JPH09251677A - Playback apparatus and mode discrimination method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] When the C / N ratio of a reproduced signal is lowered,
Even if there is a large difference between the current reproduction speed and the tape speed at the time of recording, the recording mode of the tape can be correctly determined. SOLUTION: A track pair number is recorded in each track on a tape. The track pair number is detected from the tape reproduction signal. For example, measurement is performed until the same track pair number appears. This measurement is
It depends on the mode. The mode is determined from this measured value. The track pair number is I of each sync block.
Since it is recorded in D, even if the CN ratio is bad, it can be surely detected. Also, the reliability of this measured value is determined by determining how many times the frame boundary has been passed. Therefore, it is less likely that the mode is erroneously determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus in which a plurality of modes having different tape speeds can be set, and the reproducing mode can be automatically set by judging the recording mode of the tape, and a recording mode of the tape. A mode determination method for determining.

[0002]

2. Description of the Related Art For example, in an 8 mm VTR, a long-time recording mode called an LP mode can be set in addition to a standard mode called an SP mode. Further, in a digital VTR in which a video signal is digitized and compressed by using DCT and recorded, an SSP mode in which the tape feeding speed is 1.5 times can be set in addition to the SP mode. As described above, in the VTR, a plurality of modes in which the tape feeding speed is different can be set, and therefore, at the time of reproduction, it is determined which recording mode the signal of the mounted tape is recorded,
In accordance with this, it is necessary to set the tape feeding speed during reproduction.

Therefore, conventionally, for example, in the 8 mm VTR, it is performed to detect the presence or absence of a periodic change of the tracking error signal at the time of reproduction and judge the recording mode of the signal recorded on the tape. . That is,
The 8 mm VTR adopts the ATF method in which the crosstalk level of an adjacent track is detected and tracking control is performed. When the ATF tracking control is performed, the tracking error signal changes differently depending on whether the mode recorded on the tape and the reproduction mode match. From this fact, the recording mode of the signal recorded on the tape can be determined by monitoring the change in the tracking error signal.

In the case of a digital VTR, additional information can be recorded in a subcode area, an AUX area, or a memory in a tape cassette called MIC. Therefore, it is considered to record the recording mode as additional information in such an area.

[0005]

However, when the change of the tracking error signal is monitored to determine the recording mode, when the C / N ratio of the reproduction signal is extremely lowered, or when the current reproduction is performed. When the difference between the speed and the tape speed during recording is large, the correct recording mode cannot be determined.
Also, in the digital VTR, when the tape recording mode is recorded in the additional information recording area,
When the C / N ratio of the reproduction signal is extremely low, or when the difference between the current reproduction speed and the tape speed at the time of recording is large, data error occurs and the correct recording mode may not be discriminated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a reproducing apparatus which can correctly determine the recording mode of a tape and can properly set the reproducing mode according to the recording mode of the tape.

Another object of the present invention is the C / N of the reproduced signal.
It is an object of the present invention to provide a mode discriminating method capable of correctly discriminating a recording mode of a tape even when the ratio is low or the difference between the current reproduction speed and the tape speed at the time of recording is large.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a plurality of modes having different tape speeds can be set, a mode at the time of recording is discriminated, and a mode suitable for the mode at the time of recording is reproduced. In, from the playback signal of the tape,
Information detecting means for detecting information continuously changing with tape feeding, timer means for measuring a time during which a predetermined amount of information continuously changing with tape feeding changes, and timer The reproducing apparatus is characterized by comprising a judging means for judging the mode at the time of recording from the value of the means and a mode setting means for setting the mode according to the judgment output of the judging means.

According to the present invention, in a mode discriminating method for discriminating a mode at the time of recording from a tape in which a plurality of modes having different tape speeds can be set, the reproduction signal of the tape is sequentially and continuously changed as the tape is fed. Information to be detected, a step of measuring the time during which the information that changes continuously and continuously with the tape feed changes by a predetermined amount, and information that changes continuously and continuously with the tape feed. Is a step of determining the mode at the time of recording from the measured value of the time during which it changes by a predetermined amount.

The track pair number is recorded on each track of the tape. For example, the time until the same track pair number appears is measured, and from this measured value,
The mode is determined. Since the track pair number is recorded in the ID of each sync block, it can be reliably detected even if the CN ratio is bad. Also, the reliability of this measured value is determined by determining how many times the frame boundary has been passed. Therefore, it is less likely that the mode is erroneously determined.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In an example of a digital VTR to which the present invention is applied, the track pair number is read to determine the recording mode. The track pair number is recorded in the ID of the sync block, and a pair track constituting one frame is sequentially numbered. For example, in the NTSC system, 1
A video signal of 1 frame is recorded on 0 track. Then, a signal is recorded by a head having a different azimuth angle for each track. In this case, the tracks having different azimuth angles are paired, and as shown in FIG. 1A, “0”, “0”,
Five track pair numbers Trp from "0" to "4" are assigned, such as "1", "1", "2", "2", ... "4", "4". 1 for PAL system
Since one frame of video signal is recorded on two tracks, as shown in FIG. 1B, “0”,
"0", "1", "1", "2", "2", ... "5",
Six track pair numbers Trp from "0" to "5" are allocated like "5".

The track pair number is recorded in the sync block ID. That is, as shown in FIG. 2, in the digital VTR, one track records an ITI area used for positioning during post-recording, an audio area for recording a digital audio signal, and a digital video signal. It is divided into a video area for playing and a sub-code area used for cueing. As shown in FIG. 3, the recording data of each track includes sync (SYNC), ID0, ID1, and IDP.
It is recorded in sync block units consisting of (parity for ID) and data (or data and parity).
As shown in FIG. 4A, sync blocks with sync block numbers “0” to “16” are arranged in the audio area. Further, as shown in FIG. 5A, sync blocks with sync block numbers “17” to “168” are arranged in the video area. As shown in FIG. 4B, track pair numbers (Trp _{0 to} Trp ₃ ) are included in ID0 and ID1 of the sync blocks in the audio area. ID of sync block of video area
As shown in FIG. 5B, the track pair numbers (Trp _{0 to} Trp ₃ ) are included in 0 and ID1.

As described above, in the digital VTR, the track pair number is assigned to each track. Since this track pair number is recorded multiple times in the ID of each sync block, it can be reliably detected even if the CN ratio is poor or the recording speed and the reproduction speed are large.

By using this track pair number, the mode of the signal recorded on the magnetic tape can be determined as follows.

As shown in FIG. 6, in the case of the NTSC system, "0", "0", "1", and
"1", "2", "2", ... "4", "4",
Five track pair numbers Tr from "0" to "4"
p is allocated. Here, the time until the same track pair number is obtained with the same azimuth head is measured. The time is measured by using the rotation of the drum of the VTR, for example, by counting the number of rotations of the drum until the same track pair number is obtained. That is, after the track pair number "0" is reproduced by the even track head, the number of rotations of the drum until the same track pair number "0" is reproduced is measured. When the track pair number "1" is reproduced by the even track head, the number of rotations of the drum until the same track pair number "1" is reproduced next is measured. Similarly, when the track pair numbers “2”, “3”, and “4” are reproduced by the even track head, the same track pair numbers “2”, “3”, and
Measure the number of rotations of the drum until "4" is reproduced.

In the NTSC system, one frame is recorded on 10 tracks, so as shown in FIG.
When the magnetic tape recorded in the P mode is reproduced in the SP mode, the measured value from the reproduction of the track pair number "0" to the reproduction of the next "0" is, for example, "5". . Note that this value will be referred to as a timer value hereinafter. Track pair number "1", "2", "3",
Also for "4", track pair number "1",
The timer values from the reproduction of "2", "3", "4" to the reproduction of the next track pair number "1", "2", "3", "4" are all "5". It will be. Also, for example, when the magnetic tape recorded in the SSP mode is reproduced in the SSP mode, each timer value is, for example, “5”.

As described above, when the recording mode of the signal recorded on the magnetic tape and the reproduction mode match,
Each track pair number "0", "1", "2",
Each of the timer values “3” and “4” is, for example, “5”.
become. On the other hand, if the recording mode of the signal recorded on the magnetic tape and the reproduction mode do not match, each track pair number “0”, “1”, “2”, “3”,
Each timer value of "4" is a different value.

For example, assume that the magnetic tape is recorded in the SSP mode, but the reproduction mode is the SP mode. Note that the SSP mode has a reproduction speed 1.5 times that of the SP mode. In this case, as shown in FIG. 7, the timer value until the same track pair number is obtained is, for example, “7.5”. Also, for example, SP for magnetic tape
Although recorded in the mode, when the reproduction mode is the SSP mode, each timer value until the same track pair number is obtained is, for example, "3.33".

From this, it is possible to determine whether the SP mode or the SSP mode is set by measuring the timer value until the same track pair number is obtained with the same azimuth head. That is, as shown in FIG.
The timer value until the same track pair number is obtained with the same azimuth head becomes "5" when the tape recorded in SP mode is reproduced in SP mode in the case of NTSC system, and is recorded in SSP mode. When a tape recorded in SP mode is played back in SP mode, it becomes "7.5" (because the counter value is an integer, it becomes "7" or "8"), and when playing a tape recorded in SP mode in SSP mode, "3.33". “(Since the counter value is an integer, it becomes“ 3 ”or“ 4 ”). When the tape recorded in SSP mode is reproduced in SSP mode, it becomes“ 5 ”.

Further, in the case of the PAL system, the timer value until the same track pair number is obtained with the same azimuth head is S for a tape recorded in SP mode.
It will be "6" when played in P mode, "9" when played in SP mode for tape recorded in SSP mode, and "4" when played in SSP mode for tape recorded in SP mode. , When the tape recorded in the SSP mode is reproduced in the SSP mode, it becomes "6".

By the way, actually, the head of the same azimuth cannot always pick up the track pair number. Due to the azimuth angle, the same track pair number may not be picked up by more than one frame with the same azimuth head. Therefore, the measured timer value may differ from the above-mentioned timer value. Therefore, the break of the frame is detected to judge the reliability of the measured timer value.

That is, FIG. 9 shows a case where the tape recorded in the SP mode is reproduced in the SSP mode. Here, it is assumed that the track pair number “2” can be picked up by the even track head on the track T1 of the frame (1). In the next frame (2), the even track head does not trace the track T2 of the same azimuth with the track pair number “2” but traces the track T3 of the reverse azimuth (odd track). The number "2" cannot be picked up. In the frame (3), the even track head traces the track T4 of the same azimuth with the track pair number "2", and the track pair number "2" can be picked up. Track pair number “2” on track T1 of frame (1)
If the track pair number "2" can be picked up by the track T2 of the frame (2) after the track pair is picked up, the timer value has a reliable value, but the track pair number "2" can be picked up by the track T1 of the frame (1). After the track pair number "2"
Is picked up in the track T4 of the frame (3), the timer value becomes larger than the original value and becomes an unreliable value.

Therefore, the break of the frame is detected, and the timer value is made valid only when the break of the frame is once. The frame break can be detected by whether or not the track pair number starts to decrease. That is, the track pair number Trp increases to “0”, “1”, “2”, ... “4” in the same frame, and returns from “4” to “0” at the frame boundary. . From this, the previous track pair number is compared with the current track pair number, and when the current track pair number is smaller than the previous track pair number, it can be determined that the frame is a break.

FIG. 10 shows an example of a mode discriminating circuit in a digital VTR to which the present invention is applied. In FIG. 10, the reproduction signal of the tape 1 is supplied to the digital signal processing circuit 2. The digital signal processing circuit 2 processes the reproduced signal and extracts the track pair number Trp. The Trp discriminating circuit 3 discriminates the reproduced track pair number Trp. The determined Trp number is supplied to the timer counter 5 and the phase change counter 6.

At the same time, the track pair number from the digital signal processing circuit 2 is supplied to the register 4 and the comparator 7. Comparator 7
Then, this track pair number is compared with the previous track pair number. Thereby, the boundary of the frame is determined. The output of the comparator 7 is supplied to the phase change counter 6.

The timer counter 5 counts the timer value until the same track pair number is obtained with the same azimuth head. In the case of the NTSC system, there are five types of track pair numbers from "0" to "4", so this timer counter is composed of five counters corresponding to the track pair numbers "0" to "4". ing.

The phase change counter 6 counts the number of times the frame boundary is crossed. NTS
In the case of the C method, since there are five types of track pair numbers from "0" to "4", this timer counter is
5 corresponding to track pair numbers "0" to "4"
It consists of two counters. The frame border is
It is detected from the output of the comparator 7.

From the output of the timer counter 5, the timer value until the same track pair number is obtained with the same azimuth head can be obtained. This timer value is supplied to the decision circuit 8. The number of times the frame boundary is crossed can be obtained from the output of the phase change counter 6. The number of times the frame boundary is exceeded is supplied to the decision circuit 8.

The judging circuit 8 judges the recording mode of the tape based on the outputs of the timer counter 5 and the phase change counter 6. That is, the timer value from the output of the timer counter 5 until the same track pair number is obtained with the same azimuth head is given. Based on the output of the phase change counter 6, only the number of times that the frame boundary is crossed once is used as a reliable value. In the case of the NTSC system, when the reproduction mode is set to the SP mode and the count value is "5", the tape recording mode is S.
If the count value is "7" or "8", the tape recording mode is determined to be the SSP mode. If the count value is "3" or "4" when the reproduction mode is set to the SSP mode, it is determined that the tape recording mode is the SP mode, and if the count value is "5", the tape recording mode is It is determined that the SSP mode is set.

The judgment output of the judgment circuit 8 is supplied to the mode setting circuit 10. In the mode setting circuit 10, the judgment circuit 8
The reproduction mode is set in accordance with the judgment output from. The output of the mode setting circuit 10 is supplied to the capstan motor 11. The rotation of the capstan motor 11 is controlled according to the output of the mode setting circuit 10.

The above control can be performed by software. 11 and 12 are flowcharts showing the processing at this time. In FIGS. 11 and 12, it is determined whether or not the track pair number has been picked up (step S2) while incrementing the five timer counters with pulses at predetermined intervals, for example, drum rotation pulses (step S1).

When the track pair number can be picked up, the current track pair number is stored (step S3), and the previous track pair number is read (step S4).
Then, the track pair number of this time is compared with the previous track pair number (step S5). If the track pair number of this time is smaller than the previous track pair number, it is a frame boundary, and therefore the fage change counter indicating the number of frame boundaries is incremented (step S6). Then, it is determined whether the value of the phase change counter is "1" (step S7). If the current track pair number is not smaller than the previous track pair number, it is determined whether the value of the phase change counter is "1" as it is (step S7). If the value of the phase change counter is "1", the value of the timer counter is read (step S8).

Then, pattern judgment processing is performed. That is, it is determined what the value of this timer counter is (step S9). If the value of the timer counter is "7" or "8", it is determined that the pattern is the SSP mode (step S10). If the value of the timer counter is "3" or "4", it is determined to be the SP mode pattern (step S11). Otherwise, it is determined to be an error pattern (step S12).

When a pattern is determined in steps S10, S11 and S12, a reproduction mode setting process is performed according to the pattern. That is, the timer counter is initialized to "0" and the phase change counter is initialized to "0" (step S13). Then, it is determined what the pattern is (step S14). Pattern is SS
In the P mode, it is judged whether or not the SSP mode set count number has reached the maximum value (for example, 10 times) (step S15), and if the SSP mode set count number has not reached the maximum value (for example, 10 times), the SSP The mode setting count number is incremented (step S16).
The maximum number of SSP mode setting counts (eg 10 times)
Is reached, the reproduction mode is set to the SSP mode (step S17).

When the pattern is judged to be the SP mode in step S14, it is judged whether or not the SP mode set count number has reached the maximum value (for example, 5 times) (step S18), and the SP mode set count number is the maximum value. If it has not reached (for example, 5 times), the SP mode setting count number is incremented (step S19). When the SP mode set count reaches the maximum value (for example, 5 times),
The playback mode is set to the SP mode (step S2)
0).

If it is determined in step S14 that the pattern is in the error mode, the SSP mode set count number and SSP mode
The P mode setting count number is initialized to "0" (step S21).

In this way, when the reproduction mode setting process is completed according to the pattern, the pattern is reset (step S22), and when not recorded, the SP mode is set (step S23). Then, the process returns to step S1.

When setting the SSP mode,
For example, it is determined whether the SSP mode set count has reached 10 times. Further, when the SP mode is set, it is determined whether or not the SP mode set count has reached, for example, five times. Thus, by switching the actual mode after the mode determination is performed a plurality of times, it is possible to eliminate the error in the mode setting. Further, the maximum value of the SSP mode set count number is, for example, 10 times, whereas the maximum value of the SP mode set count number is, for example, 5 times because the SP mode is prioritized. This SS
The maximum value of the P-mode set count number and the maximum value of the SP-mode set count number are appropriately selected according to the specifications of the set and the usage.

In the above example, the track pair number is used to determine the mode, but the track pair number is not the only one that can be used to determine the mode. If the information changes continuously and sequentially as the tape runs, it can be used in the same manner as the track pair number. For example, in addition to the track pair number, an absolute track number, time code, etc. can be used.

[0040]

According to the present invention, the track pair number is recorded on each track of the tape. For example, measurement is performed until the same track pair number appears, and the mode is determined from this measurement value. Since the track pair number is recorded in the ID of each sync block, it can be reliably detected even if the CN ratio is bad. Also, the reliability of this measured value is determined by determining how many times the frame boundary has been passed. Then, the mode is determined by using the highly reliable measurement value. Therefore, it is less likely that the mode is erroneously determined.

[Brief description of drawings]

FIG. 1 is a schematic diagram used to describe a track pair number.

FIG. 2 is a schematic diagram used to describe a recording track of a digital VTR.

FIG. 3 is a schematic diagram used to describe a track pair number.

FIG. 4 is a schematic diagram used to describe a track pair number.

FIG. 5 is a schematic diagram used to describe a track pair number.

FIG. 6 is a schematic diagram used to describe an embodiment of the present invention.

FIG. 7 is a schematic diagram used for describing an embodiment of the present invention.

FIG. 8 is a schematic diagram used for describing an embodiment of the present invention.

FIG. 9 is a schematic diagram used for describing an embodiment of the present invention.

FIG. 10 is a block diagram used to describe an embodiment of the present invention.

FIG. 11 is a flowchart used to describe an embodiment of the present invention.

FIG. 12 is a flowchart used to describe an embodiment of the present invention.

[Explanation of symbols]

5 ... Timer counter, 6 ... Phase change counter, 8 ... Judgment circuit, 10 ... Mode setting circuit

Claims (12)

[Claims] 1. A reproducing apparatus adapted to set a plurality of modes having different tape speeds, discriminating a mode at the time of recording, and reproducing in a mode suitable for the mode at the time of recording. From the above, information detecting means for detecting information that continuously and sequentially changes with tape feeding, and timer means for measuring a time during which a predetermined amount of information that continuously and sequentially changes with tape feeding change. And a mode setting means for setting the mode according to the judgment output of the judging means, and a judging means for judging the recording mode from the value of the timer means. 2. The track pair number is the information that continuously and sequentially changes as the tape is fed.
The playback device described. 3. The reproducing apparatus according to claim 2, wherein the timer means counts a time from the reproduction of the track pair number to the next reproduction of the same track pair number. 4. The determination means is configured to make a determination using a highly reliable count value of the time from when a track pair number is reproduced to when the same track pair number is reproduced next time. The reproducing apparatus according to claim 3. 5. The reproducing apparatus according to claim 1, wherein the information that continuously and sequentially changes as the tape is fed is a track number. 6. The reproducing apparatus according to claim 1, wherein the information that is continuously and sequentially changed as the tape is fed is a time code. 7. A mode discriminating method for discriminating a mode at the time of recording from a tape in which a plurality of modes having different tape speeds can be set, in which a reproduction signal of the tape is continuously changed as the tape is fed. Of the information to be recorded, the step of measuring the time during which the information that changes continuously and continuously with the feeding of the tape changes by a predetermined amount, and the value of continuously changing with the feeding of the tape. And a step of determining a mode at the time of recording from a measured value of time during which a certain amount of information changes by a predetermined amount. 8. The track pair number is the information that continuously and sequentially changes as the tape is fed.
Described mode determination method. 9. The time when a predetermined amount of information that changes continuously and continuously with the feeding of the tape changes is measured from the reproduction of the track pair number to the next reproduction of the same track pair number. 9. The mode determining method according to claim 8, which counts time. 10. The judgment of the mode at the time of recording is made by selecting a reliable one of the count values of the time from the reproduction of a track pair number to the next reproduction of the same track pair number. 9. The mode determining method according to claim 8, wherein. 11. The mode discriminating method according to claim 7, wherein the information which continuously and sequentially changes as the tape is fed is a track number. 12. The mode discriminating method according to claim 7, wherein the information which is successively changed as the tape is fed is a time code.