JP2006030577A - Method and device for coded transmission of music - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously reproduce a plurality of pieces of music without generating a soundless period and to enable reproduction from a specified piece of music among the plurality of pieces of music when sample data of the plurality of music are encoded and then the encoded data are decoded and reproduced. <P>SOLUTION: An encoding device 100 encodes the whole sample data stream of the plurality of pieces of music to generate an MP3 frame and also generates sectioning position data indicating sectioning positions between pieces of music in all the whole data stream. When a specified piece of music is specified among the plurality of pieces of music, a server 200 sends sectioning position data relating to the indicated music and MP3 frame to a client 300, which decodes the MP3 frame and selects sample data belonging to the specified music in an obtained sample data stream to output the sample data as audio. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for encoding and transmitting sample data of an audio waveform of a song and reproducing it as audio on the receiving side.

  Various content distribution systems are provided in which a server distributes music content via a network such as a wired LAN or a wireless LAN in response to a request from a client. According to this content distribution system, the user can send a request to the server via the client while in his / her room and enjoy the music provided from the server in response to this request. In this type of content distribution system, normally, in order to perform transmission efficiently, encoding data obtained by compressing and encoding audio waveform sample data using, for example, an MP3 (MPEG-1 Layer 3) encoding algorithm. Data is prepared in the server as music content, and this encoded data is distributed to the client. One example of this type of content distribution system is described in Non-Patent Document 1, for example.

Yamaha Music Cast (registered trademark) catalog August 2003

  By the way, regarding the above-described conventional content distribution system, for example, there is a need to send music contents of all songs of a live performance album from a server to a client, and to continuously reproduce each music content on the client side. Usually, in a live performance, sound is generated between songs, and when a CD on which this live performance is recorded is reproduced, the sound between such songs is also reproduced. However, in a conventional content distribution system, encoded data is generated in units of music and distributed as music content. Therefore, even if the music content of each song of the album is sent from the server to the client and each song can be continuously played back on the client side, there is a silent period between the played songs and the CD. Compared to playback, the music is unnatural. The reason is as follows.

  In a compression encoding algorithm such as MP3, a predetermined number of sample data is set as one frame, and compression encoding is performed in units of this frame. Here, when a predetermined number of pieces of sample data are taken out from the beginning of the song and compression encoded, the number of sample data less than one frame remains at the end of the song. In this case, generally, sample data having a value of 0 (hereinafter referred to as zero data) is supplemented to form one frame, which is compression-coded. In a conventional content distribution system, such compression encoding is performed in units of music and stored as music content on a server. Therefore, even if encoded data for a plurality of songs can be continuously decoded and played back on the client side, zero data is played back between songs and a silent section occurs. As a means for solving this problem, with respect to live performance albums, it is conceivable to collect sample data of all the songs in the album, not in units of songs, and to perform compression coding on the sample data. However, when this method is adopted, the server only has encoded data obtained by compressing and encoding all the songs in the album, so the necessary data is sent to the client side to play the specific song in the album or after the specific song. This causes a problem that it is impossible to play the song.

  The present invention has been made in view of the above circumstances, and in the case where a plurality of pieces of sample data are encoded and then the encoded data is decoded and reproduced, the plurality of pieces of music are generated without causing a silent period. It is an object of the present invention to provide a method and an apparatus for encoding and playing back audio that can be continuously played back and can be played back from a specific piece of music.

In order to solve the above-mentioned problems, the present invention takes out a predetermined number of sample data from all sample data strings of a plurality of songs and framing them, and gives each frame to an encoding means to generate encoded data. When the reproduction of a specific song in the plurality of songs is instructed, based on the delimiter position data related to the designated song The encoded data necessary for reproducing the designated music is specified, the specified encoded data is supplied to the decoding means, and the samples belonging to the specified music are obtained from the sample data string obtained from the decoding means Provided is a method for encoding and transmitting music, wherein data is selected and output as sound.
The present invention also provides an encoding means for encoding sample data and outputting the encoded data, and extracting a predetermined number of sample data from all sample data sequences of a plurality of songs into frames, and assigning each frame to the encoding means. And a control means for generating delimiter position data indicating delimiter positions between songs in all the sample data strings of the plurality of songs, and outputting at least a part of the encoded data and delimiter position data An encoding device comprising an output unit is provided.
Further, the present invention provides a predetermined number of pieces of sample data from all sample data sequences of a plurality of songs, framed the encoded data obtained by encoding each frame, and all the sample data sequences of the plurality of songs. Input means for acquiring break position data indicating a break position between songs, decoding means for decoding encoded data obtained by the input means and outputting sample data, and in accordance with a control signal, from the decoding means The audio output means for outputting the sample data to be output as audio, and the specific position based on the break position data related to the specific music obtained by the input means when an instruction to play the specific music in the plurality of music is given The timing at which the sample data corresponding to the start position of the music is output from the decoding means is obtained, and the samples after the start position are obtained. Data to provide a reproducing apparatus, characterized by a control means for outputting a control signal to the sound output unit to be outputted as a voice from the voice output unit.
According to the present invention, when a plurality of pieces of sample data are encoded, and then the encoded data is decoded and reproduced, the plurality of pieces of music can be continuously reproduced without causing a silent period, and You can also play from a specific song.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a content distribution system according to an embodiment of the present invention. This content distribution system is a system that distributes music content, and includes an encoding device 100, a server 200, and one or a plurality of clients 300.

  The encoding device 100 is a device that performs compression encoding of various music sample data, and outputs the encoded data obtained thereby as music content. The control unit 101, the storage unit 102, the encoder 103, And an output unit 104. The storage unit 102 has an area for storing sample data to be encoded, and an area for storing music content obtained by encoding. Sample data of a plurality of songs is stored in the former area. The sample data of each song includes sample data of a plurality of songs obtained by live recording. Some music contents stored in the latter area include only encoded data corresponding to the original sample data, but in addition to this, the delimiter position data together with the encoded data corresponding to the original sample data There are things that include. This break position data will be described later. The encoder 103 is a device that performs compression encoding of sample data read from the storage unit 102 under the control of the control unit 101. The encoder 103 according to the present embodiment performs compression encoding of sample data according to an MP3 compression encoding algorithm, and outputs an MP3 frame that is encoded data. The output unit 104 is an apparatus that outputs music content in such a manner that data stored in the storage unit 102 is distributed via a network or recorded on a recording medium such as a CD in accordance with an instruction from the control unit 101. It is.

  The control unit 101 performs control for causing the encoder 103 to encode the sample data of each song in the storage unit 102 in accordance with an instruction from the user of the encoding device 100. When encoding of one song in the storage unit 102 is instructed, the control unit 101 reads 1152 sample data of the song from the storage unit 102 by 1152 samples, gives it to the encoder 103 as a frame, and sends it to the encoder 103 for each frame. Encoding is performed, and the MP3 frame obtained as a result is written in the storage unit 102 as music content. On the other hand, when the encoding of a plurality of pieces of sample data obtained by live recording, for example, among the data in the storage unit 102 is instructed, the control unit 101 encodes all the sample data strings for the instructed plurality of songs. The encoder 103 is caused to generate the break position data for each of the instructed plural songs, and the MP3 frame and the break position data obtained from the encoder 103 are written in the storage unit 102 as music contents. Here, the delimiter position data is the position of the sample data at the beginning of each song in the entire sample data string for a plurality of designated songs, more specifically, each sample obtained by counting the sample data at the beginning of the first song as the first. Indicates the serial number of the sample data at the beginning of the song. The control unit 101 causes the output unit 104 to output the music content stored in the storage unit 102 in this manner in accordance with an instruction from the user.

  The server 200 is connected to one or a plurality of clients 300 via a network such as a LAN. The server 200 is a device that distributes music content in response to a request from the client 300, and includes a control unit 201, a storage unit 202, a buffer 203, and a network interface 204. The storage unit 202 stores music content acquired in advance from the encoding device 100. The buffer 203 is a device for temporarily storing MP3 frames of music content to be transmitted to the client 300. The network interface 204 is a device that controls communication with the client 300.

  In response to a distribution request from the client, the control unit 201 reads out the requested music content from the storage unit 202 and transmits it via the buffer 203 and the network interface 204. In the present embodiment, there are a case where a distribution request for music content consisting of only one song is given from the client 300 and a case where a distribution request for music content such as an album consisting of a plurality of songs is given from the client 300. The latter distribution request can be further divided into three types. The first distribution request is a distribution request for all the songs in the album, the second distribution request is a distribution request for a specific song in the album, and the third distribution request is after a specific song in the album Is a distribution request for all songs.

  When the first distribution request is given, the control unit 201 reads out the music content of the requested album from the storage unit 202, and sends a series of MP3 frames in this music content to the client 300. On the other hand, when the second distribution request is given, the control unit 201 reads the music content of the album including the requested specific music from the storage unit 202. Then, the control unit 201 refers to the break position data in the music content, and selects an MP3 frame necessary for playing a specific song on the client 300 side from all the MP3 frames in the music content. . Further, the control unit 201 creates timing data Non and Noff necessary for controlling the output period of the sample data decoded on the client 300 side by referring to the break position data in the music content. Then, the control unit 201 sends timing data Non and Noff to the client 300, and subsequently sends the selected MP3 frame. When the third distribution request is given, the control unit 201 sends to the client 300 only the MP3 frame and timing data Non necessary for playback of the specific music and subsequent pieces on the client 300 side. The MP3 frame selection method and the timing data Non and Noff creation methods will be described in detail in the operation description of the present embodiment in order to avoid duplication of description.

  The client 300 is a device that sends a music content distribution request to the server 200 in accordance with a user operation and reproduces the music content distributed from the server 200 in response to the request, and includes a control unit 301, an operation unit 302, a display A unit 303, a network interface 304, a buffer 305, a decoder 306, and an audio output unit 307. The operation unit 302 includes an operation element such as a keypad, and transmits the operation information to the control unit 301. The display unit 303 is a device that displays various types of information in accordance with instructions from the control unit 301. The network interface 304 is a device that controls communication with the server 200. The buffer 305 is a device that temporarily stores MP3 frames received from the server 200 via the network interface 304. The decoder 306 is a device that sequentially reads and decodes the MP3 frames in the buffer 305 and outputs sample data. The audio output unit 307 is a D / A converter that converts the sample data output from the decoder 306 into an analog signal, an amplifier that adjusts the level of the analog signal output from the D / A converter, and an output signal of the amplifier as a sound. And a speaker that outputs as The control unit 301 is a device that performs control for sending a music content distribution request to the server 200 in accordance with the operation information given from the operation unit 302 and reproduction control of the music content sent from the server 200 in response to the distribution request. is there.

Next, the operation of this embodiment will be described.
First, the operation of the encoding apparatus 100 when an instruction to encode sample data of a plurality of pieces of music obtained by live recording is given will be described. First, the control unit 101 extracts 1152 samples from the sample data sequence of the first song among the designated plurality of songs as frames, and gives each frame to the encoder 103. As a result, the MP3 frame obtained from the encoder 103 is stored. Write to part 202.

  Here, if the number of samples of sample data of one song is not an integer multiple of 1152, the number of samples of sample data extracted last from the sample data sequence of that song is 1152 samples necessary for constituting one frame. Less than. Therefore, the control unit 101 compensates for this shortage by supplementing the sample data at the beginning of the second song, and the sample data of 1152 samples comprising the sample data at the end of the first song and the sample data at the beginning of the second song. Is given to the encoder 103, and the resulting MP3 frame is written into the storage unit 102.

  At this time, the control unit 101 writes the delimiter position data N2 indicating the number of samples corresponding to the first sample data of the second song counted from the first sample data of the first song in the storage unit 102. The same processing as described above is performed for the second, third, and subsequent songs.

  When the last sample data is extracted from the sample data sequence of the last song and the number of extracted samples is less than 1152, the control unit 101 compensates for the zero data corresponding to the shortage and makes 1152 samples. A frame composed of sample data is formed, this frame is given to the encoder 103, and the MP3 frame obtained as a result is written in the storage unit. As a result of the above processing, the storage unit 102 stores the separation position data N2 to Nm indicating the position of the first sample data of each of the second to mth (last song) songs, as shown in FIG. Music content comprising MP3 frame groups obtained from a sample data sequence in which sample data sequences of minutes are collected together is obtained.

  In the present embodiment, the music content obtained in this way is supplied from the encoding device 100 to the server 200 and stored in the storage unit 202. The music content may be supplied from the encoding device 100 to the server 200 via the network, or the music content is written in a recording medium such as a CD in the encoding device 100, and this recording medium is stored in the server. You may supply in the aspect of making it read to 200. FIG.

  Next, it is assumed that after the music content of the album is stored in the storage unit 202 of the server 200 in this way, a distribution request for all the songs in the album is given from the client 300. In this case, the control unit 201 of the server 200 reads out the music content of the requested album from the storage unit 202 and sequentially transmits MP3 frames in the music content to the client 300. In the client 300, the MP3 frame is accumulated in the buffer 305, then decoded into sample data by the decoder 306, and output as sound from the audio output unit 307. In this case, in the decoder 306, zero data is not decoded at the joint portion of each song, so that the user can enjoy a live performance without an unnatural silence section.

Next, an operation when a distribution request for the k-th song in the album is given from the client 300 to the server 200 will be described.
In this case, the control unit 201 of the server 200 reads the music content of the album including the requested song from the storage unit 202, and k-th song break position data Nk and Nk + 1-th song break position included therein. The data is sent to the client 300 as timing data Non and Noff. Next, the control unit 201 obtains the frame number Fs of the first MP3 frame to be transmitted and the last frame number Fe of the MP3 frame to be transmitted by the following formula, and the frame numbers Fs to Fe of all the MP3 frames of the music content of the album are obtained. Each MP3 frame is sequentially extracted and sent to the client 300.
Fs = Int (Nk / 1152) +1 (1)
Fe = Int (Nk + 1/1152) +1 (2)

  FIG. 2B shows timing data Non and Noff sent to the client 300 as described above, and MP3 frames having frame numbers Fs to Fe. As shown in FIG. 2B, the first MP3 frame to be transmitted is MP3 that is several frames (e.g., j frame) before the frame containing the first sample data of the kth song. The last MP3 frame to be transmitted is an MP3 frame corresponding to the frame including the first sample data of the (k + 1) th music piece. Here, the required number of frames j depends on the music piece and the bit rate, but the client side can calculate the required number of frames j by analyzing the MP3 frame having the frame number Fs. In some cases, the client 300 may request distribution of the last song in the album. In this case, only the corresponding MP3 frame and timing data Non are sent to the client 300, and the timing data Noff is not sent.

On the client 300 side that has received the timing data Non and Noff and the MP3 frames having the frame numbers Fs to Fe, the following operation is performed.
First, the timing data Non and Noff received from the server 200 are sent to the control unit 301 via the network interface 304. The MP3 frame received from the server 200 is accumulated in the buffer 305 via the network interface 304.
Upon receiving the timing data Non and Noff, the control unit 301 obtains timing data Ton and Toff according to the following equation.
Ton = mod (Non / 1152) + 1152 × j (3)
Toff = Noff−Non + Ton (4)

  Prior to the start of reproduction, the control unit 301 instructs the audio output unit 307 to mute the audio output. In accordance with this instruction, the audio output unit 307 disables the output of the amplifier at the subsequent stage of the D / A conversion unit.

  When a certain amount of MP3 frames are accumulated in the buffer 305, the control unit 301 instructs the decoder 306 to start the decoding process. As a result, the decoder 306 sequentially extracts the MP3 frames having the frame numbers Fs to Fe in the buffer 305, performs decoding processing, and outputs sample data at a constant sampling rate as shown in FIG. The control unit 301 counts the number of sample data output from the decoder 306. After j MP3 frames are decoded and 1152 × j sample data are output, when further decoding of the (j + 1) th MP3 frame starts, the count value of the sample data eventually becomes a value indicated by the timing data Ton. To reach. At this time, the control unit 301 instructs the audio output unit 307 to cancel mute as shown in FIG. As a result, a series of sample data starting from the first sample data of the k-th song in the album is output from the audio output unit 307 as sound.

  The controller 301 continues counting the number of sample data thereafter. Then, when the decoder 306 decodes the MP3 frame having the frame number Fe and starts outputting sample data of that frame, the count value of the sample data eventually reaches the value indicated by the timing data Toff. At this time, the control unit 301 instructs the audio output unit 307 to mute as shown in FIG. Therefore, after the last sample data of the kth song is output as sound, the sound output by the sound output unit 307 stops.

Next, an operation when a distribution request for all the kth and subsequent songs in the album is given from the client 300 to the server 200 will be described.
In this case, only the MP3 frame and timing data Ton necessary for the reproduction of all the kth and subsequent songs are sent from the server 200 to the client 300, and the client 300 matches the timing at which the first sampling data of the kth song is decoded. Thus, the mute in the audio output unit 307 is released, and all the kth and subsequent songs are reproduced.

  As described above, according to the present embodiment, music contents of a plurality of songs such as live performance albums can be supplied to a client and played back without causing a silent period between songs on the client side. Even if there is a request for distribution of a specific song among multiple songs, the MP3 frame necessary for playing the song is sent to the client, and the part from the start point to the end point of the song is played back accurately on the client side can do.

  In the present embodiment, when the k-th song in the album is distributed, the distribution is performed from the MP3 frame of the frame j frames before the frame including the first sample data of the k-th song. This is because the MP3 compression encoding algorithm is intended to improve sound quality when encoding a certain frame, and if it is determined that the amount of sound information is large, borrow the bits of the previous MP3 frame. This is because the so-called bit borrowing in which compression encoding is performed is taken into consideration. In this embodiment, since the MP3 frame corresponding to the frame including the first sample data of the k-th song is sent to the client 300 from the MP3 frame several frames before it, the bit is borrowed. Even if it is, the frame including the first sample data of the k-th song can be accurately decoded.

In addition to what has been described above, various embodiments are possible as embodiments of the present invention. For example:
(1) Embodiment in which fade-in and fade-out are performed at a break between songs At the time of switching of songs, the spectrum distribution of the speech waveform changes abruptly. For this reason, when the sample data strings of a plurality of songs are encoded together, when the encoded data obtained by this encoding is decoded and reproduced as a sound, the song switching time and the actual song switching time There may be a slight gap between the two. The present embodiment avoids this inconvenience by using the break position data.

  In the present embodiment, the client 300 grasps the start timing and end timing of the song based on the break position data, and gradually increases the gain of the amplifier in the audio output unit 307 for a predetermined period from the song start timing. And the gain of the amplifier in the audio output unit 307 is gradually reduced for a predetermined period before the music end timing, and the audio output is faded out. This fade-in / fade-out is performed when a specific song in the album is reproduced on the client 300, or when a discontinuous song such as the first song and the third song is reproduced.

(2) Embodiment as a reproducing apparatus such as a CD As an embodiment of the present invention, there may be a reproducing apparatus such as a CD. FIG. 3 is a block diagram showing the configuration of the CD playback apparatus according to the present embodiment. In this figure, an operation unit 402, a display unit 403, a buffer 405, a decoder 406, and an audio output unit 407 have the same configuration as that provided in the client 300 of FIG. The CD reading unit 404 is a device that reads data recorded on a CD. In the present embodiment, the CD reading unit 404 is loaded with a CD on which separation position data and MP3 frames as shown in FIG. 2 are recorded. In the following, it is assumed that segment position data and MP3 frames for a plurality of songs obtained from a live performance are recorded on this CD.

  When the control unit 401 receives an instruction to reproduce the k-th song of the plurality of songs recorded on the CD via the operation unit 402, the control unit 401 acquires the break position data via the CD reading unit 404, Timing data Ton and Toff and frame numbers Fs to Fe necessary for reproducing the k-th song are obtained by the same method as in the first embodiment. Then, the control unit 401 instructs the CD reading unit 404 to read the MP3 frames having the frame numbers Fs to Fe. As a result, the instructed MP3 frames are sequentially read from the CD and stored in the buffer 405. The control unit 401 instructs the decoder 406 to start decoding when a certain amount of the MP3 frame is accumulated in the buffer 405. Thereafter, the control unit 401 counts the number of sample data output from the decoder 406, instructs the audio output unit 407 to cancel mute when the count value becomes Ton, and when the count value becomes Toff. The audio output unit 407 is instructed to mute.

  In some cases, the CD playback apparatus may be instructed to play back all kth and subsequent songs. The operation in this case is the same as that in the case where an instruction to reproduce the kth song is given, except that the generation of timing data Toff and the mute instruction based on the timing data Toff are not performed.

It is a block diagram which shows the structure of the content delivery system which is one Embodiment of this invention. It is a time chart which shows operation | movement of the embodiment. It is a block diagram which shows the structure of the CD reproduction apparatus which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Coding apparatus, 101 ... Control part, 102 ... Storage part, 103 ... Encoder, 104 ... Output part, 200 ... Server, 201 ... Control part, 202 ... Storage part, 203 ... Buffer 204 204 Network interface 300 Client 301 Control unit 302 Operation unit 303 Display unit 304 Interface 305 Buffer 306 Decoder 307 Audio Output unit 400... Client 401 401 control unit 402 operation unit 403 display unit 404 CD reading unit 405 buffer 406 decoder 407 audio output unit

Claims (3)

A predetermined number of sample data are extracted from all sample data sequences of a plurality of songs and framed, and each frame is given to the encoding means to generate encoded data. Generate break position data indicating
When the reproduction of a specific song in the plurality of songs is instructed, based on the separation position data related to the designated song, the encoded data necessary for the reproduction of the designated song is specified, Encoding and reproducing sound characterized by: providing the specified encoded data to decoding means, selecting sample data belonging to a specified song from the sample data sequence obtained from the decoding means, and outputting it as sound How to do. Encoding means for encoding sample data and outputting the encoded data;
A predetermined number of sample data is taken out from all sample data sequences of a plurality of songs and framed, and each frame is given to the encoding means to perform encoding, and the delimiter position between songs in the sample data sequences of the plurality of songs Control means for generating break position data indicating
An encoding device comprising: output means for outputting at least a part of the encoded data and the delimiter position data. A predetermined number of sample data is extracted from all sample data sequences of a plurality of songs, framed, and encoded data obtained by encoding each frame, and the delimiter positions between songs in all the sample data sequences of the plurality of songs Input means for obtaining the delimiter position data to be indicated;
Decoding means for decoding encoded data obtained by the input means and outputting sample data;
Sound output means for outputting sample data output from the decoding means as sound in response to a control signal;
When the reproduction of the specific music in the plurality of music is instructed, sample data corresponding to the start position of the specific music is output from the decoding means based on the break position data related to the specific music obtained by the input means. And a control means for obtaining a timing and outputting a control signal to the sound output means so that sample data after the start position is output as sound from the sound output means.

Images