JP5012859B2 - Volume control device - Google Patents

Description

  The present invention relates to an apparatus for adjusting the volume level of audio data (for example, content). More specifically, the present invention relates to a device that automatically adjusts the volume level of audio data and outputs it as audio by an external device.

  Conventional Patent Document 1 describes a playback device that receives and plays back content from a network. This playback apparatus has a function of automatically adjusting the playback volume of content with different audio levels.

  The function of automatically adjusting the playback volume is realized as follows. First, the playback device detects the volume of the content with a volume detector. Then, the playback device determines whether or not the volume detected by the volume detector exceeds the threshold Th1. When the threshold value Th1 is exceeded, the playback device adjusts the volume of the content according to the volume detected by the volume detection unit. As a result, the playback apparatus adjusts the volume of the output content so that it does not become too loud for the user.

  Further, in this playback apparatus, it is determined whether or not the volume detected by the volume detector is below a threshold Th2. When the playback device is below the threshold Th2, the playback device adjusts the volume of the content according to the volume detected by the volume detector. As a result, the playback apparatus adjusts the volume of the output content so that it is not too low for the user.

JP 2003-134419 A

  However, Patent Document 1 has the following three problems.

  The first problem is that the volume level to be output is set within a certain threshold, so that the volume level inherent in the audio data is lost. For this reason, the output sound is unnaturally heard by the user.

  The second problem is that when the volume level of the audio data is lower than the threshold, the volume is considered to be adjusted to at least the threshold. Therefore, the volume level of noise (eg, background noise) included in the audio data is also considered. Will adjust. For this reason, the user hears the output voice as a noisy voice.

  The third problem is a problem that occurs when it is assumed in Patent Document 1 that there are a plurality of output forms of the external device. For example, when audio can be output in 2ch and 5.1ch output forms in an external device, the volume of the entire audio data (2ch and 5.1ch audio signals) is adjusted according to the volume level of the audio data. Therefore, it is not possible to compensate for the volume difference between the plurality of audio signals. In this case, when outputting the audio signals of 2ch and 5.1ch as sound, the volume of one is too small or too large for the user.

  The principle of the occurrence of the third problem will be described by taking 2ch and 5.1ch audio signals as an example. For example, a 2ch audio signal is generated by downmixing from a 5.1ch audio signal. In this case, in order to change the 5.1ch audio signal to the 2ch audio signal, the volume level of the 2ch audio signal is smaller than the volume level of the 5.1ch audio signal in order to prevent overflow.

This will be specifically described. For example, when down-mixing 5 channels of center (C), left (L), right (R), left surround (Ls), and right surround (Rs) to 2 channels (Lo / Ro), the following formula Can be expressed as
[Formula 1]
Lo = 1 / X x (L + r1 x C + r2 x Ls)
Ro = 1 / X x (R + r1 x C + r3 x Rs)
1 / X: Normalization factor
r1: Center downmix coefficient
r2: Ls downmix coefficient
r3: Downmix coefficient of Rs Therefore, when the maximum amplitude of each channel is 1, the signals of 5 channels are C = 0.5, L = 1, R = 1, Ls = 0.2, Rs = 0.2, respectively. If the coefficients are 1 / X = 0.3 and r1 = r2 = r3 = 0.7, Lo is as follows.
[Formula 2]
Lo = 0.3 × (1 + 0.7 × 0.5 + 0.7 × 0.2)
= 0.3 x 1.49
= 0.447
That is, Lo is 0.447, and the amplitude is less than 1/2 with respect to L = 1.

  For this reason, for example, if the volume level of the 5.1ch and 2ch audio signals is adjusted according to the volume level (L = 1) of the 5.1ch audio signal, the volume level of the 2ch audio signal becomes small. It becomes too much.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a volume adjusting device that can provide audio data having a volume more optimal for a user.

In addition, a volume control device that solves the third problem includes an acquisition unit that acquires a first audio signal that can be output in a first output form, and a second output based on the acquired first audio signal. Generating means for generating a second audio signal capable of outputting sound in a form, and volume adjusting means for adjusting volume levels of the first and second audio signals by a gain value. In the case of adjusting the volume level of the first audio signal, the volume adjusting unit adjusts the volume level of the second audio signal while adjusting the gain level based on the volume level of the first audio signal. Then, the gain value is adjusted based on the volume level of the second audio signal.

  ADVANTAGE OF THE INVENTION According to this invention, audio | voice data with a more optimal volume can be provided with respect to a user.

The figure which shows the structure of the recorder which concerns on this Embodiment Functional block diagram of LSI according to the present embodiment Functional block diagram of volume control means according to the present embodiment The figure which shows the volume adjustment example (output signal according to an input signal) which concerns on this Embodiment Flow chart showing volume adjustment operation according to the present embodiment Flow chart showing volume adjustment operation according to the present embodiment Flow chart showing volume adjustment operation according to the present embodiment The figure for demonstrating the calculation operation | movement of the maximum peak value which concerns on this Embodiment The figure for demonstrating the setting gain value which concerns on this Embodiment

(Embodiment 1)
The present embodiment will be described with reference to the drawings. In the present embodiment, the configuration and operation of the recorder 1 will be described. This will be specifically described below.

<1. Overview of the present embodiment>
The recorder 1 acquires audio data from the outside or the inside. The recorder 1 performs a volume adjustment process on the audio data. The recorder 1 outputs the audio data whose volume has been adjusted via an external device.

<2. Audio data>
The audio data may be 7.1ch, 5.1ch, 2ch audio signals, or the like. In this embodiment, the case where the recorder 1 receives an audio encoded signal obtained by encoding a 7.1ch audio signal will be described as an example. However, in the other embodiments, the present invention is not limited to this. Absent.

  In this embodiment, the audio data and the video data are collectively referred to as audio video data.

<3. Configuration of Recorder 1 (FIGS. 1 and 2)>
Before describing the configuration of the recorder 1, the relationship between the recorder 1 and other devices will be described with reference to FIG.

  The recorder 1 can acquire audio-video data from the antenna 2 connected to the outside, the Internet 100 and the optical disc 4. The recorder 1 can acquire audio / video data from the HDD 5 provided therein.

  The antenna 2 receives radio waves of television broadcasting and transmits the received signal to the recorder 1. Further, the Internet 100 transmits an audio / video data acquisition request from the recorder 1 to the external terminal, and transmits audio / video data returned from the external terminal to the recorder 1. The optical disk 4 is an optical disk such as a CD, a DVD, or a Blu-ray, and can be inserted into an optical drive provided in the recorder 1. The recorder 1 can acquire audio / video data from the optical disk 4 via the optical drive. Further, the HDD 5 is a recording device that is provided in the recorder 1 and records audio-video data. Therefore, the recorder 1 can acquire audio / video data from the HDD 5. In this way, the recorder 1 can acquire audio / video data.

  The recorder 1 performs a volume adjustment process on the audio data included in the acquired audio-video data and outputs the audio to the outside. The recorder 1 outputs sound via the surround system 10, the speaker 11, and the television 12.

  The surround system 10 can output an audio data output signal (HDMI signal) from the recorder 1 as audio. The surround system 10 can output sound in a 7.1ch output form by using seven speakers and one woofer. The speaker 11 can output an output signal (analog signal) of audio data from the recorder 1 as audio. The speaker 11 can output sound in an output form of 5.1 ch by using five speakers and one woofer. Furthermore, the television 12 can output the audio data output signal (optical digital signal) from the recorder 1 as audio. The television 12 can output sound in a 2ch output form by two speakers. The television 12 is provided with a display, and an output signal of video data from the recorder 1 can be output as a video.

  Next, the configuration of the recorder 1 will be described with reference to FIGS. The tuner 3 modulates the signal received from the antenna 2. The tuner 3 inputs the modulated signal to the LSI 6. The optical drive inputs a signal read from the optical disk 4 to the LSI 6. The HDD 5 inputs the recorded audio / video data to the LSI 6. The communication unit exchanges information with an external terminal connected to the Internet 100. When information is transmitted from the LSI 6 to the external terminal, the communication unit transmits the information to the network 100. On the other hand, when the communication unit receives information from the Internet 100, it transmits the received audio / video data to the LSI 6.

  Here, the LSI 6 can select from which information source the audio / video data is acquired. For example, when the LSI 6 is instructed to obtain information from a broadcast wave by a user operation, the LSI 6 controls the tuner 3 to acquire audio / video data of a desired channel from the broadcast wave.

  The LSI 6 is a semiconductor chip that performs volume adjustment processing on audio data included in audio / video data. The processing of the LSI 6 will be described later.

  The HDMI output terminal 7 is a terminal that outputs a signal input from the LSI 6 to the surround system 10. The analog audio output terminal 8 is a terminal that outputs a signal input from the LSI 6 to the speaker 11. The optical digital audio output terminal 9 is a terminal for outputting a signal input from the LSI 6 to the television 12. Although not shown, a DA converter is provided between the analog audio output terminal 8 and the LSI 6 to convert a digital output from the LSI into an analog output.

<4. Functional Block of LSI 6>
The LSI 6 has the following functional blocks in order to perform volume adjustment processing on audio data included in the input audio / video data. This will be specifically described below.

  The stream input unit 13 separates the input audio / video data into a video encoded signal (an example of video data) and an audio encoded signal (an example of audio data). The stream input unit 13 stores the separated video encoded signal in the video input buffer 14. The stream input unit 13 stores the separated audio encoded signal in the audio input buffer 18. The video input buffer 14 and the audio input buffer 18 are buffers that temporarily store encoded signals.

  The video decoder 15 decodes the video encoded signal read from the video input buffer 14. The video decoder 15 stores the decoded video signal in the video output buffer 16. The video output buffer 16 is a buffer that temporarily stores the decoded video signal. The video output unit 17 extracts a video signal from the video output buffer 16 and outputs it to the television 12.

  The audio decoder 19 decodes the audio encoded signal read from the audio input buffer 18. The audio decoder 19 stores the decoded audio signal in the audio output buffer 20. The audio output buffer 20 is a buffer that temporarily stores the decoded audio signal. The audio output unit 21 extracts an audio signal from the audio output buffer 20 in accordance with control from the control unit 101, and outputs the audio signal to the first volume adjustment unit 22, the second volume adjustment unit 23, or the third volume adjustment unit 24. The first volume adjustment unit 22, the second volume adjustment unit 23, and the third volume adjustment unit 24 perform volume adjustment processing on the audio signal. Then, the first volume adjustment unit 22, the second volume adjustment unit 23, and the third volume adjustment unit 24 output the audio signal subjected to the audio adjustment process to an external device (the surround system 10, the speaker 11, and the television 12).

  The control unit 101 controls the video decoder 15 and the audio decoder 19 to control the timing for decoding the video encoded signal and the audio encoded signal. In addition, the control unit 101 controls the video output unit 17 and the audio output unit 21 to control the timing for outputting the video signal and the audio signal. The control unit 101 also controls the audio output unit 21 to control the output destination of the audio signal.

[Control of the control unit 101 for the audio decoder 19]
Here, the control of the control unit 101 for the audio decoder 19 will be described.

  The control unit 101 controls the audio decoder 19 to decode the audio encoded signal. Further, the control unit 101 controls the audio decoder 19 to generate an audio signal having a new number of channels based on the decoded audio signal.

  A specific process when the control unit 101 controls the audio data 19 so as to generate an audio signal having a new number of channels will be described.

  First, the control unit 101 detects what audio signal (channel sampling frequency) is set to be output from each output terminal 7, 8, 9. Each output terminal will be described.

  An example of the HDMI output terminal 7 will be described. The HDMI output terminal 7 is configured so that connection destination information can be acquired from a connected external device (surround system 10). Therefore, the control unit 101 acquires connection destination information from the external device via the HDMI output terminal 7. The connection destination information includes, for example, information indicating that a 7.1ch audio signal can be output. Then, the control unit 101 causes the user to select the number of channels of the audio signal output from the HDMI output terminal 7 from candidates corresponding to the connection destination. Candidates for the number of channels that can be selected by the user include, for example, “7.1ch” and “no output”. Thereby, the number of channels of the audio signal output from the HDMI output terminal 7 is set by the user. In the present embodiment, it is assumed that “7.1ch” is selected as the output signal of the HDMI output terminal 7.

  Next, since the analog audio output terminal 8 is not capable of bidirectional communication unlike the HDMI output terminal 7, information on the connected external device cannot be obtained. Therefore, the control unit 101 allows the user to select the number of channels of the audio signal output from the analog audio output terminal 8 from predetermined candidates. The predetermined candidates for the number of channels that can be selected by the user include, for example, “5.1ch” and “no output”. Thereby, the number of channels of the audio signal output from the analog audio output terminal 8 is set by the user. In the present embodiment, it is assumed that “5.1ch” is selected as the output signal of the analog audio output terminal.

  Next, since the optical digital audio output terminal 9 similarly cannot perform bidirectional communication like the HDMI output terminal 7, information on the connected external device cannot be obtained. Therefore, the control unit 101 allows the user to select the number of channels of the audio signal output from the optical digital audio output terminal 9 from predetermined candidates. The predetermined candidates for the number of channels that can be selected by the user include, for example, “PCM output (2.0 ch)” and “no output”. Thereby, the number of channels of the audio signal output from the optical digital audio output terminal 9 is set by the user. In the present embodiment, it is assumed that “PCM (2.0 ch)” is selected as the output signal of the optical digital audio output terminal.

  In this way, the control unit 101 can detect what audio signal (number of channels) is set to be output from each output terminal 7, 8, 9.

  Next, the control unit 101 acquires channel information of the audio signal. For example, the control unit 101 inquires of the audio decoder 19 about the number of channels of the audio signal. In response to an inquiry from the control unit 101, the audio decoder 19 reads information indicating the number of channels of the audio signal (hereinafter referred to as channel information) from the header information of the audio encoded signal recorded in the audio input buffer 18. To the control unit 101. For example, in the present embodiment, the control unit 101 can obtain 7.1ch information as information indicating the number of channels.

  Then, the control unit 101 sets the number of channels (7.1ch, 5.1ch, 2ch) set to be output from each output terminal 7, 8, 9 and the audio signal included in the audio encoded signal. The audio decoder 19 is controlled so as to generate an audio signal having a new number of channels (5.1 ch and 2 ch) based on the channel information (7.1 ch). This is because a 7.1-ch audio signal can be obtained by decoding the audio encoded signal, so that it is necessary to newly generate 5.1-ch and 2-ch audio signals.

  Processing of the audio decoder 19 controlled by the control unit 101 will be described. Hereinafter, processing when the control unit 101 instructs the audio decoder 19 to generate audio signals having the number of channels (5.1 ch and 2 ch) will be described.

  First, the audio decoder 19 decodes the audio encoded signal. For example, the audio decoder 19 decodes an audio encoded signal to generate a 7.1ch audio signal.

  And the audio decoder 19 produces | generates an audio signal required for the production | generation according to control of the control part 101 based on the decoded audio signal. For example, the audio decoder 19 newly generates 5.1ch and 2ch audio signals by downmix based on the 7.1ch audio signals.

  The audio decoder 19 records the generated audio signal in the audio output buffer 20 for each channel. At this time, the audio decoder 19 transmits, as a pair of information, information indicating the number of channels and information indicating the address of the audio output buffer 20 in which the audio signal corresponding to the number of channels is recorded. . That is, in the present embodiment, the audio decoder 19 stores 7.1ch, 5.1ch, and 2ch audio signals in the audio output buffer 20, so that information in three pairs is transmitted. For example, when there are addresses 1 to 30000 in the audio output buffer 20, the audio decoder 19 converts 7.1ch audio signals to addresses 1 to 0500, 5.1ch audio signals to addresses 10001 to 10500, and 2ch audio. When the signal is recorded in 20001 to 20500, the audio decoder 19 transmits the following information (channel information and storage destination address) to the control unit 101.

Transmission information (1): channel information “7.1”, address “00001”
Transmission information (2): channel information “5.1”, address “10001”
Transmission information (3): channel information “2.0”, address “20001”
Here, the audio decoder 19 decodes the audio encoded signal in units of frames. The frame is, for example, 1536 samples as one unit. Note that the audio decoder 19 may transmit the transmission information to the control unit 101 each time decoding processing in units of frames is performed.

[Control of the control unit 101 for the audio output unit 21]
Next, control of the control unit 101 with respect to the audio output unit 21 will be described. The control unit 101 acquires transmission information from the audio decoder 19. The control unit 101 controls the audio output unit 21 based on this transmission information. That is, the audio output unit 21 performs processing according to the transmission information of the audio decoder 19 (first volume adjustment unit 22, second volume adjustment unit 23, third volume adjustment unit 24) and terminals (HDMI). The output terminal 7, the analog audio output terminal 8, and the optical digital audio output terminal 9) are determined. The audio output unit 21 sequentially reads out the audio signal from the audio output buffer 20 and performs processing in the corresponding block. For example, since the audio signal of the channel information “7.1” is set to be output to the surround system 10, the first volume adjustment unit 22 performs processing. Since the audio signal of channel information “5.1” is set to be output to the speaker 11, the second volume adjusting unit 23 performs processing. Since the audio signal of the channel information “2.0” is set to be output to the television 12, the third volume adjusting unit 24 performs processing.

  Here, the audio output unit 21 reads out the audio signal block by block from the audio output buffer 20 under the control of the control unit 101, and the first volume adjusting unit 22 and the like (the first volume adjusting unit 22 and the second volume adjusting unit). 23 or the third volume adjusting unit 24). Here, the block is a block of a plurality of sample data. In the present embodiment, 64 samples are used as one block. Therefore, for example, when receiving the transmission information, the audio output unit 21 sequentially reads out the sample data from the position corresponding to the address information in units of blocks and inputs the sample data to the first volume adjusting unit 22 and the like. The audio output unit 21 sequentially reads out one block of transmission information until one frame (1536 samples = 24 blocks) has been read.

  Next, processing in the first volume adjustment unit 22, the second volume adjustment unit 23, and the third volume adjustment unit 24 will be described (FIG. 3). FIG. 3 illustrates the processing of the first volume adjustment unit 22. In this operation, the volume adjustment processing for the audio signal of a certain block “N + 1” is described.

  The level detector 221 detects the peak volume level of the input signal within a predetermined time. The processing of the level detection unit 221 will be described with reference to FIG. This will be described at the beginning of playback and during playback.

  Processing at the start of reproduction will be described. The level detection unit 221 calculates the peak sound volume in the input block unit. Since the block is composed of 64 samples, a value having the largest volume level is extracted from the 64 samples. Here, for 7.1ch audio, “C” “L” “R” “Lss (left side surround)” “Rss (right side surround)” “Lsb (left side back)” “Rsb (right side back) ) ”. Therefore, when calculating the peak sound volume in the block, it is preferable to extract the sound volume level that is the highest in channel units and the highest between channels. For example, when the volume level value of “L” of the 25th sample among 64 samples is the maximum, that value becomes the peak value in the block unit. If comprised in this way, in multi-channel audio | voice data, the largest volume level (peak volume level) can be detected for every channel and the largest between channels. As a result, even when the volume adjusting units 22, 23, and 24 adjust the audio data of the entire multi-channel based on the peak volume level, the audio output of the audio data of a certain channel is prevented from being clipped. it can. That is, it is possible to avoid that the audio output of the audio data of a certain channel is partially saturated.

  The level detection unit 221 calculates the peak sound volume within a predetermined period based on the peak sound volume in the block unit thus obtained, but there is no past block at the start of reproduction. Therefore, the level detection unit 221 sets the calculated peak volume within the block unit as the peak volume within a predetermined period. The level detection unit 221 stores the calculated peak volume within the block unit.

  Next, processing during reproduction will be described. The level detection unit 221 calculates the peak sound volume in the input block unit. For example, the level detection unit 221 calculates the peak volume of the block “N + 1”. In the middle of playback, the level detection unit 221 records the peak volume in the block unit acquired in the past, so the peak volume in the block unit currently calculated (block “N + 1” in FIG. 8) and the past calculation. Using the plurality of peak volumes within the block unit (blocks “N” to “N-118” in FIG. 8), the peak volume of the largest volume within a predetermined period is calculated. In this way, the level detection unit 221 calculates the peak sound volume within a predetermined period.

  The gain setting method determination unit 222 compares the peak sound volume level detected by the level detection unit 221 with a plurality of threshold values specified in advance. The gain calculation unit 223 sets a gain value according to the comparison result.

  In this embodiment, there are four gain setting methods.

  In the first method, when the peak sound volume level is larger than the first threshold, a gain value is set such that the peak sound volume level becomes the first threshold.

  In the second method, when the peak sound volume level is equal to or lower than the first threshold value and larger than the second threshold value, a gain value is set such that the input sound volume level and the output sound volume level match. That is, a gain value that does not change the input volume level is set.

  In the third method, when the peak sound volume level is equal to or lower than the second threshold value and larger than the third threshold value, a gain value is set such that the peak sound volume level becomes the second threshold value.

  In the fourth method, when the peak volume level is equal to or lower than the third threshold value, a gain value is set such that the input volume level and the output volume level match. That is, a gain value that does not change the input volume level is set.

  As described above, the gain calculation unit 223 sets the gain value according to the comparison result of the gain setting method determination unit 222.

  Here, in the gain calculation unit 223, the gain value set when the current block “N + 1” is input with respect to the gain value set when the previous block “N” is input, When the value changes by a predetermined value or more, smoothing processing is performed. Hereinafter, a specific example of the smoothing process will be described (FIG. 9).

  In FIG. 9, it is assumed that the gain value set when the block “N” is input is “Y”, and the gain value set when the block “N + 1” is input is “X”.

  In this case, the gain calculation unit 223 adjusts the set gain at the timing of the block “N + 1” so that the gain value set when the block “N + 5” is input becomes “X”. In this way, it is possible to prevent the output volume from changing greatly when the volume level changes greatly. As a result, the change in the output volume level is made smoother and natural volume adjustment can be performed.

  The maximum gain determination processing unit 224 compares the gain value set by the gain calculation unit 223 with a predetermined gain value (maximum gain), and if the predetermined gain is exceeded, the set gain value is set to the predetermined gain. Correct to the value. With this configuration, it is possible to limit the gain adjustment range of the sound volume level, and to reduce the change in the sound volume level within a certain range.

  When the overflow determination unit 225 adjusts the peak volume level detected by the level detection unit 221 using the corrected gain value calculated by the maximum gain determination processing unit 224, the adjusted peak volume level exceeds the upper limit value. It is determined whether or not. When the overflow determination unit 225 determines that the adjusted peak volume level exceeds the upper limit value, the overflow determination unit 225 adjusts the corrected gain value so that the adjusted peak volume level becomes the upper limit value. In the present embodiment, the upper limit value is a value indicating the maximum value of the output volume level.

  The gain adjustment unit 226 adjusts the audio signal in units of blocks input to the gain adjustment unit 226 based on the adjusted gain value calculated in this way. For example, the gain adjustment unit 226 waits for the processing of the level detection unit 221 to the overflow determination unit 225 for the block “N + 1” and adjusts the volume of the audio signal of the block “N + 1” based on the adjusted gain value. Thus, for the gain adjustment of the audio signal in the block unit of the block “N + 1”, a gain value reflecting the peak value of the audio signal of the block “N + 1” can be used.

<5. Example of operation>
The volume adjustment operation of the LSI 6 of this embodiment will be described with reference to FIGS.

  The control unit 101 is based on information on whether or not it is connected to the HDMI output terminal 7, analog audio output terminal 8, optical digital audio output terminal 9, and channel information of the audio encoded signal from the audio decoder 19. Determine the number of audio signals that need to be generated. The control unit 101 controls the audio decoder 19 to generate audio signals having the number of channels that need to be generated. For example, in the present embodiment, the audio decoder 19 generates 7.1ch, 5.1ch, and 2ch audio signals. At this time, the control unit 101 acquires transmission information (channel information and storage destination address information) from the audio decoder 19.

  The control unit 101 sends transmission information to the audio output unit 21. Specifically, the control unit 101 controls the audio output unit 21 using transmission information at a timing synchronized with the video signal. For example, at the start of reproduction, the control unit 101 transmits information (1): channel information “7.1” address “00001”, transmission information (2): channel information “5.1” address “10001”, transmission information. (3): Transmit channel information “2.0” address information “20001”. In this way, the control unit 101 can output audio of each channel information while synchronizing with the video signal.

  The control unit 101 transmits the next transmission information to the audio output unit 21 at the timing of synchronization with the next video signal. The information transmitted by the control unit 101 at the next timing is, for example, transmission information (1): channel information “7.1” address “00501”, transmission information (2): channel information “5.1” address “10501”. , Transmission information (3): channel information “2.0” address information “20501”.

  The audio output unit 21 determines whether 7.1ch, 5.1ch, and 2ch audio signals exist based on the acquired transmission information. The audio output unit 21 acquires data specified by the address information from the audio output buffer 20 in accordance with the existing channel information. Then, the audio output unit 21 transmits to the corresponding audio adjustment unit.

  The processing operation of the audio output unit 21 will be described (FIG. 5). In FIG. 5, the audio output unit 21 reads sample data from the audio output buffer in units of blocks and inputs the sample data to any one of the volume adjustment units 22, 23, and 24.

  The audio output unit 21 determines whether or not the channel information “7.1” is included based on the transmission information from the control unit 101 (S1). When the channel information “7.1” is included, the audio output unit 21 acquires an audio signal in units of blocks based on the corresponding address information (S2). In addition, the audio output unit 21 outputs the acquired audio signal to the first volume control unit 22 (S3).

  The audio output unit 21 determines whether or not the channel information “5.1” is included based on the transmission information from the control unit 101 (S4). When the channel information “5.1” is included, the audio output unit 21 acquires an audio signal in units of blocks based on the corresponding address information (S5). Also, the audio output unit 21 outputs the acquired audio signal to the second volume adjustment unit 23 (S6).

  The audio output unit 21 determines whether or not the channel information “2.0” is included based on the transmission information from the control unit 101 (S7). When the channel information “2.0” is included, the audio output unit 21 acquires an audio signal in units of blocks based on the corresponding address information (S8). Also, the audio output unit 21 outputs the acquired audio signal to the third volume adjustment unit 24 (S9).

  In each of the first volume adjustment unit 22, the second volume adjustment unit 23, and the third volume adjustment unit 24, a volume adjustment process is performed. Since the operations of the first volume adjusting unit 22, the second volume adjusting unit 23, and the third volume adjusting unit 24 are the same, an example of the operation of the first volume adjusting unit 22 will be described as a representative example (FIG. 6). In the present embodiment, an example in which an audio signal of the block “N + 1” is input to the first volume adjustment unit 22 will be described. Note that the first sound volume adjusting unit 22, the second sound volume adjusting unit 23, and the third sound volume adjusting unit 24 may have different numbers of channels or sampling frequencies of audio signals, for example.

  First, the first volume adjustment unit 22 detects the peak volume level within a block unit (block “N + 1”) (T1).

  Next, the first volume control unit 22 detects the peak volume level within a predetermined period from the peak volume level within the block unit and the beak volume level within the past block unit (T2). The first volume adjusting unit 22 holds, as a history, a peak volume level within a block unit for a predetermined period (for example, 100 msec, 120 blocks). Here, the first volume control unit 22 stores a history of the peak volume level in the ring buffer. Therefore, when detecting the peak volume level in the new block unit, the first volume adjustment unit 22 deletes the oldest history and registers it in the history instead. For example, the intra-block peak volume of block “N + 1” is registered instead of the intra-block peak volume of block “N-119” in FIG.

  Next, the first volume adjustment unit 22 compares the detected peak volume level within a predetermined period with a threshold value, and determines a gain setting method (T3).

  The determination operation of the gain setting method will be described (FIG. 7). Three threshold values are used in the gain setting method determination operation. The first threshold value, the second threshold value, and the third threshold value are set in descending order of level.

First, the first volume adjusting unit 22 compares the peak volume level with the first threshold (U1). When the peak volume level> the first threshold value is YES, the first volume adjustment unit 22 selects a gain setting method such that the output volume level = the first threshold value (U2). When U1 is NO, the first volume adjuster 22 compares the peak volume level with the second threshold (U3). When the peak volume level> = the second threshold value is YES, the first volume adjustment unit 22 selects a gain setting method such that the output volume level = the input volume level (U4). The first volume adjuster 22 compares the peak volume level with the third threshold when U3 is NO (U5). The first volume adjuster 22 determines that the peak volume level> = the third threshold is YES. A gain setting method is selected such that the output volume level is equal to the second threshold (U6).
When U5 is NO, the first volume adjuster 22 selects a gain setting method such that the output volume level = the input volume level (U7).

  The first volume adjuster 22 calculates a gain value based on the gain setting method selected in step T3 (T4). The first sound volume adjusting unit 22 performs the above-described smoothing process at a certain time (for example, 4 sec) when calculating the gain. As a result, the output volume level is smoothly changed to realize natural volume adjustment.

Next, the first sound volume adjustment unit 22 compares the calculated gain value with a predesignated maximum gain value (T5).
When the gain value> the maximum gain value is YES, the first volume adjusting unit 22 corrects the gain value so that the gain value = the maximum gain value (T6).

  Next, the first volume adjuster 22 compares the gain value and the peak volume level with the upper limit (T7). When the value obtained by multiplying the gain value and the peak sound volume level> the upper limit value is YES, the first sound volume adjusting unit 22 adjusts the gain value so that the output sound volume level = the upper limit value (T8). Finally, the first volume adjusting unit 22 adjusts the volume of the audio signal of the block “N + 1”, which is the input signal, by applying the gain value set in steps T1 to T7 (T9).

<6. Setting example of gain value set in first sound volume adjusting unit 22>
A setting example of the gain value set in the present embodiment by the above-described operation will be described. Note that the setting values shown in FIG. 4 do not consider (apply) the smoothing process described above. In FIG. 4, the horizontal axis indicates the input volume level (peak volume level), and the vertical axis indicates the output volume level.

  For example, when the peak sound volume level is larger than the first threshold value (range I), it can be seen that gain adjustment is performed so that the peak sound volume level becomes the first target value. The range I is an example of a first range.

  In addition, when the peak sound volume level is larger than the second threshold value and equal to or smaller than the first threshold value (range II), it is understood that the gain adjustment is performed so that the input sound volume level = the output sound volume level. Range II is an example of the second range.

  Furthermore, it can be seen that the following gain adjustment is performed when the peak sound volume level is larger than the third threshold and equal to or less than the second threshold (range III). In other words, when the gain value is adjusted so that the peak volume level becomes the second target value, when the gain value can be adjusted below the maximum gain value, the gain value is set so as to become the second target value. When it is larger than the maximum gain value, set the maximum gain value. Range III is an example of a third range. Moreover, a range of gain values larger than the maximum gain value is an example of a predetermined range.

  In addition, when the peak volume level is equal to or lower than the third threshold (range IV), it can be seen that gain adjustment is performed so that the input volume level = the output volume level. Range IV is an example of a fourth range.

<7. Summary>
The present embodiment includes an LSI 6 that acquires audio data and an LSI 6 that adjusts the volume level of the acquired audio data with a gain value. Then, the LSI 6 calculates a gain value so that the volume level is converted into the second target value when the volume level of the audio data is smaller than the second threshold value, and when the calculated gain value is larger than the maximum gain value, Adjust the volume level of the audio data with the maximum gain value.

  In this way, since gain adjustment in a range larger than the maximum gain value is eliminated, it is possible to reduce the loss of the volume level inherent in the audio data.

  In the present embodiment, when the volume level of the audio data is equal to or smaller than the third threshold, the LSI 6 adjusts the gain value so that the volume level of the audio data is the same for input and output. Then, the LSI 6 adjusts the volume with a gain value that increases the volume level of the audio data when the volume level of the audio data is greater than the third threshold and is below the second threshold.

  In this way, it is possible to reduce the fact that the background noise increases due to the increase in audio data below the third threshold.

  In the present embodiment, an audio output unit 21 that can acquire a 7.1ch first audio signal and a 5.1ch second audio signal, and a volume adjustment unit 22 that adjusts the volume level of the acquired audio signal with a gain value. , 23, 24. When adjusting the volume level of the first audio signal, the volume adjusters 22, 23, and 24 adjust the volume level of the second audio signal while adjusting the gain level according to the volume level of the first audio signal. In this case, the gain value is adjusted according to the volume level of the second audio signal.

In this way, it is possible to compensate for the volume difference between the plurality of audio signals.
(Other embodiments)
The first embodiment has been exemplified as the present embodiment. However, the present invention is not limited to this. Therefore, another embodiment of the present invention will be described below. In addition, this invention is not limited to these, It is applicable also to embodiment modified suitably.

  In the first embodiment, the audio signal output from each output terminal (HDMI output terminal 7, analog audio output terminal 8, optical digital audio output terminal 9) is output via each adjustment processing unit. However, the present invention is not limited to this, and audio data having the same number of channels and the same sampling frequency may be output to each output terminal via the same adjustment processing unit. In this way, when performing the same output, it is not necessary to perform a plurality of audio adjustment processes.

  In the present embodiment, as shown in FIG. 5, the audio output unit 21 is configured to select the adjustment processing unit and the output terminal in a form corresponding to the channel. However, it is not limited to this.

  It should be noted that the audio data (5.1ch, 2ch) necessary for each output terminal is newly generated. However, when a plurality of channel configurations, for example, 7.1ch and 2ch are encoded in advance in the audio encoded signal, Only 5.1ch may be generated and the 2ch signal may be decoded and used.

  In the first embodiment, the recorder (FIGS. 1 and 2) has been described. However, a player without an HDD or a tuner or a set top box without an optical drive may be used.

  Further, the connection destination of each terminal in FIG. 1 is not limited to this.

  The present invention is applicable to recorders, players, televisions, personal computers, and the like.

1 Recorder 2 Antenna 3 Tuner 4 Optical Disk 5 HDD
6 LSI
7 HDMI output terminal 8 Analog audio output terminal 9 Optical digital audio output terminal 10 Surround system (7.1ch) (amplifier and speaker)
DESCRIPTION OF SYMBOLS 11 Speaker 12 Television 13 Stream input part 14 Video input buffer 15 Video decoder 16 Video output buffer 17 Video output part 18 Audio input buffer 19 Audio decoder 20 Audio output buffer 21 Audio output part 22 First sound volume adjustment part 221 Level detection part 222 Gain Setting method determination unit 223 Gain calculation unit 224 Maximum gain determination processing unit 225 Overflow determination unit 226 Gain adjustment unit 23 Second volume adjustment unit 24 Third volume adjustment unit 100 Network 101 Control unit

Claims (5)

Obtaining means for obtaining a first audio signal capable of outputting sound in a first output form;
Generating means for generating a second audio signal capable of outputting sound in a second output form based on the acquired first audio signal;
Volume adjusting means for adjusting the volume level of the first and second audio signals with a gain value;
The volume adjusting means is
When adjusting the volume level of the first audio signal, the volume level of the first audio signal is adjusted with a gain value based on a reference threshold value,
When adjusting the volume level of the second audio signal, the volume level of the second audio signal is adjusted with a gain value based on the reference threshold .
Volume control device. The volume adjusting means obtains a gain value based on the maximum volume level of the first audio signal and the reference threshold value, and based on the maximum volume level of the second audio signal and the reference threshold value. Gain value,
The volume control apparatus according to claim 1. The volume adjusting means is
When adjusting the volume level of an audio signal at a certain point in time, it is adjusted with a gain value based on the volume level of the audio signal in a certain period including the certain point in time and the reference threshold value
The volume control apparatus according to claim 1 or 2. The volume control device can be connected to an external device,
The volume control device includes:
And further comprising output means capable of outputting the first and second audio signals adjusted by the volume adjusting means to an external device in parallel.
The volume control apparatus of any one of Claims 1-3. The generating means downmixes the first audio signal to generate a second audio signal;
The volume control apparatus of any one of Claims 1-4.

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