JPH0325757A - Vcr - Google Patents

Abstract

PURPOSE:To automatically switch the reproducing process of the tapes for a new standard and a present standard by discriminating whether a PCM audio signal or a preamble signal is recorded on a part corresponding to the starting section of a track or not and switching a reproducing characteristic. CONSTITUTION:The PCM audio signal Sg of the present standard or the PCM audio signal Ss of the new standard and a multiplexing signal St are recorded on a tape 1 as the track 2G or the 2S. The signals Sg and Ss supplied to an amplifier 21 from heads 11A and 11B through a switching circuit 12 are supplied to switching circuits 22 and 41. On the other hand, when the heads 11A and 11B are placed at a corner position corresponding to the part from the starting point of the section 2P of the track 2S to the starting point of the section 2P of the track 2G, a signal Sc is supplied to the switching circuit 41 as a control signal. At this time, the switching circuit 41 is turned on. The output Ss of the switching circuit 41 becomes a signal which discriminates the standard of the PCM audio signal recorded on the tape and the signals Sg and Ss are reproduced corresponding to the standard.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a VTR.

[Summary of the invention]

For example, in an 8 mm video, the present invention distinguishes between a PCM audio track according to the first standard and a PCM audio track according to the second standard, so that the audio signal can be recorded regardless of which standard it is recorded under. This allows for proper playback.

[Conventional technology]

In the current 8mm video, the audio signal is
Although it is permitted to record and play in the M signal state,
The PCM audio signal at this time is recorded in the overscan section of the video track.

That is, Figure 3A shows the current 8mm video track format, where (1) is a magnetic tape, (2)
) to (4) are magnetic 1-racks. Then, the track (2) is rotated by a rotating magnetic head with a rotation angle of 21
This track (2) is diagonally shaped to a length corresponding to 6@, and is divided into a 36° section (2A) on the front side and a 180° section (2v) on the rear side. (2v
> includes an FM signal modulated by a luminance signal, a carrier color signal that has undergone low frequency conversion and predetermined phase processing, an FM signal modulated by a monaural audio signal, and a pilot for tracking servo during playback. Frequency multiplexing St with the signal is recorded for each field period.

Furthermore, a PCM audio signal is recorded in section (2A) of track (2). However, at this time, the recording section (including the preamble section) of the net audio signal is the section (28.38 degrees) approximately in the center of section (2A).
2P). Also, the signal actually recorded in this section (2P) is a 2-channel audio signal that is
The PCM signal is A/D converted into an M signal, and encoded for error correction during playback, such as adding an error correction code for each l field period, to this PCM signal, and the signal after this encoding process EI is is the pi-phase mark signal Sg which has been compressed on the time axis so as to be located at the time position of section (2P) and is modulated by this compressed signal.

Further, in the section (2A), the section before the section (2P) is the section where the rotating head starts traveling, and the section after the section (2V
) and is considered to be a guard interval (gap).

In addition, tracks (3) and (4) are shaped in the length direction of the tape (1) by fixed magnetic heads,
A monaural audio signal is recorded on track (3), and a cue signal is recorded on track (4).

However, the PCM recorded and reproduced in the above section (2^)
This signal is an audio signal, and the stereo left and right channel audio signals have a sampling frequency that is twice the horizontal frequency ('E31.5KHZ), and the samples are quantized with 10 bits, and Part 1
This is a signal in which 10 bits of the sample are compressed to 8 bits.

Therefore, this PCM audio signal is
The characteristics are not very good compared to PCM audio signals such as those in

By the way, in the current standard, recording and reproducing audio signals on track (3) using a fixed head is an option.

Also, track (3) is section (2A) of tape (1).
The length from this tape edge to the start end of the track (2A) (length in the tape width direction) is 0. 7 mm, which corresponds to approximately 24° of rotation angle of the rotary head when viewed in the longitudinal direction of the track (2).

Therefore, a new standard is being considered for recording and reproducing PCM audio signals using the section from the edge of the tape to the start of track (2A).

That is, in this new standard, the left and right channel audio signals have a sampling frequency of 48kHz.
, one sample is linearly quantized with 16 bits. Also,
In this new standard, the data amount of PCM audio signals will be significantly increased compared to the current standard, so the error correction code, code structure, recording modulation method, etc. will be changed.
For example, the modulation method is 8-10 conversion. and,
As shown in FIG. 3B, the section (2A) is extended to the edge of the table and has a length of, for example, 43 degrees of the rotation angle of the rotary head. A net PCM audio signal (8-10 converted signal) Ss is recorded in the section (2P) of 35.1' (including the preamble section). Further, in the section (2A), the section before the section (2P) is a scanning start section of the rotary head, and the section after it is a guard section with the section (2v).

Therefore, according to this new standard, it is possible to record and reproduce audio signals with characteristics that are equal to or better than those of other digital audio devices.

[Problem to be solved by the invention]

However, when the above-mentioned new standard was adopted, tape (1) (8 millica cents) on which audio signals were recorded according to the new standard and tape (1) on which audio signals were recorded according to the current standard. When playing back the tape (1), the user must switch the playback characteristics according to the rules used when recording the tape (1).

This invention attempts to automate such switching.

In the following description, the truck (2) according to the current standard will be referred to as a trunk (2G), and the truck (2) according to the new standard will be referred to as a truck (2S) to distinguish them.

The starting point of the recording section (2P) of the PCM audio signal is also different.

Therefore, in the present invention, it is determined whether a PCM audio signal or a preamble signal is recorded in the part corresponding to the start section of the track (2G), and if it is not recorded (A in the figure), the current The PCM audio signal is played back using the characteristics according to the standard, and when it is recorded (B in the same figure), the PCM audio signal is played back using the characteristics according to the new standard.

(Operation) Reproduction is automatically performed with corresponding reproduction characteristics according to the standards at the time of recording.

[Means to solve the problem]

Here, if the track (2G) according to the current standard and the track (2S) according to the new standard are illustrated side by side, it will look like Figure 2 A and B, and the track (2G) and (2S) will have a section ( [Example] In FIG. 1, (IIA) . (IIB) indicates a rotating magnetic head, and these heads (1 1A), (1
1B) have an angular spacing of 180° from each other and are rotated at the frame frequency. The tape (1) is run diagonally over an angular range of over 223 degrees in accordance with the new standard 1. rack length with respect to the rotating circumference of the heads (114) and (IIB).
This tape (1) is compatible with current standard or new standard PC.
As described above, the M audio signal Sg or Ss and the multiplexed signal St are recorded as tracks (2G) or (2S).

Therefore, the signals Sg or Ss and the signal St are obtained alternately from the heads (IIA) and (IIB) every l field period, but these signals are supplied to the inner circuit (l2) and the switch The signal St is continuously taken out from the path (I2), and the signal Sg or Ss is intermittently taken out every one field period.

Then, this signal St passes through the reproducing amplifier (l3);
The signal is supplied to the reproduction processing circuit (14), where the luminance signal and the carrier color signal are processed in the opposite manner to that during recording, and the color composite 1-:deo signal is output to the terminal (l5), and the FM The audio signal is processed in the opposite manner to that during recording, and a monaural audio signal is output to the terminal (16).

Also, at this time, the signal St is supplied to the servo circuit (50), and the pilot signal in the signal St causes the head (11
A), (IIB) tracking servo is performed.

Furthermore, the signal Sg or Ss from the switch circuit (12) passes through the regeneration amplifier (21) to the switch circuit (2).
2). As will be described later, this switch i (22) is connected to the state shown in the diagram when the reproduced signal of section (2A) is the signal Sg by the signal sh, and is connected to the state opposite to that shown in the diagram when the signal Ss is the reproduced signal of the section (2A). .

Therefore, when the reproduced signal is the signal Sg, this signal 'f S g is supplied to the demodulation circuit (23) through the switch circuit (22) and demodulated from the pi-phase mark signal to the PCM signal. is supplied to the decoder (24) and decoded into the original PCM signal by performing time axis expansion, error correction, and focus expansion from 8 bits to 10 bits, and this PCM signal is sent to the switch circuit (25). are supplied to the D/A converter (26) and converted into original left and right channel audio signals, and these signals are supplied to the terminal (26).
7L) and (27R).

Also, when the reproduced signal is the signal Ss, this signal
) 3 is connected to the conversion circuit (33) through the switch circuit (22).
) and undergoes 10-8 conversion, and this converted signal is supplied to a decoder (34) where time axis expansion and error correction are performed to decode it into the original PCM signal, and this PCM signal is sent to the switch. The signals are supplied to a D/A converter through a circuit (25) and converted into original left and right channel audio signals, and these signals are taken out to terminals (27L) and (27R).

Furthermore, the signal Sg or Ss from the amplifier (21) is supplied to the switch circuit (4th circuit), and a signal synchronized with the rotation of the head (1.1A>, (ilB)) is generated from the servo circuit (61). It is supplied to the precept circuit (61) and the second
The signal Sc as shown in Figure C, that is, the head (IIA
). When (IIB) is at an angular position corresponding to the start point of section (2P) of track (2S) to the start point of section (2P) of track (2G), signal Sc which becomes ``1'' is a form command. This signal Sc is supplied to the switch circuit (4l) as a control signal 2, and when Sc - is "1", the switch circuit (4l> is turned on).

Therefore, from the switch circuit (41), the table (
1) Based on the current standards. 53, S g is recorded (Fig. 2 A), no signal is obtained, and when the new standard signal Ss is recorded, that signal Ss
The beginning part (the part of the period of Sc = "'l゛)" is obtained.

So, the output signal of this switch circuit (4i) is fed to the peak detection circuit (42), and the detection output is sent to the hall 1 same circuit (43). ) and held for at least l field period. Therefore, when the signal Sg of the current standard is recorded in 7-B(1), Sh1.+
1 0 I1, and when the new Gokugo Ss is recorded, sh="bi", that is, this signal sh is a signal that has determined the standard of the PCM audio signal recorded on the tape.

Therefore, this signal Sb is supplied as a control signal to the switch circuits (22), (25) through the shaping circuit (44), and the switch circuits (22'), (25)
When it is '0', it is connected to the state shown in the figure, and Sb='”
l”, the connection is reversed to that shown in the figure, and
It is supplied to the D/A converter (26) as a sampling frequency and quantization bit 1/number switching signal.

Therefore, the signals Sg and Ss are respectively reproduced according to their standards as described above.

Further, at this time, the signal sh is supplied to the display means (45) to display whether the PCM audio signal is of the current standard or the new standard.

Since switching is performed, the configuration is simple and it is easy to use.

[Brief explanation of drawings]

Figure 1 shows: Invention L) Example 0) Systematic diagram, 2nd evil, 3rd
The figure is a circle for explanation. (IIA), (IIB) are rotating magnetic fields, (2
;0 is demodulation circuit, (24), (34) is decoding,
(26) is an I),/A converter, (33) is a conversion circuit, (42) is a 1 dark detection circuit, and (4:3,) is a hold circuit "C". (Effects of the invention)

Claims (1)

[Claims] The overscan section of the video track section is an audio track section, and this audio track section has a first standard or a second standard.
A PCM audio signal is recorded according to the standard, and the length or position of the audio track section differs between when recording the PCM audio signal according to the first standard and when recording the PCM audio signal according to the second standard. When reproducing the first or second PCM audio signal from the magnetic tape on which the first or second PCM audio signal is recorded, the first standard of the audio track section is different. Regarding the part where the PCM audio signal of the second standard is recorded, but the PCM audio signal of the second standard is not recorded,
The signal is reproduced, and when a signal is obtained by this reproduction, the reproduction system for the PCM audio signal is set to the reproduction characteristic corresponding to the first standard, and when the signal is not obtained by the reproduction, the PCM audio signal is
A VTR in which an audio signal reproduction system has reproduction characteristics that comply with the second standard.