JPH0447567A - Sound reproducing device - Google Patents

Abstract

PURPOSE:To listen to a reproducing sound with superior fidelity by outputting a regenerative signal of a less error area out of a 1st area and a 2nd area. CONSTITUTION:Each track of a recording medium 20 is provided with the 1st area 22 for recording a video and a sound and the 2nd area 24 for recording only the sound, and the device is provided with 1st and 2nd reproducing processing means 52, 54, 56, 62, 64 and 66 for processing the reproducing of regenerative signals from the 1st and 2nd areas 22 and 24 and correcting errors, a discriminating means 58 for comparing an error rate of the regenerative signal from the 1st area 22 with an error rate of the regenerative signal from the 2nd area 24 and a selecting means 68 for selecting either of the sound signals to be outputted by the 1st and 2nd reproducing processing means 52, 54, 56, 62, 64 and 66 in accordance with a result of the discrimination. Then, a regenerative signal having fewer errors out of the recorded signals of the 1st and 2nd areas 22 and 24 is selected and outputted. By this method, the reproducing sound in good quality is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a recording system in which each track of a recording medium is provided with a first area for recording video and audio and a second area for recording only audio. The present invention relates to an audio playback device.

[Prior Art] FIG. 2 shows a conventional recording and reproducing apparatus using a digital recording method, in which each track of a recording medium is provided with a first area for recording video and audio and a second area for recording only audio. A configuration block diagram is shown. In FIG. 2, 10 is an input terminal for a video signal, 12 is an input terminal for an audio signal, and an encoder 14 converts the signals input to both input terminals 10 and 12 into digital signals using a clock having a predetermined sampling frequency. Parity for error correction using a cross-interleaved Reed-Solomon code and a synchronization code for forming a synchronization block are added to the digital audio data and digital video data. Here, each synchronization block contains audio data and video data at a predetermined ratio, and F is the unit to which product code parity is added.
The CC block also includes video data and audio data at a predetermined ratio. The modulation circuit 16 subjects the output of the encoder 14 to direct current suppression modulation and applies it to the rotating magnetic head 18 . As a result, video and audio are recorded on the magnetic tape 20.

FIG. 3 shows the track pattern of magnetic tape 20. FIG. In this conventional example, a rotating magnetic head 18 records video and audio on a main portion (first area) 22 of a track of a magnetic tape 20, and after-recording is performed on a secondary portion (second area) 24 using a rotating magnetic head 30. Record audio.

In other words, the audio signal to be subjected to after-recording is supplied from the audio input terminal 12 to the encoder 26,
After being digitized, it is subjected to processing such as addition of an error correction code that constitutes a product code and formation of synchronous blocks. The modulation circuit 28 subjects the output of the encoder 26 to direct current suppression modulation and applies it to the rotating magnetic head 30 . The rotating magnetic head 30 is the third
It is placed at a position where recording can be performed in the second area 24 in the figure, and audio is recorded in the second area 24.

Of the signals recorded on the magnetic tape 20, the signals in the first area are reproduced by the rotary magnetic head 32, and the signals in the second area are reproduced by the rotary magnetic head 34. The outputs of the rotating magnetic heads 32 and 34 are sent to demodulation circuits 36 and 38, respectively.
The signal is demodulated by and supplied to decoders 40 and 42. The decoder 40 temporarily stores the output of the demodulation circuit 36 in an internal memory, and the error correction circuit 41 performs syndrome calculation to correct and interpolate errors. The decoder 40 converts the corrected and interpolated data into an analog signal, and outputs the video signal and audio signal separately to a video output terminal 44 and an audio output terminal 46. Similarly, the decoder 42 temporarily stores the output of the demodulation circuit 38 in an internal memory, and the error correction circuit 43 performs syndrome calculation to correct and interpolate errors.

The decoder 42 converts the corrected and interpolated audio data into an analog signal, and outputs a reproduced audio signal to an output terminal 48.

The error correction circuits 41 and 43 correct errors accompanying recording and reproduction through powerful error correction processing, but it is impossible to completely restore the errors. In this way, errors that cannot be corrected are interpolated using, for example, previous value interpolation, and if they still cannot be corrected, such as when a burst error occurs, the playback audio output is muted and the audio output is cut. I was doing it.

[Problems to be Solved by the Invention] When there is an error that exceeds the error correction ability as described above, there are disadvantages in that the sound sounds unnatural or the voice is interrupted discontinuously.

In addition, the second area is for after-recording,
Not normally used. Since the frequency of after-recording is generally low, the second area is not used effectively.

Therefore, an object of the present invention is to provide an audio reproduction device that solves these problems.

[Means for Solving the Problems] An audio reproduction device according to the present invention provides a first area for recording video and audio and a second area for recording only audio on each track of a recording medium, and reproduces a signal. An apparatus for reproducing audio from a recording medium having recorded thereon, the apparatus comprising first and second reproduction processing means for reproducing and error-correcting reproduction signals from first and second areas, and the first area. a determining means for comparing the error rate of the reproduced signal from the second area and the error rate of the reproduced signal from the second area, and according to the determination result of the determining means,
It is characterized by comprising a selection means for selecting audio signals output from the first and second reproduction processing means.

[Operation] The above means selects and outputs the reproduced signal with fewer errors among the recorded signals of the first and second areas. Therefore, higher quality reproduced audio can be obtained.

[Example〕 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block diagram of the configuration of a playback device that is an embodiment of the present invention. Reference numeral 50 denotes a reproducing head for reproducing the recording signal of the first area in FIG. 3, and its output is demodulated by a demodulating circuit 52. The decoder 54, like the decoder 40,
The output of the demodulation circuit 42 is temporarily stored in an internal memory, and an error correction circuit 56 performs error correction and interpolation. The error correction circuit 56 also applies the error rate of the reproduced audio data to the discrimination circuit 58, as will be described later. In addition, the playback head 6
o reproduces the recorded signal in the second area in FIG. Similar to the decoder 42, the decoder 60 temporarily stores the output of the demodulation circuit 62 in an internal memory, and the error correction circuit 66 performs error correction and interpolation. error correction circuit 6
6 also applies the error rate of the reproduced audio data to the discrimination circuit 58, as will be described later.

The audio output of the decoder 54 is applied to the a contact of the switch 68, and the audio output of the decoder 64 is applied to the b contact of the switch 68.
The switch 68 is controlled to select the audio output with the smaller error rate. That is, if the audio signal reproduced by the playback head 60, that is, the audio signal reproduced from the second area 24, has a lower error rate than the audio signal reproduced by the playback head 50, that is, the audio signal reproduced from the first area 22, , connect the switch 68 to the b contact,
Otherwise, the switch 68 is connected to the a contact.

The reproduced video output of the decoder 54 is output from the video output terminal 70, and the reproduced audio signal selected by the switch 68 is output from the audio output terminal 72.

Here, the operations of the error correction circuits 56 and 66 and the discrimination circuit 58 will be explained in detail.

From the first area 22, reproduced data in which video data and audio data are present in each synchronization block and a product code is formed as described above is obtained and stored in the memory within the decoder 54. The error correction circuit 56 corrects code errors using the inner code (inner code) of this product code, and then performs error correction using the outer code (outer code). For codes that cannot be corrected, an error flag is output, and error correction such as the above-mentioned pre-interpolation is performed.

Similarly, reproduced data in which a product code is formed for the audio data is obtained from the second area 24, and the decoder 6
4 in memory. The error correction circuit 66 corrects code errors using the inner code and then performs error correction using the outer code. Similarly, for codes that cannot be corrected using the outer code, the error correction circuit 66 outputs an error flag, and the error correction is performed. administered.

Here, the above-mentioned error rate refers to the proportion of this error-uncorrectable code to the entire code. This takes into consideration the fact that the number of outer codes per unit time is different between area 22 and area 24, which is proportional to the number of error flags. That is, the number of outer codes reproduced from the first area 22 per unit time (for example, one track) is N1, the number of error flags is El, and the number of outer codes reproduced from the second area 24 per unit time is N1. When the number of codes is N2 and the number of error flags is E2, the error correction circuit 56 outputs E+/N+ to the discrimination circuit 58, and the error correction circuit 66 outputs E2/N2 to the discrimination circuit 58.

Audio data that is generally recorded with video data is
Since they are distributed and arranged in the video data, they are strong against so-called burst errors, but because they cannot have a large degree of redundancy, they are weak against random errors.

Conversely, when audio data is recorded individually, it is weak against burst errors and strong against random errors. According to the configuration of the above-described embodiment, this point can be mutually compensated for, and an extremely good reproduced audio signal can be obtained. Furthermore, since the apparatus of this embodiment uses a recording area for so-called after-recording, there is an advantage that there is no need to prepare a dedicated recording area.

In this embodiment, the recording area 22 is reproduced by the reproduction head 50, and the recording area 24 is reproduced by the reproduction head 60. However, in reality, one rotary head continuously reproduces the areas 22 and 24. Generally, the output of this reproducing head is distributed to demodulators 52 and 62 by a gate circuit. That is, the number of heads and their arrangement can be varied in various ways.

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, the reproduced signal of the first area and the second area, whichever has fewer errors, is output, so more faithful reproduced audio can be obtained. You can listen. Even if the recording in one of the first and second areas is destroyed beyond the error correction ability, it can be covered by the reproduced audio from the other area.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration block diagram of an embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional recording/reproducing apparatus, and FIG. 3 is a track pattern diagram. 50.60: Reproduction head 52, 62: Demodulation circuit 54.
64: Decoder 56, 66: Error correction circuit 58: Discrimination circuit 70: Video output terminal 72: Audio output terminal

Claims (1)

[Claims] The first step is to record video and audio on each track of the recording medium.
A device for reproducing audio from a recording medium on which signals are recorded by providing an area and a second area for recording only audio, which performs reproduction processing on reproduction signals from the first and second areas, and performs error correction. a determining means for comparing the error rate of the reproduced signal from the first area and the error rate of the reproduced signal from the second area, and according to the determination result of the determining means. , and selection means for selecting the audio signals output by the first and second reproduction processing means.