JPH05114868A - Adpcm reproduction device - Google Patents

Abstract

PURPOSE:To preclude problems such as a noise and data destruction caused in speech reproduction switching during ADPCM speech reproduction. CONSTITUTION:The ADPCM reproduction device consists of a CD-ROM drive 2, a buffer memory 3 for the CD-ROM drive, a CPU 4, a data decision circuit 5, an ADPCM decoding circuit 7, a buffer RAM 6 for the ADPCM decoding circuit, a digital filter 8, a D/A converter 9, a speech output control circuit 10, and a speech output circuit 11 and uses a CD ROM disk on which speech data and image data are interleaved and recorded. The output of a speech is stopped temporarily at the time of the speech reproduction switching and restarted when the problem of the noise is eliminated to preclude the noise. Further, the switching is performed at the point of time when data whose switching is instructed is transferred, so the destruction of the data due to the switching and an unnatural output are eliminated.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a CD-I or CD
-Reproduction of ADPCM data such as ROM XA
The present invention relates to a DPCM reproducing device.

[0002]

2. Description of the Related Art A conventional ADPCM reproducing apparatus is, for example,
In Japanese Patent Laid-Open No. 2-285723, it is said that when switching the reproduction data, the transfer of new data is not permitted until the reproduction of the data being reproduced is finished, thereby preventing noise due to interruption of reproduction.

[0003]

The above-mentioned prior art does not consider the modes of the reproduction data before and after the switching.

In the above-mentioned prior art, since it is assumed that the data modes are the same, only the data to be transferred to the ADPCM decoding unit should be controlled even when the reproduction data is switched. However, when the data mode before switching is different from that after switching, the ADPCM decoding unit also needs to change the setting according to the data mode because the sampling frequency is different depending on the mode. Therefore, ADPCM
If the decoding unit is not set in a timely manner, the mode of the actual data and the mode of the set ADPCM decoding unit do not match, and an abnormal voice may be generated.

Further, in the above-mentioned prior art, the ADP being reproduced is being reproduced.
When the CM data has a high compression rate, the reproduction time is long, and the buffer memory for temporarily storing the data from the CD-ROM drive may overflow before the data newly instructed to be switched is reproduced. There is a nature.

Alternatively, if the arrangement of the data after the switching is far from the point of time of the switching instruction, after the data before the switching is output, a silent period longer than necessary continues until the new data after the switching is output. Makes you feel unnatural.

It is an object of the present invention to provide an ADPCM reproducing apparatus capable of switching data without feeling unnatural when reproducing ADPCM data.

[0008]

In order to achieve the above object, the present invention provides means for stopping the reproduction of ADPCM data being reproduced, and audio data remaining in the buffer RAM for temporarily storing the ADPCM data. Is provided, and means for changing the audio output level are provided.

[0009]

By the means for stopping the reproduction of the ADPCM data being reproduced and the means for invalidating the audio data remaining in the buffer RAM in which the ADPCM data is temporarily stored, the audio data before the switching is changed after the audio is switched. Never be output to. Further, the means for changing the voice output level before setting the mode of the ADPCM decoding section minimizes the voice output level and puts it in a silent state. Before switching the audio output level by means for setting a new mode of the ADPCM decoding unit while the audio output is in the silent state and changing the audio output level when the ADPCM data corresponding to the mode is transferred to the ADPCM decoding unit. By returning to the level of, prevent abnormal sound output before and after sound switching.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

The hardware block diagram of FIG. 1 is an embodiment of a system for implementing the present invention.

The ADPCM reproducing apparatus according to the present invention is C
A based on DI or CD-ROM XA standard
CD-ROM disc 1 on which DPCM data is recorded, CD-ROM drive 2 for reading data from CD-ROM disc 1, CD-ROM drive 2
Buffer memory 3 for temporarily storing data from the CPU, CPU 4 for controlling data transfer, CD-ROM drive 2
A data discrimination circuit 5 for knowing data information such as the type of transferred data, an ADPCM decoding circuit 6 for decoding ADPCM data, a buffer RAM 7 for temporarily storing the ADPCM data supplied to the ADPCM decoding circuit 6, Digital filter 8, D / A converter 9, audio output control circuit 10 for muting, fading out, and fading in audio output, audio output circuit 1
It is composed of 1.

The procedure of data reproduction in the ADPCM reproducing apparatus of the present invention will be described below.

First, the data recorded on the CD-ROM disc 1 is read by the CD-ROM drive 2 and temporarily stored in the buffer memory 3. CPU
Reference numeral 4 transfers the information of the read data to the data discriminating circuit 5. Based on the judgment of the data judgment circuit 5, the CPU 4
Transfers data from the buffer memory 3. If the data is ADPCM data, it is determined whether or not the mode instructed for reproduction matches the mode of the data. If they do not match, the data is invalidated. If they match, they are transferred to the buffer RAM 7 through the ADPCM decoding circuit 6. The ADPCM decoding circuit 6 decodes the ADPCM data in the buffer RAM 7. The decoded data is sent to the audio output control circuit 10 via the digital filter 8 and the D / A converter 9. The sound output control circuit 10 attenuates the sound if necessary, and outputs the sound through the sound output circuit 11. Also, AD
The PCM decoding circuit 6 stops the reproduction of the ADPCM data according to the control signal from the CPU 4. Furthermore, the ADPCM left in the buffer RAM 7 due to the interruption of the reproduction.
The newly written ADPCM data is reproduced, ignoring the data.

FIG. 2A shows C in the embodiment of the present invention.
It is an example of a data array on a D-ROM disc. In this example, there are two types of ADP: channel 1 in level B monaural mode and channel 2 in level C stereo mode.
CM data is recorded. Hereinafter, each is referred to as channel 1 and channel 2 data. The data of channel 1 is the data of A1 shown in FIG. 2A, and the data of channel 2 is the data of A2 shown in FIG. 2A, and both data are recorded in one sector every eight sectors. ing. In the area D shown in FIG. 2A, image data, numerical data, and the like are recorded. The data of channel 1 and the data of channel 2 have the same compression rate, but the sampling frequency is different, and therefore the setting of the ADPCM decoding circuit 6 must be changed at the time of decoding.

FIG. 2 (b) is a diagram of FIG.
It is a reproduction image of the data of (a). When the data reproduction instruction for the channel 2 is issued at the timing t1 during the data reproduction for the channel 1, the data transfer for the channel 2 is not performed until the data reproduction for the channel 1 is completed as in the conventional example. Therefore, the data reproduction of the channel 2 starts at the timing t when the data reproduction of the channel 1 ends.
It is from time 2. At this time, the setting of the ADPCM decoding circuit 6 must be changed for the channel 2 data. However, it is necessary to change the setting at a slight time in a short time after the reproduction of the channel 1 data is completed and the reproduction of the channel 2 data is started. Have difficulty. Therefore, even if the ADPCM decoding circuit 6 is set to the mode of the channel 2 or the data of the channel 2 is transferred during the reproduction of the data of the channel 1,
If the setting of the DPCM decoding circuit 6 remains in the channel 1 mode, abnormal sound is generated.

FIG. 3 is a flow chart showing the operation of this embodiment. The operation of this embodiment will be described below with reference to the flowchart of FIG.

(Step 30) At a timing t3 earlier than the timing t2 when the data reproduction of the channel 1 ends, the audio output control circuit 10 mutes or fades out and stops the audio output.

(Step 31) The mode of the ADPCM decoding circuit 6 is set for the channel 2.

(Step 32) The data discriminating circuit 5 waits for the data of channel 2 to be read.

(Step 33) The data of channel 2 is
When read from the CD-ROM drive 2, the audio output control circuit 10 cancels mute and fades in to output the audio of channel 2.

According to this embodiment, before the reproduction of the data before switching is completed, the audio output is stopped, the setting of the ADPCM decoding circuit is changed during the silent period, and the mode set in the ADPCM decoding circuit is changed. Since the audio output is started when the same data is transferred to the ADPCM decoding circuit, an abnormal audio is not output due to the mode of the data and the mode of the ADPCM decoding circuit not matching.

FIG. 4A shows an example of the data array on the CD-ROM disc in the second embodiment of the present invention.
In this example, channel 1 is in Level A stereo mode,
Two types of ADPCM data of level C stereo mode are recorded in channel 2. The data of channel 1 is A4 data shown in FIG. 4A, and one sector is recorded every eight sectors. Further, the channel 2 data is the A3 data shown in FIG. 4A, and one sector is recorded for every two sectors. D shown in FIG.
Image data and numerical data are recorded in the area of.

FIG. 4B is a reproduction image of the data of FIG. 4A in the conventional example. In addition, FIG.
It is a reproduction image of the data of (a) in this embodiment.

This embodiment will be described below while clarifying the difference from the conventional example.

First, during reproduction of channel 2 ADPCM data, at the timing t4 in FIG. 4A, when an instruction to reproduce channel 2 ADPCM data is issued, in the case of the conventional example, until the timing t5, the channel is reproduced. 2 ADP
CM data is reproduced, and AD of A4-1 from the position of t5
Playback of PCM data starts. In this case, since the data of A4-1 cannot be transferred to the position of t5, the data of 7 sectors from A4-1 to A4-4 is stored in the buffer memory 3. Therefore, if the buffer memory 3 does not have a sufficient capacity, the data read from the CD-ROM drive 2 may be destroyed.

FIG. 5 is a flow chart of the operation in the second embodiment of the present invention. The operation will be described below with reference to the flowchart of FIG.

(Step 50) When a data switching instruction is issued at the timing t4 in FIG. 4, the audio output control circuit 10 mutes or fades out the audio output to stop the audio output and silence the audio.

(Step 51) According to an instruction from the CPU 4, the ADPCM data decoding of the ADPCM decoding circuit 6 is stopped and the data in the buffer RAM 7 is invalidated.

(Step 52) The mode of the ADPCM decoding circuit 6 is set for the channel 2.

(Step 53) The data discriminating circuit 5 waits until the channel 2 data is read.

(Step 54) The data of channel 2 is
When read from the CD-ROM drive 2, the audio output control circuit 10 cancels mute and fades in to output the audio of channel 2.

According to the second embodiment of the present invention, the reproduction of the data being reproduced is interrupted at the time when the switching instruction is received, and the data remaining in the buffer RAM is invalidated. Therefore, since the data can be reproduced when the data instructed to be switched is found, the buffer memory of the CD-ROM drive does not overflow. Also, interruption of playback data or A
Since the mode change of the DPCM decoding circuit is performed during the silent period from t4 to t6, abnormal sound is not output.

FIG. 6A shows an example of the data array on the CD-ROM disc in the third embodiment of the present invention.
In this example, channel 1 is in Level A stereo mode,
Two types of ADPCM data of level C stereo mode are recorded in channel 2. Channel 1 data is A5 data shown in FIG. 6A, and one sector is recorded for every two sectors. The channel 2 data is A6 data shown in FIG. 6A, and one sector is recorded every eight sectors. D shown in FIG. 6 (a)
Image data and numerical data are recorded in the area of.

FIG. 6B is a reproduction image of the data of FIG. 6A in the conventional example. In addition, FIG.
It is a reproduction image of the data of (a) in this embodiment.

This embodiment will be described below while clarifying the difference from the conventional example.

First, during reproduction of channel 2 ADPCM data, when an instruction to reproduce channel 2 ADPCM data is issued at timing t7 in FIG. 6 (a), in the case of the conventional example, until channel timing t8, 2 ADP
The CM data is reproduced, and the AD of A2-1 is displayed from the position of t9.
Playback of PCM data starts. In this case, since there is no audio data to be reproduced from the position of t7 to the position of t8, an unnatural silence period in which the audio data is not reproduced continues after the audio switching instruction.

FIG. 7 is a flow chart of the operation in the third embodiment of the present invention. The operation will be described below with reference to the flowchart of FIG.

(Step 70) When a switching instruction to the channel 2 data is issued at the timing t7 in FIG. 6, the channel 1 voice is output until the next voice data is stored in the buffer memory 3.

(Step 71) If the voice data stored in the buffer memory is not the channel 2 voice data but the channel 1 data, the channel 1 data is set to A
The data of the channel 1 is transferred to the DPCM decoding circuit 6 and reproduced and output.

(Step 72) When the audio data stored in the buffer memory is the audio data of channel 2, the audio output control circuit 10 mutes or fades out the data of channel 1 being reproduced,
Stop audio output and silence.

(Step 73) According to an instruction from the CPU 4, the ADPCM data decoding of the ADPCM decoding circuit 6 is stopped and the data of the channel 1 in the buffer RAM 7 is invalidated.

(Step 74) The mode of the ADPCM decoding circuit 6 is set for the channel 2.

(Step 75) The audio output control circuit 10 cancels mute and fades in.
Outputs channel 2 audio.

According to the third embodiment of the present invention, even if the switching instruction is received, the data before the switching instruction is reproduced and output until the voice data for which the switching instruction is received is found. There is no. Further, since the interruption of the reproduction data and the mode change of the ADPCM decoding circuit are performed during the silent period, abnormal sound is not output.

Further, it is possible to prevent generation of noise due to switching of audio reproduction, and to prevent data destruction due to buffer overflow or output of unnatural silent data.

Note that mute, fade-out, and fade-in are used to stop the sound output, but more natural sound switching can be performed by using fade-out and fade-in than mute.

[0048]

According to the present invention, at the time of voice switching, during the reproduction of the data before switching, the output from the voice output unit is stopped to put it into a silent state, and during that time, the setting of the ADPCM decoding circuit is changed. By starting the output from the audio output unit when the settings of the ADPCM decoding circuit and the mode of the transferred data match, abnormal audio output can be prevented even when switching between data of different modes. ..

Further, when the switching is instructed, the reproduction of the audio data being reproduced is interrupted, the data before the switching remaining in the buffer RAM is invalidated, and the data is reproduced after the switching so that the data from the CD-ROM drive can be reproduced. Prevents overflow of the buffer memory that temporarily stores data.

Further, if there is a time until the data instructed to be switched is read after the switching is instructed, the data up to the switching can be reproduced to eliminate an unnecessary silent period until the actual voice switching. it can.

[Brief description of drawings]

FIG. 1 is a system block diagram of hardware according to an embodiment of the present invention,

FIG. 2 is an explanatory view of a recording state on a CD-ROM disc of one embodiment of the present invention and an image of audio data output during reproduction,

FIG. 3 is a flowchart of an embodiment of the present invention,

FIG. 4 is an explanatory diagram of a recording state on a CD-ROM disc and a sound data output image during reproduction according to the second embodiment of the present invention;

FIG. 5 is a flowchart of the second embodiment of the present invention,

FIG. 6 is an explanatory view of a recording state on a CD-ROM disc and a sound data output image at the time of reproduction according to a third embodiment of the present invention;

FIG. 7 is a flowchart of the third embodiment of the present invention.

[Explanation of symbols]

1 ... CD-ROM disc, 2 ... CD-ROM drive, 3 ... Buffer memory for CD-ROM drive, 4 ...
CPU, 5 ... Data discrimination circuit, 6 ... ADPCM decoding circuit, 7 ... ADPCM decoding circuit buffer RAM, 10 ...
Audio output control circuit, 11 ... Audio output circuit.

Claims (4)

[Claims] 1. A CD-ROM disc recording interleaved ADPCM audio data, and the CD-RO.
CD-ROM drive for reading data on M disc, and ADPC output from the CD-ROM drive
A buffer RAM that temporarily stores M data, an ADPCM decoding unit that reads the contents of the buffer RAM and performs ADPCM decoding, an audio output unit that outputs the decoded ADPCM data as audio, and the CD-RO.
In an ADPCM reproducing apparatus including an M drive, the buffer RAM, and a control unit that controls the ADPCM decoding unit, a unit that interrupts the operation of the ADPCM decoding unit and a unit that invalidates the data in the buffer RAM. An ADPCM playback device comprising: 2. The ADPCM reproducing apparatus according to claim 1, wherein the audio output unit includes means for changing an audio output level. 3. The control unit, when changing the ADPCM data being reproduced to ADPCM data of a different mode, adjusts the audio output level by a means for changing the audio output level to a minimum period during which there is no sound. The ADPCM reproducing apparatus according to claim 1 or 2, wherein the decoding mode of the ADPCM decoding unit is changed. 4. When changing the ADPCM data being reproduced to ADPCM data of a different mode, the control unit interrupts the reproduction operation of the ADPCM decoding unit at the time when the ADPCM data instructed to be changed is read out. 4. The ADPCM reproducing apparatus according to claim 1, wherein the data remaining in the buffer RAM is invalidated.