JP2008097781A - Sound reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound reproducing device capable of reproducing sound at an optional reproduction speed without interruption of sound. <P>SOLUTION: The sound reproducing device includes: a memory storing compressed audio data; a decoder decompressing the compressed audio data stored in the memory at a prescribed bit rate; a control part calculating the bit rate when the decoder decompresses the compressed audio data, on the basis of the bit rate indicated by bit rate information of the compressed audio data stored in the memory and the reproduction speed designated in advance; and a D/A converter converting the digital audio data decompressed by the decoder into an analog signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an audio playback apparatus that controls the playback speed of audio.

  FIG. 4 is a block diagram showing an audio reproducing apparatus that reads compressed audio data from an optical disc and reproduces audio. 4 includes an optical pickup 101, a servo LSI 102, a semiconductor memory 103, a decoder 104, a microcomputer 105, a D / A converter 106, a spindle motor 107, and a thread motor 108. The servo LSI 102 includes an RF amplifier 151, a signal processing circuit 152, and a control circuit 153.

  The optical pickup 101 reads compressed data from the optical disc 1. The RF amplifier 151 amplifies the compressed data signal read by the optical pickup 101. The signal processing circuit 152 processes the signal amplified by the RF amplifier 151 and outputs compressed audio data. The semiconductor memory 103 stores the compressed audio data output from the signal processing circuit 152. The decoder 104 reads and decompresses the compressed audio data stored in the semiconductor memory 103. The D / A converter 106 converts the digital audio data expanded by the decoder 104 into an analog signal. The microcomputer 105 controls the control circuit 153 included in the decoder 104 and the servo LSI 102. A control circuit 153 included in the servo LSI 102 controls the signal processing circuit 152, the spindle motor 107, and the thread motor 108. The spindle motor 107 rotates the optical disc 1. The thread motor 108 moves the optical pickup 101.

  When the sound reproducing device reproduces sound at a speed higher than the normal speed, the sound reproducing device operates according to the flowchart shown in FIG. As shown in FIG. 5, when the audio reproducing apparatus receives a double speed reproduction instruction, the optical pickup 101 reads compressed data for a fixed length from the optical disc 1 (step S501). The compressed data read by the optical pickup 101 is stored in the semiconductor memory 103 via the servo LSI 102 (step S502). The decoder 104 decompresses the compressed audio data stored in the semiconductor memory 103. The microcomputer 105 determines whether the data decompression time for a certain reproduction time has elapsed (step S503). The microcomputer 105 that has determined that the predetermined time has elapsed instructs the decoder 104 to stop the expansion (step S504). Further, the microcomputer 105 controls the control circuit 153 in the servo LSI 102 so that the optical pickup 101 moves to the track ahead of the fixed length (step S505). While the audio playback device performs double speed playback, these steps S501 to S505 are repeated.

  FIG. 6 is a diagram showing each image of compressed audio data, sound output position, and sound output based on the flowchart shown in FIG. As shown in FIG. 6, when the compressed audio data Z401 includes five data groups B1 to B5, the decoder 104 expands the compressed audio data by a fixed portion D1 to D5 of each data group. As a result, the compressed audio data Z401 is reproduced for a certain period A1 to A5 within the reproduction time.

JP 2004-206757 A

  In the above-described audio double-speed reproduction method, sound interruption occurs when the compressed audio data of the next fixed length ahead track is not stored in the semiconductor memory 103. When the decoder 104 decompresses the compressed audio data, the audio output time is shorter at a high bit rate than at a low bit rate. That is, referring to FIG. 6, when the decoder 104 expands the compressed audio data of the fixed portions D1 to D5 at a high bit rate, each time of the periods A1 to A5 becomes shorter than when the decoder 104 expands at a low bit rate. . In this case, if the time for the optical pickup 101 to move (track jump) to the position of the next fixed length ahead track on the optical disc 1 is short and the accuracy of the track jump is not good, the compressed audio that the decoder 104 should perform expansion on. A state in which data is not stored in the semiconductor memory 103 may occur. In such a case, sound interruption occurs. Further, if the capacity of the semiconductor memory 103 is small, there is a high possibility that sound interruption will occur. If sound interruptions occur frequently, it is difficult to hear.

  An object of the present invention is to provide an audio reproducing apparatus capable of reproducing audio at an arbitrary reproduction speed without interruption of sound.

  The present invention shows a memory for storing compressed audio data, a decoder for expanding compressed audio data stored in the memory at a predetermined bit rate, and bit rate information of the compressed audio data stored in the memory. A control unit that calculates a bit rate when the decoder decompresses the compressed audio data based on a bit rate and a pre-specified playback speed, and D that converts the digital audio data decompressed by the decoder into an analog signal / A converter is provided.

  In the audio reproduction device, the reproduction speed designated in advance is a reproduction speed designated by a user of the audio reproduction apparatus.

  According to the audio reproducing device of the present invention, audio can be reproduced at an arbitrary reproduction speed without interruption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an audio reproducing apparatus according to an embodiment for reading compressed audio data from an optical disc and reproducing audio. The audio reproduction device shown in FIG. 1 includes an optical pickup 101, a servo LSI 102, a semiconductor memory 103, a decoder 501, a microcomputer 502, a D / A converter 106, a spindle motor 107, and a thread motor 108. The servo LSI 102 includes an RF amplifier 151, a signal processing circuit 152, and a control circuit 153. The audio reproduction device shown in FIG. 1 is different from the audio reproduction device shown in FIG. 4 in a decoder 501 and a microcomputer 502. For this reason, in FIG. 1, the same reference numerals are assigned to components common to FIG. 4 other than the decoder 501 and the microcomputer 502.

  The optical pickup 101 reads compressed data from the optical disc 1. The RF amplifier 151 amplifies the compressed data signal read by the optical pickup 101. The signal processing circuit 152 processes the signal amplified by the RF amplifier 151 and outputs compressed audio data. The semiconductor memory 103 stores the compressed audio data output from the signal processing circuit 152. The decoder 501 reads and expands the compressed audio data stored in the semiconductor memory 103. The decoder 501 of this embodiment performs expansion processing at the bit rate indicated by the bit rate information included in the header of the compressed audio data during reproduction at normal speed, but at the bit rate specified by the microcomputer 502 during reproduction at double speed. Perform decompression processing.

  The D / A converter 106 converts the digital audio data expanded by the decoder 501 into an analog signal. The microcomputer 502 controls the control circuit 153 included in the decoder 501 and the servo LSI 102. At the time of reproduction at double speed, the microcomputer 502 calculates a bit rate to instruct the decoder 501 based on the bit rate information of the compressed audio data stored in the semiconductor memory 103 and the reproduction speed designated by the user. A control circuit 153 included in the servo LSI 102 controls the signal processing circuit 152, the spindle motor 107, and the thread motor 108. The spindle motor 107 rotates the optical disc 1. The thread motor 108 moves the optical pickup 101.

  When the audio reproduction device of the present embodiment reproduces audio at a speed faster than the normal speed, the audio reproduction device operates according to the flowchart shown in FIG. As shown in FIG. 2, when the audio reproducing apparatus receives a double speed reproduction instruction, the optical pickup 101 reads compressed data from the optical disc 1 (step S201). The compressed data read by the optical pickup 101 is stored in the semiconductor memory 103 via the servo LSI 102 (step S202). The microcomputer 502 calculates a bit rate for instructing the decoder 501 based on the bit rate of the compressed audio data stored in the semiconductor memory 103 and the reproduction speed designated by the user (step S203). The decoder 501 decompresses the compressed audio data stored in the semiconductor memory 103 at the bit rate specified by the microcomputer 502 (step S204).

  FIG. 3 is a diagram showing compressed audio data, an audio output image at normal speed reproduction, an audio output image at double speed reproduction, and an audio output image at half speed reproduction based on the flowchart shown in FIG. It is. As shown in FIG. 3, the case where the compressed audio data Z501 includes three data groups C1 to C3 will be described. At the time of reproduction at the normal speed, the decoder 501 expands the compressed audio data at the bit rate indicated by the bit rate information of the compressed audio data. As a result, the sound reproducing device outputs sounds having time lengths N1 to N4 indicated by the reference numeral Z502.

  At the time of double speed reproduction, the decoder 501 expands the compressed audio data at the bit rate calculated by the microcomputer 502. As a result, the sound reproducing device outputs sounds having time lengths F1 to F3 indicated by reference numeral Z503. The time lengths F1 to F3 of the voice Z503 are half of the time lengths N1 to N3 of the voice Z502. When decompression is performed at a rate higher than the bit rate indicated by the bit rate information of the compressed audio data, the length of time for outputting the sound is shortened. For example, when decompression is performed at a double bit rate, the audio data becomes an actual ½ amount, and the sound output time length becomes ½. At this time, it sounds as if fast-forwarding is heard.

  The decoder 501 also decompresses the compressed audio data at the bit rate calculated by the microcomputer 502 even during playback at ½ speed. As a result, the sound reproducing device outputs sounds having time lengths L1 to L3 indicated by reference numeral Z504. The time lengths L1 to L3 of the voice Z504 are twice the time lengths N1 to N3 of the voice Z502. When decompression is performed at a rate smaller than the bit rate indicated by the bit rate information of the compressed audio data, the time length for outputting the sound becomes longer. For example, when decompression is performed at a bit rate of ½, the audio data becomes twice the actual amount, and the sound output time length is doubled. At this time, it sounds like a slow playback for the sake of hearing.

  As described above, according to the audio reproduction device of the present embodiment, it is not necessary to perform a track jump during double-speed reproduction, so that the possibility of sound interruption can be eliminated. In addition, since the bit rate can be designated by the microcomputer 502, it can be played back at an arbitrary playback speed. Furthermore, since there is no problem of sound interruption, the capacity of the semiconductor memory 103 can be reduced to the minimum.

  The audio reproduction device according to the present invention is useful as an audio reproduction device that reproduces audio at an arbitrary reproduction speed without interruption.

1 is a block diagram showing an audio reproduction apparatus according to an embodiment that reads compressed audio data from an optical disc and reproduces audio. The flowchart which shows operation | movement of the audio | voice reproduction apparatus of one Embodiment. The figure which shows the compression audio data, the audio | voice output image at the time of reproduction | regeneration at normal speed, the audio | voice output image at the time of double speed reproduction | regeneration, and the audio | voice output image at the time of reproduction | regeneration at 1/2 speed | rate FIG. 2 is a block diagram showing a conventional audio reproducing apparatus that reads compressed audio data from an optical disc and reproduces audio. A flowchart showing the operation of a conventional audio reproduction apparatus The figure which shows each image of compression audio data, sound output position, and sound output

Explanation of symbols

101 Optical Pickup 102 Servo LSI
103 Semiconductor Memory 501 Decoder 502 Microcomputer 106 D / A Converter 107 Spindle Motor 108 Thread Motor 151 RF Amplifier 152 Signal Processing Circuit 153 Control Circuit

Claims (2)

A memory for storing compressed audio data;
A decoder for decompressing compressed audio data stored in the memory at a predetermined bit rate;
A control unit that calculates a bit rate when the decoder decompresses the compressed audio data based on a bit rate indicated by the bit rate information of the compressed audio data stored in the memory and a pre-specified playback speed;
A D / A converter for converting the digital audio data expanded by the decoder into an analog signal;
An audio reproducing apparatus comprising: The audio playback device according to claim 1,
The audio reproduction device characterized in that the reproduction speed designated in advance is a reproduction speed designated by a user of the audio reproduction device.

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