JP5178355B2 - Recording device - Google Patents

Description

  The present invention relates to a recording apparatus that uses a plurality of types of recording media having different recording area management methods.

  In recent years, digital cameras and digital video cameras that record captured images on a randomly accessible recording medium such as a memory card or a hard disk drive have become widespread. As a recording format of a recording medium used in these devices, a file system that manages a used area and an unused area with a management table (File Allocation Table) is known. In this file system, when there is a file write request, an unused area is found by referring to the management table, and the file is sequentially written to the unused area. This file system was also adopted by Microsoft's early computer operating system.

  However, in such a file system, when the writing and deletion of the file are repeated, the used area and the unused area are mixed, and the written file is divided. The free area is also divided, and it is difficult to secure a continuous large free area. This is a phenomenon generally called fragmentation or fragmentation. Since file fragmentation causes a decrease in access speed, it becomes a problem at the time of access requiring real-time performance such as moving image recording.

  Even when the above file system is applied to a memory card using a flash memory, the access speed may decrease due to fragmentation. The flash memory has a limited number of rewrites and a large erasure unit (rewrite unit size) (a block unit of several kilobytes to several tens of kilobytes).

  A brief description will be given with reference to FIG. In general, the erase unit or the rewrite unit of the flash memory is larger than the above-described free area management unit (cluster size) of the file system. In the example shown in FIG. 2, 4 clusters are used as an erasing unit. FIG. 2 shows a case where data recorded in the erasure unit recording area A is changed and rewritten to the erasure unit recording area B. FIG. 2A shows a state before the rewriting, and FIG. Indicates the state during and after rewriting.

  In FIG. 2A, unused clusters and used clusters are mixed in the recording area A. The logical address of the recording area A is set from 0x100000 to 0x13ffff.

  Here, it is assumed that it is necessary to write new data to the cluster 2 starting from the logical address 0x110000. In the flash memory, it is impossible to partially overwrite the recording area A. Therefore, data movement and logical address assignment change are performed inside the card. That is, the storage data (old data) in the recording area A is read and combined with the new data, and written in the recording area B of the erasing unit at a position physically different from the recording area A. Then, the logical addresses 0x100,000 to 0x13ffff assigned to the recording area A are assigned to the recording area B. The data to be written to the logical address 0x110000 is actually written to the cluster 2 ′ in the recording area B. The data of the clusters 1 and 3 in the recording area A are copied to the clusters 1 'and 3' in the area B, respectively.

  Such an internal copy operation at the time of rewriting causes a decrease in writing speed. Of course, fragmentation proceeds even when viewed by physical address. As for reading, even if it is fragmented, the copying operation as described above is not involved, so the speed reduction is negligible.

  On the other hand, in a hard disk, the frequency of physical movement of the magnetic head due to fragmentation increases, and the speed of both reading and writing decreases.

  For such a problem, Patent Document 1 describes the following technique. That is, a distinction is made between data that requires real-time writing (real-time data) and data that does not (non-real-time data). Then, based on the free space information of the recording medium, real-time data is written in a relatively high transfer rate area, and non-real-time data is written in a relatively low transfer rate area.

  In recent years, some memory cards using a flash memory have defined a minimum guaranteed recording rate that takes into account a decrease in speed due to fragmentation. For example, Secure Digital Specialties Physical Layer Spec. Version 2.0 defines a speed class for enabling real-time data represented by moving images to be recorded without failure. The speed class will be described with reference to FIG.

  The recording area on the memory card is divided by a unit called AU (Allocation Unit), and the degree of fragmentation is measured for each AU. The size of the AU is determined for each card according to the erase unit of the flash memory inside the memory card. The minimum recording unit of real-time data in recording to which the speed class is applied is referred to as RU (Recording Unit). The RU is defined as an integer multiple of the cluster size of the management table method described above. When all the clusters in the RU are unused clusters, the RU is treated as an unused RU. The AU is composed of a plurality of RUs. The minimum recording speed for unused RUs in the AU is defined according to the ratio of used RUs among all the RUs constituting the AU. The lower the ratio of used RU, the higher the recording speed. By selecting an AU that can be recorded at a speed higher than the bit rate of the recording data, real-time data can be reliably recorded on the card.

A specific example will be described with reference to FIG. In the example shown in FIG. 3, when the empty RU rate in the AU is 100%, the writable speed is set to 6 MB / sec. Similarly, 4 MB / sec is set for 75%, 2 MB / sec for 50%, and 1 MB / sec for 25%. When a stream with a bit rate of 3 MB / sec is recorded in real time on this memory card, recording at a bit rate of stream data can be continued by using an area where the ratio of unused RU is 100% or 75%.
JP 2000-267904 A

  In recent years, video cameras capable of using a plurality of recording media having different recording area management characteristics such as a memory card and a hard disk have appeared. In addition to real-time video recording / playback, video cameras having a function of copying content between recording media, a function of easily editing content, and the like have also appeared.

  Due to the increase in the capacity of recording media, it is conceivable that the user may repeatedly use operations such as recording, playback, editing, and deletion of a large amount of content, and fragmentation of files on the recording medium is likely to proceed. It can be said that it has come.

  In the prior art, even when a plurality of recording media can be used in combination, the writing / reading speed characteristics corresponding to the fragmentation rate are not taken into consideration for each type of recording medium. Simply, a uniform control method of selecting a write destination area according to the real-time property / bit rate of data at the time of writing is simply applied. Therefore, for example, a memory card has a problem that high-speed reading is not used even in a fragmented area. Further, there is a problem that a free area is not used effectively because a fragmented area is not used.

  An object of the present invention is to solve such problems, and to provide a recording apparatus that is resistant to fragmentation and that effectively uses a free area.

In order to achieve the above object, a recording apparatus according to the present invention includes a generating unit that generates moving image data, a first recording medium interface that writes the moving image data to a first recording medium, and a moving image from a second recording medium. A second recording medium interface for reading data; a first mode in which the moving image data generated by the generating means is written to the first recording medium; and the moving image data recorded on the second recording medium Mode switching means for switching the second mode written to one recording medium, and control means for controlling the first recording medium interface based on unused areas included in each of the plurality of recording areas of the first recording medium In the first mode, the control means includes a size of the unused area among a plurality of recording areas of the first recording medium. A first area larger than the second area is selected, and the moving image data generated by the generating unit is written to the selected first area. In the second mode, the second area The first recording medium interface is controlled so that the moving image data recorded on the second recording medium is written to the second area when the reading speed is higher than the reading speed corresponding to the rate of the moving image data. characterized in that it.

  According to the present invention, in a recording apparatus that uses a plurality of recording media having different characteristics, it is possible to effectively use a free space while guaranteeing real-time recording / reproduction as much as possible even when fragmentation occurs. .

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

  FIG. 1 is a schematic block diagram of a video camera 10 according to an embodiment of the present invention.

  The video camera 10 includes a memory card 30 using a flash memory and a hard disk drive (HDD) 34 as a plurality of recording media having different recording area management methods, and the captured moving image data is designated by the HDD 34 and the memory card 30. Can be recorded. The memory card 30 is an example of a recording medium that writes data with a rewrite size exceeding the free space management unit of the file system and reads data with a size smaller than the free space management unit. The HDD 34 is an example of a recording medium that reads and writes data with a size equal to or smaller than the free space management unit of the file system.

  The video camera 10 of this embodiment also has a real-time recording mode and a copy mode as operation modes. In the real-time recording mode, stream data including a photographed video is recorded on the memory card 30 or the HDD 34 in real time. In the copy mode, recording data, for example, stream data is copied between the memory card 30 and the HDD 34.

  The imaging unit 12 converts the optical image of the subject into an electrical signal. The video signal processing unit 14 A / D converts the video signal from the imaging unit 12 and performs predetermined image processing such as gamma correction, color balance adjustment, and color conversion. The frame memory 16 is used to temporarily store the image data from the video signal processing unit 14 for display and recording processing.

  The microphone 18 takes in external audio and outputs an audio signal. The audio signal processing unit 20 performs A / D conversion on the audio signal from the microphone 18 and encodes it using the PCM encoding method. The PCM buffer 22 stores the PCM audio data from the audio signal processing unit 20 for recording processing.

  During recording, the codec (CODEC) 24 compresses and encodes the image data stored in the frame memory 16 and the PCM audio data stored in the PCM buffer 22 to generate stream data in a predetermined format. That is, the codec 24 corresponds to stream data generation means. The generated stream data is temporarily stored in the stream buffer 26 and recorded in the memory card 30 through the card interface (I / F) 28 and in the HDD 34 through the HDD interface 32. The codec 24 also decompresses the compressed image data and the compressed audio data of the stream data read from the memory card 30 or the HDD 34 in the reproduction mode.

  The user uses the operation unit 36 for the user to input various instructions to the video camera 10. The display unit 38 is composed of a liquid crystal display panel, and displays video captured by the imaging unit 12 during recording, and displays playback video during playback. The display unit 38 also displays information such as a setting menu for the video camera 10, a recording time, and a remaining battery level.

  A CPU (Central Processing Unit) 40 controls each part of the video camera 10. The file system 42 provides information necessary for writing and reading files on the memory card 30. The write management unit 44 manages writing to the memory card 30 and the HDD 34 in cooperation with the file system 42. The write management unit 44 functions as a recording sequence determination unit.

  Specifically, when the recording destination is the memory card 30, the write management unit 44 calculates the writable speed of each area in the memory card 30 from the fragmentation state of the memory card 30 and the performance information of the memory card 30. To do. In response to the data write request, the write management unit 44 determines a write area on the memory card 30 according to the data bit rate. When the recording destination is the HDD 34, the write management unit 44 performs write control different from these.

  When the memory card 30 is connected, the write management unit 44 acquires necessary information from the memory card 30 by the process shown in FIG. 6 and makes the speed class applicable.

  First, the file system of the connected memory card 30 is mounted (S1), and the AU size is acquired from the memory card 30 (S2). Next, the RU size is determined (S3). The RU size is not less than the cluster size and less than the AU size, and the minimum size is determined by the standard according to the recording rate, and is determined so as to satisfy this.

  An operation when a moving image is recorded on the memory card 30 will be described. In the moving image recording mode, the image signal from the imaging unit 12 is converted into video frame data by the video signal processing unit 14 and stored in the frame memory 16. The audio signal processing unit 20 converts the audio signal from the microphone 18 into PCM audio data and stores it in the PCM buffer 22. The codec 24 encodes and multiplexes these video data and audio data to generate a single stream data. This stream data is buffered in the stream buffer 26. The above processing is performed in parallel during moving image recording, and stream data is continuously written in the stream buffer 26.

  The write manager 44 controls the writing of stream data to the memory card 30 while managing the write area of the memory card 30 so that the stream buffer 26 does not overflow.

  First, the ratio of used RUs (hereinafter referred to as the AU fragmentation rate) is examined for each AU, rearranged in order of size, and held as an AU information table. At this point, the write management unit 44 functions as a free area detection unit. FIG. 4 shows an example of the AU table of the memory card 30. In this embodiment, each AU is managed by being classified into three areas A, B, and C according to the fragmentation rate. Area A is a real-time writable area, and the writing speed defined by the speed class is equal to or higher than the stream bit rate r. Area B is a real-time non-writable area, and the writing speed defined by the speed class is less than the bit rate r of the stream. The area C is an area where there is no empty cluster in the AU and is a used area that cannot be written because all are used areas.

  This AU information table is updated to the latest state every time data is written to the memory card 30 during recording. The area A is used as a real-time data write destination, and the area B is used as a non-real-time data write destination.

  FIG. 7 shows a control flowchart of the write management unit 44. The operation of the write management unit 44 will be described with reference to FIG.

  When recording is started, the recording bit rate r is acquired (S11), and the AU information table is updated (S12). The update of the AU information table is also a process of acquiring the fragmentation rate for each AU and collating it with the recording bit rate r to classify each AU into areas A, B, and C.

  If the size of the area A is equal to or larger than the predetermined value Ath (S13), it is determined that there is a recordable free area, and the recording is continued. Waiting for the accumulation of stream data of at least the minimum writing unit in the stream buffer 26, and monitoring the presence or absence of a recording stop instruction (S14). In this embodiment, the minimum writing unit is an AU size defined for each card.

  When there is a recording end instruction (S15), unwritten data is written to the memory card 30 and the recording is ended (S17).

  If there is no instruction to end recording and stream data of the minimum writing unit or more is accumulated in the stream buffer 26, the stream data is written in the area A (S16). In response to this writing, the AU information table is updated (S12).

  Steps S12 to S16 are repeated during recording.

  An operation in a copy mode for copying data between recording media will be described. Here, an operation of copying moving image stream data from the HDD 34 to the memory card 30 will be described. The user uses the operation unit 36 to select a stream to be copied and instruct to start copying. The stream data of the designated stream is read from the HDD 34 by the HDD interface 32. The read stream data is temporarily buffered by the stream buffer 26 and then written to the memory card 30 by the card interface 28.

  The write management unit 44 controls writing to the memory card 30 as follows. FIG. 8 shows the control flowchart.

  First, the bit rate Rstream is acquired by reading the management file corresponding to the copy source stream (S21). This is an operation corresponding to the bit rate acquisition means. Subsequently, the read (read) speed Pred of the memory card 30 is acquired (S12). This is an operation corresponding to the reading speed acquisition means. This measurement is performed under the condition that a certain number of RUs are randomly read. This speed Read is the read speed under the worst condition in which fragmentation in RU units occurs when accessing in RU units. The read speed Pred acquired here is used later for write control.

  Further, the AU information table of the memory card 30 is acquired (S23). If there is no remaining amount, a warning that there is no remaining amount is displayed (S31), and the process ends. On the other hand, if the remaining amount exceeds a certain amount, the stream is copied (S25 to S30).

  When the read speed Read is higher than the bit rate Rstream of the stream (S25), copying from the HDD 34 to the memory card 30 is executed (S28 to S30). That is, a certain amount of stream data is read from the copy source HDD 34 and written to the stream buffer 26 (S29). The stream data in the stream buffer 26 is written to the memory card 30 in units of RU (S30). Steps S29 and S30 are repeated until copying of all data is completed (S28).

  By setting the unit of writing to the memory card 30 as RU, it is ensured that reading is in time during reproduction. In this embodiment, at the time of copying, first, the area B is selected and data is written. Then, after all the data is written in the AU of the area B, the data is written in the area A.

  By controlling the data writing at the time of copying in this way, it is possible to leave the area A where data can be written at high speed and to make the moving image recording time as long as possible. This also corresponds to copying the recording data of the HDD 34 to an area of the memory card 30 that is equal to or higher than the reading speed corresponding to the recording data rate.

  If the read speed Pred is lower than the bit rate Rstream, that is, slower (S25), continuous reproduction cannot be guaranteed. However, there is no problem for archiving purposes. Therefore, in this case, the display unit 38 displays that the continuous reproduction cannot be guaranteed and notifies the user, and then the user is allowed to select whether or not to continue copying (S26). If the user selects not to copy (S27), the process ends without performing anything. When the user selects to continue copying (S27), as described above, copying is executed in steps S28 to S30.

  The reason why writing to the memory card 30 is in units of RU is to maintain consistency with writing control by speed class. In general, a memory card is much faster to read than to write. Further, even if fragmented, a physical seek as seen in the HDD does not occur. Therefore, by performing such control, it is possible to guarantee continuous reproduction in many cases even for a stream having a high bit rate that cannot meet the real time recording.

  Next, writing control in moving image recording when the HDD 34 is a recording destination will be described. Since the operation itself up to the generation of the stream data is the same as that when the memory card 30 is used as the recording destination, description thereof is omitted.

  The HDD 34 is fixedly connected to the video camera 10. Performances such as seek time and sequential access speed of the HDD 34 are set so as not to fail even during recording of moving image recording. However, if fragmentation progresses, a large amount of seeks may occur, and there is a possibility that buffer overflow will occur without writing the stream data of the moving picture in time. Therefore, the write management unit 44 classifies the recording area in the HDD 34 into the following three areas D, E, and F in units (hereinafter referred to as WU) obtained by dividing the recording area into predetermined sizes that are integral multiples of the cluster size. And manage. Area D is a real-time writable area where all clusters in the area are unused. The area E is an area where used clusters exist in the area, and is a real-time writable area where real-time writing should be avoided. Area F is an area where all the clusters in the area have been used. FIG. 5 is an example of this free area management table.

  When writing is performed on the WU classified in the region D, no seek occurs during writing, and sequential writing is performed. Accordingly, high-speed writing is possible. By appropriately setting the size of the WU according to the bit rate of the recording data, it is possible to avoid the occurrence of seek between writings as much as possible, and recording can be performed without failure. The area E is used as a recording destination for non-real time data.

  FIG. 9 shows a control flowchart of the write management unit 44 when a moving image is recorded in the HDD 34.

  When recording is started, a recording bit rate r is acquired (S41), and a WU size corresponding to the bit rate r is determined (S42). Next, the free space management table is updated (S43). The update of the free area management table is a process of confirming the presence or absence of a used cluster for each WU and reclassifying the areas into areas D, E, and F.

  In the updated free area management table, it is determined that there is a free area if the area D exists more than a certain margin amount (S44). Stream data corresponding to the size of WU is accumulated in the stream buffer 26 or the user's recording end instruction is waited (S45). When the stream data is accumulated in the stream buffer 26 by the size of the WU, the stream data is written to the WU in the area D (S47), and steps S43 and after are repeated.

  If there is an instruction to end recording in the middle (S46), the non-written data is written in the HDD 34 without waiting for the stream accumulation in the writing unit (S48), and the process is ended. Also, in the updated free area management table, even when the area D is less than a certain margin amount (S44), unwritten data is written in the HDD 34 (S48), and the process is terminated.

  By recording the stream data in the area D, it is possible to keep the occurrence frequency of seek due to fragmentation below a certain value, thereby guaranteeing real-time writing.

  When copying stream data from the memory card 30 to the HDD 34, continuous reproduction of the copied moving image stream data is ensured by performing the same write control as when moving images are recorded in the HDD 34 in real time. FIG. 10 shows a control flowchart of the write management unit 44 when the stream data is copied from the memory card 30 to the HDD 34.

  After starting recording, the bit rate r of the stream is acquired (S51), and the WU size corresponding to the bit rate r is determined (S52). Next, the free space management table is updated (S53).

  It is checked whether the area D is larger than the stream size to be copied (S54). If the area D is sufficient, copying is executed (S58 to S61). That is, a certain amount of stream data is read from the copy source memory card 30 and written to the stream buffer 26 (S59). The stream data in the stream buffer 26 is written to the HDD 34 in units of WU (S60), and the free space management table for the HDD 34 is updated (S61). These steps S59 to S61 are repeated until the copying of all data is completed (S58).

  When the area D is less than the stream size (S54), it is checked whether the area E is equal to or larger than the stream size (S55). If the size of the area E is equal to or larger than the stream size, it is determined that continuous reproduction cannot be guaranteed but copying is possible. In this case, after displaying a message indicating that continuous reproduction cannot be guaranteed, the user is inquired whether to continue copying (S56). When the user selects to continue copying (S57), copying is executed (S58 to S61).

  If the necessary amount of the area E does not exist (S55), a message indicating that there is no free area that can be copied is displayed (S62), and the process ends.

It is a schematic block diagram of one Example of this invention. It is explanatory drawing of the speed fall by the fragmentation of the file system in the memory card 30 It is a figure explaining the concept of the speed class in a memory card It is explanatory drawing of the example of AU information management table of the memory card 30. 4 is an explanatory diagram of an example of a free space management table in the HDD. FIG. 4 is a flowchart showing processing when a memory card 30 is inserted into the video camera 10. 4 is a flowchart of write control when recording a moving image on the memory card 30. It is a flowchart figure of the writing control at the time of copying a moving image stream to the memory card 30. 4 is a flowchart of write control when a moving image is recorded in the HDD. 4 is a flowchart of write control when copying a moving picture stream to the HDD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Video camera 12 Image pick-up part 14 Video signal processing part 16 Frame memory 18 Microphone 20 Audio | voice signal processing part 22 PCM buffer 24 Codec 26 Stream buffer 28 Memory interface 30 Memory card 32 HDD interface 34 HDD
36 Operation unit 38 Display unit 40 CPU (Central processing unit)
42 File System 44 Write Manager

Claims (3)

Generating means for generating video data;
A first recording medium interface for writing the moving image data to a first recording medium;
A second recording medium interface for reading moving image data from the second recording medium;
A first mode for writing the moving image data generated by the generating means to the first recording medium, and a second mode for writing the moving image data recorded on the second recording medium to the first recording medium. Mode switching means for switching;
Control means for controlling the first recording medium interface based on unused areas included in each of the plurality of recording areas of the first recording medium
And
In the first mode, the control means selects and selects a first area in which the size of the unused area is larger than the second area among the plurality of recording areas of the first recording medium. The moving image data generated by the generating unit is written to the first area, and in the second mode, the reading speed of the second area is higher than the reading speed corresponding to the rate of the moving image data. In this case, the recording apparatus controls the first recording medium interface so that the moving image data recorded on the second recording medium is written in the second area . The control means, in the second mode, the moving image data recorded on the second recording medium when the reading speed of the second area is not higher than the reading speed corresponding to the rate of the moving image data. The recording apparatus according to claim 1, wherein the recording apparatus inquires of the user whether or not to write the data to the first recording medium. In the second mode, when the user instructs writing after the inquiry to the user in the second mode, the control means stores the second recording medium in the second area of the first recording medium. The first recording medium interface is controlled to write the moving image data recorded on the recording medium. When the user instructs not to write the moving image data, the moving image data is recorded on the second recording medium to the first recording medium. 3. The recording apparatus according to claim 2, wherein the moving image data is not written.

Images