JPH03250460A - Coding signal recording for audio signal and recording and reproducing device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of pulse noise at an overwriting point by forcibly conforming a coding frame to a recording frame with a frame setting signal at the time of overwriting and starting recording accordingly. CONSTITUTION:A coding frame reset signal S3 is outputted in advance by a reset signal generating part 3 in order to conform the lead of the coding frame to the rising edge of a frame synchronizing signal S5 of the recording frame of a signal recording and reproducing part 4 at an overwrite starting point based on a reference of the frame synchronizing signal. A recording input signal is compressed and coded by a signal compression part 2 with the reset coding frame to output a recording coding signal S4, and recording is started from a recording starting point by a signal recording and reproducing part 4. By this constitution, the recording can be performed with a synchronization pattern of the coding frame conformed to the head of the recording starting point, and without misinterpreting one part of the coding signal after overwriting at the time of reproducing, the occurrence of an abnormal sound, such as pulse noise, etc., can be suppressed at the overwriting point.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an encoded signal recording and reproducing apparatus for audio signals that encodes a digital audio signal frame by frame and records the encoded signal at a different frame period.

Conventional technology In recent years, with the development of high-efficiency encoding technology, it is time for the technology to efficiently encode digital signals such as audio and images, and to record and play them with high efficiency, to expand its application fields. is approaching.

Conventionally, high-efficiency encoding technology has widely used a technique that achieves high-efficiency encoding by constructing a frame from a plurality of digital signals and encoding the frame. Examples of such techniques include quasi-instantaneous companding techniques and subband encoding techniques. Quasi-instantaneous companding technology achieves high efficiency by decomposing data into a mantissa part and an exponent part, and keeping the exponent part constant for a plurality of pieces of data making up a frame. In addition, subband coding technology divides the original signal into multiple frequency bands using a bandpass filter, and performs quasi-instantaneous companding by appropriately allocating the number of bits in the mantissa part for each band, resulting in highly efficient coding. The goal is to achieve the following.

The sampling frequency of digital audio signals that undergo such encoding is currently 48kHz.

44.1kHz and 32kHz are often used,
Since several sampling frequencies are used in this way, if the number of samples constituting an encoded frame is held constant, the period of the encoded frame changes depending on the sampling frequency. On the other hand, the period of the recording/reproduction frame is often selected to be a constant period, regardless of the sampling frequency, for reasons such as error correction. For this reason, the frame period for recording and reproduction is often not an integral multiple of the encoding frame period.

An example of a conventional encoded signal recording and reproducing apparatus for audio signals using quasi-instantaneous companding technology will be described below.

FIG. 3 shows a block diagram of a conventional encoded signal recording and reproducing apparatus for audio signals.

In FIG. 3, 31 is an AD conversion section, 32 is a signal compression section, 33 is a signal recording/reproducing section, 34 is a signal expansion section, and 35 is a D
This is the A conversion section.

The operation of the audio signal recording and reproducing apparatus configured as described above will be described below.

The AD converter 31 samples and quantizes the input signal S31,
It is output as an input digital audio signal S32. The signal compression unit 32 compresses and encodes the input digital audio signal 832 in units of encoded frames, and outputs it as an encoded signal S33. The transmission recording/reproducing unit 33 receives the encoded signal 833
A signal recording/reproducing unit 33 on a recording medium, for example, a magnetic tape.
Record and playback in recording frame units. The signal expansion section 34 expands and decodes the encoded signal 834 reproduced by the signal recording and reproduction section 33, and outputs it as an output digital audio signal S35. Further, when the signal decompression unit 34 detects an error such as an undetectable synchronization pattern of the encoded signal 834, it outputs an error signal 838. When the error signal 33B is not input, the DA converter 35 converts the output digital audio signal S35 into an analog signal and outputs it as an output signal. Further, when the error signal 83B is input, the output signal is faded out and nothing is output. Note that the error signal is generally also output from the signal recording/reproducing section 33, but in this embodiment, to simplify the explanation of the operation,
It is assumed that there is no error in the signal recording/reproducing section 33.

FIG. 4 is a timing diagram for explaining the operation of the conventional encoded signal recording/reproducing apparatus. Hereinafter, the operation of each part will be explained according to this diagram.

First, the operation during recording will be explained.

FIG. 4 shows an example of quasi-instantaneous companding in which one encoded frame consists of 8 samples of lo-I7, where A is the input signal, B is the encoded signal, and C is the output signal.

If an input signal A as shown in Fig. 4 is input, A
The D converter 31 samples and quantizes the input signal A (input signal 531) and outputs it as input digital audio signals 1O-I7. The signal compression unit 32 obtains a scale factor SF from the maximum value of the amplitudes of the input digital audio signals 832, and also normalizes the input digital audio signals IO to I7 using this scale factor SF to obtain quantized data Do-D7. demand. These data are added to a synchronization pattern (indicated by a square) to construct a frame as shown in encoded signal B. By repeating the above processing every 8 samples, encoded signal B (encoded signal 533) is created. Here, data compression is performed by encoding the scale factor SF and the quantized data DO to D7 with an appropriate number of bits smaller than the number of bits of the input signal. Coded signal B (coded signal 5) obtained in this way
33) is recorded on a recording medium by the signal recording/reproducing section 33 in units of frames of the signal recording/reproducing section.

Next, the operation during playback will be explained.

The signal recording/reproducing section 33 reproduces the encoded signal B (encoded signal 534) from the recording medium. The signal expansion unit 34 outputs an output digital audio signal 535 (00-07) from the encoded signal B using the synchronization pattern as a reference. Further, if a synchronization pattern cannot be detected or if a synchronization pattern is detected in the middle of an encoded frame, an error signal 836 is output.

When the error signal 83E3 is not input, the DA converter 35 outputs an output digital audio signal 835 (00 to 0
7) into an analog signal and outputs it as an output signal 837. Further, when the error signal 83B is input, the output signal is faded out and nothing is output.

Problems to be Solved by the Invention However, in the conventional audio signal encoded signal recording and reproducing device, when an encoded signal is overridden on a recording medium in which an encoded signal has already been recorded, the recording frame for recording and reproducing the encoded signal is Since the encoded frame and the encoded frame do not match, when this is played back, part of the encoded data is misinterpreted, causing abnormal sounds such as pulse noise at the override point. Ta.

This problem will be explained below using the case of quasi-instantaneous companding as an example.

Figure 5 is a timing diagram to illustrate this problem.
D is a frame synchronization signal of the signal recording/reproducing section 33, E is a recorded input signal, F is a recorded encoded signal, G is a recording input signal, H is a recording encoded signal, ■ is a recording/decoding signal, and J is a recording/decoding signal. is the output signal. Here, the part indicated by ■ of the encoded signal is
Represents the synchronization pattern of encoded frames. In the recorded encoded signal F, AS is a scale factor, and AO-A2 is quantized data normalized by a scale factor As.

In the recording encoded signal H, BS is the scale factor, BO~B
7 is quantized data normalized by the scale factor BS. It is also assumed that recording onto the recording medium is performed at the frame period indicated by the rising edge of the frame synchronization signal of the signal recording/reproducing section 33. It is assumed that a recorded encoded signal F, which is a signal shown in the recorded input signal E encoded, has been recorded on the recording medium in advance. Next, the signal shown in the recording input signal G is overridden from the frame shown by the mark on the frame synchronization signal.

At this time, it is assumed that an encoded signal obtained by encoding the input signal G to be recorded is outputted from the signal compression section 32 at an encoded frame timing like the recording encoded signal H. Since recording is performed frame by frame in the signal recording/reproducing section 33, recording is started from the point indicated by the mark. Therefore, an encoded signal such as the recorded/decoded signal I, which is a combination of the unshaded portions of the recorded encoded signal F and the recorded encoded signal H, remains on the recording medium. When this is played back, as shown in the output signal J, the section a before the override of the encoded frame at the recording start point is played back correctly, but the quantized data (BO-84) does not correspond to this section. Since it is decoded using the scale factor (As), it will be output with an incorrect amplitude. Section C
is faded out because no synchronization pattern can be detected, and is normally reproduced again from section d.

In this way, in the conventional encoded signal recording and reproducing device for audio signals, when the encoded signal is overridden, the frame for recording and reproducing the encoded signal does not match the encoded frame, so the encoded signal cannot be changed during playback. There was a problem in that some parts were misinterpreted and abnormal noises such as pulse noise were generated at the override point.

The present invention solves the above-mentioned conventional problems, and provides a coded signal for audio signals that can suppress the occurrence of abnormal sounds when a discontinuity occurs in the coded signal at an override point due to editing or splice recording. The purpose of this invention is to provide a recording/playback device.

Means for Solving the Problems In order to achieve this object, an encoded signal recording and reproducing apparatus for audio signals according to the present invention inputs a digital audio signal and an encoded frame reset signal, and inputs a digital audio signal and an encoded frame reset signal, and then inputs a digital audio signal and an encoded frame reset signal. A signal compression means for compressing and encoding a digital audio signal and outputting an encoded signal with a synchronization pattern added thereto; and a signal compression means for inputting a frame synchronization signal to match the timing of the encoded frame and the recording frame at the recording start point. and a signal recording means that records the encoded signal in units of recording frames and outputs a frame synchronization signal of the recording frame.

Operation The encoded signal recording and reproducing device for audio signals of the present invention has the above-described configuration, and is configured so that the encoded frame of the signal compression means is reset by the reset signal generating means at the time of override, thereby recording the synchronization pattern of the encoded frame. You can record according to the beginning of the starting point. This prevents part of the encoded signal after override from being erroneously interpreted during playback, and interpolation processing is automatically performed at the override start point to suppress the generation of pulse noise at the override point. can.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an encoded signal recording and reproducing apparatus for audio signals in an embodiment of the present invention.

In FIG. 1, 1 is an AD conversion section, 2 is a signal compression section, and 3
4 is a signal recording/reproducing section; 5 is a signal compressing section; and 6 is a DA converting section.

The operation of the signal reproducing apparatus of this embodiment configured as described above will be described below.

The AD converter 1 samples and quantizes the input signal S1 and outputs it as an input digital audio signal S2. The signal compression unit 2 compresses and encodes each encoded frame in synchronization with the encoded frame reset signal S3, and outputs it as an encoded signal S4. The signal recording and reproducing section 4 records and reproduces the encoded signal S4 on a recording medium in units of recording frames. The reset signal generating section 3 resets the encoded frame so that the recording start point and the beginning of the encoded frame coincide with each other at the start of override, based on the frame synchronization signal S5 of the recording frame of the signal recording/reproducing section 4. The encoded frame reset signal S3 is output. The signal expansion unit 5 expands and decodes the encoded signal S6 reproduced by the signal recording and reproducing unit 4, and outputs it as an output digital audio signal S7.

Furthermore, when an error such as an undetectable synchronization pattern of the encoded signal S6 is detected, an error signal S8 is output.

When the error signal S8 is not input, the DA converter 6 converts the output digital audio signal S7 into an analog signal and outputs it as an output signal S9. Further, when the error signal S8 is input, the output signal is faded out and nothing is output.

FIG. 2 is a timing diagram for explaining the operation of this encoded signal recording and reproducing device for audio signals at the time of overriding, where K is a frame synchronization signal of the signal recording and reproducing section 4;
L is a recorded input signal, M is a recorded encoded signal, N is a recording input signal, O is a recorded encoded signal, P is a recorded/decoded signal, and Q is an output signal. Here, the part of the encoded signal indicated by - represents the synchronization pattern of the encoded frame. In the recorded encoded signal M, As is a scale factor, and AO to A2 are quantized data normalized by the scale factor As. When the recording encoded signal is 0, BS is the scale factor, BO
~B7 is quantized data normalized by the scale factor BS. Further, recording onto the recording medium is performed at a frame period indicated by the rising edge of the frame synchronization signal of the signal recording/reproducing section 33.

It is assumed that a recorded encoded signal M obtained by encoding a signal shown in a recorded input signal is previously recorded on a recording medium in exactly the same way as a conventional encoded signal recording/reproducing apparatus for audio signals. The override shall be performed starting from the frame indicated by the mark on the frame synchronization signal. Immediately before starting the override, the reset signal generating unit 3 generates an encoded frame reset signal in advance so that the beginning of the encoded frame coincides with the rising edge of the frame synchronization signal S5 at the override start point using the frame synchronization signal K as a reference. Output S3.

The signal compression unit 2 compresses and encodes the record input signal N using the reset encoded frame, and outputs the record encoded signal O. Thereafter, the signal recording/reproducing section 4 starts recording from the recording start point indicated by the mark, thereby recording a signal on the recording medium in the form shown in the recording/decoding signal P. When this is reproduced, as shown in the output signal Q, the recorded encoded signal P is correctly reproduced in the section e in the figure, and the synchronization pattern is detected in the middle of the encoded frame in the section f.
An error signal 8 is output from the signal compression section 5, and an output signal Q
is faded out. Furthermore, in section g, the recorded encoded signal 0 is correctly reproduced.

As described above, according to this embodiment, the encoded frame of the signal compressor 2 is reset by the reset signal generator 3 at the time of override, and the synchronization pattern of the encoded frame is recorded in alignment with the beginning of the recording start point. This prevents the encoded signal immediately after the override point from being erroneously interpreted during playback, and interpolation processing etc. are automatically performed at the override start point, thereby suppressing the generation of pulse noise at the override point.

Effects of the Invention The encoded signal recording and reproducing device for audio signals of the present invention has the following features:
With the above configuration, by forcibly matching the encoded frame and recording frame with the frame reset signal at the time of override and starting recording, the data is recorded on the recording medium from the beginning of the encoded frame to be recorded at the override start point. recorded. This prevents the part of the encoded signal immediately after the override point from being misinterpreted during playback, and processing such as interpolation or fade-out is automatically performed at the override start point. It is possible to suppress the occurrence of abnormal noise at points.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an encoded signal recording and reproducing apparatus for audio signals according to an embodiment of the present invention, FIG. 2 is a timing diagram showing the operation of the same embodiment, and FIG. 3 is a conventional audio signal FIG. 4 is a block diagram showing the configuration of the encoded signal recording and reproducing device. FIG. 4 is a timing diagram showing the operation of the conventional encoded signal recording and reproducing device for audio signals. FIG. 5 shows the operational problems of the conventional example. FIG. 2 is a timing chart for explanation. 1... DA conversion section, 2... Signal compression section, 3
. . . Reset signal generation section, 4. Signal recording/reproduction section, 5. Signal expansion section, 6. DA conversion section.

Claims (2)

[Claims] (1) An encoded signal recording device for audio signals that compresses and encodes a digital audio signal in encoded frame units and records the digital audio signal in a recording frame period different from the encoding frame period, the digital audio signal and an encoded frame reset signal, and compresses and encodes the digital audio signal at the reset encoding frame period, and outputs an encoded signal with a synchronization pattern added thereto; and the recording frame. reset signal generating means for inputting a frame synchronization signal and outputting the encoded frame reset signal for matching the timing of the encoded frame and the recording frame at a recording start point; 1. An encoded signal recording apparatus for audio signals, comprising: a signal recording means for recording an encoded signal and outputting a frame synchronization signal of the recording frame. (2) The encoded signal recording device for audio signals according to claim 1 is provided with a signal reproducing means for reproducing the encoded signal and a signal expansion means for expanding and decoding the encoded signal into a digital audio signal. A coded signal recording and reproducing device for audio signals.