JP4717101B2 - Video recording device - Google Patents

Description

  The present invention relates to a moving image recording apparatus, and more particularly to a moving image recording apparatus that is applied to, for example, a video camera and records a moving image signal on a recording medium in a compressed state.

An example of a conventional video camera of this type is disclosed in Patent Document 1. According to this conventional technique, the compression rate of the still image signal of the next frame is calculated based on the compression rate, the compression size, and the target size of the still image signal of the current frame forming the moving image. To shorten the time required for
JP 2000-184330 A (page 4)

  However, in the conventional technique, since the target size is fixed, it takes time to record the compressed still image signal of each frame on a recording medium with a low recording speed. In other words, the conventional technique has a problem that the continuous recordable time of moving images depends on the recording characteristics of the recording medium.

  Therefore, a main object of the present invention is to provide a moving image recording apparatus capable of controlling the continuous recordable time of moving images.

  A first invention includes a processor equipped with a multitask OS and records a moving image signal on a recording medium in a compressed state. In the moving image recording apparatus, a plurality of tasks executed by the processor is a moving image signal compression process. A first task involved in the recording process and a second task involved in the recording process of the compressed moving image signal. The first task is a discriminating process for periodically discriminating the recording processing speed of the compressed moving image signal; The moving image recording apparatus includes a changing process of changing a compression rate of the moving image signal based on the determination result.

  The second invention is a capturing means for capturing a moving image signal, a compressing means for compressing the moving image signal every predetermined number of screens to generate a compressed moving image signal, a recording means for recording the compressed moving image signal on a recording medium, A moving image recording apparatus comprising: a determining unit that periodically determines a processing speed of the unit; and a changing unit that changes a compression rate of the compressing unit based on a determination result by the determining unit.

  In the first invention, the moving image signal is recorded on the recording medium in a compressed state under the control of a processor equipped with a multitask OS. Here, the plurality of tasks executed by the processor include a first task related to the compression processing of the moving image signal and a second task related to the recording processing of the compressed moving image signal. Further, the first task includes a determination process for periodically determining the recording processing speed of the compressed moving image signal, and a change process for changing the compression rate of the moving image signal based on the determination result of the determination process.

  In a multitasking OS, each of a plurality of tasks is executed only in a time division manner. Then, the recording processing speed of the compressed moving image signal varies depending on the load variation of each task. Therefore, the recording processing speed is periodically determined, and the compression rate of the moving image signal is changed according to the determination result. Thereby, it is possible to control the continuous recordable time of moving images.

  Preferably, the second task includes a transfer process for transferring the compressed moving image signal to the recording medium by a predetermined amount. When other tasks are executed, the second task is interrupted each time a specified amount of transfer is completed.

  When capturing a moving image signal according to capture conditions, the plurality of tasks further include a third task related to adjustment of capture conditions. When the capturing condition is adjusted by the third task, this adjustment process becomes a fluctuation factor of the recording processing speed.

  Preferably, the capturing unit includes a capturing unit that captures a subject, and the capturing condition includes a capturing condition of the capturing unit. In this case, whether or not the shooting conditions need to be adjusted depends on external factors such as the brightness and hue of the subject. The third task is activated at an arbitrary timing, and the recording processing speed varies accordingly.

  In the case where the compressed moving image signal is temporarily stored in the memory, in the determination process, the recording processing speed is preferably determined based on the size of the unrecorded compressed moving image signal stored in the memory.

  In the second invention, the moving image signal captured by the capturing means is compressed for each predetermined number of screens by the compressing means. The compressed moving image signal generated thereby is recorded on the recording medium by the recording means. The processing speed of the recording means is periodically determined by the determining means, and the changing means changes the compression rate of the compressing means based on the determination result of the determining means.

  Preferably, a bus connected to the memory is used for transferring moving image signals and compressed moving image signals. The zoom unit performs an electronic zoom process on the moving image signal in a manner selected by the selection unit. When the enlargement zoom is selected by the selection unit, the zoom unit extracts a part of the moving image signal using the memory, and performs the enlargement zoom on the extracted moving image signal. Accordingly, when enlargement zoom is selected, the bus is used for transferring the moving image signal, and the occupation rate of the bus for transferring the compressed moving image signal, that is, the processing speed of the recording means is reduced.

  In the case where the compressed moving image signal is temporarily stored in the memory, in the determination process, the recording processing speed is preferably determined based on the size of the unrecorded compressed moving image signal stored in the memory.

  According to these inventions, since the recording processing speed is periodically determined and the compression rate of the moving image signal is changed according to the determination result, the continuous recordable time of the moving image can be controlled.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  Referring to FIG. 1, a digital video camera 10 of this embodiment includes an image sensor 12. An aperture unit (not shown) and an optical lens (not shown) are disposed in front of the image sensor 12, and an optical image of the subject is irradiated onto the image sensor 12 through these members.

  When the shooting mode is selected by the mode switch 62, a corresponding status signal is given from the system controller 56 to the CPU 52. The CPU 52 is a multitasking CPU equipped with a multitasking OS such as μITRON. In the shooting mode, a plurality of tasks such as a shooting processing task, a shooting condition control task, and a BG (Back Ground) processing task are executed in parallel. . Specifically, each task is executed in a time-sharing manner in accordance with a preset priority order and in response to a vertical synchronization signal described later.

  In the shooting processing task, the operator can select a desired shooting mode from a plurality of shooting modes by operating the menu key 60. Any one of the resolution and frame rate of the captured image, the sound system of the captured sound, the bit rate, and the sampling rate differs in each imaging mode. When a desired shooting mode is selected, a corresponding information signal is provided from the system controller 56 to the CPU 52. The CPU 52 stores shooting mode information (resolution, frame rate, sound method, bit rate, sampling rate) indicating the selected shooting mode and the file name of the movie file to be created in the register rgst.

  The CPU 52 also instructs the timing generator (TG) 14 to shoot at the resolution and frame rate indicated by the shooting mode information. The TG 14 generates a timing signal according to a desired shooting mode (resolution, frame rate) based on the vertical synchronization signal and the horizontal synchronization signal output from the signal generator (SG) 16, and drives the image sensor 12 by a raster scan method. . A raw image signal (charge) having a desired resolution is output from the image sensor 12 at a desired frame rate. The output raw image signal passes through the CDS / AGC circuit 18 and the A / D converter 20 and is digitally transmitted. The signal is input to the signal processing circuit 22 as raw image data as a signal.

  When the set zoom magnification is “1.0”, the signal processing circuit 22 performs a series of signal processing such as white balance adjustment, color separation, and YUV conversion on the raw image data input from the A / D converter 20. To generate 1.0 times YUV data. When the set zoom magnification is less than “1.0”, the raw image data input from the A / D converter 20 is first subjected to reduction zoom by the zoom circuit 22a, and the series of signals described above after reduction zoom. Processing is executed. The YUV data generated by such processing is stored in the SDRAM 26 via the bus B1 and the memory control circuit 26.

  On the other hand, when the set zoom magnification is larger than “1.0”, that is, when zoom processing is required, the zoom circuit 22a first converts the raw image data input from the A / D conversion device 20 into the bus B1 and The data is temporarily written in the SDRAM 26 through the memory control circuit 24. Subsequently, the zoom circuit 22a reads the raw image data of a part of area necessary for the enlargement zoom process through the bus B1 and the memory control circuit 24, and performs the enlargement zoom on the read raw image data of the part of the area. The enlarged raw image data is converted into YUV data by the series of signal processing described above. As a result, YUV data having a magnification larger than “1.0” is generated. The generated YUV data is stored in the SDRAM 26 via the bus B1 and the memory control circuit 26.

  The video encoder 28 reads YUV data from the SDRAM 26 through the bus B1 and the memory control circuit 24, and encodes the read YUV data into a composite image signal. The encoded composite image signal is supplied to the monitor 30. As a result, a real-time moving image (through image) of the subject is displayed on the monitor 30.

  In the shooting condition control task, the CPU 52 controls shooting conditions such as aperture amount, exposure time, white balance adjustment gain, and electronic zoom magnification. Specifically, the aperture amount or the exposure time is adjusted according to the brightness of the subject, the white balance adjustment gain is corrected according to the color of the subject, and the state signal indicating the operation state of the zoom key 64 is changed. Adjust the electronic zoom magnification. As a result, fluctuations in the brightness and hue of the through image are prevented, and the zoom magnification of the through image changes in response to the operation of the zoom key 64.

  When a zoom magnification larger than “1.0” is selected by the zoom key 64, processing for temporarily storing the raw image data as described above in the SDRAM 26 is executed.

  When the shutter button 58 is pressed by the operator and a corresponding status signal is given from the system controller 56, the CPU 52 creates a movie file storing the photographed moving image on the recording medium 50. Here, the recording medium 50 is a detachable recording medium, and can be accessed by the I / F 46 when the recording medium 50 is mounted in the slot 48. The recording medium 50 is provided with a CPU 50a, a buffer memory 50b, and a hard disk 50c. A FAT area 501c, a root directory area 502c, and a data area 503c are formed on the hard disk 50c as shown in FIG. Data is written to the data area 503c by a predetermined amount via the buffer memory 50b.

  When recording a moving image, the CPU 52 activates a BG processing task. At this time, an instruction list 52a as shown in FIG. 4 is created so that processing can be smoothly performed between the photographing processing task and the BG processing task.

  In the instruction list 52a, first, commands and parameters corresponding to “BG process start”, “file creation”, “table creation”, and “file open” are set. The BG processing task is started by “BG processing start”, and the file name of the movie file and the size information indicating “0” are written in the root directory area 502c shown in FIG. 6 by “file creation”. In “table creation”, an empty area table 52c as shown in FIG. 7 is created. According to FIG. 7, the start address and the empty size of each empty area formed in the data area 503c are set in order of increasing size. In “file open”, a handle number for specifying a movie file to which data is written is created.

  When the preparation for data writing is completed in this way, the CPU 52 performs a thumbnail image capturing process and header information creating process in the next one frame period in order to create a movie file header. First, the signal processing circuit 22 is instructed to perform thinning processing, and the JPEG codec 32 is instructed to perform compression processing. The signal processing circuit 22 performs a thinning process in addition to the above-described YUV conversion, and writes the thumbnail YUV data generated thereby into the SDRAM 26 through the bus B1 and the memory control circuit 24. The JPEG codec 32 reads thumbnail YUV data from the SDRAM 26 through the bus B1 and the memory control circuit 24, and performs JPEG compression on the read thumbnail YUV data. The JPEG codec 32 then writes the JPEG raw data Rth of the thumbnail image generated by JPEG compression into the SDRAM 26 through the bus B1 and the memory control circuit 24.

  The CPU 46 also creates the JPEG header Hth of the thumbnail image by itself and writes the created JPEG header Hth into the SDRAM 26 through the bus B1 and the memory control circuit 24. The CPU 46 further creates header information Hinf including the above-described shooting mode information, and writes the created header information Hinf into the SDRAM 26 through the bus B1 and the memory control circuit 24. As a result, the JPEG raw data Rth, the JPEG header Hth, and the header information Hinf are mapped to the SDRAM 26 as shown in FIG.

  “File write” is set in the instruction list 52a. By executing this “file writing” by BG processing, JPEG raw data Rth, JPEG header Hth and header information Hinf are read from the SDRAM 26 and given to the recording medium 50 via the bus B1 and the I / F circuit 46. It is done. As a result, the movie file header shown in FIG. 7 is created in the data area 503c shown in FIG. The JPEG data TH shown in FIG. 7 is formed by the JPEG header Hth and the JPEG raw data Rth.

  When the creation of the movie file header is completed, the CPU 52 performs an image capturing process and an audio capturing process each time a vertical synchronization signal is generated.

  In the image capturing process, the JPEG header created by itself is written into the SDRAM 26 through the bus B1 and the memory control circuit 24, and a compression instruction is given to the JPEG codec 32. When a compression command is given, the JPEG codec 32 reads YUV data of the current frame from the SDRAM 26 through the bus B1 and the memory control circuit 24, and compresses the read YUV data to a target size. When JPEG raw data of the current frame is generated by the compression process, the JPEG codec 32 writes the JPEG raw data to the SDRAM 26 through the bus B1 and the memory control circuit 24.

  Here, the target size at the time of JPEG compression is changed according to the recording status on the recording medium 50. In other words, if the recording processing speed is low, the processing may fail due to a bottleneck, so the recording status of the recording medium 50 is periodically detected, and the target size at the time of JPEG compression is changed according to the detection result. . This target size changing process will be described in detail later.

  In the voice capturing process, a processing command is given to the signal processing circuit 38. When a processing command is given, the signal processing circuit 38 writes audio data corresponding to one frame stored in the SRAM 38a into the SDRAM 26 through the bus B1 and the memory control circuit 38a. As a result of such image capture processing and audio capture processing being performed for each frame period, the JPEG header, JPEG raw data, and audio data of each frame are mapped to the SDRAM 26 as shown in FIG.

  In FIG. 2, serial numbers 0, 1, 2,... Are attached to the JPEG header and JPEG raw data for each frame, but continuous numbers 0, 1, 2,. Attached. Also, JPEG data for one frame is formed by the JPEG header and JPEG raw data to which the same numbers are attached, and a marker SOI (Start Of Image) as shown in FIG. And EOI (End Of Image).

  The CPU 52 also creates JPEG raw data access information, JPEG header access information, and JPEG data index information every time one frame period elapses, and audio data access information and audio data every time three frame periods elapse. Create index information for.

  The access information of JPEG raw data consists of the data size of each frame and the start address in the SDRAM 26, and the access information of the JPEG header also consists of the data size of each frame and the start address in the SDRAM 26. The index information of JPEG data consists of the data size of each frame and the distance from the beginning of the movie file when it is written on the recording medium 50.

  The audio data access information is composed of a data size corresponding to 3 frames and the start address in the SDRAM 26, and the index information of the audio data is the data size corresponding to 3 frames and the movie file when written to the recording medium 50. It consists of the distance from the head.

  The access information is created in the access information table 52b shown in FIG. 5, and the index information is created in the SDRAM 26 in the manner shown in FIG. According to FIG. 5, the SDRAM address and data size of JPEG raw data for 3 frames, the SDRAM address and data size of JPEG header for 3 frames, and the SDRAM address and data size of audio data equivalent to 3 frames are Associated with each other. Further, according to FIG. 3, the position information and size information of audio data corresponding to three frames and the position information and size information of JPEG data for three frames are alternately mapped to the SDRAM 26.

  Note that there may be a difference in the sampling frequency of the audio signal between actual processing by hardware and calculation by software. In this embodiment, decimation / interpolation is applied to the index information and access information of JPEG data to compensate for this deviation. This thinning / interpolation process will be described in detail later.

  The CPU 52 sets “file write” in the instruction list 52 a based on the above-described access information in order to write the audio data corresponding to 3 frames and the JPEG data of 3 frames to the recording medium 50. When this “file writing” is executed by the BG process, the audio data corresponding to 3 frames and the JPEG data of 3 frames are read from the SDRAM 26 and transferred to the recording medium 50 via the bus B1 and the I / F circuit 46. Given. In the data area 503c of the recording medium 50, an audio chunk consisting of audio data corresponding to 3 frames and an image chunk consisting of 3 frames of JPEG data are recorded. As shown in FIG. 8, audio chunks and image chunks are mapped alternately on the movie file.

  When the shutter button 58 is pressed again, the CPU 52 stops the image capture and the sound capture and designates “write file” in the instruction list 52a in order to record the index information created in the SDRAM 26 in the manner shown in FIG. Set to. When this “file writing” is executed by the BG processing task, the index information is read from the SDRAM 26 and given to the recording medium 50 via the bus B 1 and the I / F circuit 46. As a result, the index chunk shown in FIG. 8 is formed at the end of the movie file. In the index chunk, the position and size of the audio data file on the file are managed every time corresponding to three frames, and the position and size of the JPEG data file are managed on a frame-by-frame basis.

  When the creation of the index chunk is completed, the CPU 52 calculates the total size value of the movie file created this time, and sets “write file” to the instruction list 52a in order to write the calculated total size value in the movie file header. By executing this file writing by the BG processing task, the total size value is added to the header information Hinf of the movie file header, thereby completing the creation of the movie file that satisfies the QuickTime standard.

  Subsequently, the CPU 52 sets “file close” and “BG processing end” in the instruction list 52a. When “file close” is executed by the BG process, the size information written in the root directory area 502c and the FAT information written in the FAT area 501c are updated. Specifically, the file name of the movie file created this time is detected from the directory entry, and the size information assigned to the detected file name is updated from “0” to the total size value. In addition, the FAT information is updated so that a link is formed in the writing area (cluster) of the movie file created this time. The BG process is ended by “BG process end”.

  When a playback mode is selected by the mode switch 62 and a desired movie file is selected by the menu key 60, a corresponding status signal is given to the system controller 56. The CPU 52 detects the selected movie file from the recording medium 50, and reproduces the audio data and JPEG data in the detected movie file. At this time, the playback order follows the index information in the movie file.

  If the index information created in the manner shown in FIG. 3 is present in the movie file, the audio data and JPEG data are in the order of audio data 0, JPEG data 0-2, audio data 1, JPEG data 3-5,. It is read from the recording medium 50. The read audio data and JPEG data are first stored in the SDRAM 26 by the memory control circuit 24. The CPU 52 gives decompression instructions to the JPEG codec 32 in the order according to the index information of JPEG data, and gives processing instructions to the signal processing circuit 40 in the order according to the index information of the audio data.

  The JPEG codec 32 reads JPEG raw data forming JPEG data of a desired frame from the SDRAM 26 through the bus B1 and the memory control circuit 24, and performs JPEG decompression on the read JPEG raw data. The YUV data generated by the JPEG decompression is stored in the SDRAM 26 through the bus B1 and the memory control circuit 24, and then supplied to the video encoder 28 through the bus B1 and the memory control circuit 24. As a result, a corresponding reproduced image is displayed on the monitor 30.

  The signal processing circuit 40 reads audio data corresponding to the desired three frames from the SDRAM 26 through the bus B1 and the memory control circuit 24, and accumulates the read audio data in the SRAM 40a. The audio data stored in the SRAM 40 a is then converted into an analog audio signal by the D / A converter 42, and the converted audio signal is output from the speaker 44.

  By repeating such processing, the playback moving image is displayed on the monitor 30, and an audio signal synchronized with the playback moving image is output from the speaker 44.

  When the shooting mode is selected, the CPU 52 executes the shooting process task shown in FIGS. 13 to 19 and the BG process task shown in FIGS. 20 to 21 in accordance with the control program stored in the ROM 54.

  First, referring to FIG. 13, in step S1, a shooting mode determination process is performed. Specifically, a menu showing a plurality of shooting modes is displayed on the monitor 30 and a desired shooting mode is determined in response to an operation of the menu key 52. When the shooting mode is determined, the process proceeds to step S3, and shooting mode information indicating the determined shooting mode is created. The setting information is, for example, “resolution: VGA”, “frame rate: 30 fps”, “acoustic method: monaural”, “bit rate: 8 bits”, “sampling rate: 8040 Hz”. In step S5, the file name of the movie file created by the current photographing process is determined. The file name is, for example, “VCLP0003.MOV”. The created / determined shooting mode information and file name are registered in the register rgst.

  In step S7, various variables are initialized. Specifically, each of the variables i, frmcnt, flsz, BG_RemData, pre_flsz, t_sz and aud_sz is set to “0”, the variable trgt_sz is set to the maximum value MAX, and the variable audsz_fps is set to the theoretical value LG.

  Here, the variables i and frmcnt are both variables indicating the frame number. The variable i continues to be incremented in response to the vertical synchronization signal, and the variable frmcnt is cyclically updated between “0” and “3” in response to the vertical synchronization signal. Of the numerical values “0” to “3” taken by the variable frmcnt, “0” to “2” are actually meaningful. As described above, one image chunk is formed by three frames of JPEG data. The variable frmcnt is used to specify what number data of the image chunk the JPEG data of interest is.

  The variable flsz is a variable indicating the total size value of JPEG raw data generated by JPEG compression. The variable BG_RemData is a variable that indicates the size of JPEG raw data for which the “file write” instruction is set in the instruction list 52 a shown in FIG. 4 but is not yet recorded on the recording medium 50. The variable pre_flsz is a variable indicating the total size value of the JPEG raw data already recorded on the recording medium 50.

  The variable trgt_sz is a variable indicating a target size value when compressing the YUV data of each frame, and the variable t_sz is a variable used for calculating the target size value.

  The variable aud_sz is a variable indicating the total size value (bytes) of the captured audio data, and the variable audsz_fps is a variable indicating the size value of the audio data corresponding to one frame. However, the theoretical value LG set as the variable audsz_fps is a size value of audio data corresponding to one frame determined based on a sampling rate in software calculation. For example, if the actual sampling rate of the determined shooting mode is 8043 Hz, the sampling rate in software calculation is 8040 Hz, and the theoretical value LG is 268 (= 8040/30) bytes. The numerical value of 8040 Hz is based on the fact that data transfer on hardware is executed in units of 1 word (= 4 bytes) and that the theoretical value LG can be expressed by an integer.

  In step S9, a processing command is given to each of the TG 14, the signal processing circuit 22, and the video encoder 28 in order to display a through image. On the monitor 30, a through image of the subject is displayed. When the operator presses the shutter button 58 while the through image is displayed, “BG processing start”, “file creation”, “table creation”, and “file open” are respectively shown in FIG. 4 in steps S11 to S19. Set to the list number “0” to “3” of the instruction list 52a shown.

Referring to Table 1, “FILE_STRT” is set as a command in “BG processing start”, FILE_CREATE is set as a command in “file creation”, drive number (the number of the drive that drives the recording medium 44), and file path Is set. In “table creation”, FILE_SET_ALLOC and drive number are set as a command and parameter 1, and in “file open”, FILE_OPEN, drive number and file path are set as parameters and parameters 1. The file path set in “file creation” includes the size information and the file name determined in step S25, and the size information and the file name are written in the directory entry. However, since the movie file is incomplete, the size information indicates “0”.
When the vertical synchronization signal is output from SG16 after the processing of step S19 is completed, YES is determined in step S21, and the value of variable i is determined in step S23. If the variable i is a value equal to or greater than “1”, the process proceeds directly to step S31. If the variable i is “0”, the process proceeds to steps S31 through steps S25 to S29.

  In step S25, a thumbnail image capturing process is performed. Specifically, the JPEG header Hth created by itself is written in the SDRAM 26, and the signal processing circuit 22 and the JPEG codec 32 are instructed to perform thinning processing and compression processing.

The signal processing circuit 22 performs thinning processing of YUV data over one frame period, and writes the thumbnail YUV data generated thereby into the SDRAM 26 through the bus B1 and the memory control circuit 24. The JPEG codec 32 reads the thumbnail YUV data from the SDRAM 26 through the bus B1 and the memory control circuit 24, performs JPEG compression processing on the read thumbnail YUV data to generate JPEG raw data Rth, and generates the JPEG raw data Rth. Data is written to the SDRAM 26 through the bus B1 and the memory control circuit 24. The JPEG header Hth and JPEG raw data Rth are mapped to the SDRAM 26 as shown in FIG.
In the following step S27, header information Hinf including the above-described shooting mode information (resolution, frame rate, sound system, bit rate, sampling rate) is created, and this header information Hinf is written to the SDRAM 26 through the bus B1 and the memory control circuit 24. . The header information Hinf is mapped on the JPEG header Hth as shown in FIG.

  When the header information Hinf, the JPEG header Hth, and the JPEG raw data Rth forming the movie file header are stored in the SDRAM 26 in this way, “file write” is changed to list numbers “4” and “4” in the instruction list 52a shown in FIG. Set in the column of 5 ". As can be seen from Table 1, in “file write”, FILE_WRITE, handle number (obtained by the file open process), SDRAM address, data size, and data type are set as a command, parameters 1, 2, 3, and 4. Two “file writing” are set because the header information Hinf and the JPEG header Hth are continuous on the SDRAM 26, but the JPEG raw data Rth is stored at a distant position.

  In the column of the list number “4”, the start address of the header information Hinf is set as the SDRAM address, the total size of the header information Hinf and the JPEG header Hth is set as the data size, and “movie file header” is set as the data type Is done. In the column of the list number “5”, the start address of JPEG raw data Rth is set as the SDRAM address, the size of JPEG raw data Rth is set as the data size, and “movie file header” is set as the data type. The As a result, on the movie file header shown in FIG. 8, header information Hinf, JPEG header Hth, and JPEG raw data Rth continue in this order. As described above, the JPEG data TH is formed by the JPEG header Hth and the JPEG raw data Rth.

  In step S31, a compression processing instruction is given to the JPEG codec 32. This compression processing instruction includes a target size value according to the variable trgt_sz. The JPEG codec 32 reads one frame of YUV data from the SDRAM 26 through the bus B1 and the memory control circuit 24, compresses the read YUV data to create JPEG raw data having a size close to the target size, and The generated JPEG raw data is written into the SDRAM 26 through the bus B1 and the memory control circuit 24. The JPEG raw data is mapped to the SDRAM 26 in the manner shown in FIG. As described above, the JPEG data of the frame is formed by the JPEG header and JPEG raw data obtained in the same frame, and the markers SOI and EOI are written at the beginning and the end of the JPEG data.

In step S33, a processing command is given to the signal processing circuit 38 in order to perform audio data capturing processing corresponding to one frame. The signal processing circuit 38 writes audio data corresponding to one frame supplied from the A / D converter 36 and held in the SRAM 38 a to the SDRAM 26 through the bus B 1 and the memory control circuit 24. The audio data is mapped to the SDRAM 26 in the manner shown in FIG. The signal processing circuit 38 also returns to the CPU 52 the size value of the audio data written into the SDRAM 26, that is, the capture size value. For this reason, in step S35, the calculation according to Equation 1 is executed, and the returned fetch size value is added to the variable aud_sz.
[Equation 1]
aud_sz = aud_sz + take-in size value When the calculation of Equation 1 is completed, it is determined in step S37 whether JPEG compression has been completed. When the JPEG compression based on the compression command in step S31 is completed, the JPEG codec 32 returns the size value of the generated JPEG raw data, that is, the compression size value and the compression completion signal, to the CPU 46. For this reason, in step S37, it is determined YES when the compression completion signal is returned.

In step S39, the calculation of Equation 2 is executed to add the returned compressed size value to the variable flsz.
[Equation 2]
flsz = flsz + compressed size value In step S41, the JPEG header created by itself is written into the SDRAM 26 through the bus B1 and the memory control circuit 24, and in step S43, the index information of the JPEG data of the current frame is transmitted through the bus B1 and the memory control circuit 24. Write to SDRAM 26. The JPEG header is mapped to the SDRAM 26 as shown in FIG. 2, and the index information is mapped to the SDRAM 26 as shown in FIG.

  As described above, in the movie file index chunk, the position and size of the JPEG data on the file are managed for each frame. For this reason, in step S43, position information and size information of one frame of JPEG data are created as index information. On the movie file, one image chunk is formed by three frames of JPEG data. For this reason, in step S43, the position of the three consecutive frames in the current frame is specified from the variable frmcnt, thereby determining at which position in the SDRAM 26 the index information is to be created.

  In step S45, JPEG raw data of the current frame and access information of the JPEG header are created in the access information table 52b shown in FIG. That is, the head address information and size information of the JPEG raw data of the current frame existing in the SDRAM 26 are created as the access information of the JPEG raw data of the current frame, and the head address information and size information of the JPEG header of the current frame existing in the SDRAM 26 are obtained. Created as access information of the JPEG header of the current frame. Each created access information is assigned to a variable i set in the access information table 52b.

  When the process of step S45 is completed, the variable i is compared with the frame rate value FPS of the current shooting mode in step S47. If the frame rate in the current shooting mode is 30 fps, the frame rate value FPS is “30”, and the variable i is compared with “30”. If i <FPS, the process directly proceeds to step S83, but if i ≧ FPS, the process proceeds to step S81 through steps S49 to 81.

In step S49, it is determined whether the variable frmcnt is less than “2”. If YES, it is determined in step S51 whether the condition of Equation 3 is satisfied. On the other hand, if the variable frmcnt is “2” or more, it is determined in step S59 whether or not the condition of Equation 4 is satisfied.
[Equation 3]
aud_sz- (audsz_fps * (i + 1))> audsz_fps
[Equation 4]
(Audsz_fps * (i + 1))-aud_sz> audsz_fps
aud_sz is the total size value of the audio data actually captured, and audsz_fps * (i + 1) is a product of the number of frames from the start of capture and the theoretical value LG. In both Equation 3 and Equation 4, the difference value between the two values is compared with the theoretical value LG. As long as the difference value is equal to or less than the theoretical value LG, the process proceeds to step S63 as it is. However, if the difference value exceeds the theoretical value LG, the process proceeds to step S63 via steps S53 to S57 or step S61.

  For example, if the actual sampling rate is 8043 Hz and the sampling rate in software calculation is 8040 Hz, the error between them is 3 Hz. Then, a shift of 3 bytes occurs in the size value of the audio data corresponding to 1 second. Since the theoretical value LG is 268 bytes, the condition of Equation 3 is satisfied at a rate of about once every 90 seconds, and steps S53 to S57 are processed. If the actual sampling rate is 8034 Hz and the sampling rate in software calculation is 8040 Hz, the error between them is 6 Hz. At this time, the condition of Formula 4 is satisfied at a rate of about once every 45 seconds, and the process of step S61 is executed.

  In step S53, each of variables i and frmcnt is incremented. In step S55, the same image index information as the previous time, that is, the same index information as that created in the previous step S43 is created in the SDRAM 26, and in step S57, the same access information as the previous time, that is, the same as the access information created in the previous step S45. Access information is created in the access information table 52b. When the process of step S57 is completed, the process proceeds to step S63. On the other hand, in step S61, each of the variables i and frmcnt is decremented, and then the process proceeds to step S63.

  Therefore, when the index information is set in the SDRAM 26 as shown in FIG. 9A and the access information is set in the access information table 52b as shown in FIG. 10A, the condition shown in Equation 3 is satisfied. By the processing of steps S53 to S57, the index information of the same JPEG data is set in the SDRAM 26 as shown in FIG. 9B, and the access information of the JPEG raw data and JPEG header forming the same JPEG data is shown in FIG. ) As shown in the access information table 52b.

  According to FIG. 9A, the index information of the JPEG data P is set in the SDRAM 26. In this state, the variable frmcnt is incremented and the index information created in the immediately preceding step S43 is revalidated, so that the index information of the JPEG data P is interpolated as shown in FIG. 9B. After the index information of JPEG data P is interpolated, the index information of JPEG data P + 1 is set as shown in FIG. 9C.

  According to FIG. 10A, access information of JPEG raw data P and JPEG header P is assigned to variable i (= P). In this state, the variable i is incremented, and the access information created in the immediately preceding step S45 is validated again, so that the access information of the JPEG raw data P and the JPEG header P is changed to the variable i as shown in FIG. (= P + 1). After the access information of JPEG raw data P and JPEG header P is interpolated, as shown in FIG. 10C, the access information of JPEG raw data P + 1 and JPEG header P + 1 is assigned to variable i (= P + 2). .

  On the other hand, when the index information is set in the SDRAM 26 as shown in FIG. 11A and the access information is set in the access information table 52b as shown in FIG. In step S61, a part of the index information is overwritten by the subsequent index information as shown in FIG. 11 (B), and a part of the access information becomes the subsequent access information as shown in FIG. 12 (B). Overwritten by

  According to FIG. 11A, the index information of JPEG data P and the index information of JPEG data P + 1 are set in the SDRAM 26. Since the variable frmcnt is decremented in this state, the index information of the JPEG data P + 1 is overwritten with the index information of the JPEG data P + 2 as shown in FIG. As a result, the index information of the JPEG data P + 1 is thinned out. Next to the index information of JPEG data P + 2, the index information of JPEG data P + 3 is set as shown in FIG.

  According to FIG. 12A, access information for JPEG raw data P and JPEG header P and access information for JPEG raw data P + 1 and JPEG header P + 1 are set in access information table 52b. Since the variable i is decremented in this state, the access processing information of the JPEG raw data P + 1 and the JPEG header P + 1 becomes the JPEG raw data P + 2 and the JPEG header P + 2 as shown in FIG. It is overwritten by the access information. As a result, the access information of the JPEG data P + 1 is thinned out. Next to the access information of the JPEG raw data P + 2 and the JPEG header P + 2, the access information of the JPEG raw data P + 3 and the JPEG header P + 3 is set as shown in FIG.

  Note that, by incrementing the variable i in step S53, the determination of NO is continued in the next step S51. Further, by decrementing the variable i in step S61, the determination of NO is continued in NO step S59 from the next time onward.

  In step S63, a remainder when the variable i is divided by the frame rate value FPS (= i% FPS) is determined. If the remainder is not “0”, the process proceeds to step S83 as it is. If the remainder is “0”, the process proceeds to steps S83 through steps S65 to S81. Since the remainder is “0” once every 30 frames, the processes of steps S65 to S81 are executed once every 30 frames.

In step S65, an operation according to the equation 5 is performed on the variables flsz and pre_flsz, and an operation according to the equation 6 is performed on the difference value Δflsz obtained by the equation 5, the variable BG_RemData, and the frame rate value FPS.
[Equation 5]
Δflsz = flsz-pre_flsz
[Equation 6]
t_sz = (Δflsz−BG_RemData) / FPS
In Equation 5, the variable flsz is the total size value of JPEG raw data obtained by JPEG compression, and the variable pre_flsz is the total size value of JPEG raw data already recorded on the recording medium 50. As will be described later, the variable pre_flsz is updated only once every 30 frames, and the calculation according to Equation 5 is also updated only once every 30 frames, so the difference value Δflsz is generated in the latest 30 frames. The total size of JPEG raw data.

  In Equation 6, the variable BG_RemData is a total size value of JPEG raw data in which an instruction of “file writing” is set in the instruction list 52a but is not yet recorded on the recording medium 50. This variable BG_RemData decreases as the time required for the “file writing” process decreases, and conversely increases as the time required for the “file writing” process increases. The subtracted value obtained by subtracting the variable BG_RemData from the difference value Δflsz reflects the current “file write” processing speed, and the divided value obtained by dividing the subtracted value by the frame rate value FPS is lower than the current processing speed. The amount of change in the variable BG_RemData at is a compressed size value that falls within a specified range. Such a compressed size value is calculated as a variable t_sz.

  Here, as a factor of fluctuation in the processing speed of “file writing”, in addition to the characteristics of the recording medium 50 such as the processing speed of the CPU 50a and the capacity of the buffer memory 50b, tasks other than the occupation ratio of the bus B1 and the BG processing task The processing status of this can be considered.

  As described above, when a zoom magnification larger than “1.0” is selected by operating the zoom key 64, the raw image data is temporarily stored in the SDRAM 26 and then input to the signal processing circuit 22. At this time, the raw image data is given to the SDRAM 26 via the bus B1 and returned to the signal processing circuit 22 via the bus B1. The occupation ratio of the bus B1 is increased by the transfer process of the raw image data, and the processing speed of “file writing” is thereby lowered.

  Also, when the brightness or color tone of the subject changes greatly due to camera panning or tilting, a shooting condition control task is activated to adjust the aperture amount, exposure time, white balance adjustment gain, and the like. Since each task cannot be executed at the same time, when the shooting condition control task is activated, the BG processing task is interrupted, thereby reducing the processing speed of “file writing”.

  In this embodiment, the variable t_sz is periodically updated in consideration of the fluctuation in the processing speed of such “file writing”. As a result of updating the variable t_sz, the target size value and thus the JPEG compression rate are updated as will be described later.

  In step S69, the calculated variable t_sz is compared with the variable trgt_sz. If t_sz <trgt_sz, the variable t_sz is compared with the minimum value MIN in step S71. If t_sz ≧ MIN, the process proceeds directly to step S79. If t_sz <MIN, the variable t_sz is updated to the minimum value MIN in step S73, and then the process proceeds to step S79. On the other hand, if it is determined in step S69 that t_sz ≧ trgt_sz, the variable t_sz is compared with the maximum value MAX in step S75. If t_sz ≦ MAX, the process proceeds directly to step S79. If t_sz> MAX, the variable t_sz is updated to the maximum value MAX in step S77, and then the process proceeds to step S79. In step S79, the variable t_sz is set as the variable trgt_sz.

  According to Equation 6, when the variable BG_RemData is large, the variable t_sz is small. Conversely, when the variable BG_RemData is small, the variable t_sz is large. Therefore, “t_sz <trgt_sz” means that the amount of unrecorded JPEG data is large, that is, the processing speed of “file writing” is slow. “T_sz ≧ trgt_sz” means that the amount of unrecorded JPEG data is small, that is, the recording characteristics of the recording medium 50 are excellent.

  Therefore, when the variable t_sz is lower than the variable trgt_sz, the variable t_sz is set as the variable trgt_sz in order to validate a smaller target size value (higher JPEG compression rate) in the next one second. As a result, the size of the JPEG data generated in the next one second becomes smaller than the JPEG data generated in the current one second, and the failure of the processing due to the decrease in the processing speed of “file writing” is avoided. .

  On the other hand, when the variable t_sz is greater than or equal to the variable trgt_sz, the variable t_sz is set to the variable trgt_sz in order to validate a larger target size value (lower JPEG compression rate) in the next one second. As a result, the size of the JPEG data generated in the next 1 second becomes larger than the JPEG data generated in the current 1 second, and image quality deterioration due to the compression process is reduced.

In step S81, the calculation of Expression 7 is performed on the variables flsz and BG_RemData to update the variable pre_flsz.
[Equation 7]
pre_flsz = flsz−BG_RemData
According to Equation 7, the total size value of unrecorded JPEG raw data is subtracted from the total size value of JPEG raw data generated so far. Since this calculation is also executed every 30 frames, the variable pre_flsz is updated at a rate of once every 30 frames. In the next calculation, that is, the calculation of Equation 5 after 30 frames, the updated variable pre_flsz is subtracted from the latest variable flsz.

  In step S83, the variable frmcnt is incremented, and in the subsequent step S85, the value of the incremented variable frmcnt is determined. If the variable frmcnt is “1” or “2”, the process directly proceeds to step S95. If the variable frmcnt is “3”, the process proceeds to steps S95 through steps S87 to S93.

  In step S87, the index information of the audio data is written into the SDRAM 26. On the movie file shown in FIG. 7, one audio chunk is formed by audio data for a time corresponding to three frames. In the index chunk, the position and size of the audio data file are managed every time corresponding to 3 frames. For this reason, in step S85, position information and size information of audio data corresponding to the latest three frames are created, and the created index information is written in the SDRAM 26 as shown in FIG.

  In subsequent step S89, the access information of the audio data is written in the access information table 52b. That is, the start address information and size information of audio data corresponding to three frames existing in the SDRAM 26 are created as access information, and the created access information is written into the access information table 52b. At this time, the access information is associated with the access information of the JPEG data of three frames of interest.

  In step S91, referring to the JPEG raw data for three frames set in the access information table 52b, the access information for the JPEG header for three frames, and the access information for audio data corresponding to three frames, "Is set in the instruction list 52a shown in FIG. As shown in FIG. 2, audio data corresponding to three frames is continuous on the SDRAM 26, but three frames of JPEG raw data and JPEG header are distributed discretely on the SDRAM 26. Therefore, in step S91, a total of seven “file write” is set in the instruction list 52a.

  In the first “file write” among the seven “file write”, the SDRAM address indicates the start address of the audio data corresponding to the three frames of interest, and the data size is the audio data of the three frames of interest. Indicates the size, and the data type indicates an audio chunk. Here, the start address and data size are equal to the SDRAM address and data size forming the access information created in step S87.

  In the “file write” set to the second, fourth and sixth, the SDRAM address indicates the start address of the JPEG header of the three frames of interest, the data size indicates the size of the JPEG header of the three frames of interest, and The data type indicates a JPEG header. Here, the start address and data size are equal to the SDRAM address and data size forming the access information of the JPEG header of the latest three frames created in step S45 or S57.

  In the “file write” set in the third, fifth and seventh, the SDRAM address indicates the start address of the JPEG raw data of the three frames of interest, and the data size indicates the size of the JPEG raw data of the three frames of interest. The data type indicates JPEG raw data. Here, the start address and data size are equal to the SDRAM address and data size forming the access information of the latest three frames of JPEG raw data created in step S45 or S57.

  By executing the instructions in the instruction list 52a in the BG processing task, the audio data corresponding to 3 frames and the 3 frames of JPEG data are read from the SDRAM 26 by the memory control circuit 24, and the buses B1 and I / F The signal is supplied to the recording medium 50 through the circuit 46. As a result, audio chunks and image chunks are alternately distributed on the movie file shown in FIG.

In step S93, the calculation of Equation 8 is executed to add the size value of the 3 frames of JPEG raw data set in the instruction list 52a in step S91 to the variable BG_RemData.
[Equation 8]
BG_RemData = BG_RemData + JPEG raw data size value In step S95, the frame number i is incremented, and in the subsequent step S97, it is determined whether or not the shutter button 58 has been operated. As long as the shutter button 58 is not pressed, the processes in steps S21 to S95 are repeated, and the JPEG header, JPEG raw data, and audio data generated in each frame are mapped to the SDRAM 26 as shown in FIG.

  When the shutter button 58 is pressed, the process proceeds to step S99 to determine the value of the variable frmcnt. If the variable frmcnt is “3”, the process directly proceeds to step S103. If the variable frmcnt is “1” or “2”, “file write” is set in the instruction list 52a in step S101, and the process proceeds to step S103. move on.

  When the variable frmcnt is “1”, the last audio chunk and image chunk are formed by one frame of audio data and JPEG data, and a total of three “file write” is set in the instruction list 52a. When the variable frmcnt is “2”, the last audio chunk and image chunk are formed by audio data and JPEG data for two frames, and a total of five “file write” is set in the instruction list 52a. As a result, an audio chunk consisting of audio data for one frame or two frames and an image chunk consisting of one frame or two frames of JPEG data are formed in the movie file.

  In step S103, “file write” is set in the instruction list 52a in order to write the index information shown in FIG. 3 to the movie file. The SDRAM address and data size set here indicate the start address and total size of the index information shown in FIG. 3, and the data type indicates a movie file header. By executing this “file writing” by the BG process, an index chunk including all index information shown in FIG. 3 is formed at the end of the movie file.

  In step S105, the total size of the movie file is calculated based on the size information included in the index information, and the calculated total size data is written in the SDRAM 26. In subsequent steps S107 to S111, “file write”, “file close”, and “BG processing end” are set in the instruction list 52a. The SDRAM address and data size set by “file writing” indicate the head address and data size of the total size data, and the data type indicates the movie file header. Also, “FILE_CLOSE” is set as a command in “file close”, and FILE_END is set as a command in “BG processing end”.

  By executing “file writing” by the BG process, the total size value is added to the size information of the movie file header. In addition, the “file close” is executed by the BG process, so that the size information of the directory entry (size information written based on the process of step S15) is updated from “0” to the total size value, and is created this time. The FAT information in the FAT area 501c is updated so that a link is formed in the written area of the movie file. The BG process is terminated by “BG process end”.

  In order to write the total size value in the movie file header, it is necessary to update the write destination address. In practice, “seek processing” is set in the instruction list 52a prior to the setting of “file write” in step S105. Is set.

  The BG processing task follows the flowcharts shown in FIGS. First, in step S121, the list number L of the reading destination is set to “0”, and in the subsequent step S123, it is determined whether or not the command read from the list number L is FILE_STRT. If “YES” here, the list number L is incremented in a step S125, and the contents of the command read from the incremented list number L are discriminated in each of the steps S127, S131, S135, S139, and S147.

  If the read command is FILE_CREATE, “YES” is determined in the step S127, and a file creating process is performed in a step S129. Specifically, the recording medium 50 is specified by the drive number set in the parameter 1, and based on the file path set in the parameter 2, the file name and the size information indicating the size 0 are displayed in the directory entry of the recording medium 50. Write. When the process is finished, the process returns to step S125.

  If the read command is FILE_SET_ALLOC, YES is determined in step S131, and table creation processing is performed in step S133. That is, the recording medium 50 is specified by the drive number set in the parameter 1, and the free space table 52c shown in FIG. 7 is created with reference to the FAT information. When the process is finished, the process returns to step S125.

  If the read command is FILE_OPEN, the process proceeds from step S135 to step S137, and file open processing is performed. That is, the recording medium 50 is specified by the drive number set in the parameter 1, the file is specified based on the file path set in the parameter 2, and the handle number assigned to this file is created. The created handle number is used for photographing processing. When the process is finished, the process returns to step S125.

  If the read command is FILE_WRITE, the process proceeds from step S139 to step S141, and file write processing is performed. Specifically, the movie file to be written is specified by the handle number set in parameter 1, and the read start address and read size are specified in accordance with the SDRAM address and data size set in parameters 2 and 3. Then, based on the read start address and the read size, data is read from the SDRAM 26 in units of words, and the read data is given to the CPU 50a of the recording medium 50 together with the write destination movie file information.

  If the read size set in parameter 3 is larger than the buffer memory 50b provided in the recording medium 50, a BUSY signal is returned from the CPU 50a to the CPU 52 when the buffer memory 50b is full. The process of step S141 is interrupted in response to the BUSY signal. When a sufficient free space is secured in the buffer memory 50b by data transfer from the buffer memory 50b to the hard disk 50c, a READY signal is returned from the CPU 50a to the CPU 52. The processing in step S141 is resumed in response to this READY signal.

  When the transfer of the data corresponding to the read size set in parameter 3 to the recording medium 50 is completed, the read size is accumulated and the FAT indicating the link state of the write cluster every time one cluster is written. Create information. The integrated value of the data size and the FAT information are held in the SDRAM 26.

In step S143, the data type set in parameter 4 is determined. If the data type is not “JPEG raw data”, the process directly returns to step S125. If the data type is “JPEG raw data”, the calculation according to Equation 9 is executed in step S145, and then the process returns to step S125.
[Equation 9]
BG_RemData = BG_RemData-JPEG raw data size value According to Equation 9, the data size set in the parameter 3 is subtracted from the variable BG_RemData. As a result, the variable BG_RemData indicates the size of JPEG raw data set in the instruction list 52a but not yet recorded on the recording medium 50.

  If the read command is FILE_CLOSE, the process advances from step S147 to step S149 to perform file close processing. Specifically, the size information assigned to the file name of the open movie file is updated with the total size value held in the SDRAM 26, and the FAT information in the FAT area 501c is updated with the FAT information held in the SDRAM 26. . When the process is completed, the process returns to step S125.

  If the read command is FILE_END, NO is determined in step S147, and the process returns to step S121. The BG process shifts to a standby state.

  As can be seen from the above description, a plurality of frames of YUV data forming a moving image are recorded on the recording medium 50 in a compressed state under the control of the CPU 52 equipped with a multitask OS. Here, the plurality of tasks executed by the CPU 52 include an imaging processing task related to compression processing of a plurality of frames of YUV data, and a BG processing task related to recording processing of a plurality of frames of JPEG data. Further, the photographing process task includes a determination process (S63) for periodically determining the recording processing speed of JPEG data, and a change process (S79) for changing the compression rate of the YUV data based on the determination result.

  In a multitasking OS, each of a plurality of tasks is executed only in a time division manner. Then, the recording processing speed of JPEG data varies depending on the load variation of each task. The zoom circuit 22a once writes the raw image data to the SDRAM 26 through the bus B1 and the memory control circuit 24 when the enlargement zoom is selected by the zoom key 64, and part of the raw image data through the bus B1 and the memory control circuit 24. Read-out and enlargement zoom are performed on the read raw image data. For this reason, even when the enlargement zoom is selected, the recording processing speed is reduced due to the decrease in the occupation ratio of the bus B1. Therefore, in this embodiment, the recording processing speed is periodically determined, and the compression rate of the YUV data is changed according to the determination result. Thereby, it is possible to control the continuous recordable time of moving images.

  In this embodiment, image compression is performed using the JPEG method, but the MPEG method may be adopted instead of the JPEG method, and the target size value may be updated in units of GOPs.

  In this embodiment, the target size value is updated every 30 frames. However, in order to facilitate software calculation, a frame corresponding to a power of 2 such as 32 frames, 64 frames, and 128 frames. The target size may be updated every number.

  Further, in this embodiment, the threshold used for determining whether or not to adjust the number of frames is set to the amount of audio data equivalent to one frame (= 268 bytes), but this threshold is an integral multiple of 268 bytes. It is good.

  In this embodiment, the number of frames of JPEG data is adjusted when performing the recording process. However, the number of frames may be adjusted during the reproduction process.

  Further, in this embodiment, thinning / interpolation is performed on both access information and index information. However, when controlling the reproduction order of JPEG data based only on index information, thinning / interpolation is performed only on index information. May be applied. As a result, it is possible to prevent the loss of JPEG data due to the access information thinning process.

  Furthermore, in this embodiment, the FAT system is employed as the moving image signal recording system, but a UDF (Universal Disk Format) system may be employed instead.

  Furthermore, although this embodiment has been described using a digital video camera, it goes without saying that the present invention can also be applied to, for example, a stationary hard disk recorder for recording TV programs.

It is a block diagram which shows one Example of this invention. It is an illustration figure which shows an example of the mapping state of SDRAM. It is an illustration figure which shows another example of the mapping state of SDRAM. It is an illustration figure which shows an example of a structure of an instruction | indication list. It is an illustration figure which shows an example of a structure of an access information table. It is an illustration figure which shows an example of a structure of a recording medium. It is an illustration figure which shows an example of a structure of an empty area table. It is an illustration figure which shows the structure of the movie file of a completion state. It is an illustration figure which shows a part of creation processing of index information. It is an illustration figure which shows a part of creation processing of an access information table. It is an illustration figure which shows another part of creation processing of index information. It is an illustration figure which shows another part of creation processing of an access information table. It is a flowchart which shows a part of operation | movement of CPU when performing an imaging | photography process task. It is a flowchart which shows a part of other operation | movement of CPU when performing an imaging | photography process task. It is a flowchart which shows a part of other operation | movement of CPU when performing an imaging | photography process task. It is a flowchart which shows a part of further another operation | movement of CPU when performing a photographing process task. It is a flowchart which shows a part of other operation | movement of CPU when performing an imaging | photography process task. It is a flowchart which shows a part of other operation | movement of CPU when performing an imaging | photography process task. It is a flowchart which shows a part of further another operation | movement of CPU when performing a photographing process task. It is a flowchart which shows a part of operation | movement of CPU when performing a BG processing task. It is a flowchart which shows another part of operation | movement of CPU when performing a BG processing task.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Digital video camera 12 ... Image sensor 22, 38, 40 ... Signal processing circuit 26 ... SDRAM
32 ... JPEG codec 34 ... Microphone 44 ... Recording medium 52 ... CPU

Claims (5)

In a moving image recording apparatus that includes a processor equipped with a multitask OS and records image data of a plurality of screens forming a moving image on a recording medium in a compressed state.
The plurality of tasks executed by the processor includes a first task related to the compression processing of image data and a second task related to the recording processing of compressed image data,
The first task includes an addition process for adding a value corresponding to the size of the compressed image data corresponding to the first number of screens to a predetermined parameter value each time image data corresponding to the first number of screens is compressed. ,
The second task subtracts a value corresponding to the size of compressed image data corresponding to the second screen from the predetermined parameter value every time compressed image data corresponding to the second number of screens is recorded. And the first task further includes a change process for changing the compression rate of the image data so as to increase as the predetermined parameter value increases.   The moving image recording apparatus according to claim 1, wherein the second task includes a transfer process for transferring the compressed image data to the recording medium by a specified amount. Further comprising a capturing means for capturing the image data of the plurality of screens according to a capturing condition;
The moving image recording apparatus according to claim 1, wherein the plurality of tasks further includes a third task related to adjustment of the capturing condition. The capturing means includes photographing means for photographing a subject,
The moving image recording apparatus according to claim 3, wherein the capturing condition includes a photographing condition of the photographing unit.   5. The moving image recording apparatus according to claim 1, wherein the predetermined parameter value indicates a size of image data that has been compressed but not yet recorded.

Images