JP2010068028A - Electronic camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: in a conventional moving picture photographic, settings of sound processing mode are fixed without depending upon the frame rate of a moving picture to be recorded, and the capacity of a moving picture file is not taken into consideration. <P>SOLUTION: An electronic camera 101 includes a moving picture photographing part which photographs a moving picture at a predetermined frame rate, a sound acquiring part which converts a sound input during the photography of the moving picture by the moving picture photographing part into a digital signal with predetermined settings, and a control part which varies the settings for the conversion of the sound into the digital signal by the sound acquiring part according to the frame rate of the moving picture photographed by the moving picture photographing part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic camera that records moving images and sound.

Electronic cameras that record moving images and audio are widely used. Such an electronic camera can select a shooting mode (image size and frame rate) when shooting a moving image, but the audio recording method is often the same. In view of this, there has been considered an electronic camera that can perform a plurality of recording settings corresponding to various moving image shooting scenes such as concert shooting, conference shooting, and landscape shooting (see, for example, Patent Document 1).
JP 2006-217111 A

  However, in the conventional technology, it is possible to record audio suitable for various movie shooting scenes by selecting the recording setting corresponding to the shooting mode, but considering the file capacity when recording moving images and audio on the recording medium It was not what I did. Alternatively, it is necessary to manually change the recording setting when recording audio.

  An object of the present invention is to provide an electronic camera capable of reducing a file capacity to be recorded in accordance with a frame rate of a moving image to be shot in an electronic camera that records a moving image and sound.

  An electronic camera according to the present invention includes a moving image capturing unit that captures a moving image at a predetermined frame rate, and an audio acquisition unit that converts audio input during capturing of the moving image to the digital signal with a predetermined setting by the moving image capturing unit. And a control unit that changes a setting when the sound acquisition unit converts the sound into a digital signal according to a frame rate of a moving image captured by the moving image capturing unit.

  Preferably, the control unit varies at least one of a sampling rate and a quantization bit number of audio converted into a digital signal by the audio acquisition unit according to a frame rate of a moving image shot by the moving image shooting unit. It is characterized by doing.

  Preferably, when the frame rate of the moving image is low, the control unit selects at least one of a low sampling rate and a small number of quantization bits when the sound acquisition unit converts the sound into a digital signal. When the frame rate of the moving image is high, at least one of a high sampling rate or a large number of quantization bits is selected when the sound acquisition unit converts the sound into a digital signal. .

  Preferably, when the frame rate of the moving image is low, the control unit performs control or quantization bit number lower than the current value of the sampling rate when the sound acquisition unit converts the sound into a digital signal. When the frame rate of the moving image is high, control is performed to increase the sampling rate to be higher than the current value of the sampling rate when converting the audio into a digital signal. Alternatively, at least one control of increasing the number of quantization bits from the current value is performed.

  Preferably, the relationship between the setting of the frame rate of the moving image captured by the moving image capturing unit and the setting of at least one of the sampling rate and the number of quantization bits of the audio converted into a digital signal by the audio acquisition unit is shown. A table is provided, and the control unit sets at least one of an audio sampling rate and a quantization bit number corresponding to a moving image frame rate with reference to the table.

  Preferably, the table includes an image priority mode table that prioritizes a frame rate of a moving image and an audio priority mode table that prioritizes sound quality, and the image priority mode table or the audio priority mode A selection means for selecting a table is further provided.

  According to the present invention, in an electronic camera that records moving images and audio, at least one of the audio sampling rate and the number of quantization bits is automatically changed according to the frame rate of the moving images. The capacity of the moving image file to be recorded can be reduced according to the frame rate.

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

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of an electronic camera 101 according to the first embodiment. Note that the electronic camera 101 according to the present embodiment has a moving image shooting mode in which a moving image and sound are simultaneously recorded.

  In FIG. 1, an electronic camera 101 includes a photographing optical system 102, an image sensor 103, an AFE (analog front end) 104, a buffer memory 105, an image processing unit 106, a system bus 107, a flash memory 108, CPU 109, recording IF 110, monitor drive unit 111, liquid crystal monitor 112, operation unit 113, TG (timing generator) 114, microphone 115, audio input unit 116, A / D conversion unit 117, audio And a processing unit 118.

  Light incident from the subject is imaged on the light receiving surface of the image sensor 103 via the photographing optical system 102.

  A photoelectric conversion unit is two-dimensionally arranged on the light receiving surface of the image sensor 103, converts the imaged light into an electrical signal, and outputs it to the AFE 104.

  The AFE 104 performs A / D conversion after performing noise removal and amplification of the electrical signal output from the image sensor 103. The A / D converted digital image data is temporarily stored in the buffer memory 105.

  The image processing unit 106 performs white balance processing and color interpolation processing on the image data temporarily stored in the buffer memory 105, and compression processing of the image data according to the JPEG standard, and the like as a captured image via the system bus 107. The data is stored in the memory card 110b connected to the recording I / F 110. Note that the image data may be stored in the flash memory 108.

  The image data stored in the memory card 110 b connected to the recording I / F 110 is read according to a command from the CPU 109 and an image is displayed on the liquid crystal monitor 112 via the monitor driving unit 111.

  On the liquid crystal monitor 112, for example, in a still image shooting mode, when a preview image captured continuously in time by the image sensor 103 or a release button 202 (see FIG. 2 described later) of the operation unit 113 is pressed. A still image (main image) actually captured by the image sensor 103 is displayed. Alternatively, in the moving image shooting mode, a moving image captured continuously in time at a predetermined resolution and frame rate preset by the image sensor 103 is displayed on the liquid crystal monitor 112. When the electronic camera 101 is set to the moving image shooting mode, moving image shooting starts when the release button 202 of the operation unit 113 is pressed, and moving image shooting ends when the release button 202 is pressed again.

  Here, each image is defined. The preview image is an image that is sequentially and sequentially photographed by the image sensor 103 in order to determine a photographing composition or the like when photographing a still image or a moving image. The main image is a still image captured by the image sensor 103 when the release button 202 is pressed. A moving image is a series of images taken continuously in time at a predetermined resolution and a predetermined frame rate.

  The flash memory 108 stores setting values such as the shooting mode and shooting conditions of the electronic camera 101. Also, various parameters when the CPU 109 performs processing are stored, and the stored contents are updated according to the operation of the CPU 109. In particular, in this embodiment, the frame rate at the time of moving image shooting, the sampling rate of the audio signal, the number of quantization bits, and the like are stored in advance according to the moving image shooting mode. Note that these settings can be changed by the user operating the operation member 114.

  The CPU 109 is a processor that operates according to a program stored in advance inside and controls the electronic camera 101 in an integrated manner.

  2, the operation unit 113 includes a power button 201, a release button 202, a zoom button 203, a cross key 204 (up key 204a, down key 204b, left key 204c, and right key 204d. ), A confirmation button 205 and the like. The user operates the electronic camera 101 by operating these operation buttons. In addition, operation information of these operation buttons is output to the CPU 109. The CPU 109 controls the overall operation of the electronic camera 101 in accordance with operation information input from the operation unit 113.

  The TG 114 outputs a timing signal to the image sensor 103 and the AFE 104 in accordance with an instruction from the CPU 109. For example, when capturing a through image, a timing signal for reading out an image signal corresponding to the resolution of the through image is output from the image sensor 103. Further, at the time of photographing the main image, a timing signal for reading out an image signal corresponding to the resolution of the main image is output from the image sensor 103. Further, at the time of shooting a moving image, a timing signal for reading out an image signal is output from the image sensor 103 in accordance with the resolution and frame rate of the moving image.

  Next, a configuration for performing voice input in the electronic camera 101 will be described. In the moving image shooting mode, an audio signal is captured at the same time as time-lapse moving image shooting as described above. In FIG. 1, an analog audio signal input from a microphone 115 is amplified by an audio input unit 116 and converted into digital audio data by an A / D conversion unit 117. The audio data output from the A / D conversion unit 117 is temporarily stored in the buffer memory 105. Then, the audio processing unit 118 performs audio compression or the like by a predetermined method, and the image data is stored in the memory card 110b connected to the recording I / F 110 as a predetermined moving image file. Note that audio data and moving image files may be stored in the flash memory 108.

<Operation of Electronic Camera 101>
Next, the operation of the electronic camera 101 in the moving image shooting mode will be described. As shown in FIG. 3, the electronic camera 101 according to the present embodiment has three moving image modes: a moving image mode A, a moving image mode B, and a moving image mode C. In the present embodiment, in the moving image mode A, the moving image frame rate is set to 60 fps (frames / second), the audio sampling rate is set to 44.1 kHz, and the quantization bit number is set to 16 bits. In the moving image mode B, the frame rate of the moving image is set to 30 fps, the audio sampling rate is set to 22.05 kHz, and the quantization bit number is set to 12 bits. Furthermore, in the moving image mode C, the moving image frame rate is set to 15 fps, the audio sampling rate is set to 11.05 kHz, and the quantization bit number is set to 8 bits. These settings are stored in advance in the flash memory 108.

  Also, the number of pixels of the moving image set in FIG. 3 may be fixed (640 × 480 pixels) regardless of the type of moving image mode, as shown in FIG. 4A, for example. As shown in (b), it may be changed depending on the type of moving image mode. For example, in the case of FIG. 4B, the number of pixels is three types: (640 × 480 pixels) in moving image mode A, (320 × 240 pixels) in moving image mode B, and (160 × 120 pixels) in moving image mode C. Composed.

  Alternatively, as shown in FIG. 5A, the audio sampling rate may be fixed at 22.05 kHz and only the number of quantization bits may be changed regardless of the type of moving image mode. As shown in the figure, regardless of the type of moving image mode, only the sampling rate may be changed by fixing the number of audio quantization bits to 16 bits.

  Note that these audio processing settings stored in advance in the flash memory 108 can be arbitrarily changed by the user in the setting menu. For example, in the audio processing setting menu shown in FIG. 6A, the “sampling rate” and “quantization bit” of the audio input corresponding to the three moving image modes of moving image mode A, moving image mode B, and moving image mode C. The current setting value of “Number” is displayed. The user can input either the sampling rate values 251, 252, and 253 items for each moving image mode, the quantization bit number 254, 255, or 256 items, or the “OK” button 257 or the “cancel” button 258 to the operation unit 113. The cross key 204 included is selected by operating. At this time, the selected items and buttons are displayed with a thick frame, and the user can know which part is selected. When the confirm button 205 included in the operation unit 113 is pressed, the selection of the selected item or button is confirmed. For example, when it is desired to change the audio sampling rate of the moving image mode A in FIG. 6A, the item of the audio sampling rate “44.1 kHz” of the moving image mode A is changed to the cross key 204 (up key 204a, down key 204b, left The key 204c and the right key 204d) are operated and selected, and the confirm button 205 is pressed. When the confirm button 205 is pressed, candidate values for the audio sampling rate in the moving image mode A are displayed in a pull-down menu as shown in FIG. The user selects a sampling rate to be set from the pull-down menu candidate values by operating the upper key 204a and the lower key 204b of the cross key 204, and presses the confirm button 205. For example, when “11.025 kHz” in the pull-down menu is selected and the confirm button 205 is pressed, the audio sampling rate in the moving image mode A is displayed as 11.025 kHz as shown in FIG. If the displayed content is OK, the “OK” button 257 is selected with the cross key 204 and the confirm button 205 is pressed. When canceling the changed setting contents and ending, select the “Cancel” button 258 with the cross key 204 and press the confirm button 205. In the case of cancellation, the setting value before the change is applied. Further, the setting of the number of quantization bits can be changed by the same operation. Further, the setting of the sampling rate and the setting of the number of quantization bits in the moving image mode B and the moving image mode C can be similarly changed.

  Here, the capacity of the moving image file stored in the memory card 110b connected to the recording I / F 110 will be described. For example, in FIG. 7A, the settings of audio processing are the same in the three moving image modes A, B, and C (sampling rate: 44.1 kHz, quantization bit number: 16 bits), and the moving image frame rate is different (60 fps). , 30 fps, 15 fps). In FIG. 7A, the image data and audio data indicate the ratio of the data capacity when moving images are captured during the same period (for example, 5 minutes). Accordingly, since the audio processing settings are the same, the volume of audio data is constant regardless of the type of moving image mode, but the volume of image data varies depending on the frame rate, and the image data for the entire capacity of the moving image file Data and audio data also change in proportion.

  For example, in the moving image mode A, since the frame rate of the moving image is as high as 60 fps, the capacity of the image data is large, and the ratio of the image data to the audio data is large. In the moving image mode B, since the frame rate of the moving image is lowered to 30 fps, the ratio of the image data to the audio data is smaller than that in the moving image mode A. Further, in the moving image mode C, the frame rate of the moving image is reduced to 15 fps, so the ratio of the image data to the audio data is smaller than that in the moving image mode B.

  Here, as shown in FIG. 7A, even when the frame rate of the moving image is changed, if the setting of the audio processing is the same, the ratio of the audio data to the entire moving image file increases, and the frame of the moving image is increased. Even if an attempt is made to reduce the rate of the entire moving image file by lowering the rate, the volume of the audio data does not change, so that there is a problem that the effect of reducing the entire moving image file is reduced.

  Therefore, in the present embodiment, as shown in FIG. 7B, the moving image file is recorded by changing the audio processing setting according to the frame rate of the moving image. For example, when the frame rate of the moving image is 60 fps, the audio sampling rate is 44.1 kHz and the number of quantization bits is 16 bits. When the frame rate of the moving image is 30 fps, the audio sampling rate is 22.05 kHz, When the number of quantization bits is 12 bits, and the frame rate of the moving image is 15 fps, the audio sampling rate is 11.025 kHz and the number of quantization bits is 8 bits. As a result, as shown in FIG. 7B, as the frame rate of the moving image becomes lower (the image file size becomes smaller), the audio file size also becomes smaller, and the image becomes larger than the entire moving image file size. The file capacity of data and audio data can be maintained in a well-balanced manner, and the effect of reducing the file capacity of the moving image itself is increased. That is, it is possible to record a moving image for a long time. In general, when a user reduces the frame rate of a moving image, the user often wants to record for a long time. However, since the audio processing settings (sampling rate and the number of quantization bits) are the same regardless of the moving image frame rate, the volume of the audio data is the same. On the other hand, in the present embodiment, when the frame rate of the moving image is lowered, the setting of the audio processing is changed (at least one setting of lowering the sampling rate or decreasing the number of quantization bits is set. Change), the capacity of the moving image file is reduced, so that recording can be performed for a long time. In the present embodiment, for example, the motion JPEG standard is assumed as the format of the moving image file.

  Next, a flowchart at the time of moving image shooting by the electronic camera 101 according to the present embodiment will be described with reference to FIG. The flowchart of FIG. 8 operates according to a program incorporated in the CPU 109 in advance. Note that the photographer presses the power button 201 of the imaging apparatus 101 to turn on the power before the process of step S101. As described above, the CPU 109 displays a preview of the image captured by the image sensor 103 via the imaging optical system 102 on the liquid crystal monitor 112. The photographer confirms the subject to be photographed while viewing the preview display. Further, it is assumed that the electronic camera 101 is set to the moving image shooting mode, and the audio processing setting for each moving image mode is stored in advance in the flash memory 108 as described with reference to FIG. Hereinafter, the processing will be described in order from the processing in which the photographer presses the release button 202 and starts the moving image shooting processing.

  (Step S101) When the photographer presses the release button 202, the moving image photographing process is started.

  (Step S102) The CPU 109 refers to the setting contents stored in the flash memory 108 and sets the frame rate of the moving image according to the moving image mode. For example, when the moving image mode A is set, the TG 114 is instructed so that the frame rate is 60 fps, and timing control is performed when the imaging element 103 and the AFE 104 capture a subject.

  (Step S103) The CPU 109 refers to the setting content (table) stored in the flash memory 108, and reads out the audio processing setting content corresponding to the frame rate of the moving image. For example, when the table of FIG. 3 is stored in the flash memory 108 and in the moving image mode A, it can be seen that the sampling rate of audio processing is 44.1 kHz and the number of quantization bits is 16 bits.

  (Step S104) The CPU 109 sets the sampling rate and the number of quantization bits of the audio processing read from the flash memory 108. Specifically, the A / D converter 117 is instructed to convert an analog audio signal into digital data at the audio processing sampling rate and the number of quantization bits.

  (Step S105) The CPU 109 starts moving image recording. In other words, the moving image captured by the image sensor 103 and the audio signal input from the microphone 115 have the predetermined frame rate, the number of pixels, the sampling rate, and the number of quantization bits, respectively, as described above. Data is converted into data and recording is started as a moving image file in the memory card 110b connected to the recording I / F 110. Note that the moving image file may be stored in the flash memory 108.

  (Step S106) The CPU 109 determines whether or not to finish moving image shooting. That is, it is determined whether or not the user has pressed the release button 202 again. If the release button 202 has been pressed, the process proceeds to step S107 to end the moving image shooting. If the release button 202 has not been pressed, the process returns to step S105 to continue moving image shooting.

  (Step S107) The CPU 109 ends the shooting of the moving image. That is, the moving image file recorded on the memory card 110b connected to the recording I / F 110 is closed, and the moving image shooting ends.

  As described above, the electronic camera 101 according to the present embodiment automatically sets at least one of the audio sampling rate and the number of quantization bits according to the frame rate of the moving image in the moving image shooting mode for recording the moving image and the sound. Since it varies, the file capacity to be recorded can be reduced according to the frame rate of the moving image to be shot.

  In particular, when the frame rate of the moving image is low, when the audio signal is converted into a digital signal by the A / D conversion unit 117, at least one of a low sampling rate and a small number of quantization bits is performed. Is fast, when the A / D converter 117 converts the sound into a digital signal, at least one of a high sampling rate or a large number of quantization bits is used. When the quality of the moving image is low and the quality of the moving image is low, the sound quality is also low and recorded. Therefore, the capacity of the moving image file can be efficiently reduced without giving the user a sense of incongruity.

  In this embodiment, only one table showing the relationship between the setting of the frame rate of the moving image and the setting of the sampling rate and the number of quantization bits of the audio processing is provided. A plurality of tables such as a priority mode table and a voice priority mode table that prioritizes sound quality may be provided. In this case, an image priority mode table or an audio priority mode table is selected in advance in the setting menu of the electronic camera 101, and the selection contents are stored in the flash memory 108. For example, in the case of the image priority mode, at least one setting of a sampling rate or a smaller number of quantization bits than the audio processing setting shown in FIG. 3 is set. FIG. 9A shows an example of the image priority mode table. In FIG. 9A, compared with the table of FIG. 3, for example, the audio sampling rate in the moving image mode A is changed from 44.1 kHz to 22.05 kHz, and the number of quantization bits is changed from 16 bits to 12 bits. Even a moving image file can be recorded for a long time without degrading image quality. FIG. 9B shows an example of a voice priority mode table. In FIG. 9B, compared with the table of FIG. 3, for example, the audio sampling rate in the moving image mode B is changed from 22.05 kHz to 44.1 kHz, and the quantization bit number is changed from 12 bits to 16 bits. Even when the frame rate of the image is slow, recording can be performed without reducing the sound quality, which is effective when recording a concert or the like. In this way, the user can set the audio processing suitable for each application only by selecting the image priority mode or the audio priority mode, and the user does not need to understand complicated parameters of the audio processing. .

  In the present embodiment, at least one of the sampling rate of the audio processing and the number of quantization bits is changed according to the frame rate of the moving image, but the audio compression method and the audio compression rate may be changed. I do not care.

  Furthermore, in the present embodiment, the moving image frame rate is fixed to 60 fps or the like during moving image shooting. However, in the case of a shooting mode in which the moving image frame rate changes during moving image shooting, the moving image changes. The audio processing setting may be automatically changed according to the frame rate of the image. In this case, when the frame rate of the moving image becomes slow, at least one of the control for lowering the sampling rate of the A / D converter 117 below the current value or the control for reducing the number of quantization bits below the current value is performed. When the frame rate of the moving image increases, at least one of control for increasing the sampling rate of the A / D converter 117 higher than the current value or control for increasing the number of quantization bits higher than the current value is performed. As a result, since the audio processing setting is appropriately changed according to the frame rate of the moving image, the capacity of the moving image file can be reduced more efficiently.

1 is a block diagram of an electronic camera 101 according to a first embodiment. 2 is an explanatory diagram showing an external appearance of an electronic camera 101. FIG. It is explanatory drawing which shows the setting example 1 of the frame rate and audio | voice process of a moving image. It is explanatory drawing which shows the setting example 2 of the frame rate and audio | voice process of a moving image. It is explanatory drawing which shows the example 3 of a setting of the frame rate of a moving image and audio | voice processing. It is explanatory drawing which shows the example of a sound processing setting menu. It is explanatory drawing which shows a moving image file capacity | capacitance. It is a flowchart which shows the process of moving image shooting mode. It is explanatory drawing which shows the example of a table of image priority mode and audio | voice priority mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Electronic camera 102 ... Shooting optical system 103 ... Image pick-up element 104 ... AFE
105 ... Buffer memory 106 ... Image processing unit 108 ... Flash memory 109 ... CPU
110 ... Recording IF 111 ... Monitor drive unit 112 ... Liquid crystal monitor 113 ... Operating unit 114 ... TG 115 ... Microphone 116 ... Audio input unit 117 ... A / D conversion Unit 118 ... Audio processing unit 201 ... Power button 202 ... Release button 203 ... Zoom button 204 ... Cross key 204a ... Up key 204b ... Down key 204c ... Left key 204d ... Right key 205 ... Confirm button

Claims (6)

A video shooting unit for shooting moving images at a predetermined frame rate;
An audio acquisition unit that converts audio input while capturing a moving image in the moving image capturing unit into a digital signal with a predetermined setting;
An electronic camera comprising: a control unit configured to change a setting when audio is converted into a digital signal by the audio acquisition unit according to a frame rate of a moving image captured by the moving image capturing unit. The electronic camera according to claim 1,
The control unit varies at least one of an audio sampling rate and a quantization bit number converted into a digital signal by the audio acquisition unit according to a frame rate of a moving image captured by the moving image capturing unit. Electronic camera. The electronic camera according to claim 2,
The controller is
When the frame rate of the moving image is slow, when converting the sound into a digital signal in the sound acquisition unit, at least one of a low sampling rate or a small number of quantization bits is selected,
When the frame rate of the moving image is fast, at least one of a high sampling rate and a large number of quantization bits is selected when the sound acquisition unit converts the sound into a digital signal. The electronic camera according to claim 2,
The controller is
When the frame rate of the moving image is low, at the time of converting the sound into a digital signal by the sound acquisition unit, at least one of control for lowering the current value of the sampling rate or control for lowering the current value of the number of quantization bits Control
When the frame rate of the moving image is high, at the time of converting the sound into a digital signal by the sound acquisition unit, at least one of the control to increase the current value of the sampling rate or the control to increase the current value of the quantization bit number An electronic camera characterized by controlling The electronic camera according to any one of claims 1 to 4,
A table showing a relationship between setting of a frame rate of a moving image shot by the moving image shooting unit and setting of at least one of a sampling rate and a quantization bit number of audio converted into a digital signal by the audio acquisition unit;
The electronic camera is configured to set at least one of an audio sampling rate and a quantization bit number corresponding to a moving image frame rate with reference to the table. The electronic camera according to claim 5,
The table is composed of an image priority mode table that prioritizes image frame rate and an audio priority mode table that prioritizes sound quality,
The electronic camera further comprising selection means for selecting the image priority mode table or the audio priority mode table.

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