(19)
(11)EP 2 395 504 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
18.09.2013 Bulletin 2013/38

(21)Application number: 09839878.7

(22)Date of filing:  13.02.2009
(51)Int. Cl.: 
G10L 19/04  (2013.01)
H04R 5/00  (2006.01)
H04S 1/00  (2006.01)
G10L 19/008  (2013.01)
(86)International application number:
PCT/CN2009/070428
(87)International publication number:
WO 2010/091555 (19.08.2010 Gazette  2010/33)

(54)

STEREO ENCODING METHOD AND APPARATUS

STEREOKODIERUNGSVERFAHREN UND -VORRICHTUNG

PROCEDE ET DISPOSITIF DE CODAGE STEREO


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK TR

(43)Date of publication of application:
14.12.2011 Bulletin 2011/50

(73)Proprietor: Huawei Technologies Co., Ltd.
Shenzhen, Guangdong 518129 (CN)

(72)Inventors:
  • WU, Wenhai
    Guangdong 518129, Shenzhen (CN)
  • LANG, Yue
    Guangdong 518129, Shenzhen (CN)
  • MIAO, Lei
    Guangdong 518129, Shenzhen (CN)
  • LIU, Zexin
    Guangdong 518129, Shenzhen (CN)
  • HU, Chen
    Guangdong 518129, Shenzhen (CN)
  • ZHANG, Qing
    Guangdong 518129, Shenzhen (CN)

(74)Representative: Thun, Clemens et al
Mitscherlich & Partner Sonnenstraße 33
80331 München
80331 München (DE)


(56)References cited: : 
EP-A1- 1 814 104
CN-A- 101 091 206
US-A1- 2006 190 247
EP-A1- 1 953 736
CN-A- 101 253 557
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] The present invention relates to the field of stereo technologies, and in particular, to a stereo encoding method and apparatus.

    BACKGROUND OF THE INVENTION



    [0002] A stereo technology is for the purpose of transmitting or reconstructing a certain specified sound field, so as to reproduce acoustic and spatial characteristics of an original sound field for listeners. In recent years, with the development of a computer technology and digital signal processing technology, and due to the needs of development of high-definition television sound systems and home audiovisual systems, the stereo technology has undergone significant development, and meanwhile, higher requirements are imposed on the stereo technology, especially stereo encoding and decoding technologies.

    [0003] The conventional stereo encoding methods may be categorized into two types: one type is early waveform-based stereo encoding method, and the other type is currently commonly-used parametric stereo encoding method. In the parametric stereo encoding method, generally, left and right channel signals are down-mixed rather than being directly encoded, the down-mixed signals are encoded, and some extra sideband information is also encoded. At a decoding end, a stereo signal is recovered by using the down-mixed signals and the sideband information.

    [0004] The quality of the stereo signal depends, to a large extent, on the quality of the down-mixed signals. The more synchronous are the left and right channel signals, the less information is lost in the down-mixing process. Generally, distances from a sound emitting object to two microphones recording sounds the left and right channels may change or be different, which inevitably leads to a delay between the left and right channel signals. The left and right channel signals cannot be completely synchronized. If the delay can be adjusted in the down-mixing process, that is, the left and right channel signals are synchronized, the quality of the synthesized stereo signal may be improved to a great extent. An example for such a delay adjustment approach is for example described in US 2006/0190247 A1.

    [0005] FIG 1 is a schematic flow chart of a stereo encoding method in the prior art. Referring to FIG 1, firstly, a residual signal is obtained by performing down-sampling 4, Linear Predictive Coding (LPC) analysis, and LPC filtering on the left and right channel signals. Then, delays of the left and right channel signals are respectively extracted, and if the delays of two continuous frames of the left and right channel signals are different, a delay adjustment is performed before the down-mixing process.

    [0006] However, the following deficiencies of the prior art have become apparent.

    [0007] Because the left and right channel signals need to be spliced and added in the delay adjustment process, distortion is introduced, and the stereo signals with different characteristics have different distortion effects on discontinuity of interframe data during the splicing and adding process. According to the prior art, as the characteristics of the stereo signals are not differentiated during a delay adjustment, and the delay adjustment is performed immediately as long as delays of two continuous frames of the left and right channel signals are different, serious distortion may be caused.

    SUMMARY OF THE INVENTION



    [0008] The present invention provides a stereo encoding method and apparatus, so as to reduce distortion caused by a delay adjustment.

    [0009] According to the first aspect of the present invention a stereo encoding method includes: extracting a current interchannel delay of a stereo sound signal and a previous delay adjacent to the current interchannel delay; performing adjustment frame judgment according to characteristics of the current stereo sound signal when the current delay and the previous delay are different; and performing a delay adjustment on the stereo sound signal by using the current interchannel delay if it is judged that a frame where the current delay occurs is an adjustment frame.

    [0010] According to the second aspect of the present invention a stereo encoding apparatus includes: a delay extracting unit, configured to obtain a current interchannel delay of a stereo sound signal and a previous delay adjacent to the current interchannel delay; a judging unit, configured to perform adjustment frame judgment according to characteristics of the current stereo sound signal when the current delay and the previous delay that are obtained by the delay extracting unit are different; and a delay adjusting unit, configured to perform a delay adjustment on the stereo sound signal by using the current interchannel delay when the judging unit judges that a frame where the current delay occurs is an adjustment frame.

    [0011] It can be known from the description of the foregoing technical solutions that, the current interchannel delay of the stereo sound signal and the previous delay adjacent to the current interchannel delay are extracted, the adjustment frame judgment is performed according to the characteristics of the current stereo sound signal when the current delay and the previous delay are different, and the delay adjustment is performed on the stereo sound signal by using the current interchannel delay only when it is judged that the frame where the current delay occurs is the adjustment frame. In this way, the delay may be adjusted only at a suitable time for an adjustment, thereby the distortion caused by a delay adjustment may be reduced.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0012] To illustrate the technical solutions in the embodiments of the present invention or in the prior art more clearly, the accompanying drawings for describing the embodiments or the prior art are described briefly in the following.

    FIG. 1 is a schematic flow chart of a stereo encoding method in the prior art;

    FIG. 2 is a flow chart of a stereo encoding method according to an embodiment of the present invention;

    FIG. 3 is a schematic flow chart of a stereo encoding method according to an embodiment of the present invention;

    FIG. 4 is a flow chart of determining voiced and unvoiced sounds in a channel according to an embodiment of the present invention; and

    FIG. 5 is a schematic structural diagram of a stereo encoding apparatus according to an embodiment of the present invention.


    DETAILED DESCRIPTION OF THE EMBODIMENTS



    [0013] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention are described in further detail in the following with reference to embodiments and the accompanying drawings. It is obvious that the embodiments to be described are only a part rather than all of the embodiments of the present invention.

    [0014] Referring to FIG. 2, a stereo encoding method provided in an embodiment of the present invention includes the following steps:

    Step 21: Extract a current interchannel delay of a stereo signal and a previous delay adjacent to the current interchannel delay.

    Step 22: Perform adjustment frame judgment according to characteristics of the current stereo signal when the current delay and the previous delay are different.

    Step 23: Perform a delay adjustment on the stereo signal by using the current interchannel delay if it is judged that a frame where the current delay occurs is an adjustment frame.



    [0015] According to the stereo encoding method of the embodiment of the present invention, the current interchannel delay of the stereo signal and the previous delay adjacent to the current interchannel delay are extracted, the adjustment frame judgment is performed according to the characteristics of the current stereo signal when the current delay and the previous delay are different, and the delay adjustment is performed on the stereo signal by using the current interchannel delay only when it is judged that the frame where the current delay occurs is the adjustment frame, so that the delay is adjusted only at a suitable time for an adjustment. Therefore, distortion caused by a delay adjustment may be reduced.

    [0016] FIG. 3 is a schematic flow chart of a stereo encoding method provided by an embodiment of the present invention. Compared with the prior art, firstly, a residual signal is obtained by performing down-sampling 4, LPC analysis, and LPC filtering on left and right channel signals, and then delays of the left and right channel signals are respectively extracted. It is judged whether a delay adjustment is suitable before down-mixing when the delays of two continuous frames of the left and right channel signals are different. When the delays of the two continuous frames are different, at a place where a delay adjustment needs to be performed on the stereo signal, adjustment frame judgment is performed according to characteristics of the current stereo signal; and if it is judged that a frame where the current delay occurs is an adjustment frame, a delay adjustment is performed on the stereo signal by using a current interchannel delay.

    [0017] According to the embodiments of the present invention, the following judging methods for performing the adjustment frame judgment according to the characteristics of the stereo signal are provided.

    [0018] One method is to perform the judgment according to a type of the stereo signal. The method specifically includes: determining that the frame where the current delay occurs is the adjustment frame when the stereo signal is an unvoiced frame or a silent frame; and determining that the frame where the current delay occurs is a non-adjustment frame when the stereo signal is a voiced frame.

    [0019] FIG 4 is a flow chart of determining voiced and unvoiced sounds in a channel. Referring to FIG. 4, in this flow, the type of a stereo signal is judged according to an average value, a maximum value, and a zero-crossing rate within a pitch period of the stereo signal. Firstly, the pitch period of the signal is extracted, and value of a counter Count is initialized to be 0; then the maximum value and the average value within the pitch period are extracted, and the average value is compared with a pre-set threshold of an average value, and if the average value is greater than the pre-set threshold of an average value, the value of the counter is increased by 1 (count+1); otherwise, the count remains unchanged. Next, a ratio of the maximum value to the average value within the pitch period is compared with a set ratio threshold, and if the ratio is greater than the ratio threshold, the value of the counter is increased by 1 (count+1); otherwise, the count remains unchanged. Afterwards, the zero-crossing rate is acquired and compared with a set zero-crossing rate threshold, and if the zero-crossing rate is greater than the zero-crossing rate threshold, the value of the counter is increased by 1 (count+1); otherwise, the count remains unchanged. Finally, the count is compared with 2, and if the count is greater than 2, it is judged that the signal is a voiced frame; if count is not greater than 2, it is judged that the signal is an unvoiced frame.

    [0020] It should be noted that judgment method of the silent type may be processed similar to the judgment method of the unvoiced sound. According to the foregoing judgment process, during calculation and programming, 1 may be output for a voiced frame, and 0 may be output for an unvoiced frame or a silent frame.

    [0021] The type of the entire stereo signal is determined by the types of the left and right channel signals. And only when the types of the left and right channel signals are voiced signals at the same time, it is judged that the stereo signal is a voiced signal.

    [0022] Another method is to perform the judgment according to energy of a stereo signal. The method specifically includes: determining that the frame where the current delay occurs is an adjustment frame when frame energy of the stereo signal is less than a set threshold value; and determining that the frame where the current delay occurs is a non-adjustment frame when the frame energy of the stereo signal is greater than or equal to the set threshold value.

    [0023] Still another method is to perform the judgment according to a combination of the type and energy of the stereo signal. The method specifically includes: determining that a frame where a current delay occurs is an adjustment frame if the stereo signal is an unvoiced frame or a silent frame and frame energy of the stereo signal is less than a certain set threshold value; determining that the frame where the current delay occurs is a non-adjustment frame if the stereo signal is not an unvoiced frame or a silent frame or frame energy of the stereo signal is not less than a certain set threshold value; or, determining that the frame where the current delay occurs is the adjustment frame; determining that the frame where the current delay occurs is a non-adjustment frame if the stereo signal is not an unvoiced frame or a silent frame or frame energy of the stereo signal is not less than a certain set threshold value.

    [0024] Accordingly, the foregoing judging methods are only used as exemplary embodiments of the present invention, and are not particularly limited in the present invention. For example, as for voice signals having loud background noise or music signals having weak periodicity, other methods may be used to perform the adjustment frame judgment.

    [0025] Referring to FIG. 5, an embodiment of the present invention further provides a stereo encoding apparatus, which includes a delay extracting unit 51, a judging unit 52, and a delay adjusting unit 53.

    [0026] The delay extracting unit 51 is configured to obtain a current interchannel delay of a stereo signal and a previous delay adjacent to the current interchannel delay.

    [0027] The judging unit 52 is configured to perform adjustment frame judgment according to characteristics of the current stereo signal when the current delay and the previous delay that are obtained by the obtaining delay unit are different.

    [0028] The delay adjusting unit 53 is configured to perform a delay adjustment on the stereo signal by using the current interchannel delay when the judging unit judges that a frame where the current delay occurs is an adjustment frame.

    [0029] Preferably, the judging unit 52 includes any one of the following modules: a type judging module, an energy judging module, and a type and energy judging module.

    [0030] The type judging module is configured to perform the adjustment frame judgment according to a type of the stereo signal.

    [0031] The energy judging module is configured to perform the adjustment frame judgment according to energy of the stereo signal.

    [0032] The type and energy judging module is configured to perform the adjustment frame judgment according to a combination of the type and energy of the stereo signal.

    [0033] Specifically, the type judging module is configured to judge that the frame where the current delay occurs is the adjustment frame when the stereo signal is an unvoiced frame or a silent frame, and judge that the frame where the current delay occurs is a non-adjustment frame when the stereo signal is a voiced frame.

    [0034] The energy judging module is configured to judge that the frame where the current delay occurs is the adjustment frame when frame energy of the stereo signal is less than a certain set threshold value, and judge that the frame where the current delay occurs is a non-adjustment frame when the frame energy of the stereo signal is greater than or equal to the certain set threshold value.

    [0035] The type and energy judging module is configured to judge that the frame where the current delay occurs is the adjustment frame when the stereo signal is an unvoiced frame or a silent frame and frame energy of the stereo signal is less than a certain set threshold value; otherwise, judge that the frame where the current delay occurs is a non-adjustment frame; or, the type and energy judging module is configured to judge that the frame where the current delay occurs is the adjustment frame when the stereo signal is an unvoiced frame or a silent frame or frame energy of the stereo signal is less than a certain set threshold value; otherwise, judge that the frame where the current delay occurs is a non-adjustment frame.

    [0036] Accordingly, the judging unit is not limited to be implemented by the foregoing judging modules, the foregoing modules are described as exemplary embodiments of the present invention, and other determining modules may be used to perform the adjustment frame judgment, which is only limited by the appended claims.

    [0037] According to the stereo encoding apparatus provided by the embodiment of the present invention, the delay extracting unit 51 extracts the current interchannel delay of the stereo signal and the previous delay adjacent to the current interchannel delay, the judging unit 52 performs the adjustment frame judgment according to the characteristics of the current stereo signal when the current delay and the previous delay are different, and the delay adjusting unit 53 performs the delay adjustment on the stereo signal by using the current interchannel delay only when the frame where the current delay occurs is the adjustment frame, so that the delay is adjusted only at a suitable time for an adjustment, thereby distortion caused by a delay adjustment can be reduced.

    [0038] It should be noted that, persons of ordinary skill in the art may understand that all or a part of the processes of the methods according to the embodiments may be implemented by a computer program instructing relevant hardware. The program may be stored in a computer readable storage medium. When the program is executed, the processes of the methods according to the embodiments are performed. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), or a Random Access Memory (RAM).

    [0039] All functional units according to the embodiments of the present invention may be integrated in one processing module, or may exist as separate physical units; or two or more than two units may also be integrated in one module. The integrated module may be implemented through hardware, or may also be implemented in a form of a software functional module. When the integrated module is implemented in the form of the software functional module and sold or used as a separate product, the integrated module may be stored in a computer readable storage medium. The storage medium may be a ROM, a magnetic disk, an optical disk, or the like.

    [0040] The foregoing specific embodiments are not intended to limit the present invention which is only limited by the appended claims.


    Claims

    1. A stereo encoding method, comprising:

    extracting (21) a current interchannel delay of a stereo sound signal and a previous delay adjacent to the current interchannel delay;

    performing (22) adjustment frame judgment according to characteristics of the current stereo sound signal when the current delay and the previous delay are different; and

    performing (23) a delay adjustment on the stereo sound signal by using the current interchannel delay if it is judged that a frame where the current delay occurs is an adjustment frame.


     
    2. The method according to claim 1, wherein the performing the adjustment frame judgment according to the characteristics of the current stereo sound signal comprises one of the following:

    performing the adjustment frame judgment according to a type of the stereo sound signal; or

    performing the adjustment frame judgment according to energy of the stereo sound signal; or

    performing the adjustment frame judgment according to a combination of the type and energy of the stereo sound signal.


     
    3. The method according to claim 2, wherein the performing (22) the adjustment frame judgment according to the type of the stereo sound signal comprises:

    determining that the frame where the current delay occurs is the adjustment frame when the stereo sound signal is an unvoiced frame or a silent frame; and

    determining that the frame where the current delay occurs is a non-adjustment frame when the stereo sound signal is a voiced frame.


     
    4. The method according to claim 2, wherein the performing the adjustment frame judgment according to the energy of the stereo sound signal comprises:

    determining that the frame where the current delay occurs is the adjustment frame when frame energy of the stereo sound signal is less than a certain set threshold value; and

    determining that the frame where the current delay occurs is a non-adjustment frame when the frame energy of the stereo sound signal is greater than or equal to the certain set threshold value.


     
    5. The method according to claim 2, wherein the performing the adjustment frame judgment according to a combination of the type and energy of the stereo sound signal comprises:

    determining that the frame where the current delay occurs is the adjustment frame if the stereo sound signal is an unvoiced frame or a silent frame and frame energy of the stereo sound signal is less than a certain set threshold value; and

    determining that the frame where the current delay occurs is a non-adjustment frame if the stereo sound signal is not an unvoiced frame or a silent frame or frame energy of the stereo sound signal is not less than a certain set threshold value


     
    6. The method according to claim 2, wherein the performing the adjustment frame judgment according to a combination of the type and energy of the stereo sound signal comprises:

    determining that the frame where the current delay occurs is the adjustment frame if the stereo sound signal is an unvoiced frame or a silent frame or frame energy of the stereo sound signal is less than a certain set threshold value; and

    determining that the frame where the current delay occurs is a non-adjustment frame if the stereo sound signal is not an unvoiced frame or a silent frame or frame energy of the stereo sound signal is not less than a certain set threshold value.


     
    7. A stereo encoding apparatus, comprising:

    a delay extracting unit (51), configured to obtain a current interchannel delay of a stereo sound signal and a previous delay adjacent to the current interchannel delay;

    a judging unit (52), configured to perform adjustment frame judgment according to characteristics of the current stereo sound signal when the current delay and the previous delay that are obtained by the delay extracting unit are different; and

    a delay adjusting unit (53), configured to perform a delay adjustment on the stereo sound signal by using the current interchannel delay when the judging unit judges that a frame where the current delay occurs is an adjustment frame.


     
    8. The apparatus according to claim 7, wherein the judging unit (52) comprises any one of following modules:

    a type judging module, configured to perform the adjustment frame judgment according to a type of the stereo sound signal;

    an energy judging module, configured to perform the adjustment frame judgment according to energy of the stereo sound signal; and

    a type and energy judging module, configured to perform the adjustment frame judgment according to a combination of the type and energy of the stereo sound signal.


     
    9. The apparatus according to claim 8, wherein
    the type judging module is configured to determine that the frame where the current delay occurs is the adjustment frame when the stereo sound signal is an unvoiced frame or a silent frame, and determine that the frame where the current delay occurs is a non-adjustment frame when the stereo sound signal is a voiced frame.
     
    10. The apparatus according to claim 8, wherein
    the energy judging module is configured to determine that the frame where the current delay occurs is the adjustment frame when frame energy of the stereo sound signal is less than a certain set threshold value, and determine that the frame where the current delay occurs is a non-adjustment frame when the frame energy of the stereo sound signal is greater than or equal to the certain set threshold value.
     
    11. The apparatus according to claim 8, wherein
    the type and energy judging module is configured to determine that the frame where the current delay occurs is the adjustment frame if the stereo sound signal is an unvoiced frame or a silent frame and frame energy of the stereo sound signal is less than a certain set threshold value; and
    determine that the frame where the current delay occurs is a non-adjustment frame if the stereo sound signal is not an unvoiced frame or a silent frame or frame energy of the stereo sound signal is not less than a certain set threshold value
     
    12. The apparatus according to claim 8, wherein
    the type and energy judging module is configured to determine that the frame where the current delay occurs is the adjustment frame if the stereo sound signal is an unvoiced frame or a silent frame or frame energy of the stereo sound signal is less than a certain set threshold value; determine that the frame where the current delay occurs is a non-adjustment frame if the stereo sound signal is not an unvoiced frame or a silent frame or frame energy of the stereo sound signal is not less than a certain set threshold value.
     


    Ansprüche

    1. Stereocodierungsverfahren, das Folgendes umfasst:

    Extrahieren (21) einer aktuellen Zwischenkanalverzögerung eines Stereoklangsignals und einer früheren Verzögerung benachbart zu der aktuellen Zwischenkanalverzögerung;

    Ausführen (22) einer Einstellrahmenbeurteilung in Übereinstimmung mit Eigenschaften des aktuellen Stereoklangsignals, wenn die aktuelle Verzögerung und die frühere Verzögerung verschieden sind; und

    Ausführen (23) einer Verzögerungseinstellung an dem Stereoklangsignal unter Verwendung der aktuellen Zwischenkanalverzögerung, falls beurteilt wird, dass ein Rahmen, in dem die aktuelle Verzögerung auftritt, ein Einstellrahmen ist.


     
    2. Verfahren nach Anspruch 1, wobei das Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit den Eigenschaften des aktuellen Stereoklangsignals einen der folgenden Schritte umfasst:

    Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit einem Typ des Stereoklangsignals; oder

    Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit einer Energie des Stereoklangsignals; oder

    Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit einer Kombination aus dem Typ und der Energie des Stereoklangsignals.


     
    3. Verfahren nach Anspruch 2, wobei das Ausführen (22) der Einstellrahmenbeurteilung in Übereinstimmung mit dem Typ des Stereoklangsignals Folgendes umfasst:

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, wenn das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist; und

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, wenn das Stereoklangsignal ein Sprachrahmen ist.


     
    4. Verfahren nach Anspruch 2, wobei das Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit der Energie des Stereoklangsignals Folgendes umfasst:

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, wenn die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist; und

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, wenn die Rahmenenergie des Stereoklangsignals größer oder gleich dem bestimmten festgelegten Schwellenwert ist.


     
    5. Verfahren nach Anspruch 2, wobei das Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit einer Kombination aus dem Typ und der Energie des Stereoklangsignals Folgendes umfasst:

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, falls das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist und die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist; und

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, falls das Stereoklangsignal kein sprachfreier Rahmen oder kein stiller Rahmen ist oder die Rahmenenergie des Stereoklangsignals nicht kleiner als ein bestimmter festgelegter Schwellenwert ist.


     
    6. Verfahren nach Anspruch 2, wobei das Ausführen der Einstellrahmenbeurteilung in Übereinstimmung mit einer Kombination aus dem Typ und der Energie des Stereoklangsignals Folgendes umfasst:

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, falls das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist oder die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist; und

    Bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, falls das Stereoklangsignal kein sprachfreier Rahmen oder kein stiller Rahmen ist oder die Rahmenenergie des Stereoklangsignals nicht kleiner als ein bestimmter festgelegter Schwellenwert ist.


     
    7. Stereocodierungsvorrichtung, die Folgendes umfasst:

    eine Verzögerungsextraktionseinheit (51), die konfiguriert ist, eine aktuelle Zwischenkanalverzögerung eines Stereoklangsignals und einer früheren Verzögerung benachbart zu der aktuellen Zwischenkanalverzögerung zu erhalten;

    eine Beurteilungseinheit (52), die konfiguriert ist, eine Einstellrahmenbeurteilung in Übereinstimmung mit Eigenschaften des aktuellen Stereoklangsignals auszuführen, wenn die aktuelle Verzögerung und die frühere Verzögerung, die durch die Verzögerungsextraktionseinheit erhalten werden, verschieden sind; und

    eine Verzögerungseinstelleinheit (53), die konfiguriert ist, eine Verzögerungseinstellung an dem Stereoklangsignal unter Verwendung der aktuellen Zwischenkanalverzögerung auszuführen, wenn die Beurteilungseinheit beurteilt, dass ein Rahmen, in dem die aktuelle Verzögerung auftritt, ein Einstellrahmen ist.


     
    8. Vorrichtung nach Anspruch 7, wobei die Beurteilungseinheit (52) eines der folgenden Module umfasst:

    ein Typbeurteilungsmodul, das konfiguriert ist, die Einstellrahmenbeurteilung in Übereinstimmung mit dem Typ des Stereoklangsignals auszuführen;

    ein Energiebeurteilungsmodul, das konfiguriert ist, die Einstellrahmenbeurteilung in Übereinstimmung mit der Energie des Stereoklangsignals auszuführen; und

    ein Typ- und Energiebeurteilungsmodul, das konfiguriert ist, die Einstellrahmenbeurteilung in Übereinstimmung mit einer Kombination aus dem Typ und der Energie des Stereoklangsignals auszuführen.


     
    9. Vorrichtung nach Anspruch 8, wobei
    das Typbeurteilungsmodul konfiguriert ist, zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, wenn das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist, und zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, wenn das Stereoklangsignal ein Sprachrahmen ist.
     
    10. Vorrichtung nach Anspruch 8, wobei
    das Energiebeurteilungsmodul konfiguriert ist, zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, wenn die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist, und zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, wenn die Rahmenenergie des Stereoklangsignals größer oder gleich dem bestimmten festgelegten Schwellenwert ist.
     
    11. Vorrichtung nach Anspruch 8, wobei
    das Typ- und Energiebeurteilungsmodul konfiguriert ist, zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, falls das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist und die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist; und
    zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, falls das Stereoklangsignal kein sprachfreier Rahmen oder kein stiller Rahmen ist, oder die Rahmenenergie des Stereoklangsignals nicht kleiner als ein bestimmter festgelegter Schwellenwert ist.
     
    12. Vorrichtung nach Anspruch 8, wobei
    das Typ- und Energiebeurteilungsmodul konfiguriert ist, zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, der Einstellrahmen ist, falls das Stereoklangsignal ein sprachfreier Rahmen oder ein stiller Rahmen ist oder die Rahmenenergie des Stereoklangsignals kleiner als ein bestimmter festgelegter Schwellenwert ist;
    zu bestimmen, dass der Rahmen, in dem die aktuelle Verzögerung auftritt, kein Einstellrahmen ist, falls das Stereoklangsignal kein sprachfreier Rahmen oder kein stiller Rahmen ist oder die Rahmenenergie des Stereoklangsignals nicht kleiner ist als ein bestimmter festgelegter Schwellenwert.
     


    Revendications

    1. Procédé de codage stéréo, comprenant les étapes consistant à :

    extraire (21) un délai entre voies actuel d'un signal sonore stéréo et un délai précédent adjacent au délai entre voies actuel ;

    procéder (22) à une évaluation de trame d'ajustement en fonction de caractéristiques du signal sonore stéréo actuel si le délai actuel et le délai précédent sont différents ; et

    procéder (23) à un ajustement de délai sur le signal sonore stéréo à l'aide du délai entre voies actuel s'il est évalué qu'une trame au niveau de laquelle se produit le délai actuel est une trame d'ajustement.


     
    2. Procédé selon la revendication 1, dans lequel l'étape consistant à procéder à l'évaluation de trame d'ajustement en fonction des caractéristiques du signal sonore stéréo actuel comprend l'une des étapes consistant à :

    procéder à l'évaluation de trame d'ajustement en fonction d'un type du signal sonore stéréo ; ou

    procéder à l'évaluation de trame d'ajustement en fonction de l'énergie du signal sonore stéréo ; ou

    procéder à l'évaluation de trame d'ajustement en fonction d'une combinaison du type et de l'énergie du signal sonore stéréo.


     
    3. Procédé selon la revendication 2, dans lequel l'étape consistant à procéder (22) à l'évaluation de trame d'ajustement en fonction du type du signal sonore stéréo comprend les étapes consistant à :

    établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse ; et

    établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo est une trame voisée.


     
    4. Procédé selon la revendication 2, dans lequel l'étape consistant à procéder à l'évaluation de trame d'ajustement en fonction de l'énergie du signal sonore stéréo comprend les étapes consistant à :

    établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée ; et

    établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si l'énergie de trame du signal sonore stéréo est supérieure ou égale à la certaine valeur limite fixée.


     
    5. Procédé selon la revendication 2, dans lequel l'étape consistant à procéder à l'évaluation de trame d'ajustement en fonction d'une combinaison du type et de l'énergie du signal sonore stéréo comprend les étapes consistant à :

    établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse et si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée ; et

    établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo n'est pas une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo n'est pas inférieure à une certaine valeur limite fixée.


     
    6. Procédé selon la revendication 2, dans lequel l'étape consistant à procéder à l'évaluation de trame d'ajustement en fonction d'une combinaison du type et de l'énergie du signal sonore stéréo comprend les étapes consistant à :

    établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée ; et

    établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo n'est pas une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo n'est pas inférieure à une certaine valeur limite fixée.


     
    7. Appareil de codage stéréo, comprenant :

    une unité d'extraction de délai (51), conçue pour obtenir un délai entre voies actuel d'un signal sonore stéréo et un délai précédent adjacent au délai entre voies actuel ;

    une unité d'évaluation (52), conçue pour procéder à une évaluation de trame d'ajustement en fonction de caractéristiques du signal sonore stéréo actuel si le délai actuel et le délai précédent obtenus par l'unité d'extraction de délai sont différents ; et

    une unité d'ajustement de délai (53), conçue pour procéder à un ajustement de délai sur le signal sonore stéréo à l'aide du délai entre voies actuel si l'unité d'évaluation évalue qu'une trame au niveau de laquelle se produit le délai actuel est une trame d'ajustement.


     
    8. Appareil selon la revendication 7, dans lequel l'unité d'évaluation (52) comprend l'un quelconque des modules suivants :

    un module d'évaluation de type, conçu pour procéder à l'évaluation de trame d'ajustement en fonction d'un type du signal sonore stéréo ;

    un module d'évaluation d'énergie, conçu pour procéder à l'évaluation de trame d'ajustement en fonction de l'énergie du signal sonore stéréo ; et

    un module d'évaluation de type et d'énergie, conçu pour procéder à l'évaluation de trame d'ajustement en fonction d'une combinaison du type et de l'énergie du signal sonore stéréo.


     
    9. Appareil selon la revendication 8, dans lequel
    le module d'évaluation de type est conçu pour établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse, et établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo est une trame voisée.
     
    10. Appareil selon la revendication 8, dans lequel
    le module d'évaluation d'énergie est conçu pour établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée, et établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si l'énergie de trame du signal sonore stéréo est supérieure ou égale à la certaine valeur limite fixée.
     
    11. Appareil selon la revendication 8, dans lequel
    le module d'évaluation de type et d'énergie est conçu pour établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse et si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée ; et établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo n'est pas une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo n'est pas inférieure à une certaine valeur limite fixée.
     
    12. Appareil selon la revendication 8, dans lequel
    le module d'évaluation de type et d'énergie est conçu pour établir que la trame au niveau de laquelle se produit le délai actuel est la trame d'ajustement si le signal sonore stéréo est une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo est inférieure à une certaine valeur limite fixée ; établir que la trame au niveau de laquelle se produit le délai actuel est une trame qui n'est pas une trame d'ajustement si le signal sonore stéréo n'est pas une trame non voisée ou une trame silencieuse ou si l'énergie de trame du signal sonore stéréo n'est pas inférieure à une certaine valeur limite fixée.
     




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    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description