Patent Description:
In recent years, music distribution using a high resolution sound source, which is audio data having a sound quality exceeding that of a music CD (CD-DA), has been increasingly performed.

In music distribution using a digital signal delta-sigma-modulated by a <NUM>-bit signal (hereinafter, also referred to as a DSD (Direct Stream Digital) signal), not only a <NUM> times DSD signal (64DSD signal) with <NUM> times a sampling frequency of <NUM> of a CD used in a super audio CD (SACD), but also a <NUM> times DSD signal (128DSD signal) and a <NUM> times DSD signal (256DSD signal) have been experimentally distributed.

The sampling frequency of the DSD signal is higher than that of a PCM (Pulse Code Modulation) signal, and thus a communication capacity in a case of performing streaming distribution is larger than that of the PCM signal. For example, when one frame is <NUM> seconds for a stereo (two-channel) signal, a data capacity of the <NUM>-DSD is about <NUM> Mbit per frame. PTL <NUM> through PTL <NUM> show various methods for converting a DSD signal into a PCM signal. In PTL <NUM> through PTL <NUM>, various techniques for reducing the computation complexity of the conversion process are introduced, such as the use of pre-computed tables to use in order to speed-up the conversion.

Therefore, the present applicant has previously proposed, in PTL <NUM>, a compression method in which a DSD signal is losslessly compressed and transmitted.

Meanwhile, as a countermeasure corresponding to a circumstance of a communication path, for example, there is a technique such as MPEG-DASH (Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP) in which a plurality of pieces of encoded data expressing the same content at different bit rates are stored in a content server, and a client apparatus receives, in a streaming manner, desired encoded data from among the plurality of pieces of encoded data in accordance with a communication capacity of a network.

The present applicant has proposed, in PTL <NUM>, a method of dynamically selecting a better-quality DSD signal for listening in accordance with a capacity of a communication line, from among signals of the same content and different bit-rates, e.g., a 64DSD signal, a 128DSD signal, and a 256DSD signal, by using a streaming method such as the MPEG-DASH, in music distribution using a DSD signal. It is to be noted that even when the DSD signal is compressed by using the compression method, or the like disclosed in Patent Document <NUM>, a bit rate becomes larger than that of the PCM signal, and therefore it is preferable to prepare distribution using the PCM signal as well.

In order to effectively utilize resources on distribution side, however, it is desirable that data type prepared on the distribution side be one type.

The present technology has been made in view of such a circumstance, and makes it possible to cope with an output of a PCM signal using one DSD signal. Means for Solving the Problem.

A signal processing apparatus according to an aspect of the present technology is defined by claim <NUM>.

A signal processing method according to an aspect of the present technology is defined by claim <NUM>.

A program according to an aspect of the present technology is defined by claim <NUM>.

It is to be noted that it is possible to achieve the signal processing apparatus according to an aspect of the present technology by causing the computer to execute the program.

It is possible to provide the program by transmission via a transmission medium or by recording in a recording medium.

The signal processing apparatus may be an independent apparatus or may be an internal block that constitutes one apparatus.

According to an aspect of the present technology, it is possible to cope with the output of the PCM signal using one DSD signal.

It is to be note that the effects described here are not necessarily limitative, and may be any of the effects described in the present disclosure.

Hereinafter, description is given of an embodiment for carrying out the present technology (hereinafter, referred to as an embodiment). It is to be noted that the description is given in the following order.

<FIG> is a block diagram illustrating a configuration example of an embodiment of a reproduction system to which the present technology is applied.

A reproduction system <NUM> of <FIG> includes at least a distribution apparatus <NUM> and a reproduction apparatus <NUM>, and is a system in which the reproduction apparatus <NUM> acquires audio data from the distribution apparatus <NUM> and reproduces the acquired audio data.

Audio data obtained by collecting respective sound sources of a plurality of contents by a microphone <NUM> and by performing delta-sigma modulation is stored in the distribution apparatus <NUM>.

More specifically, an audio signal of a predetermined sound source (e.g., content A) collected by the microphone <NUM> is amplified by an amplifier (AMP) <NUM> and supplied to a delta-sigma (ΔΣ) modulator <NUM>.

The delta-sigma modulator <NUM> converts an inputted analog audio signal into a digital signal (AD conversion) by delta-sigma modulation. For example, the delta-sigma modulator <NUM> preforms delta-sigma modulation on the inputted analog audio signal at a sampling frequency that is <NUM> times a sampling frequency of <NUM> of a CD (Compact Disc), and stores a resulting DSD signal in the distribution apparatus <NUM>. The DSD signal obtained by the delta-sigma modulation at the sampling frequency that is <NUM> times the sampling frequency of <NUM> has a bit rate of <NUM> MMbps, and thus is also referred to as <NUM> DSD data in the following.

The distribution apparatus <NUM> stores the <NUM> DSD data of a plurality of contents generated as described above.

When requesting audio data of a predetermined content from the distribution apparatus <NUM>, the reproduction apparatus <NUM> selects either the <NUM> DSD data or PCM_AAC data that is audio data of a format reproducible by itself, and requests the selected data from the distribution apparatus <NUM>. Alternatively, the reproduction apparatus <NUM> may select either the <NUM> DSD data or the PCM_AAC data in accordance with a communication capacity of a network <NUM>, and request the selected data from the distribution apparatus <NUM>.

Here, the PCM_AAC data is a signal obtained by compression encoding on a PCM signal having a sampling frequency of <NUM> (<NUM>×<NUM>) and a quantization bit of <NUM> bits by an encoding method of AAC (Advanced Audio Coding).

The distribution apparatus <NUM> transmits the <NUM> DSD data or the PCM_AAC data of a specified content to the reproduction apparatus <NUM> in response to a request of the reproduction apparatus <NUM>.

The distribution apparatus <NUM> includes a control unit <NUM>, a storage unit <NUM>, a PCM conversion unit <NUM>, an encoding unit <NUM>, and a transmission unit <NUM>.

The control unit <NUM> acquires a content transmission request of the reproduction apparatus <NUM> via the transmission unit <NUM>, and so controls each unit in the distribution apparatus <NUM> as to transmit audio data of a requested content.

More specifically, for example, in a case where the reproduction apparatus <NUM> requests <NUM> DSD data as audio data of the content A, the control unit <NUM> causes the transmission unit <NUM> to supply the <NUM> DSD data of the content A stored in the storage unit <NUM>, and causes the transmission unit <NUM> to transmit the <NUM> DSD data to the reproduction apparatus <NUM>.

For example, in a case where the reproduction apparatus <NUM> requests PCM_AAC data as the audio data of the content A, the control unit <NUM> operates the PCM conversion unit <NUM> and the encoding unit <NUM> to generate the PCM_AAC data from the <NUM> DSD data of the content A stored in the storage unit <NUM>, and causes the transmission unit <NUM> to transmit the generated PCM_AAC data to the reproduction apparatus <NUM>.

The storage unit <NUM> stores <NUM> DSD data of each of a plurality of contents.

The PCM conversion unit <NUM> converts the <NUM> DSD data supplied from the storage unit <NUM> into a PCM signal having a sampling frequency of <NUM> and a quantization bit of <NUM> bits, thereby generating a PCM signal and supplying the generated PCM signal to the encoding unit <NUM>. It is to be noted that the sampling frequency and the quantization bit number of the PCM signal to be generated are exemplary, and are not limitative.

The encoding unit <NUM> performs compression encoding on the PCM signal supplied from the PCM conversion unit <NUM> by an encoding method of AAC (Advanced Audio Coding), and supplies a resulting PCM_AAC data to the transmission unit <NUM>.

The transmission unit <NUM> receives a transmission request for audio data transmitted from the reproduction apparatus <NUM> via the network <NUM>, and supplies the transmission request to the control unit <NUM>.

In addition, the transmission unit <NUM> transmits the audio data of the predetermined content supplied from the storage unit <NUM> or the encoding unit <NUM> to the reproduction apparatus <NUM> via the network <NUM>. The <NUM> DSD data is supplied as audio data from the storage unit <NUM>, and the PCM_AAC data is supplied from the encoding unit <NUM>.

The reproduction apparatus <NUM> receives digital audio data transmitted from the distribution apparatus <NUM>, converts the received digital audio data into an analog signal, and outputs the converted analog signal to an analog LPF <NUM>.

The analog LPF (low pass filter) <NUM> performs filter processing to remove a high-frequency component, and outputs a signal after the filter processing to a power amplifier <NUM>.

The power amplifier <NUM> amplifies an analog audio signal outputted from the analog LPF <NUM>, and outputs the amplified analog audio signal to a speaker <NUM>. The speaker <NUM> outputs the audio signal supplied from the power amplifier <NUM> as a sound.

An analog output portion configured by the analog LPF <NUM>, the power amplifier <NUM>, and the speaker <NUM> may be incorporated as a portion of the reproduction apparatus <NUM>.

<FIG> illustrates a transmission mode of audio data transmitted by the distribution apparatus <NUM> to the reproduction apparatus <NUM>.

The transmission mode of the audio data transmitted by the distribution apparatus <NUM> to the reproduction apparatus <NUM> may take several forms depending on the configuration of the reproduction apparatus <NUM>.

For example, in a case where audio data reproducible by the reproduction apparatus <NUM> is fixed by either <NUM> DSD data or PCM_AAC data, the distribution apparatus <NUM> transmits either the <NUM> DSD data or the PCM_AAC data reproducible by the reproduction apparatus <NUM>, as illustrated in A of <FIG>. In a case where a data format of the audio data reproducible by the reproduction apparatus <NUM> is known, only a content to be reproduced is designated from the reproduction apparatus <NUM> to the distribution apparatus <NUM>. It is to be noted that, in <FIG>, for simplicity, the <NUM> DSD data is described as DSD data, and the PCM_AAC data is described as PCM data.

Further, for example, in a case where the reproduction apparatus <NUM> is an apparatus that is able to reproduce <NUM> DSD data and PCM_AAC data of the same content while performing switching between them as necessary even during reproduction of one content, the distribution apparatus <NUM> performs seamless switching between <NUM> DSD data and PCM_AAC data of the same content for transmission in response to a request of the reproduction apparatus <NUM>, as illustrated in B of <FIG>. The <NUM> DSD data has a higher sound quality but a larger data amount, and the PCM_AAC data has a lower sound quality but a smaller data amount than the <NUM> DSD data. Accordingly, for example, the reproduction apparatus <NUM> appropriately selects the <NUM> DSD data or the PCM_AAC data in accordance with the communication capacity of the network <NUM>, and reproduction the selected data while performing switching.

It is to be noted that, in a case of seamlessly reproducing the <NUM> DSD data and the PCM_AAC data while performing switching between them, a delay occurs in the PCM_AAC data by a period of time required for PCM data conversion processing by the PCM conversion unit <NUM> and a period of time required for compression encoding processing by the encoding unit <NUM>. The distribution apparatus <NUM> is able to transmit this delay value as metadata to the reproduction apparatus <NUM> in advance, thus enabling the reproduction apparatus <NUM> to perform seamless switching between <NUM> DSD data and PCM_AAC data on the basis of the delay value.

There is MPEG-DASH (Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP), as a standard of a method in which a client apparatus receives desired encoded data, from among a plurality of pieces of stored encoded data, in a streaming manner in accordance with the communication capacity of the network. The distribution apparatus <NUM> performs switching between the <NUM> DSD data and the PCM_AAC data as necessary for transmission in accordance with a format conforming to the MPEG-DASH standard, and the reproduction apparatus <NUM> receives the transmitted data and reproduces the received data.

The distribution apparatus <NUM> is also able to transmit both of the <NUM> DSD data and the PCM_AAC data simultaneously. For example, as illustrated in C of <FIG>, it is possible for audio data on front right side and front left side to be transmitted as <NUM> DSD data having a high sound quality, and audio data on rear right side and rear left side to be transmitted as PCM_AAC data having a small data amount.

As described above, the distribution apparatus <NUM> is able to cope with transmission of both of the <NUM> DSD data and the PCM_AAC data by simply storing, as audio data for distribution, one piece of DSD data of the <NUM> DSD data.

<FIG> is a block diagram illustrating a detailed configuration example of the PCM conversion unit <NUM>.

The PCM conversion unit <NUM> includes an extraction section <NUM> and a filtering section <NUM>, and converts the <NUM> DSD data into a PCM signal having a predetermined sampling frequency. In the present embodiment, the PCM conversion unit <NUM> performs conversion into a PCM signal having a sampling frequency of <NUM>.

The extraction section <NUM> extracts a predetermined number of sampling data from the <NUM> DSD data supplied from the storage unit <NUM> for each predetermined interval determined by the sampling frequency of <NUM> of the PCM signal.

The filtering section <NUM> generates a PCM signal by filtering the predetermined number of sampling data extracted for each predetermined interval in the extraction section <NUM>, and outputs the generated PCM signal to the encoding unit <NUM>.

Description is given of PCM conversion processing performed by the PCM conversion unit <NUM> with reference to <FIG>.

First, description is given of sampling extraction processing performed by the extraction section <NUM> with reference to <FIG> and <FIG>.

Now, respective pieces of sampled data of <NUM> DSD data of a predetermined content before PCM conversion are set as:
D[<NUM>], D[<NUM>], D[<NUM>], D[<NUM>],. , and
respective pieces of sampled data of PCM data after the PCM conversion are set as:
PCM[<NUM>], PCM[<NUM>], PCM[<NUM>], PCM[<NUM>],.

The sampled data D[n] of the <NUM> DSD data is represented by a <NUM>-bit signal of "<NUM>" or "<NUM>"; however, in an operation in signal processing, "<NUM>" is represented by "-<NUM>", and operation is performed using "<NUM>" or "-<NUM>". It is to be noted that, in the following, the sampling data is simply referred to also as a sample.

One sample of the <NUM> DSD data is <NUM>/(<NUM>*<NUM>) [sec], and one sample of the PCM data having a sampling frequency of <NUM> is <NUM>/<NUM> [sec], and thus the PCM conversion unit <NUM> outputs data for each of (<NUM> *<NUM>)/<NUM>=<NUM> samples.

Accordingly, the extraction section <NUM> extracts a predetermined number of samples from samples of the <NUM> DSD data at an interval of <NUM> samples. In the present embodiment, the number of samples extracted by the extraction section <NUM> is set to <NUM>. Accordingly, the extraction section <NUM> extracts <NUM> samples in the vicinity of the <NUM> DSD data sample to allow each sample position of m times (m is a non-negative integer) the <NUM> samples to be the center sample, and supplies the extracted samples to the filtering section <NUM>.

<FIG> illustrates a correspondence relationship between the samples of the <NUM> DSD data extracted by the extraction section <NUM> and the PCM data PCM[n] after the PCM conversion.

The m times the <NUM> samples are <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. , <NUM>, <NUM>, <NUM>, <NUM>,. , and thus the center position samples of the extracted samples corresponding to respective pieces of PCM[n] are <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. , <NUM>, <NUM>, <NUM>, <NUM>,.

Then, the <NUM> samples are extracted from around respective center position samples, and thus the extracted samples corresponding to PCM[<NUM>] are D[-<NUM>] to D[<NUM>] around D[<NUM>], the extracted samples corresponding to PCM[<NUM>] are D[-<NUM>] to D[<NUM>] around D[<NUM>], and the extracted samples corresponding to PCM[<NUM>] are D[-<NUM>] to D[<NUM>] around D[<NUM>]. However, D"n" in which n is negative is processed as "-<NUM>" because of lack of data of the content.

As an instance of not including the D"n" in which n is negative, for example, as illustrated in <FIG>, the extracted samples corresponding to PCM[<NUM>] are D[<NUM>] to D[<NUM>] around D[<NUM>], the extracted samples corresponding to PCM[<NUM>] are D[<NUM>] to D[<NUM>] around D[<NUM>], and the extracted samples corresponding to PCM[<NUM>] are D[<NUM>] to D[<NUM>] around D[<NUM>].

<FIG> illustrates a relationship between the center position sample of the <NUM> DSD data and the <NUM> samples to be extracted, for each of PCM[<NUM>] to PCM[<NUM>].

The maximum error between the predetermined interval determined by the sampling frequency of the PCM signal and the center position sample to be actually extracted is half a sampling period of the DSD signal, and thus the maximum error is <NUM>/(<NUM>*<NUM>)=<NUM> [µsec] for the case of the <NUM> DSD data. Time resolution of human hearing is said to be about <NUM> [µsec]; frequency conversion of <NUM> [µsec] is <NUM>, and frequency conversion of <NUM> [µsec] is <NUM>, and thus an error of <NUM> [µsec] does not constitute an error that greatly influences a sound quality.

As described above, the extraction section <NUM> extracts a predetermined number of samples (<NUM> samples) from the samples of the <NUM> DSD data supplied from the storage unit <NUM> around a predetermined interval (<NUM> samples) determined by the sampling frequency of <NUM> of the PCM signal, and outputs the extracted samples to the filtering section <NUM>.

Although the example described above is an example in which the <NUM> DSD data is converted into the PCM signal having the sampling frequency of <NUM>, it is possible to perform the conversion into a PCM signal having any sampling frequency. In addition, the DSD data is not limited to the <NUM> DSD data; <NUM> DSD data having a sampling frequency that is twice the <NUM> DSD data, <NUM> DSD data having a sampling frequency that is four times the <NUM> DSD data, or the like may be used. In a case where the bit rate of the DSD data or the sampling frequency of the PCM signal changes, it is possible to cope with the change only by changing the interval between the center position samples in accordance with its sampling ratio.

Further, it is possible to arbitrarily determine the number of samples to be extracted from around the center position sample, in accordance with accuracy of the PCM signal to be converted and the processing load.

Next, description is given of filtering processing performed by the filtering section <NUM> with reference to <FIG> and <FIG>.

The <NUM> DSD data is a binary signal of "<NUM>" or "<NUM>" (" <NUM>" or "-<NUM>" for the operation in the signal processing) as described above, and thus it is possible for the filtering section <NUM> to execute the filtering processing only by addition instead of product-sum operation as in the filtering of the normal PCM signal.

Now, assuming that the <NUM> samples extracted from around the predetermined center position samples supplied from the extraction section <NUM> are represented by DA[<NUM>] to DA[<NUM>], and filter coefficients of <NUM> taps applied by the filtering section <NUM> to DA[<NUM>] to DA[<NUM>] are K[<NUM>] to K[<NUM>], a filter operation performed by the filtering section <NUM> is represented by ΣDA[n]*K[n] (n=<NUM> to <NUM>). Here, DA[n] is "<NUM>" or "-<NUM>", and thus it is easily understood that it is possible to perform an operation of the filter operation expression only by addition without the need for multiplication.

Although the addition may be performed by detecting data bit by bit, the data becomes redundant as processing of CPU, and thus, for example, the filtering section <NUM> divides the <NUM>-bit data of DA[<NUM>] to DA[<NUM>] for each <NUM> bits, and performs an operation using a plurality of partial sum tables prepared in advance in a unit of <NUM> bits.

For example, description is given of an example in which D[<NUM>] to D[<NUM>] which are extracted samples corresponding to the PCM[<NUM>] are subjected to the filter operation, as illustrated in <FIG>.

First, D[<NUM>] to D[<NUM>] supplied from the extraction section <NUM> as extracted samples corresponding to the PCM[<NUM>] are DA[<NUM>] to DA[<NUM>] which are data to be filtered.

DA[<NUM>] to DA[<NUM>] are divided for each <NUM> bits of DA[<NUM>] to DA[<NUM>], DA[<NUM>] to DA[<NUM>], DA[<NUM>] to DA[<NUM>],. , DA[<NUM>] to DA[<NUM>], and DA[<NUM>] to DA[<NUM>].

The filtering section <NUM> holds a partial sum table BT0 illustrated in <FIG> for the first <NUM> bits DA[<NUM>] to DA[<NUM>].

The partial sum table BT0 of <FIG> associates <NUM> patterns of bit patterns employable by DA[<NUM>] to DA[<NUM>] and operation results C<NUM> to C<NUM> resulting from a preliminary operation of ΣDA[n]*K[n] (n=<NUM> to <NUM>) at that time, each other, for storage.

The filtering section <NUM> refers to the partial sum table BT0 of <FIG> stored therein and determines the operation result corresponding to the actual data of DA[<NUM>] to DA[<NUM>] to thereby calculate a partial sum T0. The partial sum T0 is any one of C<NUM> to C<NUM>.

Returning to <FIG>, the filtering section <NUM> similarly refers to partial sum tables BT1 to BT31 to thereby determine partial sums T1 to T31, for DA[<NUM>] to DA[<NUM>], DA[<NUM>] to DA[<NUM>],. , DA[<NUM>] to DA[<NUM>], and DA[<NUM>] to DA[<NUM>], which are other data divided for each <NUM> bits.

That is, the filtering section <NUM> refers to the partial sum table BT1 to calculate the partial sum T1 corresponding to the actual data of DA[<NUM>] to DA[<NUM>]; refers to the partial sum table BT2 to calculate the partial sum T2 corresponding to the actual data of DA[<NUM>] to DA[<NUM>]; and similarly refers to the partial sum table BT31 to calculate the partial sum T31 corresponding to the actual data of DA[<NUM>] to DA[<NUM>].

Finally, the filtering section <NUM> performs an operation of sum of the partial sums T0 to T31 corresponding to the <NUM> partial sum tables BT0 to BT31, respectively, and calculates PCM[<NUM>].

Accordingly, the filtering section <NUM> is able to calculate the PCM data corresponding to the extracted samples D[<NUM>] to D[<NUM>] only by <NUM> table references and <NUM> additions.

It is to be noted that a delay value of transmission data with respect to the DSD data in a case where the PCM data is transmitted is able to be calculated in advance when the number of taps of the filtering section <NUM> is determined.

In the above-described example, in order to simplify the description, the example has been described in which <NUM> samples are extracted from around respective center position samples in the extraction section <NUM> and the number of taps of the filtering section <NUM> is set to <NUM>.

Actually, in a case where a PCM signal having a sampling frequency of <NUM> with accuracy of, for example, about <NUM> [dB] is generated from the <NUM> DSD data, the number of taps of the filtering section <NUM> needs to be about <NUM>. In this case, creating a partial sum table in a unit of <NUM> bits enables an operation only by <NUM> table references and <NUM> additions. Assuming that the addition is one clock, <NUM>*<NUM>=<NUM> MIPS holds true, which is a level that is processible even by a mobile-based CPU and is sufficiently achievable.

Next, with reference to a flowchart of <FIG>, description is given of audio data transmission processing of the distribution apparatus <NUM> that performs seamless switching between the <NUM> DSD data and the PCM_AAC data of a predetermined content for transmission in response to a request of the reproduction apparatus <NUM>.

First, in step S1, the control unit <NUM> of the distribution apparatus <NUM> supplies a delay value of the PCM_AAC data to the transmission unit <NUM>, and causes the transmission unit <NUM> to transmit the delay value as metadata to the reproduction apparatus <NUM>.

In step S2, the control unit <NUM> receives, via the transmission unit <NUM>, the transmission request of the content transmitted from the reproduction apparatus <NUM>, and determines whether the audio data of the requested content is PCM_AAC data.

In a case where, determination is made in step S2 that the requested audio data is PCM_AAC data, the processing proceeds to step S3, in which the extraction section <NUM> of the PCM conversion unit <NUM> acquires <NUM> DSD data of the requested content from the storage unit <NUM>, and extracts a predetermined number of samples from the acquired <NUM> DSD data for each predetermined interval determined by a sampling frequency of the PCM signal. In the present embodiment, in a case where a PCM signal having a sampling frequency of <NUM> is generated, <NUM> samples having each sample corresponding to m times the <NUM> samples as the center position sample are sequentially extracted.

In step S4, the filtering section <NUM> generates a PCM signal by filtering a predetermined number of samples extracted for each predetermined interval in the extraction section <NUM>, and outputs the generated PCM signal to the encoding unit <NUM>. In the present embodiment, the filtering section <NUM> generates one sample of the PCM signal by performing <NUM> table references and <NUM> additions for the <NUM> samples supplied from the extraction section <NUM> using <NUM> partial sum tables BT0 to BT31, and outputs the generated one sample of the PCM signal to the encoding unit <NUM>.

In step S5, the encoding unit <NUM> performs compression encoding on the PCM signal supplied from the filtering section <NUM> by the AAC encoding method, and supplies the resulting PCM_AAC data to the transmission unit <NUM>.

In step S6, the transmission unit <NUM> transmits the PCM_AAC data obtained by the compression encoding in the encoding unit <NUM> to the reproduction apparatus <NUM>.

Meanwhile, in a case where determination is made in step S2 that the requested audio data is not PCM_AAC data, i.e., the requested audio data is <NUM> DSD data, the processing proceeds to step S7, in which the transmission unit <NUM> acquires <NUM> DSD data of the requested content from the storage unit <NUM>, and transmits the acquired <NUM> DSD data to the reproduction apparatus <NUM>.

In step S8, the transmission unit <NUM> determines whether the transmission of the audio data is finished. For example, in a case where no audio data has been supplied from either the storage unit <NUM> or the encoding unit <NUM>, the transmission unit <NUM> determines that the transmission of the audio data has been finished.

In a case where determination is made in step S8 that the transmission of the audio data has not been finished yet, the processing returns to step S2, and the processing from steps S2 to S8 described above is repeated.

Meanwhile, in a case where determination is made in step S8 that the transmission of the audio data has been finished, the audio data transmission processing is finished.

As described above, in a case where PCM_AAC data is requested as audio data of a content from the reproduction apparatus <NUM>, the distribution apparatus <NUM> is able to generate a PCM signal from the <NUM> DSD data stored in the storage unit <NUM> and to transmit the generated PCM signal to the reproduction apparatus <NUM>. That is, the distribution apparatus <NUM> is able to transmit audio data of one content by performing switching between the DSD data and the PCM_AAC data in response to a request of the reproduction apparatus <NUM>.

In addition, the distribution apparatus <NUM> transmits, as a delay value, a period of time required for the conversion processing for conversion into the PCM signal to the reproduction apparatus <NUM> in advance, enabling achievement of complete synchronization of the DSD data and the PCM_AAC data, thus making it possible for side of the reproduction apparatus <NUM> to perform seamless switching between the DSD data and the PCM_AAC data for reproduction.

For example, in a distribution apparatus that transmits predetermined encoded data in response to a request of a client apparatus, as in the MPEG-DASH, it is generally necessary to generate and store encoded data of both of the DSD signal and the PCM signal in advance by synchronizing the sampling frequencies.

According to the distribution apparatus <NUM> using the present technology, it is sufficient to store only the DSD data in the storage unit <NUM> as the audio data of the content, thus making it possible to cope with the transmission of the PCM signal only using one DSD signal.

It is to be noted that the storage unit <NUM> of the distribution apparatus <NUM> may store <NUM> DSD data resulting from delta-sigma modulation at a sampling frequency that is <NUM> times the sampling frequency of <NUM> of a CD, thus making it possible to configure the distribution apparatus <NUM> to generate <NUM> DSD data or <NUM> DSD data by downsampling from the <NUM> DSD data and to transmit the generated DSD data, or to generate a PCM signal having any sampling frequency such as <NUM> or <NUM> from the <NUM> DSD data and to transmit the generated PCM signal.

It is to be noted that the audio data transmission processing described above is a processing example in the case of the audio data transmission mode illustrated in B of <FIG>. In the audio data transmission mode illustrated in A of <FIG>, in a case where PCM_AAC data is transmitted, it is sufficient to execute the processing from steps S3 to S6, and in a case where <NUM> DSD data is transmitted, it is sufficient to execute the processing of step S7.

<FIG> is a block diagram illustrating a detailed configuration example of the reproduction apparatus <NUM> of <FIG>.

The reproduction apparatus <NUM> of <FIG> is an apparatus that is able to perform seamless switching between the <NUM> DSD data and the PCM_AAC data of a predetermined content for reproduction.

The reproduction apparatus <NUM> includes a control unit <NUM>, a communication unit <NUM>, a decoding unit <NUM>, a PCM upsampling unit <NUM>, a delta-sigma (ΔΣ) modulation unit <NUM>, a switching unit <NUM>, a clock supply unit <NUM>, and a delta-sigma demodulation unit <NUM>.

The control unit <NUM> controls an overall operation of the reproduction apparatus <NUM>. For example, when a user instructs reproduction of a predetermined content stored in the distribution apparatus <NUM> in an unillustrated operation unit, the control unit <NUM> selects one piece of audio data from two pieces of audio data (DSD data and PCM_AAC data) corresponding to a content that is instructed to be reproduced in accordance with the communication capacity of the network <NUM>, and requests the selected piece of audio data from the distribution apparatus <NUM> via the communication unit <NUM>. It is to be noted that, in <FIG>, illustration of control signals from the control unit <NUM> to the respective units is omitted.

In a case where audio data is acquired as streaming data of a content in accordance with the MPEG-DASH, the control unit <NUM> acquires an MPD file previously, and causes the communication unit <NUM> to access a predetermined address of the distribution apparatus <NUM> on the basis of the acquired MPD file, thereby causing the communication unit <NUM> to acquire desired audio data. The MPD file includes, for example, information on the delay value of the PCM_AAC data.

The communication unit <NUM> requests audio data (DSD data and AAC data) of the content instructed to be reproduced, from the distribution apparatus <NUM> on the basis of an instruction of the control unit <NUM>. In a case where the DSD data and the AAC data are set as first and second audio data, respectively, and switching is performed from the first audio data to the second audio data, the communication unit <NUM> simultaneously acquires two of the first and second audio data before or after the switching, and acquires one of the audio data in a case where no switching is necessary.

The communication unit <NUM> acquires digital audio data transmitted from the distribution apparatus <NUM>. In a case where the acquired audio data is <NUM> DSD data, the communication unit <NUM> supplies the acquired <NUM> DSD data to the switching unit <NUM>. Meanwhile, in a case where the acquired audio data is PCM_AAC data, the communication unit <NUM> supplies the acquired PCM_AAC data to the decoding unit <NUM>.

The decoding unit <NUM> decodes the PCM_AAC data supplied from the communication unit <NUM> by a decoding method corresponding to the encoding method, and outputs a PCM signal resulting from the decoding to the PCM upsampling unit <NUM>.

The PCM upsampling unit <NUM> upsamples the PCM signal supplied from the decoding unit <NUM> to have the same frequency as the sampling frequency of the <NUM> DSD data, and outputs the upsampled PCM signal to the delta-sigma modulation unit <NUM>. Specifically, the PCM upsampling unit <NUM> upsamples the PCM signal to have <NUM> and outputs the upsampled PCM signal to the delta-sigma modulation unit <NUM>.

The delta-sigma modulation unit <NUM> performs delta-sigma modulation on the upsampled PCM signal to generate <NUM> DSD data, and outputs the generated <NUM> DSD data to the switching unit <NUM>.

The switching unit <NUM> selects one of the <NUM> DSD data that is an output of the communication unit <NUM> or the <NUM> DSD data that is an output of the delta-sigma modulation unit <NUM>, and outputs the selected <NUM> DSD data to the delta-sigma demodulation unit <NUM> in the subsequent stage.

The switching unit <NUM> is supplied with a delay value transmitted from the distribution apparatus <NUM>. In a case where the switching unit <NUM> performs switching from the <NUM> DSD data that is an output of the communication unit <NUM> to the <NUM> DSD data that is an output of the delta-sigma modulation unit <NUM>, delay is performed for the <NUM> DSD data by a combined value of the delay value transmitted from the distribution apparatus <NUM> and a delay value resulting from processing from the decoding unit <NUM> to the delta-sigma modulation unit <NUM>, and thereafter the switching is performed. This makes it possible to perform seamless switching even during reproduction of a content.

The clock supply unit <NUM> supplies a clock signal CLK2 corresponding to the <NUM> DSD data to the delta-sigma demodulation unit <NUM>. In the present embodiment, the clock supply unit <NUM> generates the clock signal CLK2 of <NUM> and supplies the clock signal CLK2 to the delta-sigma demodulation unit <NUM>.

The delta-sigma demodulation unit <NUM> demodulates (performs delta-sigma demodulation on) the <NUM> DSD data supplied from the switching unit <NUM> using the clock signal CLK2 supplied from the clock supply unit <NUM>, and outputs a demodulation result to the analog LPF <NUM> (<FIG>) in the subsequent stage. It is possible to configure the delta-sigma demodulation unit <NUM>, for example, by an FIR (finite impulse response) digital filter.

The above configuration enables the reproduction apparatus <NUM> to perform seamless switching between the <NUM> DSD data and the PCM_AAC data of the predetermined content for reproduction.

Next, description is given of a mode for simultaneous transmission of both of the <NUM> DSD data and the PCM_AAC data.

For example, as illustrated in C of <FIG>, the distribution apparatus <NUM> transmits <NUM> DSD data having a high sound quality for audio data on the front right side and the front left side, and transmits PCM_AAC data having a small data amount for audio data on the rear right side and the rear left side.

The storage unit <NUM> also stores the audio data on the rear right side and the rear left side as the <NUM> DSD data; in a case where the audio data is transmitted as PCM data, the <NUM> DSD data is converted into the PCM data by the PCM conversion unit <NUM>, and the converted PCM data is transmitted to the reproduction apparatus <NUM>. The <NUM> DSD data on the front right side and the front left side is also transmitted to the reproduction apparatus <NUM> in parallel with the PCM data on the rear right side and the rear left side. The configuration of the distribution apparatus <NUM> is the same as that described with reference to <FIG>.

It is to be noted that, in a case where predetermined conditions such as the capability of the reproduction apparatus <NUM> and the communication capacity of the network <NUM> are satisfied, the <NUM> DSD data may be transmitted as it is, as a matter of course, also for the audio data on the rear right side and the rear left side, similarly to the front right side and the front left side.

<FIG> is a block diagram illustrating a configuration example of the reproduction apparatus <NUM> that simultaneously receives the <NUM> DSD data on the front right side and the front left side and the PCM_AAC data on the rear right side and the rear left side, and outputs sounds from two speakers on the front right side and the front left side.

In <FIG>, portions corresponding to those in <FIG> are denoted by the same reference numerals, and descriptions thereof are omitted where appropriate.

The reproduction apparatus <NUM> includes the communication unit <NUM>, the decoding unit <NUM>, the delta-sigma (ΔΣ) modulation unit <NUM>, the clock supply unit <NUM>, the delta-sigma demodulation unit <NUM>, a delay unit <NUM>, a surround processing unit <NUM>, and a mixer <NUM>. The mixer <NUM> includes addition units <NUM> and <NUM> and a delta-sigma modulation unit <NUM>.

The communication unit <NUM> receives DSD_FL data that is <NUM> DSD data on the front left side and DSD_FR data that is <NUM> DSD data on the front right side, which are transmitted from the distribution apparatus <NUM>, and supplies the received pieces of data to the delay unit <NUM>.

In addition, the communication unit <NUM> receives AAC_RL data that is PCM_AAC data on the rear left side and AAC_RR data that is PCM_AAC data on the rear right side, which are transmitted from the distribution apparatus <NUM>, and supplies the received pieces of data to the decoding unit <NUM>.

The delay unit <NUM> delays the DSD_FL data and the DSD_FR data supplied from the communication unit <NUM> by a combined value of the delay value transmitted from the distribution apparatus <NUM> and a delay value resulting from processing of the decoding unit <NUM>, the surround processing unit <NUM>, and the delta-sigma modulation unit <NUM>, and supplies the delayed pieces of data to the mixer <NUM>. The DSD_FL data outputted from the delay unit <NUM> is supplied as DSD_FL1 data to the addition unit <NUM> of the mixer <NUM>, and the DSD_FR data outputted from the delay unit <NUM> is supplied as DSD_FR1 data to the addition unit <NUM> of the mixer <NUM>.

The decoding unit <NUM> decodes the AAC_RL data that is the PCM_AAC data on the rear left side and the AAC_RR data that is the PCM_AAC data on the rear right side, to obtain PCM_RL data and PCM_RR data, respectively. The obtained PCM_RL data and PCM_RR data are supplied to the surround processing unit <NUM>.

The surround processing unit <NUM> executes surround conversion processing, in which even an output from speakers on front side is heard as if it came from rear side, on each of PCM_RL data that is PCM data on the rear left side and PCM_RR data that is PCM data on the rear right side, which are supplied from the decoding unit <NUM>. The surround conversion processing causes the PCM_RL data on the rear left side to be converted into PCM_FL data on the front left side and the PCM_RR data on the rear right side to be converted into PCM_FR data on the front right side, and the converted pieces of data are supplied to the delta-sigma modulation unit <NUM>.

The delta-sigma modulation unit <NUM> performs delta-sigma modulation on each of the PCM_FL data that is a PCM signal on the front left side and the PCM_FR data that is a PCM signal on the front right side. DSD_FL2 data resulting from the delta-sigma modulation of the PCM_FL data on the front left side is supplied to the addition unit <NUM> of the mixer <NUM>. DSD_FR2 data resulting from the delta-sigma modulation of the PCM_FR data on the front right side is supplied to the addition unit <NUM> of the mixer <NUM>.

The addition unit <NUM> of the mixer <NUM> adds the DSD_FL1 data from the delay unit <NUM> and the DSD_FL2 data from the delta-sigma modulation unit <NUM> together, and supplies DSD_FLa data that is an addition result to the delta-sigma modulation unit <NUM>.

The addition unit <NUM> of the mixer <NUM> adds the DSD_FR1 data from the delay unit <NUM> and the DSD_FR2 data from the delta-sigma modulation unit <NUM> together, and supplies DSD_FRa data that is an addition result to the delta-sigma modulation unit <NUM>.

The delta-sigma modulation unit <NUM> performs delta-sigma modulation on the DSD_FLa data from the addition unit <NUM>, and supplies DSD_FLb data that is DSD data after the modulation, to the delta-sigma demodulation unit <NUM>. In addition, the delta-sigma modulation unit <NUM> performs delta-sigma modulation on the DSD_FRa data from the addition unit <NUM>, and supplies DSD_FRb data that is DSD data after the modulation, to the delta-sigma demodulation unit <NUM>.

The delta-sigma demodulation unit <NUM> demodulates (performs delta-sigma demodulation on) the DSD_FLb data supplied from the delta-sigma modulation unit <NUM> using the clock signal CLK2 supplied from the clock supply unit <NUM>, and outputs an analog signal Front_L on the front left side that is a demodulation result, to the analog LPF <NUM> (<FIG>).

In addition, the delta-sigma demodulation unit <NUM> demodulates (performs delta-sigma demodulation on) the DSD _FRb data supplied from the delta-sigma modulation unit <NUM> using the clock signal CLK2 supplied from the clock supply unit <NUM>, and outputs an analog signal Front_R on the front right side that is a demodulation result, to the analog LPF <NUM> (<FIG>).

Next, with reference to a flowchart of <FIG>, description is given of audio data reproduction processing performed by the reproduction apparatus <NUM> of <FIG>, in which both of front two-channel <NUM> DSD data and rear two-channel PCM_AAC data are simultaneously received and outputted only from two front speakers.

First, in step S10, the communication unit <NUM> receives the delay value transmitted as metadata from the distribution apparatus <NUM>, and supplies the received delay value to the control unit <NUM>.

In step S11, the communication unit <NUM> receives the front two-channel <NUM> DSD data and the rear two-channel PCM_AAC data.

More specifically, the communication unit <NUM> receives the DSD_FL data that is the <NUM> DSD data on the front left side and the DSD_FR data that is the <NUM> DSD data on the front right side, which are transmitted from the distribution apparatus <NUM>, and supplies the received pieces of data to the delay unit <NUM>. In addition, the communication unit <NUM> receives the AAC_RL data that is the PCM_AAC data on the rear left side and the AAC_RR data that is the PCM_AAC data on the rear right side, which are transmitted from the distribution apparatus <NUM>, and supplies the received pieces of data to the decoding unit <NUM>.

In step S12, the delay unit <NUM> delays the DSD_FL data and the DSD_FR data supplied from the communication unit <NUM> by a predetermined period of time, and supplies the delayed pieces of data to the mixer <NUM>. The delay time as used here corresponds to a sum value of the delay value transmitted from the distribution apparatus <NUM> and the delay value resulting from the processing of the decoding unit <NUM>, the surround processing unit <NUM>, and the delta-sigma modulation unit <NUM>.

In step S13, the decoding unit <NUM> decodes the AAC_RL data on the rear left side and the AAC_RR data on the rear right side which are supplied from the communication unit <NUM>. The PCM_RL data and the PCM_RR data resulting from the decoding are supplied to the surround processing unit <NUM>.

In step S14, the surround processing unit <NUM> executes surround conversion processing for each of the PCM_RL data on the rear left side and the PCM_RR data on the rear right side which are supplied from the decoding unit <NUM>. The surround conversion processing causes the PCM_RL data on the rear left side to be converted into the PCM_FL data on the front left side and the PCM_RR data on the rear right side to be converted into the PCM_FR data on the front right side, and the converted pieces of data are supplied to the delta-sigma modulation unit <NUM>.

In step S15, the delta-sigma modulation unit <NUM> performs delta-sigma modulation on each of the PCM_FL data on the front left side and the PCM_FR data on the front right side. The DSD_FL2 data resulting from the delta-sigma modulation is supplied to the addition unit <NUM> of the mixer <NUM>, and the DSD_FR2 data is supplied to the addition unit <NUM> of the mixer <NUM>.

The processing of step S12 and the processing of steps S13 to S15 are executed in parallel. An output timing at which the DSD_FL data and the DSD_FR data are outputted, respectively, as the DSD_FL1 data and the DSD_FR1 data from the delay unit <NUM> in step S12 coincides with an output timing at which the DSD_FL2 data and the DSD_FR2 data are outputted from the delta-sigma modulation unit <NUM> in step S15.

In step S16, each of the addition units <NUM> and <NUM> of the mixer <NUM> adds first DSD data from the delay unit <NUM> and second DSD data from the delta-sigma modulation unit <NUM> together. More specifically, the addition unit <NUM> adds the DSD_FL1 data from the delay unit <NUM> and the DSD_FL2 data from the delta-sigma modulation unit <NUM> together, and supplies the DSD_FLa data that is the addition result to the delta-sigma modulation unit <NUM>. The addition unit <NUM> adds the DSD_FR1 data from the delay unit <NUM> and the DSD_FR2 data from the delta-sigma modulation unit <NUM> together, and supplies the DSD_FRa data that is the addition result to the delta-sigma modulation unit <NUM>.

In step S17, the delta-sigma modulation unit <NUM> performs delta-sigma modulation on the addition result. That is, the delta-sigma modulation unit <NUM> performs delta-sigma modulation on the DSD_FLa data from the addition unit <NUM>, and supplies the DSD_FLb data after the modulation to the delta-sigma demodulation unit <NUM>. In addition, the delta-sigma modulation unit <NUM> performs delta-sigma modulation on the DSD_FRa data from the addition unit <NUM>, and supplies the DSD_FRb data after the modulation to the delta-sigma demodulation unit <NUM>.

In step S18, the delta-sigma demodulation unit <NUM> performs delta-sigma demodulation on the DSD_FLb data and the DSD_FRb data after the delta-sigma modulation supplied from the delta-sigma modulation unit <NUM> using the clock signal CLK2 supplied from the clock supply unit <NUM>, and outputs the analog signal Front_L on the front left side and the analog signal Front_R on the front right side, which are demodulation results, to the analog LPF <NUM>, thereby finishing the audio data reproduction processing.

The audio data reproduction processing as described above enables the reproduction apparatus <NUM> to simultaneously receive both of the front two-channel <NUM> DSD data and the rear two-channel PCM_AAC data, to convert the received pieces of data into signals for the two front speakers, and to output the converted signals.

It is to be noted that, in the example described above, the delay unit <NUM> that delays the received DSD data by a predetermined period of time is provided on side of the reproduction apparatus <NUM>; however, the delay unit <NUM> may be configured to be provided in the distribution apparatus <NUM> on distribution side to allow for supply of DSD data delayed by a predetermined period of time.

In the above-described embodiment, the description has been given of the configuration of a server client system in which the distribution apparatus <NUM> is used as a server apparatus and the reproduction apparatus <NUM> is used as a client apparatus to distribute the DSD data or the PCM_AAC data as audio data via the network <NUM>.

However, the present technology is not limited to the server client system, and is also applicable to, for example, a PCM signal conversion apparatus that converts DSD data stored in the storage unit <NUM> into PCM data and records the converted PCM data in a recording medium such as a BD (Blu-ray (registered trademark) Disc) or a DVD (Digital Versatile Disc).

<FIG> is a block diagram illustrating a configuration example of the PCM signal conversion apparatus. In <FIG>, portions corresponding to those of the distribution apparatus <NUM> of <FIG> are denoted by the same reference numerals, and descriptions thereof are omitted.

The PCM signal conversion apparatus <NUM> of <FIG> is provided with a drive <NUM> instead of the transmission unit <NUM> of the distribution apparatus <NUM> of <FIG>.

The drive <NUM> drives a recording medium <NUM> such as a BD or a DVD, and records, as audio data of a content, the <NUM> DSD data supplied from the storage unit <NUM> and the PCM_AAC data supplied from the encoding unit <NUM>, in the recording medium <NUM>.

In the storage unit <NUM>, audio data of a content is stored as DSD data with emphasis on a sound quality. Suppose a situation, for example, where audio data to be combined with an image is generated using a PCM signal and recorded in the recording medium <NUM>.

As the DSD signal, a sampling frequency that is <NUM> times, <NUM> times, or <NUM> times the sampling frequency of a CD is used, whereas a sampling frequency of <NUM> is typically used for an image.

In general, in a case of generating a PCM signal of <NUM> from <NUM> DSD data, it is common to first down-convert the <NUM> DSD data to a PCM signal of about <NUM>*<NUM> and thereafter generate data by linear interpolation, or the like; however, the sound quality deteriorates due to the interpolation. In addition, in a case where the sound quality is prioritized, a method is conceivable in which the <NUM> DSD data is down-converted to a PCM signal of <NUM>*<NUM> in the same manner; a signal after the down-conversion is up-converted <NUM> times; and further the up-converted signal is down-converted to <NUM>/<NUM>. However, although this method enables accurate conversion to a PCM signal of <NUM>, the processing is slow and impractical.

Meanwhile, according to the PCM signal conversion apparatus <NUM>, it is possible to generate a PCM signal of <NUM> accurately and easily from DSD data and to record the generated PCM signal in the recording medium <NUM> such as a BD or a DVD.

A series of processing executed by the signal processing apparatus such as the distribution apparatus <NUM>, the reproduction apparatus <NUM>, and the PCM signal conversion apparatus <NUM> described above is able to be executed by hardware or is able to be executed by software. In a case where the series of processing is executed by software, a program constituting the software is installed in a computer. Here, examples of the computer include a microcomputer incorporated in dedicated hardware and a general-purpose personal computer that is able to execute various functions by installing various programs.

<FIG> is a block diagram illustrating a configuration example of hardware of a computer that executes the series of processing described above by a program.

In the computer, a CPU (Central Processing Unit) <NUM>, a ROM (Read Only Memory) <NUM>, and a RAM (Random Access Memory) <NUM> are coupled to one another by a bus <NUM>.

An input/output interface <NUM> is further coupled to the bus <NUM>. An input unit <NUM>, an output unit <NUM>, a storage unit <NUM>, a communication unit <NUM>, and a drive <NUM> are coupled to the input/output interface <NUM>.

The input unit <NUM> includes a keyboard, a mouse, a microphone, a touch panel, an input terminal, and the like. The output unit <NUM> includes a display, a speaker, an output terminal, and the like. The storage unit <NUM> includes a hard disk, a RAM disk, a nonvolatile memory, and the like. The communication unit <NUM> includes a network interface, and the like. The drive <NUM> drives a removable recording medium <NUM> such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.

In the computer configured as described above, for example, the CPU <NUM> loads the program stored in the storage unit <NUM> into the RAM <NUM> via the input/output interfaces <NUM> and the bus <NUM> and executes the program, to thereby perform a series of processing such as the audio data transmission processing and the audio data reproduction processing described above. The RAM <NUM> also appropriately stores data and the like necessary for the CPU <NUM> to execute various types of processing.

In the computer, the program is able to be installed in the storage unit <NUM> via the input/output interface <NUM> by mounting the removable recording medium <NUM> on the drive <NUM>. In addition, the program is able to be received by the communication unit <NUM> via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting, and installed in the storage unit <NUM>. Moreover, the program is able to be installed in advance in the ROM <NUM> or the storage unit <NUM>.

It is to be noted that the program executed by the computer may be a program in which processing is performed in time series in the order described in the present specification, or may be a program in which processing is performed in parallel or at a necessary timing when a call is made, etc..

It is to be noted that, in the present specification, a system means a set of a plurality of components (apparatuses, modules (parts), etc.); it doesn't matter whether or not all the components are in the same housing. Accordingly, a plurality of apparatuses housed in separate housings and coupled via a network and one apparatus in which a plurality of modules is housed in one housing are each a system.

The embodiment of the present technology is not limited to the above-described embodiment, and various modifications are possible within a scope not departing from the gist of the present technology.

For example, it is possible to employ a mode in which all or portions of the above-described embodiments are combined as appropriate.

For example, it is possible, in the present technology, to adopt a configuration of cloud computing in which one function is shared and processed jointly by a plurality of apparatuses via a network.

It is possible for each step described in the above flowcharts to be executed by one apparatus, and, in addition, to be shared and executed by a plurality of apparatuses.

Further, in a case where a plurality of pieces of processing are included in one step, it is possible for the plurality of pieces of processing included in the one step to be executed by one apparatus, and, in addition, to be shared and executed by a plurality of apparatuses.

It is to be noted that the effects described herein are merely illustrative and are not limitative, and may include effects other than those described in the present specification.

Claim 1:
A signal processing apparatus (<NUM>) suitable for generating a PCM signal having a predetermined sampling frequency from a digital signal delta-sigma-modulated by a <NUM>- bit signal, referred to as DSD signal, the signal processing apparatus comprising:
a storage unit (<NUM>) that is configured to store the DSD signal;
an extraction section (<NUM>; <NUM>) that is configured to, in a case where the PCM signal having a predetermined sampling frequency is generated from the DSD signal, extract a predetermined number of samples from the DSD signal around samples at a predetermined interval determined by the predetermined sampling frequency;
a filtering section (<NUM>; <NUM>) that is configured to generate the PCM signal having the predetermined sampling frequency by filtering the extracted predetermined number of samples; and
a transmission unit (<NUM>) that is configured to transmit the DSD signal and the PCM signal to a reproduction apparatus (<NUM>), the DSD signal comprising front side audio data having a higher sound quality and higher data amount, and the PCM signal comprising rear side audio data having a lower sound quality and lower data amount,
wherein the transmission unit is configured to also transmit a delay value of the PCM signal with respect to the DSD signal to the reproduction apparatus.