JP3550110B2 - Signal processing circuit and signal processing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a signal processing circuit and a signal processing method, and more particularly, to a signal processing circuit and a signal processing method for switching and outputting a plurality of digital audio data.
[0002]
[Prior art]
With the progress of multimedia technology in recent years, application devices (for example, DVD players and digital TV broadcast tuners) that integrally handle a plurality of media such as digitized video, audio, and data have begun to spread. Devices such as a DVD player and a digital TV tuner use a digital audio interface commonly called IEC60958 for transmitting digital audio data to peripheral devices. This interface is used not only for transmitting audio data but also for transmitting inter-device audio encoded data that has been compression-encoded based on standards such as MPEG, Dolby AC-3, and DTS. In a DVD player, a digital TV tuner, and the like, there is a demand for switching midway of data transmitted by a digital audio interface, that is, switching output between audio data and audio encoded data. The output switching between audio data and audio encoded data by the DVD player is performed, for example, when the same audio is reproduced in the DVD video and the viewer gives an instruction to switch the audio. Further, when two types of digital data are stored in the same track of a DVD video disc (for example, when the first audio is an MPEG stream and the second audio is linear PCM which is audio data), the first audio to the second audio are stored. This is also performed when an instruction is received from the viewer to switch the output between two sounds. Further, when the DVD video can be previewed in various languages, the instruction is also performed when an instruction to switch Japanese data as the first sound to data in another language as the second sound is received. Also, when a digital TV tuner performs channel switching to select a digital broadcast, output switching between audio data and audio encoded data may be performed.
[0003]
Hereinafter, a signal processing circuit that switches output between audio data and audio encoded data in a DVD player, a digital TV tuner, or the like will be described.
[0004]
FIG. 4 is a block diagram showing a configuration of a conventional signal processing circuit. The signal processing circuit illustrated in FIG. 4 includes signal generation units 101 and 102, a signal switching unit 103, a conversion unit 104, and a control unit 105. The signal creation unit 101 creates audio data D101. The signal creation unit 102 creates audio encoded data D102 encoded based on standards such as MPEG, Dolby AC-3, and DTS. The control unit 105 outputs the switching instruction signal S102 and the identifier ID101 in response to the signal S101 indicating the switching instruction from the viewer. The identifier ID 101 belongs to the channel status of the IEC60958 standard and is information for identifying audio data or audio encoded data. Signal switching section 103 outputs speech data D101 from signal creation section 101 or speech encoded data D102 from signal creation section 102 as signal D103 in response to switching instruction signal S102 from control section 105. The conversion unit 104 converts the signal D103 from the signal switching unit 103 into a digital signal of a format conforming to IEC60958, and outputs the digital signal as a signal D104.
[0005]
FIGS. 5A and 5B are diagrams showing a format of a digital signal conforming to IEC60958. The signal D104 output from the conversion unit 104 is composed of a plurality of continuous words as shown in FIG. At the beginning of each word is a synchronization signal, followed by audio data, and at the end is additional information. The additional information describes information about data transmitted on this channel. One bit of the additional information includes a channel status bit. Two subframes each consisting of one word of an audio sample are combined into one frame, and are used, for example, for L and R of a stereo signal. Further, one block is formed by 192 frames, and this block is one unit. In the bits such as the channel status described above, 192 bits in the block are configured as the channel status for one block. As shown in FIG. 5B, in the channel status of 192 frames, that is, one block, the second bit is used as an identifier representing audio data or encoded audio data. In a digital signal conforming to IEC60958, if the bit is 0, it is identified as audio data, and if it is 1, it is identified as encoded audio data. Therefore, 192 frames of data are required to determine whether the data is audio data or audio encoded data.
[0006]
Next, the operation of the signal processing circuit shown in FIG. 4 when receiving a voice switching instruction from a viewer during reproduction of a disc by a DVD player or the like will be described with reference to FIG.
[0007]
At time T1, the signal switching unit 103 is connected to the signal generation unit 101, and outputs the audio data D101 from the signal generation unit 101 as the signal D103.
[0008]
At time T2, when there is a switching instruction from the viewer, the signal S101 switches. In response to the switching of the signal S101, the control unit 105 switches the switching signal S102 and the identifier ID101. In response to the switching of the switching signal S102, the signal switching unit 103 switches the connection from the signal generation unit 101 to the signal generation unit 102. At this time, the identifier in the channel status of the output signal D104 may be switched to audio encoded data and output in the middle of a block where audio data is expected.
[0009]
As described above, when there is a switching instruction from the viewer in the middle of the audio data D101 output from the signal switching unit 103, the output D103 of the signal switching unit 103 is immediately changed from the audio data D101 to the audio encoded data D102. Switch. As a result, in the conversion unit 104, the audio data is switched from the audio data to the audio coded data in the middle of the block in which the identifier in the channel status indicates the audio data, that is, between time T2 and T3, and the receiver such as an AV amplifier is used. Outputs speech encoded data as speech data, so that a noise signal is generated in the receiver (noise A).
[0010]
In a receiver such as an AV amplifier that receives an output signal D104 immediately after the identifier in the channel status in the conversion unit 104 has changed from a block expecting audio data to a block expecting audio encoded data, A time (period from time T3 to T4) in which the controller recognizes the output signal and performs control is required. However, since the time is not taken into account, recognition and control of the switched voice data or voice coded data are not performed accurately, and a noise signal is generated in the receiver (noise B).
[0011]
[Problems to be solved by the invention]
As described above, in the conventional signal processing circuit, when switching the output from audio data to audio encoded data upon receiving an audio switching instruction from a viewer at the time of reproducing a disc by a DVD player or the like, the identifier in the channel status of the output signal is In some cases, audio data is switched to encoded data and output in the middle of a block displaying audio data. Further, when the output is switched from the audio encoded data to the audio data, the audio data may be output in the middle of the block in which the identifier in the channel status of the output signal indicates the audio encoded data. Therefore, if a receiver such as a digital AV amplifier with a built-in decoder as a peripheral device switches to the encoded data in the middle of the block where the identifier in the channel status is expecting the audio data, the receiver returns to the channel status after the next block. Until the identifier is changed to indicate audio encoded data, the reproduction continues as audio data, causing noise.
[0012]
Further, when the output level of the audio data is high when the output is switched between the audio data and the encoded audio data, a shock sound may be generated. Further, when the output is switched, it is necessary for the receiver such as an AV amplifier that receives the output signal to have a time for the system controller to recognize the output signal and perform control. However, since the time is not taken into account, the recognition and control of the voice data or voice coded data after the switching is not performed accurately, and noise generated at the time of voice switching such as generation of a noise signal at the receiver is annoying to the viewer. It is uncomfortable.
[0013]
Conventionally, in order to prevent such a malfunction of the decoder at the time of switching the audio output, and the occurrence of noise and shock noise, when switching the output audio while watching the DVD video, the viewer temporarily stops the operation of the DVD player and temporarily stops the operation. It is necessary to perform the operation of reproducing the disc again after the switching operation, which is inconvenient.
[0014]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a signal processing circuit capable of switching audio output even when a disc is reproduced by a DVD player or the like. .
[0015]
[Means for Solving the Problems]
A signal processing circuit according to the present invention includes audio data creation means, audio encoded data creation means, signal switching means, control means, and conversion means. The audio data creating means creates audio data. The voice coded data generating means generates voice coded data. The signal switching means receives the audio data created by the audio data creation means and the audio encoded data created by the audio encoded data creation means, and selectively outputs the received audio data or encoded audio data. The control means outputs an identifier for identifying whether the data is audio data or encoded audio data. The conversion means outputs a signal in a format having a data portion including data from the signal switching means and additional information including an identifier from the control means. The control means switches the identifier from the state indicating the audio data to the state indicating the audio coded data, and then converts the audio data generated by the audio data generating means into the audio coded data generated by the audio coded data generating means. The signal switching means is controlled so as to switch the output to data.
[0016]
Preferably, the conversion means converts the data from the signal switching means into a signal having a format conforming to the IEC60958 standard and outputs the signal.
[0017]
According to the above signal processing circuit, even when an output switching instruction is received at the time of reproducing a disc by a DVD player equipped with the above signal processing circuit, the coded audio data guaranteed in the IEC60958 standard block is supplied to the decoder. Therefore, it is possible to prevent the malfunction of the decoder and the occurrence of noise, which have conventionally occurred. Therefore, the audio output switching operation which could only be performed when the operation of the DVD player or the like has been stopped can be performed at the time of operating the disc, and the viewer can easily perform the audio switching operation while watching the video. It is possible to improve convenience.
[0018]
Preferably, the audio data creating unit performs a mute process in response to the control unit switching the identifier from the state indicating audio data to the state indicating encoded audio data.
[0019]
Preferably, the control means controls the signal switching means to switch the output from the encoded audio data to the audio data, and then switches the identifier from the state indicating the encoded audio data to the state indicating the audio data.
[0020]
According to the signal processing circuit, even when an output switching instruction is received at the time of reproducing a disc by a DVD player equipped with the signal processing circuit, audio data guaranteed within the IEC60958 standard block can be supplied to the decoder. As a result, it is possible to prevent the conventional decoder from malfunctioning and generating noise. Therefore, the audio output switching operation which could only be performed when the operation of the DVD player or the like has been stopped can be performed at the time of operating the disc, and the viewer can easily perform the audio switching operation while watching the video. It is possible to improve convenience.
[0021]
Preferably, the control means switches the identifier from a state indicating audio data to a state indicating audio encoded data, further waits a predetermined number of IEC60958 standard blocks, and then converts the audio data to audio encoded data. The signal switching means is controlled so as to switch the output.
[0022]
According to the signal processing circuit, in the receiver such as an AV amplifier that receives the output signal at the time of output switching, the time for the system controller to recognize the output signal and perform control is considered, and the output signal at the time of switching is output. Even in a receiver that requires time to perform recognition and control, recognition and control of the voice coded data after switching are performed accurately, and it is possible to output voice without generating a noise signal in the receiver.
[0023]
Preferably, after the silent data portion is inserted at the end of the audio data, the output of the signal switching means is switched from the audio data to the audio encoded data.
[0024]
In the above signal processing circuit, in a receiver such as an AV amplifier which receives the output signal at the time of output switching, the system controller recognizes a silent data portion, and thereby controls the output of the receiver in advance by controlling the mute processing and converting the audio data into an audio codec. Since it is possible to predict switching to coded data, even if invalid data occurs at the time of switching, it is possible to output sound without generating a noise signal in a receiver or the like.
[0025]
Preferably, the silence data portion is inserted at the end of the encoded audio data, and then the output of the signal switching means is switched from the encoded audio data to the audio data.
[0026]
In the signal processing circuit, in a receiver such as an AV amplifier that receives the output signal at the time of output switching, the system controller recognizes a silent data portion, and thereby controls the output of the receiver in advance from the control of the mute process and the audio encoded data. Since switching to audio data can be predicted, even when invalid data occurs at the time of switching, it is possible to output audio without generating a noise signal in a receiver or the like.
[0027]
The signal processing method according to the present invention comprises: a conversion unit that outputs a signal in a format having a data portion including given data and additional information including a given identifier; A signal processing method for providing an identifier for identifying whether there is any audio data or audio encoded data, wherein after switching the identifier given to the conversion means from a state indicating audio data to a state indicating audio encoded data, The data to be provided to the conversion means is switched from the data to the encoded voice data.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.
[0029]
(1st Embodiment)
FIG. 1 is a block diagram showing the overall configuration of the signal processing circuit according to the first embodiment of the present invention. The signal processing circuit shown in FIG. 1 is provided in a device such as a DVD player or a digital TV tuner, and is used for transmitting digital audio data to peripheral devices. The signal processing circuit shown in FIG. 1 includes signal generation units 1 and 2, a signal switching unit 3, a conversion unit 4, and a control unit 5.
[0030]
The signal generator 1 generates audio data D1. The signal generator 2 generates encoded audio data D2 encoded based on standards such as MPEG, Dolby AC-3, and DTS.
[0031]
The signal switching unit 3 outputs the audio data D1 from the signal generation unit 1 or the encoded audio data D2 from the signal generation unit 2 as a signal D3 in response to the switching instruction signal S2 from the control unit 5.
[0032]
The conversion unit 4 converts the signal D3 from the signal switching unit 3 into a digital signal having a format conforming to the IEC60958 standard, that is, a format as shown in FIG. At this time, the conversion unit 4 sets the second bit of the channel status of 192 frames, that is, one block, to 0 or 1 according to the identifier ID1 from the control unit 5. Specifically, "0" is set when the identifier ID1 from the control unit 5 indicates audio data, and "1" is set when the identifier ID1 indicates audio encoded data. Further, the converter 4 outputs to the controller 5 a signal S3 indicating which part of the block of the IEC60958 standard the signal D4 is.
[0033]
The control unit 5 outputs the switching instruction signal S2 and the identifier ID1 in response to the signal S1 indicating the switching instruction from the viewer and the signal S3 from the conversion unit 4. The identifier ID1 belongs to the channel status of the IEC60958 standard and is information for identifying audio data or audio encoded data. The control unit 5 controls the timing at which the switching instruction signal S2 and the identifier ID1 are output according to the signal S3 from the conversion unit 4.
[0034]
Next, the operation of the signal processing circuit configured as described above will be described. In the following, an operation when an audio switching instruction is received from a viewer during reproduction of a disc by a DVD player or the like will be described.
[0035]
First, a case where audio data is switched to audio encoded data will be described with reference to FIG.
[0036]
At time T1, the signal switching unit 3 is connected to the signal generation unit 1 and outputs the audio data D1 from the signal generation unit 1 as a signal D3.
[0037]
Next, at time T2, the signal S1 switches according to the switching instruction from the viewer. In response to the switching of the signal S1, the control unit 5 instructs the signal creating unit 1 to perform the mute process and switches the identifier ID1. In response to the instruction from the control unit 5, the signal creation unit 1 performs a mute process on the audio data D1 to lower the audio output level.
[0038]
On the other hand, even if the signal S1 is switched at the time T2, the control unit 5 does not immediately switch the switching instruction signal S2. The control unit 5 switches the switching instruction signal S2 at time T3 after waiting a predetermined number of IEC60958 standard blocks. Thus, at the time of output switching, the time for the system controller to recognize and control the output signal in the receiver such as an AV amplifier that receives the signal D4 is taken into consideration, and the recognition and control of the voice coded data after switching are performed accurately. Therefore, it is possible to output a sound without generating a noise signal in the receiver.
[0039]
The control unit 5 switches the switching instruction signal S2 when detecting at the time T3 that the cycle of the block of the IEC60958 standard has ended based on the signal S3 from the conversion unit 4. The signal switching unit 3 switches the connection from the signal generation unit 1 to the signal generation unit 2 in response to the switching of the switching instruction signal S2 from the control unit 5, and the conversion unit 4 receives the identifier ID1 and outputs it as the output signal D4. I do. Thus, regardless of the timing of the switching instruction from the viewer, the signal D4 is output without switching to the audio coded data in the middle of the block where the identifier in the channel status expects the audio data.
[0040]
Further, at time T2, the signal creation unit 1 performs mute processing on the audio data D1 to lower the audio output level, and switches the switching instruction signal S2 at time T3. Since data during the mute processing from time T2 to time T3 is held, the data structure of the output signal D4 during the mute processing can also be guaranteed.
[0041]
When switching from the audio data D1 to the encoded audio data D2, the audio data D1 may be switched to the encoded audio data D2 after inserting a silent data portion at the end. Thereby, at the time of output switching, the system controller in the receiver such as an AV amplifier that receives the output signal D4 recognizes the silence data portion, mutes the output of the receiver in advance, or switches from audio data to audio encoded data. Can be predicted. As a result, even when invalid data that is not a digital signal conforming to IEC60958 occurs at the time of switching in the conversion unit 4, it is possible to output sound without generating a noise signal in a receiver or the like.
[0042]
Next, a case of switching from speech encoded data to speech data will be described with reference to FIG.
[0043]
At the time T1, the signal switching unit 3 is connected to the signal generation unit 2 and outputs the encoded voice data D2 from the signal generation unit 2 as a signal D3.
[0044]
Next, at time T2, the signal S1 switches according to the switching instruction from the viewer. In response to the switching of the signal S1, the control unit 5 switches the switching instruction signal S2. The signal switching unit 3 switches the connection from the signal generation unit 2 to the signal generation unit 1 in response to the switching of the switching instruction signal S2 from the control unit 5. Thereafter, at time T3, the control unit 5 switches the identifier ID1.
[0045]
Here, the switching instruction signal S2 is switched in accordance with the switching instruction from the viewer, but the switching signal S2 is switched in accordance with the timing at which the signal S3 from the converter 4 detects that the cycle of the IEC60958 standard block has ended. You may. As a result, when the output of the signal switching unit 3 is switched, the audio data D1 including the synchronization signal at the beginning is output.
[0046]
Further, when switching from the coded audio data D2 to the coded audio data D1, a silent data portion may be inserted at the end of the coded audio data D2 before switching to the audio data D1. Thereby, at the time of output switching, the system controller in the receiver such as the AV amplifier which receives the output signal D4 recognizes the silent data portion, and performs muting processing of the output of the receiver or the like, or switches from the voice coded data to the voice data. Can be predicted. As a result, even when invalid data that is not a digital signal conforming to IEC60958 occurs at the time of switching in the conversion unit 4, it is possible to output sound without generating a noise signal in a receiver or the like.
[0047]
As described above, in the signal processing circuit according to the first embodiment, when receiving an output switching instruction from a viewer at the time of reproducing a disc by a DVD player, the signal processing circuit outputs a signal at the timing of detecting that the cycle of the IEC60958 standard block has ended. In order to adjust the output switching timing of the switching unit 3, the output data D4 whose cycle is guaranteed can be supplied to a peripheral device such as a digital AV amplifier with a built-in decoder via a digital audio interface. As a result, it is possible to eliminate the operation failure and the noise caused by the decoder, which have conventionally occurred.
[0048]
Also, when switching the output between the audio data D1 and the encoded audio data D2, the audio data D1 is muted to temporarily lower the audio level, thereby preventing the generation of a shock sound when the audio is switched. Can be. Therefore, the audio output switching operation which could only be performed when the operation of the DVD player was stopped in the past can be performed during disc playback, and the viewer can switch the audio from Japanese to another language while watching the video. Can be easily performed.
[0049]
Also, for example, when switching the output of a plurality of pieces of encoded audio data, such as when a plurality of pieces of encoded audio data are recorded on a track of a DVD video disc, the timing of the output switching is detected by detecting the periodic state of both pieces of data. , The output is switched while guaranteeing the cycle of both data, and the same effect as described above can be obtained.
[0050]
【The invention's effect】
According to the signal processing circuit of the present invention, even when an output switching instruction is received at the time of reproducing a disc by a DVD player equipped with the signal processing circuit, the encoded audio data guaranteed in the IEC60958 standard block is transmitted to the decoder. Thus, it is possible to prevent the decoder from malfunctioning and noise from occurring conventionally. Therefore, the audio output switching operation which could only be performed when the operation of the DVD player or the like has been stopped can be performed at the time of operating the disc, and the viewer can easily perform the audio switching operation while watching the video. And convenience can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a signal processing circuit according to a first embodiment of the present invention.
FIG. 2 is a time chart for explaining an operation of switching from audio data to audio encoded data.
FIG. 3 is a time chart for explaining an operation of switching from audio encoded data to audio data.
FIG. 4 is a block diagram showing an overall configuration of a conventional signal processing circuit.
FIGS. 5A and 5B are diagrams showing a format of a digital signal conforming to IEC60958.
FIG. 6 is a time chart for explaining the operation of the signal processing circuit shown in FIG. 3 when receiving a voice switching instruction from a viewer during reproduction of a disc by a DVD player or the like.
[Explanation of symbols]
1, 2 signal creation unit 3 signal switching unit 4 conversion unit 5 control unit

Claims (2)

Voice data generating means for generating voice data;
Voice encoded data generating means for generating voice encoded data,
The receiving voice data and the speech encoded data, and the signal switching means for outputting the voice data or the speech encoded data selectively,
Control means for outputting an identifier for identifying whether the data is audio data or audio encoded data,
A signal processing circuit example Bei and conversion means for outputting a signal of a format having the additional information including the identifier from the control means and the data portion comprising data from said signal switching means,
The control means,
After switching the identifier to a state indicating the speech encoded data from the state indicating the audio data, and controls the signal switching means to switch the output to the speech encoded data from the voice data,
further,
A signal processing circuit , wherein the audio data has a silent data portion inserted at the end . The signal processing circuit according to claim 1,
The conversion means,
A signal processing circuit for converting data from the signal switching means into a signal having a format conforming to the IEC60958 standard and outputting the signal.

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