 26a for a reference signal, a second output 26b for a test signal and an input 22 for a test signal. Included, wherein the first and second outputs (26a, 26b) are connected to a measuring device (28) for assessing the quality of the audio signal. The method according to any one of claims 9 to 11, Rhythm detector (24) is characterized in that it has a transmission line (26c) connected with the measuring device (28) to inform the measuring device (28) of the start or end of the measurement.