Still camera with time division recording of audio and video signals

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a still camera for coding and decoding image data and voice data with respect to a photographed image and recording and reproducing these data from a recording medium.

2. Description of the Related Art

When a photographing operation of such a still camera is continuously performed at a high speed, it is possible to obtain a reproduced image such as a moving picture. For example, an NTSC signal can be obtained if a field picture is recorded and telproduced every 1/60 second.

Accordingly, when the continuous photographing operation is performed to obtain a reproduced image such as a moving picture in the above still camera, it is desirable to perform a reproducing operation in addition to a voice which is not required so much in the case of a still picture. For example, Japanese Patent Application Laying Open (KOKAI) No. 2-280484 shows a camera for recording and reproducing a visual image and a voice. This camera can record a continuously photographed image and a continuously spoken voice.

In the above camera for recording and reproducing a visual image and a voice, it is necessary to dispose a processing circuit for recording an aural signal so that the camera is large-sized. Further, when there is no change in sound volume in accordance with purposes of utilization such as narration and back ground music (BGM), all voices are uniformed at a reproducing time of the camera so that it is hard to hear and understand these voices. Furthermore, an editing operation of the image and the voice is complicated when the image and the voice are simply recorded to a recording medium.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a still camera for preferably recording and reproducing a photographed image and a voice from a recording medium by a simplified structure.

In accordance with a first structure of the present invention, the above object can be achieved by a still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a voice to an electric signal; voice data coding means for coding voice data converted to the electric signal; means for recording the coded voice data to the recording medium; and means for sharing the image data coding means and the voice data coding means in time division.

In accordance with a second structure of the present invention, the image data coding means and the voice data coding means have a quantizing processing section of a discrete cosine transformation and a weight of each of frequency bands of a quantizing table can be changed in accordance with a voice mode set from the exterior of the camera.

In accordance with a third structure of the present invention, unit voice data can be recorded to a header portion of a still picture image file in the recording medium.

In accordance with a fourth structure of the present invention, the above object can be also achieved by a still camera comprising photographing means for photographing a photographed object and outputting image data; image data coding means for coding the image data; means for recording the coded image data to a recording medium; means for converting a voice an electric signal; voice data coding means for coding voice data converted to the electric signal; means for recording the coded voice data to the recording medium; and time divisional coding means for sharing portions of the image data coding means and the voice data coding means in time division; the time divisional coding means coding the image data for an effective image data period and coding the voice data for a vertical or horizontal blanking period.

In accordance with a fifth structure of the present invention, the voice data coding means has a memory for storing the voice data before coding for the effective image data period.

In accordance with a sixth structure of the present invention, an interrupt signal relative to the completion of coding processing of effective image data can be outputted from the image data coding means to central processing means.

In accordance with a seventh structure of the present invention, the image data coding means makes a quantizing table by scaling and calculating a basic quantizing table using a scale factor, and the central processing means can read the quantizing table.

In accordance with an eighth structure of the present invention, a sampling frequency of the voice in the converting means for converting this voice to an electric signal is set to an integer multiple of a frame frequency or a field frequency of an image.

In accordance with a ninth structure of the present invention, the above object can be also achieved by a still camera comprising means for reading coded image data out of a recording medium; image data decoding means for decoding the read image data; means for reading coded voice data out of the recording medium; voice data decoding means for decoding the read voice data; and time divisional decoding means for sharing portions of the image data decoding means and the voice data decoding means in time division; the time divisional decoding means decoding the image data for an effective image data period and decoding the voice data for a vertical or horizontal blanking period.

In accordance with a tenth structure of the present invention, the voice data coding means has a memory for storing the decoded voice data for the effective image data period.

In accordance with an eleventh structure of the present invention, an interrupt signal relative to the completion of decoding processing of effective image data can be outputted from the image data decoding means to central processing means.

As mentioned above, in the first structure of the still camera of the present invention, the image data coding means and the voice data coding means are shared in time division. Accordingly, image and voice data can be recorded to a recording medium so that the size of a circuit structure constituting the coding means, cost of the circuit structure and power consumption can be reduced.

In the second structure of the present invention, a weight of each of frequency bands of the quantizing table is changed so that voice recording frequency characteristics can be arbitrarily changed in accordance with purposes of uses and a voice can be recorded in a desirable state.

In the third structure of the present invention, unit voice data are recorded to a header portion of a still picture image file so that the synchronous relation between the image and voice data is held even when the image data are edited. Further, the image data are edited in conformity with a general still picture standard format.

In accordance with the fourth structure of the present invention, portions of the image data coding means and the voice data coding means are shared in time division. The image data are coded for an effective image data period. The voice data are coded for a vertical or horizontal blanking period. Accordingly, the time division can be efficiently made so that the still camera can be made compact and cheaply manufactured.

In accordance with the fifth structure of the present invention, the voice data coding means has a memory for storing the voice data before coding for the effective image data period. Accordingly, the voice data can be coded without losing the voice data for the effective image data period.

In accordance with the sixth structure of the present invention, the image data coding means transmits the completion of coding processing of effective image data to a CPU by using an interrupt signal. Accordingly, when the image data coding means is constructed by a variable length coding system, it is not necessary for the CPU to monitor the completion of image data coding at any time so that system performance can be improved.

In accordance with the seventh structure of the present invention, the image data coding means makes a quantizing table by scaling and calculating a basic quantizing table using a scale factor, and a microprocessor can read the quantizing table. Accordingly, when JPEG as a still picture coding international standard is used in an image data coding system and the scale factor is used to control a coding amount, it is not necessary to take time for calculating the quantizing table recorded to a JPEG file by the central processing unit (CPU) so that a moving picture can be recorded.

In the eighth structure of the present invention, a sampling frequency of a voice in the converting means for converting this voice to an electric signal is set to an integer multiple of a frame frequency or a field frequency of an image. Accordingly, for example, when the voice for a field period is recorded to a header region of the JPEG file, a unit recording period of the voice is equal to an integer multiple of that of the image so that the synchronous relation between the voice and the image is completely provided.

In the ninth structure of the present invention, portions of the image data decoding means and the voice data decoding means are shared in time division. The image data are decoded for an effective image data period and the voice data are decoded for a vertical or horizontal blanking period. The ninth structure commonly has image and voice decoding sections so that the construction of the decoding means is simplified and the time division is efficiently made and the still camera can be made compact and cheaply manufactured.

In the tenth structure of the present invention, the voice data coding means has a memory for storing the decoded voice data for the effective image data period. Accordingly, the voice data are held and normally outputted while the image data are decoded.

In the eleventh structure of the present invention, the completion of decoding processing of effective image data can be transmitted from the image data decoding means to the central processing unit by using an interrupt signal. Accordingly, when the image data coding means is constructed by a variable length coding system, it is not necessary for the CPU to monitor the completion of image data decoding at any time so that system performance can be improved.

Further objects and advantages of the :present invention will be apparent from the following description of the preferred embodiments of the present invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of a still camera in accordance with a first embodiment of the present invention;

FIG. 2 is a block diagram showing the construction of a data coding section;

FIG. 3 is a timing chart of time divisional processing of image data and voice data

FIG. 4 is a view for explaining a recording state of data in a memory card;

FIG. 5 is a block diagram showing the construction of a still camera in accordance with a second embodiment of the present invention;

FIG. 6 is a timing chart of time divisional processing of image data and voice data;

FIG. 7 is a timing chart of time divisional processing of image data and voice data; and

FIG. 8 is a view for explaining a recording state of data in a memory card.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of a still camera in the present invention will next be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the construction of a still camera in accordance with a first embodiment of the present invention. In FIG. 1, a known camera circuit 1 is constructed by a charge coupled device (CCD), etc. as a photographing means. A microphone 2 converts a voice to an electric signal. Each of reference numerals 3 and 4 designates an analog/digital (A/D) converting circuit. A data coding section 5 has an image data coding section 6 and a voice data coding section 7. A buffer random access memory (buffer RAM) 8 corresponding to one field time is disposed in the voice data coding section 7. An image memory 9 is disposed to store image data. A voice memory 10 is disposed to store voice data. A memory controller 11 is disposed to control operations of the image memory 9 and the voice memory 10.

An interface (I/F) circuit 12 is disposed to electrically connect a memory card 13 as a recording medium to each of constructional portions of the camera. An operating section 14 is disposed to set various kinds of operating modes of the camera. A liquid crystal display (LCD) 15 displays a set operating mode of the camera. A central processing unit (CPU) 16 controls operations of the above constructional pot t ions of the camera.

In FIG. 1, the data of a photographed image picked up by the charge coupled device (CCD) of the camera circuit 1 are converted to a digital signal by the A/D converting circuit 3 and are transmitted to the image data coding section 6. The image data are coded in the image data coding section 6 by a DCT system as a compression standard of a still picture and are stored to the image memory 9. The image memory 9 has a First-In First-Out (FIFO) structure so that the image data are sequentially recorded to the memory card 13 through the interface circuit 12.

The above processings are executed in real time in synchronization with each of synchronous signals outputted from an unillustrated synchronous signal generating circuit.

A voice is converted to an electric signal by the microphone 2 and is further converted to a digital signal by the A/D converting circuit 4. Voice data are coded by the voice data coding section 7 and are stored to the voice memory 10. The voice memory 10 also has a First-In First-Out (FIFO) structure so that the voice data are sequentially recorded to the memory card 13 through the interface circuit 12.

FIG. 2 is a block diagram showing the construction of the above data coding section 5. Reference numerals 20, 21 and 22 respectively designate a Forward DCT (FDCT) section, a quantizing section and a quantizing table. Reference numerals 23, 24 and 25 respectively designate a differential PCM (DPCM) section, a run length coding section 24 and a Huffman coding section.

In FIG. 2, image data and voice data are inputted to the quantizing section 21 through the FDCT section 20 and are quantized in this quantizing section 21 in accordance with the quantizing table 22 set from the above CPU 16. The quantized data are then Huffman-coded and outputted by the Huffman coding section 25 through the DPCM section 23 and the run length coding section 24.

FIG. 3 is a timing chart of time divisional processing of the image data and the voice data. The time divisional processing with respect to the voice data is performed for a vertical blanking period of the image data. The time divisional processing with respect to the image data is performed for a period except for the vertical blanking period. The above buffer RAM 8 is disposed in the voice data coding section 7 to perform this time divisional processing.

FIG. 4 is a view for explaining a recording state of data in the memory card 13. An upper portion of FIG. 4 shows an image file continuously photographed in real time. A lower portion of FIG. 4 shows the interior of a header portion of the image file.

In FIG. 4, only one image file of a still picture is provided at a normal photographing time of the camera. However, an image file F of a still picture is continuously recorded at a continuous photographing time of the camera. Compressed unit voice data corresponding to one field time (1/60 second) or one frame time (1/30 second) are inserted and recorded to the header portion H of the image file F. An amount of these voice data is very small in comparison with an amount of the image data.

Accordingly, the synchronous relation between the image data and the voice data is held even when the image data are edited. Further, the image data are easily edited in conformity with a general still picture standard format.

Quantization processing with respect to a discrete cosine transformation can be performed in the quantizing section 21 of the above data coding section 5. Further, a