JP2008176926A - Video sound recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a trouble where, when data is intermittently recorded by using a buffer memory in a video sound recording device, recording becomes impossible and a buffer overflows because of vibration of the device from the outside, the recorded data is discontinuous timewise resulting in incomplete reproduction of data. <P>SOLUTION: When overflowing occurs in a buffer, recording in a disk by video object units is finished. Since the recording is carried out by video object units, even when data whose recording is stopped due to buffer overflowing is reproduced, disturbance of a picture and mixing of noises in a voice are prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video / audio recording apparatus that records a video / audio digital signal on a recording medium, and more particularly to a video / audio recording apparatus that realizes continuous recording using a buffer memory.

  In the present invention, a video object is a series of video object units.

  A video object unit is an MPEG stream that can be played back independently of other video object units, includes at least one I picture, and, in addition, a group of pictures consisting of a plurality of P pictures or B pictures. (GOP).

  The video / audio recording apparatus converts video / audio input from a microphone, a CCD, or the like into a digital signal, and further compresses the signal such as MPEG to generate a compressed signal such as an MPEG stream. Then, the compressed signal is stored in a semiconductor memory, and the stored compressed signal is sequentially recorded on a recording medium such as a DVD-RAM by a disk drive such as a DVD drive.

  When recording on a recording medium, continuous compressed signals may be recorded in a plurality of areas on the recording medium. In this case, the recording operation is repeated while seeking between the areas. That is, continuous compressed signals are recorded intermittently.

  Here, the MPEG stream is temporarily stored in the semiconductor memory because the semiconductor memory functions as a buffer when the generation speed of the MPEG stream generated by the compression is higher than the recording speed for recording the MPEG stream on the recording medium. This is because recording is performed smoothly.

  However, the semiconductor memory has a certain maximum capacity and cannot store data exceeding the maximum capacity.

  Therefore, if the MPEG stream generation speed is much higher than the recording speed on the recording medium, or if the MPEG stream generation speed is higher than the recording speed on the recording medium, the buffer overflows. As a result, the newly generated MPEG stream may be discarded without being stored.

  Therefore, there arises a problem that the MPEG stream newly generated after the buffer overflow cannot be recorded on the recording medium.

  The case where the generation speed of the MPEG stream is higher than the recording speed on the recording medium can be considered as follows, for example.

  When a disk is used as a recording medium, the tracking of the pickup may be lost and recording may be interrupted by shaking or swinging the video / audio recording apparatus.

In such a state where recording is interrupted by vibration, the recording speed on the recording medium is zero, and therefore, the MPEG stream generation speed is higher than the recording speed on the recording medium. In particular, a portable device such as a video camera using a disk as a recording medium has a large problem because vibration and load on the device are large and frequently occur.

  Alternatively, in a portable device such as a video camera using a disk as a recording medium, it is necessary to use a battery as a power source. Therefore, in order to use the device for a long time, it is desirable that power consumption is small. Therefore, at the time of recording, only when the data is sufficiently accumulated in the buffer memory, the disk drive is driven to access the disk, and when the data is not sufficiently accumulated in the buffer memory, the drive of the disk drive or the like is stopped. Intermittent drive is performed.

  For example, accumulation of 25-second data and recording for 5 seconds are repeated as one cycle.

  However, there is a case where the disk cannot be accessed and recording cannot be performed due to vibration of the device.

  As described above, when intermittent driving is performed, since the state in which the recording speed on the recording medium is zero often continues for a long time, the problem of buffer overflow is significant.

  Further, when an MPEG stream is stored up to the maximum capacity of the buffer, the end of the stored MPEG stream does not always end in the form of a normally reproducible MPEG stream. That is, it does not always end in the form of a video object.

  For example, there is a possibility that a P picture necessary for generating a B picture near the end of the buffer data is not included in the buffer. In this case, there is a problem that even if an MPEG stream is reproduced, it is not normally reproduced.

  The present invention has been made in view of the above points, and an object of the present invention is to record an MPEG stream remaining in the buffer memory at the time of overflow in a video object unit when recording it on a recording medium. To provide a video / audio recording apparatus that can record video and audio input immediately before the overflow occurs in a continuously reproducible form on a recording medium in the event of an overflow. is there.

  Still another object of the present invention is to perform normal recording after the MPEG stream to be recorded on the recording medium is discontinuous in time due to overflow, after the recording to the recording medium is restored. It is an object of the present invention to provide a video / audio recording apparatus capable of eliminating the possibility of making a recording mistake without recognizing recording interruption due to overflow by automatically restarting.

  Still another object of the present invention is to re-compress the MPEG stream remaining in the buffer memory at the time of overflow at a higher compression rate, increase the free space of the buffer, and store the MPEG stream in the free buffer. An object of the present invention is to provide a video / audio recording apparatus capable of suppressing the amount of MPEG stream to be discarded.

  Still another object of the present invention is to avoid a buffer overflow by increasing the compression rate, decreasing the transfer rate, and suppressing the data increase rate in the buffer when the remaining amount of the buffer memory falls below a certain value. An object of the present invention is to provide a video / audio recording apparatus that can handle such a situation.

  Still another object of the present invention is to avoid the overflow of the buffer by increasing the compression rate step by step when the remaining amount of the buffer memory falls below a certain value, and to improve the image quality accompanying the sudden increase in the compression rate. An object of the present invention is to provide a video / audio recording apparatus capable of avoiding a sudden change in sound quality.

  Still another object of the present invention is to increase the compression rate when the remaining amount of the buffer memory falls below a certain value, reduce the transfer rate, and then reduce the compression rate when the remaining amount of the buffer memory again exceeds the certain value. A video / audio recording device that can avoid a buffer overflow and reduce the deterioration of image quality and sound quality in a short time by returning the normal compression rate to the normal transfer rate. It is to provide.

  Still another object of the present invention is to increase the compression rate when the remaining amount of the buffer memory falls below a certain value, reduce the transfer rate, and then step by step if the remaining amount of the buffer memory again exceeds the certain value. The audio / video recording can return to the normal compression rate and return the transfer rate to the normal transfer rate, thereby avoiding buffer overflows and avoiding sudden changes in image quality and sound quality due to sudden reductions in compression rate. It is to provide equipment.

  The video / audio recording apparatus according to the first aspect of the present invention comprises a video / audio input means, a conversion means, a compression means, a storage means, an arithmetic processing means, and a recording means, and the video / audio input from the video / audio input means. Is converted into a digital signal by the conversion means, the digital signal is compressed by the compression means, the compressed digital signal is stored in the storage means, and the digital signal stored in the storage means is recorded on the recording medium by the recording means In the recording apparatus, when the digital signal is stored up to the maximum storage capacity of the storage means, the recording is ended in units of video objects.

  The video / audio recording apparatus according to the second aspect of the present invention is the video / audio recording apparatus according to the first aspect of the present invention, wherein the video / audio is continuously input from the video / audio input means and the digital signal is stored up to the maximum storage capacity of the storage means. In this case, the recording is finished in units of video objects, and the recording of new video objects is started.

  A video / audio recording apparatus according to a third aspect of the present invention includes a video / audio input means, a conversion means, a compression means, a storage means, an arithmetic processing means, and a recording means, and the video / audio input from the video / audio input means. Is converted into a digital signal by the conversion means, the digital signal is compressed by the compression means, the compressed digital signal is stored in the storage means, and the digital signal stored in the storage means is intermittently recorded on the recording medium by the recording means In the video / audio recording apparatus, the transfer rate of the compression means is reduced when the data amount of the digital signal accumulated in the storage means exceeds a certain value.

  A video / audio recording apparatus according to a fourth aspect of the present invention is the video / audio recording apparatus according to the third aspect of the present invention, wherein the transfer rate of the compression means is stepped when the data amount of the digital signal accumulated in the storage means exceeds a certain value. It was made to decrease in number.

  The video / audio recording apparatus according to the fifth aspect of the present invention is the video / audio recording apparatus according to the third aspect of the present invention, wherein the transfer rate of the compression means is increased when the data amount of the digital signal stored in the storage means falls below a certain value. It was made to let you.

  The video / audio recording apparatus of the sixth aspect of the present invention is the video / audio recording apparatus of the third aspect of the present invention, wherein the transfer rate of the compression means is stepped when the data amount of the digital signal accumulated in the storage means falls below a certain value. It is intended to increase it.

  The video / audio recording apparatus according to the seventh aspect of the present invention is the video / audio recording apparatus according to the third aspect of the present invention, wherein the compression stored in the storage means when the data amount of the digital signal stored in the storage means exceeds a certain value. The signal is read out and compressed at a higher compression rate by the compression means.

  According to the present invention, when the MPEG stream remaining in the buffer memory at the time of overflow is recorded on the recording medium, the recording is ended in units of video objects. Thus, it is possible to record the video and audio input to the recording medium in a continuously reproducible form.

  Also, even when the MPEG stream recorded on the recording medium becomes discontinuous due to overflow, normal recording is automatically resumed after the recording to the recording medium is restored. Therefore, there is an effect that it is possible to eliminate the possibility that the user does not notice the recording interruption due to the overflow and makes a recording mistake.

  Further, when the remaining amount of the buffer memory falls below a certain value, the compression rate is increased, the transfer rate is decreased, and the data increase rate in the buffer is suppressed, so that the buffer overflow can be avoided.

  In addition, when the remaining capacity of the buffer memory falls below a certain value, the compression rate is increased stepwise and the transfer rate is decreased stepwise, thus avoiding buffer overflow and increasing the compression rate rapidly. It is possible to avoid a sudden change in image quality and sound quality associated with.

  In addition, when the remaining amount of buffer memory falls below a certain value, the compression rate is increased and the transfer rate is reduced.After that, when the remaining amount of buffer memory again exceeds a certain value, the compression rate is returned to the normal compression rate. Since the transfer rate is returned to the normal transfer rate, the buffer overflow can be avoided and the state where the image quality and sound quality are deteriorated can be suppressed in a short time.

  Also, if the remaining amount of buffer memory falls below a certain value, the compression rate is increased and the transfer rate is decreased.If the remaining amount of buffer memory again exceeds a certain value, the normal compression rate is gradually restored. Since the normal transfer rate is gradually returned, it is possible to avoid the overflow of the buffer and to avoid the sudden change in the image quality and the sound quality due to the sudden decrease in the compression rate.

  In addition, the MPEG stream remaining in the buffer memory at the time of overflow is recompressed at a higher compression rate, the buffer free space is increased, and the MPEG stream is stored in the free buffer. Therefore, there is an effect that the amount of the MPEG stream discarded because it is not present can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram showing a basic configuration of a video / audio recording apparatus according to a first embodiment of the present invention.

  In FIG. 1, 100 is a microphone, 101 is a CCD, 102 is an ADC, 103 is a DSP, 104 is a CODEC, 105 is a RAM, 106 is a CPU, and 107 is a disk drive. Part.

  The microphone 100 inputs sound and converts it into an electric signal. The CCD 101 receives an image and converts it into an electrical signal. The ADC 102 converts the input analog electric signal into a digital signal and outputs the digital signal. The DSP 103 processes the input analog electric signal, converts it into a digital signal, and outputs it. The CODEC 104 performs signal compression processing on the input digital signal and outputs compressed data. In the compression process, data is stored in the RAM 105 described below. The RAM 105 is a semiconductor memory and stores data. The CPU 106 performs a calculation process on the input data and outputs the calculated data. The disk drive unit 107 has a pickup and a disk drive unit, and records digital data on a storage medium such as a DVD-RAM.

  A normal recording operation and a recording operation when the RAM 105 overflows will be described with reference to FIG.

  FIG. 2 shows changes in the data amount of the RAM 105 during recording (FIG. 2-1) and the transfer rate at which the CODEC 104 transfers data to the RAM 105 (FIG. 2-2) in the video / audio recording apparatus according to the first embodiment of the present invention. ).

  The time from 2a to 2h is taken on the time axis.

  Up to 2c is a normal recording operation, and no data is transferred to the recording medium up to 2a, so that data is stored in the RAM 105. At 2a, the amount of data in the RAM 105 reaches a certain threshold value, and data transfer to the disk is started. The disk drive unit 107 accesses the recording medium between 2a and 2b, transfers data from the RAM 105 to the disk, and performs recording. As a result, the amount of data in the RAM 105 decreases.

  The operation after 2c is performed when vibration is applied. 2b to 2d are the same as 2a, but since the vibration is applied after 2c, the disk drive unit 107 cannot access the disk. Therefore, the data amount in the RAM 105 exceeds the threshold between 2c and 2d. At 2d, the data amount of the RAM 105 reaches the maximum value, and thereafter, data cannot be input to the RAM 105, and the data generated by the CODEC 104 is exhausted.

  When the vibration is reduced in 2e, the disk drive unit 107 can access the recording medium, and transfers data from the RAM 105 to the disk for recording. At the same time, since there is a free space in the RAM 105, data input to the RAM 105 is resumed. Recording ends once in 2f, and thereafter normal recording operation is performed.

  When the buffer overflows in 2d, the data stored in the RAM 105 is edited to form a VOB (video object).

  That is, the end of the data stored in the RAM 105 is cut in units of GOPs, and the data is recorded and reproduced so that it can be reproduced normally.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 1, 3, 4 and 5.

  FIG. 1 is a diagram showing a basic configuration of a video / audio recording apparatus according to a second embodiment of the present invention, which is the same as the basic configuration of the video / audio recording apparatus according to the first embodiment of the present invention. To do.

  An operation for controlling the transfer rate so that the RAM 105 does not overflow will be described with reference to FIGS. 3, 4, and 5.

  FIG. 3 shows the transition of the data amount of the RAM 105 during recording (FIG. 3-1) and the transfer rate at which the CODEC 104 transfers data to the RAM 105 (FIG. 3-2) in the video / audio recording apparatus of the second embodiment of the present invention. ) And the operation state (FIG. 3-3).

  Up to 3b is a normal recording operation.

  Consider a case where vibration is applied to the apparatus from 3a and before 3b and vibration continues until 3f.

  Due to this vibration, even if the data amount of the RAM 105 reaches the threshold value in 3b, it cannot be recorded on the disk. Therefore, the transfer rate is decreased by 20% of the normal rate in four stages from 3b to 3c, 3c to 3d, 3d to 3e, and 3e. Therefore, the CODEC 104 increases the compression rate stepwise. As a result, there is an effect that it is possible to extend the data discontinuity at 3B to 3C. Further, by changing the transfer rate in stages, there is an effect that it is possible to avoid that the quality of the reproduced video and the sound quality of the sound are rapidly deteriorated and the change is anxious.

  When the vibration stops at 3f, the disk drive unit 107 can access the recording medium and resumes recording data in the RAM 105. Therefore, the data amount in the RAM 105 decreases (from 3f to 3g).

From 3g onwards, 3b to 3h, 3h to 3i, 3i to 3j, and 3j to 3k, the transfer rate is gradually increased by 20% each time, and the reproduced video and audio are gradually reproduced. To return to normal level. This has the same effect as when the transfer rate is reduced.

  FIG. 4 is a flowchart showing the operation of controlling the transfer rate so that the RAM 105 does not overflow in the video / audio recording apparatus according to the second embodiment of the present invention.

  Ordinary recording starts when the data amount B of the RAM 105 first increases. When B exceeds the threshold Bt (S401), it is diagnosed whether the disk drive unit 107 can access the disk (S402). If recording is possible, data is transferred from the RAM 105 until there is no more data in the RAM 105 (S404). Writing to the recording medium (S 403), and after the writing is completed, accumulation of data in the RAM 105 is started again. If recording is impossible (S402), the transfer rate is changed (S405). When the data amount B in the RAM 105 exceeds the maximum data capacity Bm of the RAM 105 (S406), data input to the RAM 105 becomes impossible and the recording ends.

  FIG. 5 is a flowchart showing an example of an algorithm for reducing the transfer rate in the video / audio recording apparatus according to the second embodiment of the present invention.

  The time point 3b is T = 0, the time point 3c is T = T1, the time point 3d is T = T2, and the time point 3e is T = T3. The transfer rate R at time T is set to R = R1 between 3b and 3c, R = R2 between 3c and 3d, R = R3 between 3d and 3e, and R = R4 after 3e.

  If T> T3 (S501), R is not changed. If T> T3 is not satisfied (S501), it is determined whether T> T2. If T> T2 (S502), R is changed to R3 (S504, D507). If T> T2 is not satisfied (S502), T> T1 is determined. If T> T1 (S503), R is changed to R2 (S505, D508). If T> T1 is not satisfied (S503), R is changed to R1 (S506, D509).

  Although not illustrated in the figure, a method of changing the transfer rate linearly instead of changing the transfer rate in four stages is also conceivable. In this case, there is an effect that the quality change of the reproduced video and audio due to the change of the transfer rate becomes smoother and the change is not anxious.

1 is a block diagram showing a basic configuration of a video / audio recording apparatus according to a first embodiment of the present invention. In the video / audio recording apparatus according to the first embodiment of the present invention, the transition of the data amount of the RAM 105 during recording (FIG. 2-1) and the transfer rate (FIG. 2-2) at which the CODEC 104 transfers data to the RAM 105 are shown. It is a figure. In the video / audio recording apparatus according to the second embodiment of the present invention, the transition of the data amount of the RAM 105 at the time of recording (FIG. 3-1), the transfer rate at which the CODEC 104 transfers data to the RAM 105 (FIG. 3-2), and the operation It is the figure which showed the state (FIG. 3-3). 6 is a flowchart showing an operation of controlling a transfer rate so that a RAM 105 does not overflow in the video / audio recording apparatus according to the second embodiment of the present invention. It is the flowchart which showed an example of the algorithm which changes a transfer rate in the audiovisual recording apparatus concerning the 2nd Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Microphone, 101 ... CCD, 102 ... ADC, 103 ... DSP, 104 ... CODEC, 105 ... RAM, 106 ... CPU, 107 ... Disk drive part

Claims (7)

Video / audio input means for inputting video / audio, conversion means for converting video / audio to digital signals, compression means for compressing digital signals, storage means for storing digital signals, arithmetic processing means for performing arithmetic processing, Recording means for recording a digital signal on a recording medium, the video / audio input from the video / audio input means is converted into a digital signal by the conversion means, the digital signal is compressed by the compression means, and the compressed digital In a video / audio recording apparatus in which a signal is stored in the storage means and a digital signal stored in the storage means is intermittently recorded on a recording medium by the recording means, video / audio is continuously input from the video / audio input means. When the digital signal is stored up to the maximum storage capacity of the storage means, the video / audio recording apparatus ends recording in units of video objects.   2. The video / audio recording apparatus according to claim 1, wherein video / audio is continuously input from the video / audio input means, and when a digital signal is stored up to a maximum storage capacity of the storage means, recording is performed in units of video objects. A video / audio recording apparatus characterized in that it ends and starts recording a new video object. Video / audio input means for inputting video / audio, conversion means for converting video / audio to digital signals, compression means for compressing digital signals, storage means for storing digital signals, arithmetic processing means for performing arithmetic processing, Recording means for recording a digital signal on a recording medium, the video / audio input from the video / audio input means is converted into a digital signal by the conversion means, the digital signal is compressed by the compression means, and the compressed digital In a video / audio recording apparatus in which a signal is stored in the storage unit and the digital signal stored in the storage unit is intermittently recorded on a recording medium by the recording unit, the data amount of the digital signal stored in the storage unit is a constant value The video / audio recording apparatus is characterized in that the transfer rate of the compression means is reduced when the value exceeds.   4. The video / audio recording apparatus according to claim 3, wherein when the data amount of the digital signal stored in the storage means exceeds a certain value, the transfer rate of the compression means is reduced stepwise. Audio recording device.   4. The video / audio recording apparatus according to claim 3, wherein the transfer rate of the compression means is increased when the data amount of the digital signal stored in the storage means falls below a certain value. .   4. The video / audio recording apparatus according to claim 3, wherein when the data amount of the digital signal stored in the storage means falls below a certain value, the transfer rate of the compression means is increased stepwise. Audio recording device.   4. The video / audio recording apparatus according to claim 3, wherein when the data amount of the digital signal stored in the storage unit exceeds a predetermined value, the compressed signal stored in the storage unit is read out and further increased by the compression unit. A video / audio recording apparatus that compresses at a compression rate.

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