JP2004101638A - Signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a temporal difference is caused between an actually reproduced sound and music switching display since the time when a compressed encoded signal of each musical piece is inputted to a reproducing processor does not match the time when the reproduced sound of the musical piece is actually outputted when a plurality of musical pieces are reproduced one after another. <P>SOLUTION: The processor is configured so that the compressed encoded signal and a control signal for music switching are stored synchronously with a 1st input buffer 101 and a 2nd input buffer 102. Then the processor 100 reproduce the musical pieces while synchronously reading those signals out. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a music signal reproduction technique, and more particularly to a signal processing device that facilitates reproduction control at a music switching point when a plurality of compression-encoded music signals (music) are continuously reproduced.
[0002]
[Prior art]
2. Description of the Related Art In recent years, when a music signal is compression-encoded and stored in a storage medium, many audio devices that decompress the compression-encoded signal in the storage medium and reproduce a desired music signal have been developed.
[0003]
In such audio equipment, Non-Patent Document 1 describes a technical report that aims at making the signal processing unit an LSI.
[0004]
[Non-patent document 1]
"A single chip AV decoder for the DVD player adapting the MCP architecture"
IEEE 1998 CUSTUM INTEGRATED CIRCUIT CONFERENCE pp. 185-188
[0005]
In these audio devices, for example, a process of sequentially reproducing compression-encoded signals of a plurality of music pieces stored in a memory card as a storage medium is performed. In this case, at the time of switching between songs, the switching of the song is displayed to the user, and the processor for decoding the compression-encoded signal is initialized.
[0006]
Conventionally, when such processing is performed, for example, the compression-encoded signal is decoded one by one, and when the processing of the music is completed, the user is notified that the music has been switched, the processor is initialized, and Was decrypted.
[0007]
FIG. 3 shows a schematic diagram of this method. It is assumed that the compression coded signals C1, C2, C3, C4,... In which the music signal is compressed by AAC, MP3, WMA, etc. are input to the decoder DA in music units. The decoder DA performs decoding processing (decoding) for each music piece, and outputs reproduced sounds M1, M2, M3, M4,. In this case, there is an elongation of, for example, about 100 ms between the reproduced sounds M of the songs.
[0008]
[Problems to be solved by the invention]
However, in the above-described method, it is necessary to perform the processing at the connection point every time the music is changed, it takes time to switch between the music, and an unnatural gap G (extension) between the music as shown in FIG. ).
[0009]
On the other hand, in order to avoid such a problem, instead of performing the reproduction processing of the compression-encoded signal for each music piece, the decoding processing of the compression-encoded signal of each music piece is performed continuously, so that the inter-music piece is decoded. There were also ways to avoid the resulting unnatural gaps.
[0010]
A schematic diagram of this method is shown in FIG. The compression coded signals C1, C2, C3, C4,. The decoder DB performs decoding processing continuously, and continuously outputs reproduced sounds M1, M2, M3, M4,. In this case, no delay occurs between the reproduced sounds M of the respective songs.
[0011]
However, according to this method, the time of the switching of the music to which the compression-encoded signal is input does not match the time at which the decoding process is actually performed and the reproduced sound is output. For this reason, there is a problem in that the time at which the switch between music pieces is displayed and the time at which the music pieces are actually switched as sounds are shifted.
[0012]
The reason will be described with reference to FIGS. FIG. 5 is a configuration diagram of a conventional signal processing device. This signal processing device has a processor 200 and an input buffer 201. The processor 200 performs a decoding process, and has a function of the decoder DB in FIG. The input buffer 201 is a buffer for temporarily storing the compressed coded signal 202, that is, the compressed coded signal C in FIG. Reference numeral 203 denotes a connection point of music. At the time of the state indicated by the arrow P in FIGS. 5 and 6, the connection point 203 of the music, for example, the compression coded signal C <b> 3 has just been input to the input buffer 201.
[0013]
However, on the output side of the decoder DB, as shown by the arrow Q at the same time as the arrow P, the reproduced sound M2 corresponding to the compression coded signal C2 is reproduced. As described above, the input timing of the input buffer 201 and the output timing of the decoder DB always deviate for each music.
[0014]
By the way, in recent compression systems, each frame which is a compression processing unit of an audio signal is often encoded with a variable compression ratio (see ISO / IEC13818-7 Advanced Audio Coding). That is, in one frame, even if the real time (for example, 21 ms) of the reproduced sound is fixed, the amount of data when compression-encoded differs for each frame, and the transfer time or processing time of the bit stream of one frame is different. Constantly changing. Therefore, it is difficult to accurately know how long after which the currently input compression-encoded signal is actually decoded. For this reason, as described above, it is difficult to accurately match the time when the compression-encoded signal is input to the input buffer with the time when the music is actually reproduced as music.
[0015]
Further, when decoding each compression-encoded signal continuously, there is a problem that the processor cannot be initialized at the switching point of the music, and a click sound is generated at the switching point.
[0016]
The present invention has been made in view of such a conventional problem, and facilitates playback control at a music switching point when decoding and playing back a plurality of compressed and encoded signals of music continuously. An object is to realize a signal processing device.
[0017]
[Means for Solving the Problems]
The invention according to claim 1 of the present application is directed to a first input buffer that accumulates a compression-encoded signal for a signal that is framed at a predetermined interval, and a control signal provided for each frame is added to the compression-encoded signal. When synchronously reading out the signals stored in the second input buffer and the first input buffer and the signal stored in the second input buffer and processing the compression-encoded signal, And a processor for performing a decoding process according to the control signal given to the frame.
[0018]
According to a second aspect of the present invention, in the signal processing device according to the first aspect, the compression-encoded signal is a concatenated signal obtained by compression-encoding a plurality of music signals in music units, and the control signal is a music signal. Wherein the processor performs a process of decoding the compression-coded signal in synchronization with the connection point.
[0019]
According to a third aspect of the present invention, in the signal processing device according to the second aspect, when the control signal indicates a connection point of the music signal, the processor performs processing on a compression-encoded signal input before the control signal. The decoding processing is initialized.
[0020]
According to a fourth aspect of the present invention, in the signal processing device of the second aspect, when the control signal indicates a connection point of the music signal, the processor includes a music switching detection signal indicating that the connection point has been detected. Is generated.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
A signal processing device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a main configuration of a signal processing device according to the present embodiment, and FIG. 2 is a schematic diagram illustrating an operation principle of the signal processing device. This signal processing device includes a processor 100, a first input buffer 101, and a second input buffer 102. The compression-coded signal 103 is a signal obtained by compression-coding a plurality of music signals, that is, a signal obtained by connecting a plurality of compression-coded signals C1, C2, C3, C4,.
[0022]
The connection point 105 of the music indicates a point where the compression coded signals Ci and Ci + 1 are connected, as shown by, for example, a black circle in FIG. The control signal 104 in FIG. 1 is a sequence of flags that is true in the compression-encoded signal 103 at the point where music is linked to music.
[0023]
The first input buffer 101 temporarily stores the compressed encoded signal 103 when the compressed encoded signal 103 is read from a storage medium such as a semiconductor memory. The second input buffer 102 temporarily stores the control signal 104 read out together with the compressed and coded signal 103 in synchronization with the compressed and coded signal 103.
[0024]
The processor 100 reads the signals stored in the first input buffer 101 and the second input buffer 102 in synchronization with each other, and decodes the read signals. The function of the decoder DC in FIG. Having.
[0025]
The operation of the signal processing device having such a configuration will be described. First, the first input buffer 101 shown in FIG. 2 temporarily reads these compressed encoded signals Ci when a plurality of compressed encoded signals C1, C2, C3... To accumulate. In synchronization with this, the second input buffer 102 temporarily stores a sequence of flags that are true at the connection point of the music pieces in the compressed and coded signal 103 of FIG. 1, that is, a control signal 104. In the state shown in FIG. 2, the compressed coded signal C2 is taken into the input buffer 101, and the next compressed coded signal C3 is about to be taken.
[0026]
Next, the processor 100 (decoder DC) synchronously reads the compressed and coded signal stored in the first input buffer 101 and the control signal stored in the second input buffer 102. Then, the processor 100 decodes the compressed and coded signal read from the first input buffer 101 and outputs a reproduced signal 107. At this time, if the processor 100 recognizes that the control signal read from the second input buffer 102 is true, that is, it is a connection point of music, the processor 100 initializes a decoding process for the previous input music, The compression encoding signal newly read out this time from the first input buffer 101 is decoded, and a music switching detection signal 108 is generated.
[0027]
As shown in FIG. 2, at the output side of the decoder DA, the output timing of the music switching detection signal 10 indicated by a black circle and the timing of the break of the reproduced sound M match, so that the listener of the music is displayed on the display unit. When looking at changes in the displayed time code, music number, and the like, the user no longer feels unnatural. For this reason, the cue for music selection can be accurately performed. When this signal processing device is used as a voice recorder, the function of searching recorded conversations is improved. Further, the processor 100 can generate the music switching detection signal 108 only by monitoring the control signal of the second input buffer 102, and thus detects a music break by adding special identification data to the beginning of each frame. The signal processing load on the processor 100 is reduced as compared with the method.
[0028]
As described above, the instant at which the music is switched as the actual reproduced sound can be easily grasped, and the accurate switching of the music enables initialization of the decoding process at regular timing.
[0029]
【The invention's effect】
According to the present invention, even when a plurality of music signals that have been compression-encoded are continuously reproduced, it is possible to easily grasp the moment at which the music is switched as the actual reproduced sound, and to perform the actual reproduction at the same timing as the music switching detection signal. Songs will switch accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a main configuration of a signal processing device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing an operation of the signal processing device of the present embodiment.
FIG. 3 is a schematic diagram showing a problem of the signal processing device of Conventional Example 1.
FIG. 4 is a schematic diagram of an example of a method for solving the problem of the signal processing device of Conventional Example 1.
FIG. 5 is an explanatory diagram showing an operation of the signal processing device of the first conventional example.
FIG. 6 is a schematic diagram showing an operation of the signal processing device of Conventional Example 2.
[Explanation of symbols]
Reference Signs List 100 Processor 101 First input buffer 102 Second input buffer 103, C1 to C4 Compression coded signal 104 Control signal 105 Music connection point 106 Flag indicating music connection point 107 Playback signal 108 Music switching detection signal DA, DB , DC decoder M1 to M4 playback sound

Claims (4)

A first input buffer for storing a compressed encoded signal for a signal framed at a predetermined interval;
A second input buffer that accumulates a control signal provided for each frame in synchronization with the compression-encoded signal;
When the signals stored in the first input buffer and the second input buffer are read out in synchronization with each other and the compressed encoded signal is processed, decoding according to the control signal given to each frame is performed. A signal processing device comprising: a processor that performs processing. The compression-encoded signal is a concatenated signal obtained by compression-encoding a plurality of music signals in song units,
The control signal is a signal indicating a connection point of the music signal,
2. The signal processing device according to claim 1, wherein the processor performs a process of decoding the compression coded signal in synchronization with the connection point. The signal according to claim 2, wherein the processor, when the control signal indicates a connection point of the music signal, initializes a decoding process for a compression-encoded signal input earlier than the control signal. Processing equipment. 3. The signal processing device according to claim 2, wherein when the control signal indicates a connection point of the music signal, the processor generates a music switching detection signal indicating that the connection point has been detected.

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