JPH07221715A - Method and device for transmitting information signal - Google Patents

Abstract

PURPOSE:To easily realize addition of dummy data with simple configuration when video data of a variable length is recorded on a recording medium and the dummy data are added to the video data to produce a fixed rate in order to be in matching with a rate of a block being a recording unit. CONSTITUTION:A dummy data addition section 17 adds dummy data to variable length video data obtained by applying compression coding to a digital video signal at a video encoder 14 to form variable length data whose rate is fixed to a prescribed rate. The dummy data addition section 17 reads a quantity of data stored in a video buffer 15 every time an end detection circuit 16 detects a field end of the video signal and controls the production and addition of the dummy data depending on whether or not the quantity of data reaches, e.g. a half of the entire storage capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information signal transmission method and apparatus, and more particularly to an information signal transmission method for recording and reproducing variable length data such as compression-encoded video data on a disc-shaped recording medium. And the device.

[0002]

2. Description of the Related Art In general, when an analog video signal is digitized, the amount of data becomes enormous and it is difficult or costly to record or communicate as it is. I often do it. In particular, since the data amount of a video signal is much larger than that of an audio signal, it is important to use an encoding method with a high compression rate. In recent years, high-efficiency video signal data compression encoding requires a code per unit time. An encoding method in which the amount of the encoded output data changes, for example, a so-called variable length encoding method has been widely adopted.

FIG. 9 is a diagram for explaining an example of compression of video signal data, and A shows an analog video signal. In general, since a video signal constitutes one image in one frame or one field, the analog video signal in FIG. 9A is sampled (sampling) in the unit of one frame or one field in the time axis direction. ) Has been. This information is preserved even when this is digitized and compressed / decompressed. When compressing motion information using the correlation between frames or fields in video compression, the compression / expansion process spans several frames or fields, but the input to the compression circuit and the expansion circuit The output is an image of the original frame or field unit.

FIG. 9 shows a time unit T _V of compression of a video signal.
Shows an example of intra-field compression in which 1 field = (1/60) seconds, and the sampling frequency Fs is 13.
It is set to 5 MHz. In this example, the composite video signal is divided into a luminance (Y) signal and a color (C) signal, sampled at Fs = 13.5 MHz and quantized into 8 bits, respectively, and then the signal of B in FIG. I'm getting the data. This is 216 Mb for 13.5 MHz x 8-bit data for 2 channels of Y and C.
It is ps (megabits / second) and is 3.6 Mbits per field, that is, 450 Kwords per field when the number of words is 8 bits per word.

This is compressed field by field and a maximum of 12
In the case of variable-length data of Mbps, a maximum of 200 K bits per field, that is, a maximum of 25 K words per word of 8 bits. This is because the video data of 3.6 Mbits = 450 K words per field is compressed to 1/18 or less, and as shown in C of FIG.
The data will be compressed within K words.

In the case of such compression encoding, the compression rate is almost constant on average over a plurality of fields, but often varies in a unit of one field time.

By the way, in recent years, in the case of transmitting, that is, recording / reproducing or transmitting / receiving an information signal including video information and audio information, in recent years, in consideration of application to a so-called multimedia system,
It is becoming more common to digitize each information, code it, and synthesize it.

FIG. 10 is a diagram for explaining an example of data compression of an audio signal, and A indicates an analog audio signal. Since the audio signal is a continuous signal unlike the video signal, the compression unit can be arbitrarily selected. In this case, it is conceivable that the video signal is compressed in the unit time of compression of the video signal, that is, in the unit of time that is the same as the field or frame time or a time of an integer ratio. The unit time of these compressions does not match.

As a compression method developed for a commercially available recording / reproducing small audio disc, a sampling frequency of 44.1 kHz and stereo PCM data of left and right channels are respectively digitized into 16 bits and 512. An example of a method of compressing each sample to 212 bytes will be described.

The analog audio signal shown in A of FIG. 10 is 5 when the sampling frequency is 44.1 kHz.
The time T _A corresponding to 12 samples, that is, T _A = 512 / (44.1 × 10 ³ ) (sec) ≈11.6 (msec) is compression-coded as a unit. That is, B in FIG.
1 sample 16 bits 512 samples, or 512 × 2 words when 1 word is 8 bits, is compression-encoded to form 212 × 2 words fixed length data shown in C of FIG. The unit time of this fixed length data, for example, the data amount per second, that is, the data rate R _A is R _A = 212 × 2 × 8 / T _A (bit / sec = bps). The unit time T of such audio signal compression
_A has nothing to do with the unit time T _V of compression of the video signal, and does not have a simple integer ratio relationship.

[0011]

By the way, when variable length data such as the above-mentioned video data is transmitted, or when variable length video data and fixed length audio data are combined and transmitted, the variable length is changed. Since handling of long data as it is is inconvenient, it is often the case that a fixed rate is added by adding Sammy data.

However, in order to generate and add this dummy data, it is necessary to measure the amount of variable length data and to calculate the difference from the transmission rate of the transmission data bus.
Computational processing and circuit configuration become complicated. Further, when the data bus and the operation clock of the variable length data are operating asynchronously, the rate of the data bus and the rate of the variable length data do not exactly match, and an error occurs. For example, in the case of video data, the field When the screen is continuous, this error is gradually accumulated. Therefore, a circuit for correcting this may be needed.

The present invention has been made in view of such circumstances, and when transmitting variable-length data, it is possible to easily generate and add dummy data for a fixed rate, and the circuit configuration is simple. An object is to provide an information signal transmission method and apparatus.

Another object of the present invention is to combine and separate variable-length data and fixed-length data by adding dummy data and converting them to a fixed rate when the data is combined and transmitted. It is an object of the present invention to provide an information signal transmission method and device that can be easily and easily configured with a simple circuit configuration.

[0015]

According to an information signal transmission method of the present invention, variable length data having a variable amount of data per unit time, which is obtained by compressing and encoding input data at regular intervals, is transmitted at a constant rate. In the information signal transmission method of transmitting in blocks for each unit time, a flag that is turned on when the amount of data stored in the storage unit that stores the variable length data reaches a predetermined value is used to correspond to the above-mentioned fixed time. When the flag is detected at the end of the variable-length data, the variable-length data is continuously read from the storage means in the ON state, and the data reading from the storage means is stopped to output dummy data in the OFF state, The above blocks are transmitted.

Further, the information signal transmitting apparatus according to the present invention is
In the information signal transmission device for transmitting variable length data, which is obtained by compressing and coding input data at constant time intervals and having a variable amount of data per unit time, in blocks at constant transmission unit time and transmitting the data. The storage means for storing the obtained variable length data and outputting a flag which is turned on when the accumulated data amount reaches a predetermined value, and the variable length data read from this storage means are inputted. When the flag is detected at the end of the variable length data corresponding to the fixed time, the variable length data is continuously read from the storage means when in the on state, and the data reading from the storage means is stopped when in the off state. And means for outputting dummy data.

Here, the predetermined value of the amount of data stored in the storage means may be, for example, half the total storage capacity. In addition, it is possible to combine the variable length data and fixed length data having a constant data amount per unit time, and form a block for each transmission unit time for transmission. As the variable length data, it is preferable to use video data which is compression-coded in field units or frame units of a video signal.

[0018]

Since the generation and addition of dummy data is controlled according to whether or not the amount of data stored in the storage means has reached a predetermined value, dummy data can be added with an easy and simple structure, and error There is no accumulation.

Further, even when the variable length data and the fixed length data are combined and transmitted, the combination and separation of these data can be performed easily and with a simple circuit configuration.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, it is assumed that information signals are transmitted when recording / reproducing data to / from a recording / reproducing device in a so-called AV server that transmits / receives audio / video data to / from a plurality of terminal devices.

FIG. 1 is an encoder side of a signal transmission device for synthesizing video and audio signals as described above and transmitting them in blocks, that is, for recording / reproducing to / from a recording medium and transmitting / receiving via a communication system. An example of the configuration of is shown.

In FIG. 1, an input terminal 11 is supplied with an analog video signal, and an input terminal 21 is supplied with an analog audio signal. An analog video signal from the input terminal 11 is sent to an A / D (analog / digital) converter 13 via an amplifier 12 and converted into a digital video signal. The digital video signal from the A / D converter 13 is sent to the video encoder 14 and compression-coded into variable-length data whose data amount per unit time varies. This variable length data is obtained as data having a variable data amount equal to or less than a fixed maximum data amount for each unit time T _V of compression encoding. As the video encoder 14, for example, so-called JPEG (Joint Photographic) is used.
It is possible to use an encoder that realizes an encoding method defined by Coding Experts Group).

The variable length data from the video encoder 14 is sent to the end detection circuit 16 via the video buffer 15, and the video buffer 15 and the end detection circuit 16 form a dummy data addition section 17. There is. In the dummy data adding section 17, dummy data is added as described later to fix the data rate. This is fixed-rate data by adding dummy data to variable-length data until the maximum data amount is reached every unit time of compression encoding.

On the other hand, the analog audio signal from the input terminal 21 is sent to the A / D converter 23 via the amplifier 22 and converted into a digital audio signal, and then sent to the audio encoder 24 to be compressed and encoded. It becomes fixed length audio data. As the audio encoder 24, it is possible to use, for example, a recordable compact audio optical disk device, a compression encoding encoder used in a digital compact audio tape recorder, or the like.

The fixed length data from the audio encoder 24 is sent to the data synthesizing circuit 26 via the audio buffer 25. In the data synthesis circuit 26,
The fixed-rate variable-length video data from the dummy data adding unit 16 and the header information data from the CPU 29 are sent, and these are combined to form C of FIG. 4 or A of FIG. 6 described later. The data has a block format as shown in B. Since the additional data such as time code information and character information added to the input video signal from the amplifier 12 is lost during the compression process, it is extracted by the additional data detection circuit 18. The additional data extracted by the additional data detection circuit 18 is sent to the CPU 29, and the CPU 29 forms the header information data. Control signals are input to and output from the CPU 29 with the controller 28, and the controller 28 controls the data synthesizing circuit 26 and the buffers 15 and 25, respectively. The composite data from the output buffer 27 is sent to the interface bus 31 of the AV server, and via the interface bus 31, for example, recording of a hard disk device, a magneto-optical disk device, or a disk array device including a plurality of these devices. It is sent to the device and recorded.

Next, FIGS. 2 to 4 are diagrams for explaining the concrete structure and operation of the dummy data adding unit 17, and in FIG. 2, the video buffer 15 has a so-called FIFO (First In First First). Out) memory is used.
The video buffer 15 outputs an HF (half full) flag that is turned on and off depending on whether the amount of accumulated data is more than half of the total data capacity. The video buffer 15 has a write control signal W from the video encoder 14 and a read control signal R from the end detection circuit 16.
And the read control signal R from the controller 28 of FIG. 1 is supplied to the end detection circuit 16.

As shown in FIG. 1A, the video buffer 1
When the video data V stored in 5 is more than half of the total data capacity, the HF flag is in the ON state. The end detection circuit 16 reads the video data from the video buffer 15 and sends it to the data synthesis circuit 26 of FIG. 1, and the end of the field of the video data, that is, the end of picture (EOP) or the end of image (EOI) is detected. Then, the HF flag is read. If the HF flag at this time is ON, the video data is continuously read from the video buffer 15 and sent to the data synthesizing circuit 26 shown in FIG.

When the video data V stored in the video buffer 15 becomes less than half of the total data capacity,
As shown in B of FIG. 3, the HF flag is turned off.
If the HF flag is OFF when the end detection circuit 26 detects the end of the field of the video data, that is, the above EOP or EOI, the end detection circuit 26.
Stops reading the video data from the video buffer 15 and outputs dummy data to the data synthesizing circuit 26 as shown in B of FIG. Video buffer 1 during this time
Since the video data from the video encoder 14 is continuously written in 5, the amount of data gradually increases, and when the amount of data becomes half or more of the total data capacity, the HF flag becomes 0.
N. When the HF flag is turned on, the end detection circuit 16 stops the output of dummy data, starts reading the video data from the video buffer 15, and outputs the read video data to the data synthesizing circuit 26. send.

FIG. 4 shows the operation waveform of each part of the above operation and the synthesized output data. 4A shows the end detection output signal, FIG. 4B shows the HF flag, and FIG. 4C.
Indicates the combined output data from the data combining circuit 26. In this way, for example, the amount of dummy data written to the AV server can be adjusted to match the data rate of the transmission path. Moreover, by using the circuit of FIG. 2, dummy data can be generated with a simple circuit configuration.

Next, composite data of video and audio used in such a decoder side structure will be described with reference to FIGS. 5 and 6.

FIG. 5 shows the above-mentioned video signal of FIG. 9 and FIG.
It is a figure which shows the specific example of a synthetic | combination signal with the audio signal of 0, and each signal is compression-encoded and video data is represented by V and audio data is represented by A, respectively.
The video data V is variable-length data obtained by compression-encoding the video signal in the unit of the above-described first constant time T _V , for example, T _V = 1 field = 1/60 (second), The audio data A is fixed length data obtained by compressing the audio signal in the unit of T _A which is the second constant time described above. The fixed length data rate of this audio is R _A.

First, in FIG. 5A, the end E of the variable-length video data V, that is, the so-called end of picture (E
OP) followed by fixed-length audio data A, and a series or one block of the audio data A at this time corresponds to T _V of the audio data at the fixed rate R _A , that is, R _A × T _V Is.

As a specific example, the sampling frequency Fs of the video signal is set to 13.5 MHz, the composite video signal is divided into a luminance (Y) signal and a color (C) signal,
Video signal data of 216 Mbps (megabits / second) sampled at 13.5 MHz and quantized into 8 bits each is compressed in a unit of T _V = 1 field, and 3.6 Mbits or 450K per field.
Up to 2 words of video signal data per field
00K bits, that is, a maximum of 25K words of variable length data in a word number of 1 word 8 bits. For audio signals, the sampling frequency is 44.
1 kHz each for left and right stereo channels
Audio PCM data digitized with 6 bits is compressed into 212 bytes of fixed length data for every 512 samples, and the time T _A which is a unit time of compression is 512
/(44.1×10 ³ ) (sec), the data rate R _A of the compressed fixed length data is R _A = 212 × 2 × 8 / T _A
(Bps: bits / second).

At this time, the data amount R _A × T _V of the audio data A for each T _V = 1 field is R _A × T _V = (212 × 2 × 8 / T _A ) × (1/60) ( (Bits) = (1325/96) × 44.1 × 8 (bits), and when handling data with a 16-bit width on the data bus of the AV server, that is, when one word is 16 bits, _RA × T _V ≈304.336 × 16 (bits). This means that 304 or 305 words per T _V = 1/60 (second).

Here, consider a case where AV data is recorded in an AV server having a constant throughput or a fixed rate. Now, it is assumed that there is a server having a data transfer capacity R _S for one channel of AV data, and the minimum unit of the data amount when recording / reproducing data to / from this server is A × N. These A and N are natural numbers, N is the number of recording / reproducing devices, for example, hard disks, and A is the minimum unit of data that this recording / reproducing device can handle, that is, the so-called sector data amount. As a specific example, R _S is 14 Mbps.
Assuming that the number N of hard disks is 14 and the data amount A of one sector is 512 bytes = 512 × 8 bits, the time T required to send A × N bits of data at a data rate of 14 Mbps. _S is T _S = A × N / R _S = (512 × 8 × 14) / (14 × 10 ⁶ ) (seconds).

This AV server divides or assembles data for each T _S. Therefore, assuming that the time unit of the data input / output with the AV server is t, the relation of t with the time T _S in an integer ratio, that is, t = nT _S is the AV for recording and reproducing in real time. It will be convenient for the server. In this embodiment, n = 1, that is, t = T _S. FIG. 5B shows a state in which the data of A of FIG. 5 is divided by the block of the transmission unit t = T _S of this server.

The time T _S is the unit time T of each compression.
Since it has nothing to do with _V and T _A, it is uncertain where the start S and end E of the video data of the AV composite data are located in the server data block of the time T _S unit. Therefore, if it is recorded as it is, it becomes difficult to separate the audio data and the video data during reproduction.

By the way, since the video data V is variable length data as described above, SOP: start of picture at the start position S and E at the end position E in the data.
OP: A data pattern indicating each end of picture is often provided. If these can be discriminated at the time of reproduction, it is possible to extract the video data.
Further, since the audio data has a fixed length, it is possible to extract the audio data by presetting that a certain amount of data is the audio data from the video end EOP.

However, these special data patterns such as SOP and EOP, or control data patterns are sometimes defined so as not to appear in the video data, and in the case of unrelated audio data. Can also appear in the data. This is the same when adding data other than audio and video. In addition, the audio data, which is once compressed in the T _A time unit, is synthesized in the T _V time unit,
Further will have been divided or assembled into the T _S time units it.

In order to solve such a problem, in the embodiment of the present invention, as shown in FIG. 5C, a data block of an AV server having a constant throughput or a fixed rate is converted into a fixed amount of audio data. The video data is divided and the video data is put in the gap. That is, the dummy data D is added to the variable-length video data V to form fixed-rate variable-length data having a constant data rate, and the fixed-length variable-length data is formed within the time t of one block as a unit of transmission. Audio data A of a predetermined amount ( _RA
Xt) is distributed and the fixed rate variable length data is arranged in the remaining part.

Specifically, the audio data A compressed in the unit of T _A time is converted into data at each time t. now,
When t = T _S , R _A × t = ((212 × 8 × 2) / T _A ) × T _S = 74.7936 (bits), and when 1 word is 16 bits, audio data A is 1 block. It is sufficient to prepare for 74 words or 75 words. Whether the audio data of the current block is 74 words or 75 words can be determined by adding mark data to each block. For the audio data area in the block, 75 words are set, and when it is 74 words, one word may be discarded.

FIG. 6A shows a specific example of the structure of data in one block, that is, a so-called block format. From the block head position, for example, header data H of 3 words, audio data A of 75 words, 3506.
Word audio data V are sequentially arranged, and 1
The block is 3584 words. The audio data area may contain 74 words of audio data, and the 3506 word video data area may contain an empty area between the end and the start of the next field and may contain dummy data. .

That is, since variable-length video data is recorded in the fixed-rate server, an empty area occurs. Dummy data D is entered in this empty area as shown by B in FIG. At the time of recording, dummy data is generated and added following the end EOP of the video data, as will be described later. At the time of reproduction, the area from the end EOP of the video data to the start SOP of the next field is discriminated as an empty area, and the data of that portion is not sent to the video decoder or the data expansion circuit. The above SO in the header H
If the position information of P and EOP, that is, the number-of-words information from the block head position is described, it is possible to predict the free area in advance based on this information. If dummy data that the decoder or decompression circuit automatically ignores is written in the empty area, the empty area can be skipped and only the video data can be sent to the decoding process without reading the SOP and EOP. .

By recording in the server in units of such data blocks, at the time of reproduction, if the structure of the data block of the file, that is, the number of words in each area is known in advance, the number of words of data from the beginning of the block The data in the header area, the audio area, and the video area can be discriminated from each other only by counting, and the separation of each data can be simplified.

In addition to fixedly setting the data structure in this block, if the setting can be changed from the outside of the synthesizing / separating circuit or the like, it is set for each data file or each system. It is also possible to change.

If the data in each data area is correctly separated, the control data of each data, for example, SOP and EOP indicating the beginning and end of the above-mentioned video field data can also be used, so how is the video data divided? May be.

Actually, by writing the presence or absence of the SOP and EOP of the video and their positions, that is, the address within the block and the number of words from the beginning of the block in the header area, the start of the video field is started. I understand. Utilizing this, additional data accompanying the video signal that is lost during compression, for example, data during the vertical blanking period, time code, frame number,
It is also possible to write close caption data or the like in the header area and add it to the corresponding frame image at the time of reproduction.

If the audio data and the video data are divided into blocks at the same time as described above, the time axes of the respective data are simultaneously progressing. Therefore, if the beginning of the block at the beginning of the file and the beginning of each of the audio and video data are matched, the simultaneity of audio and video is maintained without the time lag.

Since the dummy data D in the empty area shown in FIG. 6B is originally unnecessary data, it may be considered not to record this portion in order to effectively utilize the recording medium of the server. To be That is, as shown in FIG. 6C, the empty area is filled and recorded.
Information such as the dummy data amount or the data amount of the free area is described in the header H, and control is performed so that the data does not come from the server by the free data amount during reproduction, or no data is requested to the server. By doing so, it is also possible to virtually create an empty area in the reproduction system. The throughput of the server at this time is not fixed at this time, but fluctuates. In this case, even if the recording is performed as in C of FIG. 6, the reproducing system interprets it as in B of FIG.

Next, FIG. 7 shows an example of the configuration on the decoder side corresponding to the configuration on the encoder side in FIG.

In FIG. 7, data from the interface bus 31 such as the AV server described above is supplied to the data separation circuit 42 via the input latch 41.
Further, the data from the input latch 41 is the header detection circuit 4
3 and the header H at the head position of the data block as shown in A and B of FIG. 6 is detected. The header detection circuit 43 counts the number of data or clocks from the beginning of the block and separates each data of the header area, audio area, and video area shown in A and B of FIG. 6 according to the format of the data block. To the data separation circuit 42. The format of the data block is not fixed. For example, the change information is sent from the system control circuit 30 to the CPU 44, and the CP
By controlling the header detection circuit 43 by the U44, it is possible to separate each area for a data block of an arbitrary format.

The video data separated by the data separation circuit 42 is sent to the video decoder 46, subjected to the compression encoding processing in the video encoder 14 of FIG. A (digital / analog)
It is converted into an analog video signal by the converter 47. D / A
The analog video signal from the converter 47 is taken out from the output terminal 49 via the amplifier 48.

The audio data separated by the data separation circuit 42 is sent to the audio decoder 56, and subjected to compression / decompression processing symmetrical to the compression / encoding processing in the audio encoder 24 of FIG. An A (digital / analog) converter 57 converts the analog audio signal. The analog audio signal from the D / A converter 57 is taken out from the output terminal 59 via the amplifier 58.

Further, the data separation circuit 42 separates other data existing in the header area and the like, for example, circuit control data and additional data such as time code and character information accompanying the video signal, and sends them to the CPU 44. ing. The CPU 44 sends an additional data signal accompanying the video signal to the video amplifier 48 via the additional data output circuit 54, and adds it to the video signal from the D / A converter 47.

Next, an information data signal recording / reproducing system to which the information signal transmitting method or the information signal transmitting apparatus according to the present invention is applied will be described with reference to FIG.
This information data recording / reproducing system is a system that includes a plurality of recording / reproducing devices using a disc-shaped recording medium and records and reproduces a video signal and an audio signal, that is, an AV server system.

Specifically, this AV server system records a large amount of data obtained by digitizing an AV material of an analog signal such as a commercial or a movie, and supplies the AV material to a plurality of channels at the same time according to a request. It is possible system. By using a plurality of hard disks as a recording medium for AV data, each AV material can be randomly accessed unlike the case where a conventional video tape recorder using a tape, that is, a VTR is used. This AV server system can be used for various purposes such as automatic commercial transmission, provision of karaoke, and language learning.

First, during data recording, analog AV data is input from a plurality of input channels. In the specific example of FIG. 8, the analog AV data is the signal input terminal 104,
It is input from 105 or the like. Each input analog AV data is digitized by the analog / digital (A / D) converters 108 and 109, and then the encoder 1
It is compressed at 12, 113. This is to increase the data transfer rate by compressing the digitized data because it is large in size. As a compression method, a method such as MPEG of a color moving image coding system or JPEG of a color still image coding system is generally used.

The digitally encoded data input from a plurality of input channels are sequentially input to the time division multiplexing block 114 with the timing controller 115 slightly shifting the time for each channel. The data from a certain channel is divided into a certain unit, for example, every 2 bytes for the number of hard disks, and recorded on each hard disk. Here, a hard disk is generally a problem regarding the data transfer capability of the AV server system. Therefore, by dividing the data into a plurality of hard disks and recording the data, the data transfer rate of the hard disk groups can be doubled by almost the same number.

The data time-division multiplexed by the time-division multiplexing block 114 is the timing controller 11
Under the control of 6, the data is written in the buffers 117, 118, and 119 with a certain unit of time, for example, every 2 bytes, with a slight time shift. At this time, the timing controller 11
6 controls which buffer of which time data is written. The buffers 117, 118, 119
The data written to the hard disk 12 is written to the hard disk 12 by the device control blocks 120, 121 and 122, respectively.
3, 124 and 125.

The above timing controller 11
6 and each device control block 120, 121, 122 is controlled by the server control block 126. In addition, the hard disks 123, 124,
Application information related to the data divided into 125 and recorded, for example, information such as a title is input from an input device of the host computer 101 (not shown),
It is managed by the application control block 127.

Next, when reproducing data, the host computer 101 designates which data is output to which output channel. This designation is made from the application control block 127 to the server control block 12
6 is transmitted, and where on the hard disk the desired data is recorded is specified. This information is transmitted to each device control block 120, 121, 122. Based on the above information, the hard disks 123, 1 are controlled by the device control blocks 120, 121, 122.
Data is read from 24 and 125, and each buffer 11
7, 118, 119. Each buffer 11
The data that is divided into 7, 118, and 119 is sent to the time division multiplexing block 114 under the control of the timing controller 115, and is reassembled into the original compressed data in the time division multiplexing block 114. .
This data is supplied to the desired output channel under the control of the timing controller 115. timing·
The compressed data from the time division multiplexing block 114 is sent to the decoders 110 and 111 under the control of the controller 115. The decoders 110 and 111 decompress the sent compressed data. The decompressed data is converted into the original analog AV material by the digital / analog (D / A) converters 106 and 107, and output from the signal output terminals 102 and 103.

The present invention is not limited to the above-described embodiment, and for example, various kinds of data other than video data and audio data are used as the variable length data and the fixed length data. be able to. Further, the variable length data and the fixed length data may be used in plural types instead of being used in each type.

[0063]

As described above, according to the information signal transmitting method of the present invention, the flag which is turned on when the amount of data stored in the storage means for storing the variable length data reaches a predetermined value is used. When the flag is detected at the end of the variable length data corresponding to the fixed time, the variable length data is continuously read from the storage means when in the on state, and the data reading from the storage means is stopped when in the off state. The dummy data can be added with an easy and simple configuration by outputting the dummy data. Further, it is not necessary to calculate the difference between the variable length data rate and the transmission rate, and even if these rates are asynchronous and the rates do not match accurately, no error will be accumulated.

Further, according to the information signal transmitting apparatus of the present invention, the variable length data obtained by compression coding is stored, and the flag which is turned on when the amount of accumulated data reaches a predetermined value is output. Storage means for inputting the variable length data read from the storage means, detecting the flag at the end of the variable length data corresponding to the fixed time,
By including the means for continuously reading the variable length data from the storage means in the on-state and for stopping the data read from the storage means and outputting the dummy data in the off-state, the dummy data of the simple data can be stored. Can be added.

Also, when the variable length data and the fixed length data having a constant amount of data per unit time are combined and are transmitted in the form of a block for each of the transmission unit time, the combination of these data and Separation can be performed easily and with a simple circuit configuration.

Here, when a video signal is digitized, the amount of data is generally enormous, so high-efficiency compression coding such as variable length compression coding is suitable, and the compression-coded data is Since it becomes variable length data, it is preferable to use video data as the variable length data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a configuration of an encoder side for video and audio data used in an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of a dummy data adding unit in FIG.

FIG. 3 is a diagram for explaining the operation of the configuration of FIG.

FIG. 4 is a diagram for explaining the operation of the configuration of FIG.

FIG. 5 is a diagram showing a data format used in an embodiment of the present invention.

FIG. 6 is a diagram showing a block format of a data block used in an embodiment of the present invention.

FIG. 7 is a block diagram showing an example of a configuration on the decoder side of video and audio data used in an embodiment of the present invention.

FIG. 8 is a block diagram showing a schematic configuration of an information data recording / reproducing system to which an embodiment of the present invention is applied.

FIG. 9 is a diagram for explaining an example of digitization and compression encoding of a video signal.

FIG. 10 is a diagram for explaining an example of digitization and compression encoding of an audio signal.

[Explanation of symbols]

 14 Video Encoder 15 Video Buffer 16 End Detection Circuit 17 Dummy Data Addition Section 24 Audio Encoder 25 Audio Buffer 26 Data Synthesis Circuit 27 Output Buffer 28 Controller 29, 44 CPU 41 Input Latch 42 Data Separation Circuit 43 Header Detection Circuit 46 Video Decoder 56 Audio decoder

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[Procedure amendment]

[Submission date] January 24, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The analog audio signal shown in A of FIG. 10 is 5 when the sampling frequency is 44.1 kHz.
The time T _A corresponding to 12 samples, that is, T _A = 512 / (44.1 × 10 ³ ) (sec) ≈11.6 (msec) is compression-coded as a unit. That is, B in FIG.
51 of 16 bits per sample shown in
2 channels (stereo) for 2 samples , ie
The data of 512 × 16 bits × 2 channels is compression-encoded into fixed length data of 212 × 8 bits × 2 channels shown in C of FIG. The unit time of this fixed length data, for example, the data amount per second, that is, the data rate R _A is R _A = 212 × 2 × 8 / T _A (bit / sec = bps). The unit time T of such audio signal compression
_A has nothing to do with the unit time T _V of compression of the video signal, and does not have a simple integer ratio relationship.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

By the way, when variable length data such as the above-mentioned video data is transmitted, or when variable length video data and fixed length audio data are combined and transmitted, the variable length is changed. Since it is inconvenient to handle long data as it is, dummy data is often added to make a fixed rate.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

[Figure 10]

Claims (4)

[Claims] 1. An information signal transmission method for transmitting variable length data, which is obtained by compressing and encoding input data at regular time intervals and in which the amount of data per unit time changes, in blocks at constant transmission unit time. Using a flag that turns on when the amount of accumulated data in the storage unit that stores the variable length data reaches a predetermined value, the flag is detected at the end of the variable length data corresponding to the fixed time, and the flag is turned on. In the state, the variable length data is continuously read from the storage means, in the off state, the data reading from the storage means is stopped, dummy data is output, and the information is transmitted in blocks. Method. 2. The fixed-length data having a constant amount of data per unit time and the variable-length data are combined, and the data is divided into blocks for each transmission unit time and transmitted. Information signal transmission method. 3. The information signal transmitting method according to claim 1, wherein the variable length data is video data which is compression-coded in a field unit or a frame unit of a video signal. 4. An information signal transmission apparatus for transmitting variable length data, which is obtained by compressing and encoding input data at regular time intervals and having a variable amount of data per unit time, in blocks and transmitting at constant transmission unit times. , Storing the variable length data obtained by the compression encoding,
Storage means for outputting a flag that is turned on when the amount of accumulated data reaches a predetermined value, and the variable length data read from the storage means is input to terminate the variable length data corresponding to the fixed time. In the ON state, the variable length data is continuously read from the storage means, and in the OFF state, the data reading from the storage means is stopped to output dummy data. Characteristic information signal transmission device.