JPH08140046A - Recording and reproducing device - Google Patents

Abstract

PURPOSE: To reduce omission of pictures in the case of shifting from normal reproduction to special reproduction. CONSTITUTION: At the time of a normal reproduction mode, switches 104, 105 and 114 are turned to an N side and the bit streams of data for the normal reproduction are added to a packetizing circuit 115 as they are. Also, at the time of reproducing the data for the special reproduction, a PCR and an RSI included therein are detected and stored in memories 109 and 110. At the time of a special reproduction mode, the data for the special reproduction are sent to the memory 106 and the stored PCR and RSI are switched by the switch 113 and sent from a multiplexer 111 to the packetizing circuit 115 along with the data of the memory 106. Thus, packets PSI and PCR are outputted. By using PSI output, the decoding impossible time in the decoder of a post stage is shortened, and by using PCR, the continuity of time information during mode transition is maintained and the malfunction of the decoder is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital V for recording / reproducing coded data such as highly efficient coded image data.
The present invention relates to a recording / reproducing device such as a TR.

[0002]

2. Description of the Related Art In recent years, digital processing of images has been studied. In particular, for high-efficiency encoding for compressing image data, various methods have been proposed for standardization. The high-efficiency encoding technique encodes image data at a smaller bit rate in order to improve the efficiency of digital transmission and recording. CCITT (Comito Consultafit I) is used as such a high-efficiency coding method.
nternational Telegraphique et Telephonique) is a standardization recommendation H.264 for video conferencing / video telephony. 261, JPEG (Joint Photographic Expart for color still images)
Group) method and MPEG (Moving Picture) for moving pictures
Expert Group) method is proposed. In the United States,
ATV (Advanced Television), which is a next-generation television broadcasting system using the MPEG-2 system, is under study.

FIG. 5 is an explanatory diagram for explaining the MPEG encoding system. In the figure, the arrow indicates the direction of prediction in encoding. Further, FIG. 6 shows encoding in the case of recording / reproducing image data by the MPEG encoding method.
It is explanatory drawing which shows the order of the image data by a process, the arrangement | positioning on a recording medium, an encoding (decoding) process, and a reproduction | regeneration image.

As shown in FIG. 5, the MPEG encoding system uses a GOP (Group of Pictu) with a predetermined number of frame images.
re). At least one intra-picture coded image I is included in the GOP. This intra-coded image I is D
The image data of one frame is encoded by CT (discrete cosine transform). This intra-coded image I
The image data of one frame for each predetermined a frame from
The first and second forward predictive coded images P1 and P2 are converted. In that case, the second forward predictive encoded image P2 is converted from the first forward predictive encoded image P1. Furthermore, an intra-picture coded image I or a first forward predictive coded image P1,
The image data of each frame between the second forward predictive coded image P2 and the second forward predictive coded image P2 is converted into a bidirectional predictive coded image B by bidirectional predictive coding using the image data of the front and the rear. First, the intra-picture coded image I is coded. This intra-picture coded picture I is coded only by the information in the frame and does not include prediction in the time direction.

Next, as shown in FIGS. 5 and 6, a forward predictive coded image P is created, and a bidirectional predictive coded image B is coded after the intra-picture coded image I or the forward predictive coded image P. Processing is performed. The forward predictive coded image P and the bidirectional predictive coded image B utilize the correlation with other image data. As described above, due to the prediction method of each image data, the bidirectional predictive coded image B is recorded on the recording medium after the intra-picture coded image I or the forward predictive coded image P, and the original order at the time of decoding is recorded. Returned to.

Since the intra-picture coded picture I is coded only by the information in the frame, it can be decoded only by a single piece of coded data. On the other hand, the forward predictive coded image P and the bidirectional predictive coded image B are coded by utilizing the correlation with other image data, so that they cannot be decoded by only the single coded data. Has become.

In the MPEG encoding method, the recording rate is specified (standard 1.2 Mbps), but the data length is variable. Therefore, it is not possible to specify at which position the intra-picture coded image I included in the GOP is recorded, and it is not possible to specify the data length of one GOP. The above-mentioned MPEG encoding system is applied to a digital VTR.
In the normal reproduction, the coded images I, B, and P are sequentially reproduced, so that no particular problem occurs. However, when performing special playback such as fast-forward playback for searching, etc., the encoded images I, B, P are not sequentially played back.

Further, when performing special reproduction, only a part of the recording track on the recording medium is reproduced, and the position of the intra-coded image I on the recording medium is not specified. Therefore, the intra-coded image I Is not always playable. In that case, the forward predictive coded image P and the bidirectional predictive coded image B
Cannot be played. Therefore, for example, Japanese Patent Laid-Open No. 4-29
In the technique disclosed in Japanese Patent No. 8802, encoded image data is stored in a predetermined position on a recording medium so that it can be reproduced during special reproduction, and the screen is reproduced by reproducing the data during special reproduction. I have to.

Next, in the MPEG-2 system, a coded image signal, audio signal, or other bit string is referred to as an elementary stream. A PES (Packetized Elementary Stream) packet is defined as a structure for carrying an elementary stream. This has a structure in which header information called a PES header is followed by a PES payload including the PES packet. A set of elementary streams having a common time base in this MPEG-2 system is called a program.

Two formats are defined for encoding in the MPEG-2 system. One is a Transport Stream and the other is a Program Stream. The above definitions of both the transport stream and the program stream include necessary and sufficient grammars regarding video and audio decoding and playback synchronization. The program stream is a single bit string formed by combining one or more PES packets having a common time base. A transport stream is a combination of one or more programs that have one or more time bases and are combined into a single bit string. In the above-mentioned ATV system, the transport stream is used.

In the transport stream, data such as image and audio is divided into fixed-length transmission units called transport packets and transmitted as a bit string. PCR used for synchronization in this bit string
(Program Clock Refarance) and PSI (Program Spec)
program information data such as various identification information called ific information) is incorporated as appropriate, and the decoder can detect the data to enable normal decoding of the bit string.

FIG. 7 shows an example of the above-mentioned PCR decoding circuit and shows the case of performing special reproduction. In FIG. 7, 701 is an input terminal, 702 is a subtractor, and 703 is L.
PF (Low pass Filter), 704 is an amplifier, 705 is a VCO (Voltage Controlled Oscillator), 706 is a counter, and 707 is an output terminal. The output of the counter 706 is called STC (System Time Clock). When the PCR arrives at the decoding input terminal 701, the subtracter 702 calculates a comparison value between the current STC output from the counter 706 and the arrived PCR. This comparison value is VOC by the LPF 703 and the amplifier 704.
It is output as a 0705 control signal. VOC
705 outputs a clock signal. The frequency of this clock signal changes according to the value of the control signal.

A clock signal from the VOC 705 is input from an output terminal 7 to an MPEG decoder (not shown) and used as a system clock, and a counter 706 is used.
Is input to The counter 706 counts the system clock and outputs the STC. This STC is input to the subtractor 702 so that the PLL (Phase
Locked Loop) that constitutes the feedback loop. The time interval of PCR input to the PLL is set within 100 milliseconds.

The above PSI includes PAT (Program Associat
Ion Table), PMT (Program Map Table) and other information for identifying PID (Packet ID), etc. are included. By using these information, the transport packet containing the target data is identified. There is.

When the mode is changed from the normal reproduction to the special reproduction such as search, the normal reproduction data and the special reproduction data are written as independent data, so that PCR and PSI are different. Therefore, during special reproduction, it is necessary to initialize the decoder with PCR and PSI for special reproduction data.

[0016]

FIG. 8 is an example showing a bit string reproduced from a recording medium in transport packet units. The shaded packets in the figure are packets for normal reproduction, and the other packets are packets for special reproduction. During normal reproduction, (1) PES for normal reproduction, PSI packet and PES for special reproduction,
The PSI packet is reproduced. When a signal for mode transition from normal reproduction to special reproduction such as search is given at the timing shown by the arrow in the figure, the running system of the recording medium instructed starts transitioning to the special reproduction mode, and at (2) in the figure. As shown, data cannot be reproduced until the state stabilizes. When the state becomes stable, the special reproduction data will be reproduced, but the decoder must identify the special reproduction PES packet until the special reproduction PSI packet shown by (4) in the figure is reproduced. Therefore, it is possible to reproduce only from the packet of (5) and the data cannot be decoded (3)
Occurs, and the reproduced image is disturbed or missing.

The present invention has been made in order to solve the above problems, and obtains an image reproducing apparatus which reduces the disorder and loss of reproduced images when the normal reproduction mode is changed to the special reproduction mode. Is intended.

[0018]

According to a first aspect of the present invention, encoded data including normal reproduction data including identification information and special reproduction data including identification information is recorded and reproduced, and the normal reproduction is performed at the time of recording. In a recording / reproducing apparatus configured to independently record reproduction data and special reproduction data on a recording medium in a time series, identification information included in the special reproduction data reproduced in a normal reproduction mode. And a storage means for storing the identification information detected by the detection means.

According to the fourth aspect of the invention, when the mode is changed from the normal reproduction to the special reproduction, the signal indicating the discontinuity of the time signal is incorporated in the reproduced data.

In a fifth aspect of the present invention, there are provided time signal generating means for generating a signal equivalent to the time signal in the reproduced encoded data, and control means for incorporating the signal into the reproduced encoded data. It is provided.

[0021]

According to the invention of claim 1, the identification information of the special reproduction data is detected during the normal reproduction, and this is stored.
By using the identification information stored at the time of mode transition,
It is possible to shorten the undecodable time in the decoder that decodes the reproduction coded data.

Using this method, the special reproduction PSI shown in (1) of FIG. 8 is stored during normal reproduction.
By outputting the PSI for special reproduction data when the mode transitions from normal reproduction to special reproduction such as search, the decoder immediately recognizes the special reproduction packet and decodes it from the packet of FIG. 8 (3). Therefore, it is possible to shorten the period in which the data cannot be decoded.

According to the fourth aspect of the present invention, when the mode is changed from the normal reproduction to the special reproduction, the malfunction of the decoder is prevented by incorporating the signal indicating the discontinuity of the time signal in the encoded data to be reproduced. You can

According to the invention of claim 5, the time signal in the encoded data reproduced by the time signal generating means is detected and stored, and when the mode is changed from the normal reproduction to the special reproduction, the stored time is stored. A malfunction can be prevented from occurring in the decoder by using the signal to generate a time signal with continuous continuity and incorporating it in the reproduced encoded data.

[0025]

1 is a block diagram showing a first embodiment of the present invention. This embodiment shows a case where the present invention is applied to a recording / reproducing apparatus for recording / reproducing an MPEG transport stream or an ATV bit stream. In FIG. 1, 101 is a reproduction data input terminal, 102 is an operation mode signal input terminal, 103 is a data identification signal input terminal, 104 and 105 are selection switches, 106 is a sync block memory, 107 is a PCR detection circuit, and 108 is Is P
SI detection circuit, 109 is PCR memory, 110 is PSI
Memory, 111 is a multiplexer, 112 is a control circuit,
Reference numerals 113 and 114 are selection switches, and 115 is an output terminal.

Next, the operation will be described. Input terminal 10
The bit stream input from 1 is the selection switch 1
It is input to 04. A data identification signal indicating whether the reproduced data is normal reproduction data or special reproduction data is input from the input terminal 103. The selection switch 104 is controlled by the data identification signal from the input terminal 103, and selects the N side when the input data is for normal reproduction, and selects the P side when it is for special reproduction.

When the input data is data for special reproduction, the data is input to the selection switch 105.
The selection switch 105 is controlled by the operation mode signal input from the input terminal 102, and selects the P side when the operation mode is the special reproduction mode, and selects the N side when the operation mode is the normal reproduction mode. When in special playback mode,
The input data is input to the sync block memory 106,
It is reconstructed as one frame of data. In the communication reproduction mode, the input data is input to the PCR detection circuit 107 and the PSI detection circuit 108, and the PCR and PSI are input.
Are detected and stored in the PCR memory 109 and the PSI memory 110, respectively.

The PCR detection circuit 107 is constructed, for example, as shown in FIG. In FIG. 2, 201 is an input terminal, 2
02 is a sync byte detection circuit, 203 is a first counter, 204 is a comparator, 205 is a second counter, 206
Is a shift register, and 207 is an output terminal. The packet data input from the input terminal 201 is first input to the sync byte detection circuit 202, the 8-bit sync byte included in the packet data is detected, and the packet or the like is synchronized. When the packet or the like is synchronized, the packet data is input to the first counter 203, the comparator 204 and the shift register 206.

The first counter 203 counts the number of bits of the packet. That is, the first counter 203 is
Based on the detection data of the sync byte detection circuit 202, the count value of the first counter 203 is reset, and counting is started from the bit next to the last bit in the sync byte. When the count value of the first counter 203 reaches 19 bits, the first counter 203
Outputs a comparison permission signal to the comparator 204. The bits of this signal are the adaptation field control (ad
The first bit of the aptation field control) and when this bit is 1, an adaptation field in which PCR may be included is present in the same packet.
The comparator 204 compares the bit with 1, and when the bit is 1, instructs the first counter 203 to continue the bit counting. When the bit is zero, the comparator 204
Causes the first counter 203 to stop bit counting,
It is designed to wait for the next packet to be input.

Next, when the count value reaches 36 bits, the first counter 203 outputs a comparison permission signal to the comparator 204. The bit of this signal is the PCR flag, and when this bit is 1, the PCR exists in the adaptation field in the same packet. The comparator 204 compares the PCR flag with 1, and when the flag is 1, the first
The counter 203 is caused to continue counting bits. When the flag is zero, the comparator 204 determines that the first counter 203
To stop the bit counter and wait for the next packet to be input. The first counter 203 has a count value of 40.
When the number of bits is reached, the second counter 205 is allowed to count bits. As a result, the second counter 205 counts the data portion of the PCR.

The second counter 205 counts the number of bits of PCR. The shift register 206 serial-parallel converts the PCR under the control of the second counter 205 and outputs the PCR from the output terminal 207. With the second counter 205 and shift register 206, the PC
R is extracted from the packet data as time data.
The PCR is a 42-bit bit field and is divided into two parts. One is called PCX Base 3
It is a 3-bit part and the other is an 8-bit part called a PCR extension. An 8-bit field reserved by MPEO is inserted between the PCR base and the PCR extension.

The second counter 205 is the above PC.
In order to extract the R base, the data input to the shift register 206 is left-shifted until the count value reaches 33 bits. When the count value reaches 33 bits, the shift register data is output to the outside from the output terminal 207 as 33-bit parallel data. Since the subsequent 8 bits are invalid data, the second counter 205 prohibits the shift register 206 from outputting the data and the shift operation until the count value reaches 39 bits.
After that, the second counter 205 shifts the data input to the shift register 206 to the left until the count value reaches 42 bits in order to extract the PCR extension. When the count value reaches 42 bits, the data in the shift register 206 is output to the outside from the output terminal 207 as 9-bit parallel data.

By the above operation, the PCR component P
The CR base and the PCR extension are adapted to be extracted from the packet.

Next, when the operation mode transits from the normal reproduction to the special reproduction, the control circuit 112 of FIG.
09, the PSI memory 110 is instructed to output the PCR and PSI stored during normal reproduction, and at the same time, the selection switch 113 is controlled to select the P ₁ side. The multiplexer 111 is a PCR memory 109, PS
PCR input from the I memory 110, MPE for PCR
O transport packets are multiplexed. At this time, the stop instruction (disconti
nuity indicator) Set the flag to 1. The multiplexed data is output to the selection switch 113, and when the output is completed, an output end flag is output to the control circuit 112.
Upon receiving the output end flag from the multiplexer 111, the control circuit 112 controls the selection switch 113 to control P ₂
Select the side.

When the operation mode is the normal reproduction mode, the selection switch 114 selects the N side, and the hand for normal reproduction receives the packetizing circuit 115 via the selection switch 114.
Is input to In the special reproduction mode, the selection switch 114 selects the P side, and the sync block memory 10
6 special reproduction I frame data or data obtained by multiplexing PCR and PSI of the multiplexer 111 is input to the packetization circuit 115 via the selection switch 114. The packetizing circuit 115 MPs the input data.
Output from the output terminal 116 in units of EG transport packets.

When the mode transitions from normal reproduction to special reproduction by the above operation, PCR and PSI for special reproduction data reproduced from the recording medium and stored in the memories 109 and 110 during normal reproduction are output from the output terminal 116. It
At this time, since the stop instruction flag in the packet header is set to 1, the decoder can recognize the discontinuity of the PCR value, and thus the malfunction can be prevented.

In this way, the instruction stop flag is set to 1 and the PS for special reproduction data stored during normal reproduction is set.
By transmitting I at the time of mode transition, the period in which the decoder cannot decode data can be shortened.

FIG. 3 is a block diagram showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 3, 301 is a PCR generation circuit, and 311 is a multiplexer.

Next, the operation will be described. Input terminal 10
The bit stream input from 1 is the selection switch 1
It is input to 04. A data identification signal indicating whether the reproduced data is normal reproduction data or trick reproduction data is input from the input terminal 103. The selection switch 104 is controlled by the data identification signal from the input terminal 103, and selects the N side when the input data is for normal reproduction, and selects the P side when it is for special reproduction.

When the input data is data for normal reproduction, the data is input to the PCR detection circuit 107 and the selection switch 114. PCR detection circuit 107
The PCR detected at is input to the PCR generation circuit 301. The PCR generation circuit 301 generates a PCR value to be sent out at the time of transition from the normal reproduction to the special reproduction mode, based on the input PCR value. PCR is at least 10
Since it must be input to the MPEG decoder or ATV decoder once every 0 milliseconds, the PCR generation circuit 30
1 generates a PCR value having a maximum offset of 100 milliseconds with respect to the input PCR value.

FIG. 4 is a PCR generation circuit 301 attached to FIG.
It is a figure which shows the structural example. 401 is an input terminal, 402 is a first selector, 403 is a first counter, 404 is a second counter, 405 is a clock generator, 406
Is a buffer, 407 is a second selector, 408 is a shift register, and 409 is an output terminal.

The PCR detected by the PCR detection circuit 20 is input from the input terminal 401. The first selector 402, the first counter 403, and the second counter 404 are controlled by a timing circuit (not shown). The PCR input from the input terminal 401 is converted by the first selector 402 into the first counter 403 for the PCR base and the second counter 4 for the PCR extension.
Each of them is selected and input in 04. The clock generator 405 generates a clock having a frequency of 27 MHz. This clock is input to the second second counter 404. The second counter 404 is a 9-bit counter, and after loading the PCR extension by the above operation, the PCR extension is incremented by 1 for each clock from the clock generator 405.

On the other hand, the first counter 403 is a 33-bit counter, and increases the count value by one when the count value of the second counter 404 reaches a predetermined maximum value determined in advance. Has been done. The maximum count value of the second counter 404 is 299, and when the count value, that is, the PCR extension reaches 299, the count value becomes zero, and the first counter 40
The count value of 3, that is, the PCR base is incremented by 1. The above operation causes the first counter 403 to have a frequency of 90 kHz.
The same operation as that in which the count value is increased by the clock of z is shown.

The output of the first counter 403 is input to the second selector 407. The output of the second counter 404 is input to the buffer 406 and delayed to adjust the output timing to the second selector 407.
Before the PCR extension, which is the output data of the second counter 404, is reserved by the above-mentioned MPEG 8
A bit field is inserted and output. This 8
Bit fields are called reserved bits and are usually 2
It has a value of '111111' in decimal. Second selector 4
The output of 07 is parallel-serial converted by the shift register 408, and is output from the output terminal 409 to the outside.

By the above operation, the PCR generating circuit 301 generates and outputs PCR according to the grammar defined by MPEG or ATV.

In FIG. 3, the PCR output from the PCR generation circuit 301 is stored in the PCR memory 109.
When the data input to the input terminal 101 is data for special reproduction, the data is input to the selection switch 105. The selection switch 105 is controlled by the operation mode signal input from the input terminal 102, and selects the P side when the operation mode is the special reproduction mode and the N side when the operation mode is the proper reproduction mode. In the trick play mode, the input data is input to the sync block mode 106 and reconstructed as one frame of data. In the normal reproduction mode, the input data is PSI detection circuit 108.
Is input to the PSI memory, the PSI is extracted, and stored in the PSI memory 110.

Operation mode transitions from normal playback to special playback
If so, the control circuit 112 PCR memory 109, PSI
PCR stored in the memory 110 during normal playback,
At the same time as instructing to output PSI,
Pitch by controlling the switch 113 ₁Select the side. Multip
The Lexa 311 includes a PCR memory 109 and a PSI memory 1
PCR input from 10
Multiplex in the form of sport packets. At this time, PC
The R value maintains continuity with the PCR value during normal reproduction.
The multiplexed data is output to the selection switch 113.
When the output is finished, the control circuit 112 is notified of the output end flag.
Output. The control circuit 112 is a multiplexer 311.
When the output end flag is received from the selection switch 113
Control P₂Select the side.

When the operation mode is the normal reproduction mode, the selection switch 114 selects the N side, and the data for normal reproduction is sent to the packetizing circuit 115 via the selection switch 114.
Is input to In the special reproduction mode, the selection switch 114 selects the P side, and the sync block memory 106
The 1-frame data for special reproduction or the data obtained by multiplexing the PCR and PSI of the multiplexer 311 is input to the packetizing circuit 115 via the selection switch 114. The packetizing circuit 115 MPEs the input data.
Output from the output terminal 116 in units of G transpacket.

When the mode transitions from the normal reproduction to the special reproduction by the above operation, the PCR and PSI for the special reproduction data reproduced from the recording medium and stored in the memories 109 and 110 during the normal reproduction are output from the output terminal 116. It
At this time, since the PCR value is maintained in continuity with the PCR value at the time of normal reproduction, malfunction of the decoder can be prevented.

In this way, the decoder value cannot be decoded by sending the PCR value that maintains continuity with the PCR value during normal reproduction and the PSI for special reproduction data stored during normal reproduction during mode transition. Can be shortened.

[0051]

As described above, according to the first aspect of the invention, the identification information of the special reproduction data is detected during the normal reproduction and is stored, so that the identification stored during the mode transition is detected. By using the information, it is possible to shorten the undecodable time in the decoder that decodes the reproduction coded data, and to reduce the disorder and loss of the reproduced image.

According to the invention of claim 4, when the mode is changed from the normal reproduction to the special reproduction, the signal indicating the discontinuity of the time signal is incorporated in the reproduced data, so that the malfunction of the decoder is prevented. There is an effect that can be prevented.

According to the invention of claim 5, a signal equivalent to the time signal in the encoded data to be reproduced is generated, and
When the mode is changed from the normal reproduction to the special reproduction, the above-mentioned signal having continuity is generated, and this signal is incorporated into the reproduced encoded data, whereby the malfunction of the decoder can be prevented. effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a PCR detection circuit of the first embodiment.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of a PCR generation circuit according to a second embodiment.

FIG. 5 is an explanatory diagram illustrating an MPEG encoding method.

FIG. 6 is an explanatory diagram for explaining an MPEG encoding system.

FIG. 7 is a block diagram showing a configuration of a PCR decoding circuit.

FIG. 8 is an explanatory diagram for explaining a decoding operation at the time of mode transition.

[Explanation of symbols]

 101 Playback Data Input Terminal 102 Operation Mode Signal Input Terminal 103 Data Identification Signal Input Terminal 104, 105, 113, 114 Selection Switch 106 Sync Block Memory 107 PCR Detection Circuit 108 SPI Detection Circuit 109 PCR Memory 110 PSI Memory 111 Multiplexer 112 Control circuit 115 Packetization circuit 116 Output terminal

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Claims (10)

[Claims] 1. Coded data including normal reproduction data including identification information and special reproduction data including identification information is recorded and reproduced, and the normal reproduction data and special reproduction data are time-series at the time of recording. In a recording / reproducing apparatus configured to independently and independently record on a recording medium, a detecting means for detecting identification information contained in the special reproduction data reproduced in the normal reproducing mode, and a detecting means for detecting by the detecting means. And a storage unit for storing the generated identification information. 2. When the identification information of the special reproduction data is reproduced in the normal reproduction mode, the contents of the storage means are updated with the latest reproduced identification information. Recording / playback device. 3. The recording / reproducing apparatus according to claim 1, wherein when the normal reproduction mode is changed to the special reproduction mode, the identification information stored in the storage means is read and output. 4. A time signal included in encoded data to be reproduced is detected, and when the normal reproduction mode is transited to a special reproduction mode, a signal indicating discontinuity of the time signal is incorporated into the encoded data to be reproduced. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus is configured as described above. 5. A normal reproduction mode is provided when a transition is made from the normal reproduction mode to the special reproduction mode by providing time signal generation means for generating a signal having a format equivalent to the time signal included in the encoded data to be reproduced. 2. The recording / reproducing apparatus according to claim 1, further comprising control means for generating the signal that maintains continuity with a time signal of time and incorporating the signal into the encoded data to be reproduced. 6. The recording / reproducing apparatus according to claim 5, wherein the time signal generating means generates PCR. 7. The recording / reproducing apparatus according to claim 1, wherein the encoded data is image data in which intra-frame encoded data and inter-frame encoded data are multiplexed. 8. The recording / reproducing apparatus according to claim 1, wherein the encoded data is MPEG-2 encoded data. 9. The recording / reproducing apparatus according to claim 1, wherein the encoded data is ATV encoded data. 10. The recording / reproducing apparatus according to claim 1, wherein the identification information is PSI.