JP4395282B2 - Image and audio playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image / audio recording apparatus, and more particularly to an image / audio reproduction apparatus that is applied to, for example, a digital video camera and reproduces moving image data and audio data recorded on a recording medium.
[0002]
[Prior art]
In a conventional audio / video reproduction apparatus, all moving image data reproduced from a recording medium is once stored in an internal memory, and then subjected to expansion processing by a JPEG compression / decompression circuit and output to a monitor. For example, all of the 30-second moving image data recorded on the recording medium is stored in the internal memory, and then output to the monitor through the decompression process for each frame.
[0003]
However, in such a conventional technique, it is necessary to store all of the moving picture data to be played back in the internal memory, so the amount of data that can be played depends on the capacity of the internal memory, and the moving picture exceeds the capacity of the internal memory. Data cannot be played back. Further, since the reproduction is not started unless the storage of all the moving image data is completed, it takes time to reproduce the moving image.
[0004]
Therefore, a moving image reproducing apparatus for solving the above problems is disclosed in Japanese Patent Laid-Open No. 2000-224535. In this moving image reproducing apparatus, the capacity of the internal memory can be suppressed by intermittently reading out desired image data recorded on the recording medium one frame or a plurality of frames at a time and writing it in the internal memory.
[0005]
However, in the moving image reproducing apparatus described in the above publication, when the moving image data of each frame is read from the recording medium and written into the internal memory is slower than the moving image reproducing rate, the reproduction stops halfway.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and for example, large-capacity moving image data recorded on a recording medium with a low access speed such as CF (Compact Flash (registered trademark)) can be smoothly reproduced. An object of the present invention is to provide an audio / video reproduction apparatus that can be operated smoothly.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, in the video / audio reproduction device of the present invention, when reproducing and displaying moving image data included in an AVI file recorded on a recording medium, the reproduction speed and file capacity included in the header of the AVI file are set. Header information reading means for reading, access speed detecting means for detecting the reading speed of moving image data from the recording medium, and sequentially storing a predetermined amount of moving image data read from the recording medium during reproduction display of the moving image data The moving image data to be stored in the internal memory before the reproduction display of the moving image data in order to compensate the speed difference between the reproducing speed and the reading speed from the internal memory to be stored, the reproduction speed, the file capacity, and the reading speed. An arithmetic circuit for calculating the capacity of the video, and the video data corresponding to the capacity prior to the playback display of the video data. Comprising a video data read-ahead means for storing in said internal memory reads data from the recording medium, and a reproduction displaying unit for displaying play video data recorded in the internal memory.
[0008]
Here, the moving image data includes audio data and image data compressed by a predetermined method. The image data prefetched in the internal memory is intermittently read out frame by frame by the image reading means, and then subjected to expansion processing by the expansion circuit and is output to the monitor. Audio data for one frame corresponding to the image data is also read from the internal memory by the audio reading means and output to the speaker.
[0009]
As described above, by prefetching a predetermined amount of data into the internal memory before reproducing the moving image data, the difference between the speed at which the moving image data is read from the recording medium and written to the internal memory and the moving image reproduction speed can be filled. Therefore, smooth playback can be realized. In addition, since the capacity of the pre-read video data is only the minimum necessary amount calculated by the arithmetic circuit, the capacity of the internal memory can be reduced compared to storing all the video data in the internal memory as in the past, and The time until video playback starts is shortened.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a digital video camera 10 equipped with an image / audio reproduction device of the present invention. The digital video camera 10 includes a CCD imager 12. A color filter is mounted on the front surface of the CCD imager 12, and the subject light is irradiated to the CCD imager 12 through the color filter. When the digital video camera 10 is set to the camera mode by the mode switch 14, the timing generator (TG) 20 and the vertical synchronization signal output from the signal generator (SG) 22 according to the control signal 18 issued from the system controller 16. A timing signal is generated based on the horizontal synchronizing signal, and the CCD imager 12 is driven by a progressive scan method. As a result, shooting data of the subject is output from the CCD imager 12. The output camera signal is subjected to noise removal and level adjustment by the CDS / AGC circuit 24, and then converted to digital image data by the A / D converter 26. The signal processing circuit 28 performs YUV conversion on the image data output from the A / D converter 26 to generate YUV data.
[0012]
The generated YUV data is given to the memory control circuit 32 via the data bus 30a, and the memory control circuit 32 writes the YUV data given via the data bus 30b to the internal memory 34. This is because the CCD imager 12 adopts the progressive scan method, while the monitor 36 adopts the interlaced scan method, and YUV data is temporarily stored in the internal memory 34 for conversion of the scan method. The stored YUV data is then read out by the memory control circuit 32 by the interlace scan method, and is supplied to the video encoder 38 via the data bus 30a. The video encoder 38 generates a composite image signal in accordance with the NTSC format from the input YUV data and inputs the composite image signal to the monitor 36. As a result, the moving image of the subject is displayed on the monitor 36 in real time.
[0013]
When the user presses the shutter button 40 once, the system controller 16 issues a control signal 18. The CPU 42 receives the control signal 18 and activates the microphone 44, the A / D converter 46, and the signal processing circuit 48. The signal processing circuit 48 performs predetermined processing on the audio data input via the microphone 44 and the A / D converter 46, and the processed audio data is written into the internal memory 34 via the memory control circuit 32.
[0014]
On the other hand, as the shutter button 40 is pressed, the CPU gives an image data compression command to the JPEG compression / decompression circuit 50. The JPEG compression / decompression circuit 50 outputs a YUV data read request to the memory control circuit 32 and compresses the YUV data for one frame output in response to the request. The compressed image data is stored again in the internal memory 34 via the data buses 30a and 30b.
[0015]
Unless the shutter button 40 is pressed again by the user, the digital video camera 10 continues to collect audio data and compress the JPEG compression / decompression circuit 50. Therefore, the audio data and the compressed image data are continuously stored in the internal memory 34. When the shutter button 40 is pressed, the CPU 42 disables the microphone 44, the A / D converter 46, and the signal processing circuit 48, and cancels the compression command to the JPEG compression / decompression circuit 50. The memory control circuit 32 is then given a read command for the stored audio data and compressed image data. In response to this, the memory control circuit 32 alternately reads out audio data for 1 second and compressed image data for 15 frames, and the read audio data and compressed image data are sequentially recorded on the recording medium 52 as an AVI file. It will be done.
[0016]
FIG. 2 shows the structure of the AVI file. Since the AVI file header 54 is newly created in the recording medium 52 when the shutter button 40 is operated for the first time, the audio data and the compressed image data are sequentially written after the header 54. In this embodiment, a moving image for one second consists of 15 frames, and an audio data block 56 consisting of audio data for one second and an image data block 58 consisting of compressed image data for 15 frames following each other. It shall correspond.
[0017]
In the header 54 of the AVI file, header information 60 such as the total moving image file capacity, the total number of frames, and the moving image reproduction speed, and the thumbnail image data 62 of the first frame are written. In the index 64 provided at the end, each audio data block 56 and the start address of each image frame are written. With the information written in the index 64, the audio data is managed every second and the compressed image data is managed every frame.
[0018]
When the digital video camera 10 is set to the playback mode by the mode changeover switch 14 and a desired AVI file is selected, the CPU 42 detects the selected AVI file from the recording medium 52 and displays the information of the header 54 and the index 64. Read and write to the memory 42a provided in the CPU 42. The CPU 42 includes an access speed detection circuit 42b that detects the reading speed of the moving image data from the recording medium 52, and an arithmetic circuit 42c that calculates a prefetched data amount from the detected access speed and the header information 60. After the amount of image data is stored in the internal memory 34, the reproduction of the moving image is started.
[0019]
Specifically, FIG. 3 shows an operation flow when the digital video camera 10 is set to the playback mode. First, in step S100, the CPU 42 detects the access speed to the recording medium 52. Next, in step S102, when the user selects a desired AVI file from a plurality of AVI files recorded on the recording medium 52, in step S104, the CPU 42 is described in the header 54 and index 64 of the selected AVI file. Management information is read and stored in the memory 42a. At the same time, since the read header information 60 is displayed on the monitor 36, the user confirms that the selected AVI file is correct and presses the set key 66 in step S106.
[0020]
When the set key 66 is pressed, the CPU 42 detects the moving image playback speed and the total moving image file capacity from the header information 60 of the selected AVI file in step S108. In step S110, the difference between the access speed to the recording medium 52 detected in step S100 and the information such as the moving image playback speed detected in step S108, that is, the capacity of the prefetched moving image data is calculated. For example, when the access speed to the recording medium 52 is 0.9 MB / s, the moving image playback speed is 1.0 MB / s, and the total file capacity is 30 MB, the capacity of the pre-read moving image data is 3 MB.
[0021]
Next, in S112, the CPU 42 gives an instruction to store the moving image data in the internal memory 34 for the calculation result obtained in S110. That is, in the case of the above example, 3 MB of moving image data from the beginning of the AVI file is read from the recording medium 52 and stored in the internal memory 34 before starting the reproduction of the moving image.
[0022]
When the storage of the moving image data for the calculation result is completed, the reproduction of the moving image is started. FIG. 4 shows a flow when reproducing a moving image. First, in step S114, a frame number i = 0 is given. In step S116, the moving image data detection circuit 42d provided in the CPU 42 detects whether or not the i-th moving image data with the frame number i is stored in the internal memory 34. If the i-th moving image data is stored, the process proceeds to steps S118 and S120. As will be described in detail later, reproduction of the i-th image data and reproduction of audio data are executed.
[0023]
Thereafter, when unstored moving image data is read from the recording medium 52 by a certain amount and stored in the internal memory 34 in step S122, the calculation of i = i + 1 is performed in step S124, and the frame number is advanced by one. In step S126, it is determined whether the frame number i newly set in S124 is smaller than the total number of frames j. If i <j is satisfied, the flow returns to S116, and the image and sound of the next frame are reproduced by repeating steps S116 to S126 again. The flow from S116 to S126 is set to be completed once in 1/15 seconds. When the flow from S116 to S126 is repeatedly executed, the reproduction of the image and sound is performed every 1/15 seconds. Implemented intermittently. On the other hand, if i <j is not satisfied, it means that all the frame images have been reproduced, and the process proceeds to step S128 and the process ends.
[0024]
Here, the image reproduction process in step S118 and the audio reproduction process in step S120 will be specifically described. In the image reproduction process of step S118, the CPU 42 instructs the JPEG compression / decompression circuit 50 to decompress the i-th compressed image data stored in the internal memory 34. The JPEG compression / decompression circuit 50 reads compressed image data for one frame from the internal memory 34 through the memory control circuit 32 and performs decompression processing. The decompressed image data for one frame is written into the display image area 34a in the internal memory 34 via the memory control circuit 32 again. Since the display image area 34a for storing the decompressed image data has a capacity of only one frame, the display image area 34a is overwritten every 1/15 second when the flow from step S116 to S126 is repeated. . The image data in the display image area 34a is read in response to a command output from the video encoder 38 every 1/15 second, and the video encoder 38 converts the image data into a composite image signal and outputs it to the monitor 36. As a result, when the flow of steps S116 to S126 is repeated, a moving image composed of 15 still images per second is displayed on the monitor 36.
[0025]
In the audio output process in step S116, the CPU 42 instructs the signal processing circuit 48 to perform audio processing every 1/15 second. In response to this command, the signal processing circuit 48 reads out audio data from the internal memory 34 through the memory control circuit 32 every 1/15 second and performs predetermined processing. When the processing is completed, the audio data is output from the speaker 70 via the D / A converter 68.
[0026]
If it is not detected in step S116 of FIG. 4 that storage of the i-th moving image data in the playback frame is detected, the flow proceeds to step S130 and playback is paused.
[0027]
Next, while the reproduction is paused, the CPU 42 detects the remaining file capacity in step S132. The CPU 42 calculates the prefetching amount of the moving image data again in step S134 from the detected remaining file capacity and the access speed detected in step S100. In step S136, the CPU 42 gives an instruction to record the unreproduced portion of moving image data in the internal memory 34 by the amount of pre-read from the desired AVI file stored in the recording medium 52. Note that during the steps S130 to S136, the digital video camera 10 does not accept a user's instruction to resume moving image playback. For this reason, smooth playback can be realized for a certain period of time after resuming moving image playback.
[0028]
When the prefetching of the moving image data of the unreproduced part is completed in step S136, the flow returns to step S116 and the reproduction of the moving image starts again. In step S126, the playback of the moving image is temporarily stopped because the frame number i is larger than the total number of frames j of the desired AVI file in step S126, or the processing is finished again, or the moving image data for the i-th playback frame is not detected again in step S116. Continue until it stops.
[0029]
In the above-described embodiment, the video / audio reproduction device of the present invention is mounted on the digital video camera 10, but can be applied to other electronic devices such as a digital camera, a PC, and a PDA.
[0030]
In the above-described embodiment, the image data read out and reproduced from the recording medium 52 is compressed image data compressed by the JPEG method, but the present invention reproduces compressed image data compressed by the MPEG method. It can also be applied to. However, data compressed by the MPEG method has a stream structure, and only the reference frame has image information for one frame. For this reason, after the reproduction is paused, it is necessary to bring a reference frame provided every other frame at the head of the resumed image data.
[0031]
【The invention's effect】
As described above, according to the present invention, there is provided an arithmetic circuit that calculates the capacity of video data to be pre-read for smooth playback of a video from information such as the total file capacity and playback speed and the access speed. Smooth moving image reproduction can be realized by reading out moving image data by the capacity calculated by the arithmetic circuit before reproduction and writing it in the internal memory. In addition, since the capacity of the prefetched video data is only the minimum necessary amount calculated by the arithmetic circuit, the capacity of the internal memory can be smaller than when all the video data is stored in the internal memory as in the past. In addition, the time until the start of moving image playback is shortened.
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital video camera equipped with an image / sound reproduction apparatus of the present invention.
FIG. 2 is an illustrative view showing a structure of an AVI file.
FIG. 3 is a flowchart showing a part of the operation of the video / audio reproduction device.
FIG. 4 is a flowchart showing another part of the operation of the video / audio reproduction device.
[Explanation of symbols]
30a, 30b Data bus 34 Internal memory 36 Monitor 42c Arithmetic circuit 52 Recording medium 54 Header 70 Speaker

Claims (1)

In an audio / video reproduction apparatus for reproducing and displaying moving image data included in an AVI file recorded on a recording medium,
Header information reading means for reading the playback speed and file capacity included in the header of the AVI file;
Access speed detecting means for detecting the reading speed of the moving image data from the recording medium;
An internal memory for sequentially storing a predetermined amount of moving image data read from the recording medium during reproduction and display of the moving image data;
In order to compensate for the speed difference between the reproduction speed and the reading speed, the capacity of the moving picture data to be stored in the internal memory before the reproduction display of the moving picture data is calculated from the reproduction speed, the file capacity, and the reading speed. An arithmetic circuit;
Prior to reproducing and displaying the moving image data, moving image data pre-reading means for reading moving image data corresponding to the capacity from the recording medium and storing it in the internal memory;
A video / audio reproduction device comprising: reproduction display means for reproducing and displaying the moving image data recorded in the internal memory .

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