JP2576953B2 - Disk playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing an optical disk such as a compact disk (CD), and more particularly, to a disk reproducing apparatus capable of reproducing data on an optical disk for a long time.

[Summary of the Invention]

According to the present invention, it is possible to reproduce for a long time on a single disc, and the servo system and mechanism of the disc reproducing apparatus use a large amount of compressed data in order to use the normal disc reproducing apparatus as it is. Provided is a disk reproducing apparatus which prepares channels, arranges them in the time axis direction, reproduces one of the channels at the time of reproduction, and reproduces the next channel from the beginning at the end of the channel for a long time reproduction. Is what you do.

[Conventional technology]

In the case of compact discs, etc., the playback time of a disc such as a CD is generally about 1 due to the compatibility of the device.
Time was long and required a large number of discs for long-time playback, such as a background music (BGM) device.

[Problems to be solved by the invention]

If a configuration like an autochanger with a large number of discs as described above is used, it is possible to play for a long time, but it must be transported from the position where a large number of discs are held to the position where the discs are reproduced, and the There was a disadvantage that a complicated mechanism was required.

[Means for solving the problem]

The present invention is directed to a disk reproducing apparatus which solves the above-mentioned disadvantage, and reduces the number of bits of sample data corresponding to an audio signal to a predetermined upper-order number of bits so that a multi-channel audio signal including a plurality of recorded contents in a time axis direction can be serialized. Means for reproducing the recorded disk, means for designating a channel to be reproduced from the reproduced data and extracting data of the specified channel, and audio signal data having a predetermined number of upper bits from the extracted data of the channel And a means for obtaining audio signal data corresponding to the data of the original number of bits from the floating point data corresponding to the audio signal data of the predetermined number of upper bits, and reproducing the audio signal of a predetermined channel.

Also, the number of bits of the sample data corresponding to the audio signal is reduced to a predetermined number of upper bits, data is arranged in a multi-channel serial manner in the time axis direction, and floating point data corresponding to the audio signal level of the predetermined number of bits is provided. A disk reproducing apparatus comprising means for multiplex-recording the floating point data at different positions on the time axis when recording a multi-channel audio signal arranged in synchronization with a predetermined period according to each channel on a disk. .

Also, when the multi-channel serial data is n-channel, when writing the serial data of less than n-channels, a part of the serial data of other plural channels is written to the empty channel of the n-channels. This is a disk reproducing apparatus including a recording unit.

Also, the reproduction of a multi-channel audio signal recorded on the disk in a predetermined order by the channel designation means is repeated for a predetermined number of channels, a predetermined channel is sequentially extracted from the serial data and reproduced, and the reproduction is performed for a long time. Device.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The digital signal sequence in a normal CD is the left and right channels (L, R)
Are represented by 4 bytes (B) of 8 bits and arranged in the time axis direction. FIG. 3 is a schematic diagram showing this data array. That is, 44.1K x 4B = 176.4KB for sample data for 44.1KHZ L and R channels
The data string D is / S. A frame synchronization signal S is inserted before and after this data string D at a constant period. Now, when the frame synchronization signal S is input at a period of 75 Hz, the synchronization period becomes 2352 bytes.

FIG. 2 is a schematic diagram showing a data array of a disk recorded for use in the disk reproducing apparatus of the present invention. In the present invention, an example is described in which audio data is compressed and recorded, but what is known as a floating point method is used. This method transmits only the upper significant digits of the sample data,
The shifted value is separately transmitted as floating point data, and the reproduced data is shifted by the amount indicated as the floating point at the time of reproduction to expand the dynamic range.

In a normal CD, audio data is processed by 16 bits. In the present invention, this is represented by, for example, 8 bits, and shift data of 8 bits at a floating point, that is, 0 to 8 bits of shift data of 4 bits. To indicate the amount,
It has the same dynamic range as 16 bits. The data of the above-mentioned floating point may be the same data by collecting several to several tens of samples, and by transmitting to the maximum level among them, the loss of transmission bits due to the data of the floating point is almost eliminated. Can be.

In the present invention, the transmission byte loss of the floating point data is reduced by transmitting the floating point data one for every 15 samples. In addition, if the floating point data is lost due to dropout or the like, audio data of a channel over 15 samples is lost, which has a serious effect. For this reason, in the present invention, only the floating point EP is written in a different location on the disk track as shown in FIG. 2, that is, the dual writing FP1 and FP2 is performed on the time axis. It is designed to cope with dropouts. That is, if the byte error rate is, for example, 10 ^-5 , the probability of erroneous operation of two at a time is 10 ^-10 , and the effect of dropout and the like can be almost ignored. The sampling frequency depends on the amount of the synchronization signal, the floating point data or the number of channels, but needs to be as small as possible. For example, if the sampling frequency is 31.5 KHZ as 5 channels and 8 bits, the relationship is 7: 5 with respect to the conventional sampling frequency of 44.1 KHZ, the data D between the synchronization signals S, S is 420 samples, and 420 × 5 = 2100 bytes And the floating point data of 420/15 × 4 = 28 × 4 = 112 bytes. Even if these are added, it is possible to sufficiently record on the disk track. As a result, it is possible to obtain a disk in which data having a dynamic range equivalent to 16 bits based on five channels of floating point data is recorded. Here, a band of 14 KHZ is possible and this band is sufficient when used for BGM.

Next, FIG. 1 shows a block diagram of a disk reproducing apparatus of the present invention. First, the reproduced data 11 is input in units of bytes and is reproduced in synchronization with the data clock 12. The data 11 is subjected to synchronization pattern detection by the synchronization detector 1, whereby the initial value of the channel counter 2 is set, and the channel counter 2 operates in synchronization with the data channel.

In the embodiment of the present invention, the channel counter 2 is a quinary counter. The floating point data can be synchronized with the floating point data position by counting 16 quaternary 4-channel counters 2. Next, a channel set switch 13 or the like is provided to generate one pulse each time the switch is pressed, and this is supplied to the channel set counter 3 via the OR gate circuit 15. The channel set counter 3 is also a quinary counter and counts every pulse. When the disc has finished playing once and is replayed from the beginning, and the end is returned endlessly, the return signal 14 at this time is given to the channel set counter 3 via the OR gate 15 and the channel counter is raised. Changes every time. A pulse is generated only when the value of the channel set counter 3 and the previous channel counter 2 coincide with each other by a coincidence circuit 4 composed of an exclusive OR or the like, so that predetermined channel data among the data CD of a plurality of channels in FIG. Only the data 11 is latched in the register 6 to which the data 11 is added. At this time, the floating point data latch circuit 5
Given to. If there is an error in the data here, a normal CD
The error flag 16 from the error detection circuit (not shown) is added to the matching circuit 4 to latch the latch data again to the next double written floating point data FP2. Here, if the first floating point data FP1 is correct, it is left as it is, and is not latched again. The data thus obtained is added to the shift pulse generating circuit 7, and the output of the shift pulse generating circuit 7 is applied to the register 6 to generate a pulse for shifting the data by a predetermined number. The shift pulse generating circuit 7 has a counter which increases the counter until it matches the floating point data for determining the shift value and stops when it matches, and easily obtains the shift clock if the clock until the match is used as the shift clock. I can do it. Thus, if the 8-bit data is shifted by 8 bits, the same range as that of 16 bits is obtained. As a result, data of only one predetermined channel can be selected from the serial data of a plurality of channels. The data can be converted into audio data by inputting the data into a digital-analog converter D / A 9 as a data stream having a fixed period of 31.5 KHZ by a first-in first-out memory (FIFO) 8. Here, considering the case where only four channels are recorded as serial data, in the above description, the data of the other four channels is divided into two bits in one channel portion which is an empty channel in the case of five channels, and The channel may be used as 10-bit floating point data.

〔The invention's effect〕

The present invention reproduces a multi-channel audio signal by reducing the number of bits of the sample data to a predetermined number of upper bits and reproducing a data-compressed disc by multi-channel serial recording in the time axis direction together with floating point data. The audio signal data corresponding to the original number of bits can be reproduced from the floating point data corresponding to the hour signal level, and the audio signals of the respective channels can be sequentially extracted and reproduced for a long time.

[Brief description of the drawings]

FIG. 1 is a system diagram of a disk reproducing apparatus of the present invention, FIG. 2 is a schematic view showing a disk track pattern on which serial data and floating point data of the present invention are recorded, and FIG. 3 is a data format of a conventional CD. It is a schematic diagram for demonstrating. 1 ... synchronous detector 2 ... channel counter 3 ... channel set counter 4 ... matching circuit 5 ... latch circuit 6 ... register 7 ... shift pulse generation circuit

Claims (4)

(57) [Claims] A multi-channel audio signal data including a plurality of recorded contents in a time axis direction and floating point data corresponding thereto are reduced by reducing the number of bits of sample data corresponding to the audio signal to a predetermined number of upper bits. Means for reproducing a serially recorded optical disk, means for designating a channel to be reproduced from the reproduced data and extracting data of the specified channel, and audio of the predetermined number of upper bits from the extracted data of the channel Means for obtaining audio signal data corresponding to the data of the original number of bits from the floating point data corresponding to the signal data and the audio signal data of the predetermined higher number of bits, and reproducing the audio signal of the designated channel. Disk playback device. 2. The number of bits of sample data corresponding to an audio signal is reduced to a predetermined number of upper bits to arrange data serially in a multi-channel manner in the time axis direction and to correspond to the audio signal level of the predetermined number of bits. Means for recording a multi-channel audio signal in which the floating point data is arranged in synchronization with a predetermined period according to each channel on an optical disc; and means for multiplex-recording the floating point data at different positions on the time axis. The disc reproducing apparatus according to claim 1, wherein 3. When the serial data of the multi-channel is n-channels, when recording the serial data of the channels less than the n-channels on the optical disc, a part of the serial data of the other plural channels is stored in the empty channel of the n-channels. 2. A disk reproducing apparatus according to claim 1, further comprising means for recording the data on the optical disk, and reproducing the data during reproduction to extend the reproduction time. 4. A multi-channel audio signal serial data of a multi-channel audio signal recorded by compressing data on an optical disc in a predetermined order by a channel designating means, and sequentially extracting a predetermined number of channels several times to reproduce for a long time. The disk reproducing apparatus according to claim 1, wherein: