• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention proposes a method of automatic control of transient compensation for audio normalizers characterized by several general modules such as the pseudo-envelope detector, the instantaneous value comparator and average value of the pseudo-envelope, a delay element and a gain control that modulates the sound level of the resulting signal by applying a gain opposite to the detected instantaneous noise level variation. This procedure allows to mitigate sudden changes in the sound level automatically, which is particularly useful and interesting in applications for the control of signals in the field of broadcasting. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2684315A1
    申请号:ES201730582
    申请日:2017-03-31
    公开日:2018-10-02
    发明作者:Rebeca SANZ SERRANO
    申请人:Albala Ingenieros S A；ALBALA INGENIEROS SA；
    IPC主号:
    专利说明:

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    AUTOMATIC TRANSITORIAL COMPENSATION CONTROL FOR AUDIO STANDARDIZATION SYSTEMS
    SECTOR OF THE TECHNIQUE
    The invention falls within the scope of telecommunications, and more specifically within the processing of audio signal for broadcasting.
    BACKGROUND OF THE INVENTION
    Traditionally, the existence of a sound technician in audiovisual production studies has been necessary to ensure that the characteristics of the audio produced are at the same time adequate to their content and pleasing to the human ear, avoiding stridency or unpleasant elements. The sound technician manages the mixers and the different sound sources to generate new audio tracks according to the requirements of the event produced and the style manual set by the production manager.
    The work of the sound technician in production is a complex task that requires knowledge and experience. However, when what is being produced uses content that has already been edited, the sound technician's work is limited to increasing and decreasing the sound intensity of the audio previously produced to give the sensation of continuity between the different fragments and avoid changes in the sound intensity that may be unpleasant for the listener.
    In these cases where the sound technician's job is only to increase and decrease the level of the audio to adapt it to what the listener has to perceive, it is possible to use equipment to perform this function automatically. This allows us to use the knowledge and experience of the sound technician in other less routine functions and supposes a reduction in the production costs of the programs.
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    The teams responsible for adjusting the audio level of a program to adapt them to the level that the listener has to perceive are called audio normalizers. These teams use psychoacoustic algorithms with very long time constants to determine the loudness of the program and adjust it. When one of these devices is used to perform the function of the sound technician, the result is good except at times when a program change occurs, because the response time of the algorithms they use is very slow. To solve this problem, it would be desirable to have a procedure that detects sudden changes in level that can occur between programs and corrects the behavior of the normalizer in the same way that a sound technician would do. This procedure is what is called 'automatic transient compensation control' and is the object of the invention described below.
    EXPLANATION OF THE INVENTION
    The automatic control of transient compensation proposed is a method of generating a pseudo-envelope of the signal and its subsequent treatment and analysis to obtain a dynamic gain value. The gain obtained in this way is applied to the delayed input signal, to compensate for the difference in level that may exist between the programs until the moment when the normalizer begins to operate. The proposed system also incorporates a control mechanism that includes other additional parameters to adjust the degree of compensation to be applied.
    For the generation of the pseudo-envelope (xpe (t)), the input audio signal (x (t)) is rectified and once rectified it is applied as input to a set of N picometers with different attack times (ran ) and relaxation (rm). The pseudo-envelope at each moment is set as the maximum value of the outputs of the set of picometers.
    The preliminary transient gain (gp (t)) is obtained by comparing the averaged and instantaneous values of the pseudo-envelope with a mathematical function. To calculate the applied transient gain (gta (t)) the preliminary transient gain is raised to an exponent whose value is between 0 and 1. This exponent is called the correction factor (fc), is independent of time and depends on the degree
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    of correction that is desired to apply in the compensation of the transients, the closer to 1 is, the degree of compensation of the transient will be greater and therefore a greater uniformity in the dynamics of the output audio will be achieved. The transient gain applied acts on the input audio that has been delayed in time tr seconds (xr (t)) to take into account the dynamics of the pseudo-envelope detector and that the gain is applied with a certain degree of anticipation to the level change
    The result of the automatic transient detection control described above makes it possible to reduce sudden changes in sound intensity between consecutive programs, applying a transient gain in a manner similar to what a sound technician would do.
    BRIEF DESCRIPTION OF THE DRAWINGS
    To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, where, for illustrative and non-limiting purposes, it has been represented the next:
    Figure 1.- Block diagram of the pseudo-envelope detector.
    Figure 2.- Block diagram of the automatic transient compensation control.
    PREFERRED EMBODIMENT OF THE INVENTION
    The automatic transient compensation control is designed to be used preferably in electronic equipment for audio signal processing. The procedure described above can be performed in both analog and digital implementations, although, given the current state of the art, the latter are simpler and cheaper, so that digital implementation is considered the preferred embodiment of this invention.
    To perform digital implementations it is possible to use digital signal processors (DSPs), programmable logic devices, or other devices that allow real-time audio signal processing. To validate the procedure
    proposed in this patent a digital implementation has been carried out on a professional audio processing equipment that uses FPGA type programmable logic devices.
    5 The procedure presented is capable of industrial application within the audiovisual sector, especially in the generation of broadcasts that are a result of previously recorded elements from different productions. This procedure is especially interesting for radio and television broadcasters that interleave advertising wedges with content programs, so that functionalities and mechanisms for use in this context are incorporated into the preferred embodiment of the invention.
    权利要求:
    Claims (7)
    [1]
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    1. A procedure for the automatic control of transient compensation of an audio signal characterized by being composed of the following steps:
    - A stage for obtaining the pseudo-envelope of the input audio signal, which is determined by taking the maximum value of the outputs of a set of picometers with different attack and relaxation times that serve to characterize the input signal rectified
    - A stage to obtain a gain value by comparing the average and instantaneous values of the pseudo-envelope with a mathematical function.
    - A stage for the modification of the gain obtained by means of a power function whose exponent contains a correction factor between 0 and 1.
    - A stage for the application of the resulting final gain on the input audio signal, once the time necessary to take into account the dynamics of the pseudo-envelope detector has been delayed.
    [2]
    2. A method according to claim 1, wherein the comparison function between the average of the pseudo-envelope and its instantaneous value is performed by dividing these terms (i.e. pseudo-envelope average / instantaneous value).
    [3]
    3. A method according to claim 1, whose comparison function between the average of the pseudo-envelope and its instantaneous value is a mathematical function quotient of two polynomials.
    [4]
    4. A method according to claim 1, wherein the input audio is delayed for a period of time between 0.1 ms and 100 ms.
    [5]
    5. A method according to claim 1, wherein obtaining the pseudo-envelope is carried out by using a set of 2 or more picometers.
    [6]
    6. The use of the method described in claims 1 to 5 in analog or digital electronic implementations.
    [7]
    7. The use of the method described in claims 1 to 5 in a computer program, stored in a medium readable by a computer or device with CPU (Central Processing Unit), to make a computer or device with CPU perform the procedure described .
    X (t)
    image 1
    Xp_e (t)
    Figure 1
    X (t)
    image2
    compensated
    (t)
    Figure 2
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    同族专利:
    公开号 | 公开日
    ES2684315B1|2019-03-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JPS5448107A|1977-09-22|1979-04-16|Nec Corp|Pilot controlled automatic gain adjusting system|
    US20080253586A1|2007-04-16|2008-10-16|Jeff Wei|Systems and methods for controlling audio loudness|
    EP2299590A1|2008-07-11|2011-03-23|Clarion Co., Ltd.|Acoustic processing device|
    EP2928076A1|2014-03-14|2015-10-07|Yamaha Corporation|Level adjustment device and method|
    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    ES201730582A|ES2684315B1|2017-03-31|2017-03-31|AUTOMATIC CONTROL OF TRANSIENT COMPENSATION FOR AUDIO STANDARDIZATION SYSTEMS|ES201730582A| ES2684315B1|2017-03-31|2017-03-31|AUTOMATIC CONTROL OF TRANSIENT COMPENSATION FOR AUDIO STANDARDIZATION SYSTEMS|
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