JP3716977B2 - Video file generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a moving image file generation device, and more particularly to a moving image file generation device that stores a compression-coded moving image in a file as a sample for each frame.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a moving image file generation apparatus has been proposed in which compression coding is performed at a low coding frame rate, for example, 0.5 frames per second (that is, 1 frame per 2 seconds), and the compression-coded moving images are stored in files as samples Has been. This type of conventional moving image file generation apparatus will be described with reference to FIGS.
[0003]
FIG. 5 is a block diagram showing a configuration of an MP4 file generation apparatus which is a standard file format of MPEG-4, for example, and FIG. 6 is a block diagram showing a specific configuration of the video encoder 31 of FIG.
[0004]
As shown in FIG. 5, the MP4 file generation apparatus includes a video encoder 31 that encodes an input image signal a at a predetermined encoding rate, an audio encoder 32 that encodes an input audio signal b, and a compression code. A buffer 33 for temporarily storing the encoded image data, a buffer 34 for temporarily storing the encoded audio data, and a file generated by multiplexing the encoded video data, the video bit stream as the audio data, and the audio bit stream When the file generation is finished, an end command c is input from the terminal 40.
[0005]
As shown in FIG. 6, the video encoder 31 includes an encoder 41, an end code generator 42, an adder 43, and an AND gate 44. The operation of the video encoder 31 will be described with reference to the flowchart of FIG.
[0006]
In step S11, it is determined whether or not the time for video encoding has come. If this determination becomes affirmative, the encoding unit 41 starts encoding. In step S12, the bit stream g from the encoding unit 41 is output to the buffer 33 and stored. In step S13, it is determined whether or not the encoding of one frame has been completed. If this determination is negative, the process returns to step S12, and the encoding and output of the bit stream g to the buffer 33 are continued.
[0007]
If it is determined in step S13 that the encoding of one frame has been completed, the process proceeds to step S14 to determine whether or not the end command c from the terminal 40 has been issued. When this determination is negative, the process proceeds to step S15, and the frame encoding completion message d is output. Next, the process returns to step S11. When, for example, 2 seconds elapses, the determination in step S11 becomes affirmative and the process proceeds to step S12. Thereafter, the above-described operation is repeated.
[0008]
Next, when the determination in step S14 is affirmative, the process proceeds to step S16, where the end code generation unit 42 generates a sequence end code f, and the sequence end code f is added to the end of the bit stream output e. Next, the process proceeds to step S17, where the frame encoding completion message d is output, and in step S18, the encoding stop signal h is output.
[0009]
When the video encoder 31 operates as described above, the multiplexing / file generating unit 35 in FIG. 5 receives the bit stream for one frame from the buffers 33 and 34 and one frame of the image signal when the frame encoding completion signal d is received. The audio bit stream corresponding to the time corresponding to is extracted, multiplexed in a predetermined format, and then output to a file. The encoding stop signal h output in step S18 is input to the audio encoder 32 and the multiplexing / file generating unit 35 to stop these operations.
[0010]
[Problems to be solved by the invention]
Since the sequence end code f of the video bit stream is defined by a video encoding standard such as MPEG-4 Visual, it is natural that the video encoder 31 generates the end code f as described above. It was. However, considering the output of a video bitstream in a file format such as MP4, which is an international standard format that is defined to generate a file in units of frames, the following problems arise.
[0011]
That is, with respect to the last frame of the sequence, after the end command c is issued, the end of encoding of the next frame is waited, and the video stream bit stream and the sequence end code f are combined to generate a file as frame information g Will have to do.
[0012]
As a result, when the encoding frame rate is as low as 0.5 frames per second, for example, as shown in FIG. The problem that it cannot be terminated arises. 8 shows video bit streams g1, g2, g3,..., Gn, g (n + 1) output from the video coder 31, and the lower part is multiplexed by the multiplexing / file generating unit 35. Indicates the data to be converted. As is apparent from the figure, when the end command c is issued immediately after the video bit stream gn, the end code f is added to the video bit stream g (n + 1), and the sequence is ended. It takes about 2 seconds from the issue to the end of file generation.
[0013]
Since the video bit stream g (n + 1) for at least one frame and the audio bit stream corresponding to the period are output to the file after the end command c is issued, these unnecessary information is stored in the file. This causes a problem that efficiency and accuracy are poor.
[0014]
An object of the present invention is to provide a moving image file generation device that solves the above-described problems of the prior art, terminates file generation early when an end command is issued, and prevents unnecessary information from being included in the file. It is to provide.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a moving image file generating apparatus for storing a compressed and encoded moving image in a file for each frame, and an accumulating means for accumulating a video bit stream that has been subjected to compression encoding. A file generation unit that extracts a video bitstream from the storage unit and generates a file; a sequence end code generation unit that generates a sequence end code when receiving an end command instructing the end of file generation; and sends the sequence end code to the file generation unit And the file generation means extracts the video bit stream that has been compression-encoded from the storage means upon receipt of the sequence end code, and adds the sequence end code to the video bit stream. There is a first feature.
[0017]
According to this feature, when the end command is issued, the file generation can be completed at an early stage, and unnecessary information can be prevented from being included in the file.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a specific example of the video encoder of FIG.
[0019]
As shown in FIG. 1, the moving image file generating apparatus of the present embodiment includes a video encoder 1 that compresses and encodes an input image signal, an audio encoder 2 that encodes an input audio signal b, and the video encoder 1. A buffer 3 for temporarily storing a video bit stream output e of the video encoder, a buffer 4 for temporarily storing an audio bit stream output from the audio encoder 2, and a sequence end code f from the video sequence end code generating unit 6 as a bit stream. A video sequence end code generation that generates a sequence end code f triggered by an end command c input via a terminal 7 and a multiplexing / file generation unit 5 that performs multiplexing by adding to the end of the file and then generates a file It consists of part 6. The multiplexing / file generating unit 5 includes 1 frame buffers 5a and 5b connected to the buffers 3 and 4 and a multiplexing / file generating unit 5c.
[0020]
The video encoder 1 includes an encoding unit 11 as shown in FIG. The operation of the encoding unit 11 will be described with reference to the flowchart of FIG. In step S1, it is determined whether an end command c has been issued. If this determination is negative, the process proceeds to step S2 to determine whether it is time to encode. When the determination is affirmative, the process proceeds to step S3, where the input image signal a is encoded and the video bit stream e is output to the buffer 3. In step S4, it is determined whether or not the encoding of one frame has been completed. If this determination is negative, the process returns to step S3 to continue the encoding and output to the buffer 3. When the encoding of one frame is completed and the determination in step S4 becomes affirmative, the process proceeds to step S5, and a frame encoding completion message d is output. The frame encoding completion message d is input to the multiplexing / file generating unit 5c. Thereafter, the above-described operation is repeated.
[0021]
Thereafter, when an end command c is issued, the determination in step S1 is affirmative, and the operation of the video encoder 1 is immediately ended.
[0022]
Next, the operation of the moving image file generation device will be described with reference to FIG. Normally, when receiving the frame encoding completion message d from the video encoder 1, the multiplexing / file generating unit 5c extracts a video bit stream and an audio bit stream for one frame from the 1 frame buffers 5a and 5b, After multiplexing with, output the file.
[0023]
When the end command c is input through the terminal 7, the video encoder 1 immediately stops its operation, and similarly, the audio encoder 2 immediately stops its operation. The video sequence end code generator 6 outputs a sequence end code f using the end command c as a trigger.
[0024]
In the 1-frame buffers 5a and 5b, a bit stream of one frame that has already been encoded and an audio bit stream corresponding to the video bit stream period for the one frame are stored. Therefore, when the end command c is input, the multiplexing / file generating unit 5c extracts a video bit stream for one frame from the one-frame buffer 5a and adds a sequence end code f (or video end code) to the end thereof. Then, a file is generated by multiplexing with the audio bit stream extracted from the one frame buffer 5b, and the file is output. For example, in the case of ISO / IEC 14496-2 (MPEG-4 Visual), the sequence end code f is 4 bytes in hexadecimal (000001B1).
[0025]
FIG. 4 shows a timing chart of multiplexing and file generation of this embodiment. The video bitstreams e1, e2, e3,... En encoded by the video encoder 1 are multiplexed with the audio bitstream with a delay of one cycle (for example, 2 seconds) and output to a file. When the end command c is issued, the multiplexing / file generation unit 5c receives the end command c, extracts the video bit stream en from the 1-frame buffer 5b, and adds the sequence end code f.
[0026]
Therefore, according to the present embodiment, as soon as the end command c is issued, the multiplexing of the video bit stream and the audio bit stream and the file generation operation are completed, and the moving image file generation can be ended. .
[0027]
In the above-described embodiment, an example of multiplexing and file generation has been described. However, the present invention is not limited to this, and can be applied to an apparatus that simply generates a video bitstream as a file. Further, the configuration of the above-described embodiment is merely an example, and it is obvious that other embodiments within the scope not departing from the gist of the present invention are included in the present invention.
[0028]
【The invention's effect】
As is apparent from the above description, according to the first to third aspects of the invention, when the end command is issued, the file generation can be terminated at an early stage, and unnecessary information is not included in the file. can do.
[0029]
As a result, the efficiency of moving image file generation is improved and the accuracy of the file contents is improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.
2 is a block diagram illustrating a configuration of a video encoder in FIG. 1. FIG.
FIG. 3 is a flowchart for explaining the operation of the video encoder;
FIG. 4 is a timing chart showing a main part of the operation of the present embodiment.
FIG. 5 is a block diagram showing a configuration of a conventional apparatus.
6 is a block diagram illustrating the configuration of the video encoder in FIG. 5. FIG.
7 is a flowchart for explaining the operation of the video encoder of FIG. 5;
FIG. 8 is a timing chart showing a main part of the operation of the conventional apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Video encoder, 2 ... Audio encoder, 3, 4 ... Buffer, 5 ... Multiplexing / file generation device, 5a, 5b ... 1 frame buffer, 5c ... Multiplexing File generation unit, 6... Video sequence end code generation unit, 11.

Claims (3)

In a moving image file generation apparatus that stores a compression-coded moving image in a file for each frame,
Storage means for storing a video bitstream that has been compression encoded;
File generation means for extracting a video bitstream from the storage means and generating a file;
A sequence end code generating means for generating a sequence end code when receiving an end command instructing the end of file generation, and sending to the file generating means;
When the file generation means receives the sequence end code, it extracts a video bit stream that has been compression-encoded from the storage means, and adds the sequence end code to the video bit stream. apparatus. A storage means for storing the encoded audio bitstream;
When the file generation means receives the sequence end code, it extracts a video bit stream and an audio bit stream that have been compression-encoded from the storage means, adds the sequence end code to the video bit stream, and multiplexes them. The moving image file generating device according to claim 1.   The moving image file generating apparatus according to claim 1, wherein the storage unit is a one-frame buffer.

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