JPH04285769A - Multi-media data editing method - Google Patents

Abstract

PURPOSE:To improve utilization efficiency of a storage area by synchronous video data with audio data while using a time code and combining both data by frame unit. CONSTITUTION:A time code is written on image data constructed in frames in a TC writing circuit 2 and the data are coded in a video encoder for compression. A recording starting time code is added to only the head of the audio in a TC writing circuit 5 and the data are coded in an audio encoder 6 for compression. A host computer 8 calculates a bit rate for the audio data and a bit amount of the audio data to add to the video data by one frame from a video data frame rate. The synchronization can be realized by combining the video data with the audio data by frames based on the time code included in each frame of video data while dividing the audio data with the calculated bit amount.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for editing multimedia data used for editing multimedia information for games, education, and the like.

0002

BACKGROUND OF THE INVENTION Currently, frame-structured video data for games, education, etc. is encoded to compress the amount of data and edited to be combined with audio data while being recorded on a CD-ROM. A recording/playback system for multimedia data to be played back is under development.

Conventionally, a sector interleaving method has been known as a method of recording video data and audio data on a CD-ROM while synchronizing them. This sector interleaving method is a method in which audio data is compressed to 1/n and recorded in n-sector jumps, and compressed image data is recorded in the remaining (n-1) sectors.

0004

[Problems to be Solved by the Invention] In the above-mentioned sector interleaving method for synchronizing video data and audio data recording, in order to improve the sector utilization efficiency,
There are problems in that various constraints arise, such as the number of channels of audio data and the relationship between the compression rate of video data and the compression rate of audio data.

[0005]

[Means for Solving the Problems] A multimedia data editing method according to the present invention includes the steps of adding a time code to frame-structured image data, encoding it for compression, and storing it in a memory; A step of adding a recording start time code only to the beginning of the data, decoding it for compression, and storing it in memory, and converting the audio data bit rate and video data frame rate to one frame of video data. The amount of bits of audio data to be added is calculated, and the audio data is separated from the beginning using the calculated amount of bits, and the video data and audio data are combined frame by frame based on the time code included in the header of each frame of video data. It includes the following stages.

[0006]

[Embodiment] FIG. 1 is a block diagram showing the configuration of a multimedia editing device according to an embodiment of the present invention.
is an A/D converter, 2 and 5 are time code (TC) writing circuits, 3 is a video encoder, 6 is an audio encoder, 7 is a time code reading circuit, 8 is a host computer, 9 is a bus, and 10 is a memory. . Furthermore, 11 is a buffer memory, 12 is a video decoder, and 13 and 15 are D/
A converter, 14 is an audio decoder, and 16 is a monitor.

The A/D converters 1 and 4 and the time code reading circuit 7 receive frame-structured analog video data, analog audio data, and time code (TC) from a professional video tape recorder (VTR). and are supplied. Analog video data supplied from a tape recorder is converted into digital video data by an A/D converter 1, a time code is written by a time code writing circuit 2, and a code for data compression is written by a video encoder 3. , ie, undergoes hybrid coding that combines discrete cosine transform, quantization, and variable length coding. The compressed video data is transferred to the host computer 8 via the bus 9, where it undergoes various editing and then temporarily written to the memory 10 via the bus 9 as a video capture file.

[0008] The analog signal supplied from the tape recorder
The audio data is converted into digital audio data by the A/D converter 4, a time code is written by the time code writing circuit 5, and the audio data is encoded by ADPCM for data compression by the audio encoder 3. The compressed audio data is transferred to the host computer 8 via the bus 9, where it undergoes various editing and then temporarily written to the memory 10 via the bus 9 as an audio capture file.

[0009] To create and write the video capture file and audio capture file to the memory 10, first, the video capture file is created and written to the memory 10, and then the audio capture file is created and written to the memory 10.
The capture file is created and written to the memory 10, which is performed in two steps. As shown in FIG. 2, the video capture file is composed of a video data file and a video attribute file. As shown in FIG. 3, the audio capture file is composed of an audio data file and an audio attribute file.

[0010] The video data file constituting the video capture file shown in FIG. 2 is a variable-length video data file organized in units of frames such as frame #1, frame #2, etc., as shown in FIG. A fixed-length header is added to the beginning of each block of data. Here, a block is a unit area within a frame that is equally divided prior to discrete cosine transformation. The fixed-length header contains the time code (TC), the video type (T) that indicates whether the video data is a moving image or a still image, and the frame size that indicates the number of horizontal and vertical pixels of the frame (Y signal). (DX, DY) and a quantization table (QY, QC) in which quantization tables applied to each of the Y signal and C signal are recorded in block scan order. When performing quantization in hybrid encoding, a quantization table that can be changed on a frame-by-frame basis is applied. During decoding, a dequantization table is generated for each frame from the quantization table, and dequantization corresponding to the quantization applied during encoding is performed.

The video attribute file composing the video capture file shown in FIG. 2 is shown in FIG.
As shown in the figure, the part that is added only to the first frame,
It consists of parts created for each frame. The portion added only to the first frame includes a specified frame rate (FR) specified by the user during compression, a specified bit rate (BR), and a reserved area. Also, the part created for each frame includes time information indicating the elapsed time from the reference time in hours, minutes, and seconds, a time code (TC) that includes the serial number of the frame, and whether it is a moving image or a still image. video type (T), frame holding time (F),
The above-mentioned frame size (DX, DY), capture position (DX, DY) indicating the start position of the compression area specified by the user during compression
X, Y), and a data length (DL) indicating the total amount of compressed data for one frame in bytes. The frame retention time (F) indicates how many frames of interest are retained based on 30 frames per second during playback and display. For example, when compressing an original video with a frame rate of 30 frames per second while thinning it to 15 frames per second, the frame retention time (F) during playback
"2" is designated as "2".

The audio data file constituting the audio capture file shown in FIG. 3 consists only of compressed audio data, and no header is added. In addition, as shown in Figure 6, the audio attribute file includes the compression mode (M), the recording time (RT) in hours, minutes, and seconds, the time code (STC) at the start of recording, and the data length (DL). It consists of According to this embodiment, the audio data compression mode (M) is subband ADPCM, 16KHz ADPCM, 8KHz ADPCM, and 4KHz ADP.
There are four types of commercials.

The host computer 8 includes, in addition to the above-mentioned video capture file and audio capture file, various parameters necessary to combine them to create a combination file that is multimedia information. Create a parameter file as shown in the figure below according to the user's specifications, and store it in memory 1.
Record to 0. The above video capture file and
The relationship among the audio capture file, parameter file, and combination file is illustrated in FIG. 8.

In the parameter file shown in FIG.
H" is information that specifies the recording destination channel. For video data, only one channel "V0" can be specified, and for audio data, "A0" to "A1" can be specified.
16 channels up to 5" can be specified. “VFILE
" is the file name of the video capture file, "A
FILE" is the file name of the audio capture file. "STIME" is information that specifies the recording start time of the audio capture file, and is specified in hours, minutes, seconds, and frame numbers based on the beginning of the combination file. "SBYTE" is a start byte that specifies from which byte recording of audio data into the combination file should start, with the beginning of the audio capture file as a reference (0th byte). "RBYTE" is information indicating the total number of recording bytes of audio data. "FIN" and "FOUT" are information specifying the audio fade-in speed and fade-out speed, respectively.

The combination file created by the host computer 8 according to the relationship shown in FIG. 8 and recorded in the memory 10 is structured in units of video data files, as shown in FIG. This is a 2-byte start code added to the beginning of the file. "DT" is 1-byte information that specifies the data type, and as shown in Figure 10, it indicates the data type (video/still image/audio), channel number, and whether or not subsequent data exists in the frame. Contains link bits to indicate. "DL" in FIG. 9 is the data length and indicates the total number of bytes of data, and "DATA" is compressed variable length video data or audio data. "BL" is a variable-length blank area, and all-zero dummy data is recorded at the end of the combination file so that the size of the combination file is an integral multiple of the number of bytes in one sector of the CD-ROM.

The host computer 8 synchronizes the video data and audio data frame by frame when creating the combination file. That is,
The host computer 8 adds one frame worth of video data based on the audio data bit rate determined by the compression mode (M) included in the audio attribute file and the frame rate (FR) included at the beginning of the video attribute file. Calculate the amount of bits of audio data to be recorded, and set the recording start time code (ST
By dividing the audio data using the bit amount calculated above from C) as the starting point, and combining the video data and audio data frame by frame based on the time code (TC) included in the header of the video data of each frame, Achieve synchronization of video data and audio data.

[0017]

[Effects of the Invention] As explained in detail above, the multimedia data editing method according to the present invention synchronizes video data and audio data using time codes and combines them frame by frame. Because of this configuration, there is an advantage that storage area usage efficiency can be increased compared to the conventional sector interleaving method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of an editing device to which a multimedia data editing method according to an embodiment of the present invention is applied.

FIG. 2 is a conceptual diagram showing the structure of a video capture file.

FIG. 3 is a conceptual diagram showing the structure of an audio capture file.

FIG. 4 is a conceptual diagram showing the structure of a video data file.

FIG. 5 is a conceptual diagram showing the structure of a video attribute file.

FIG. 6 is a conceptual diagram showing the structure of an audio attribute file.

FIG. 7 is a conceptual diagram showing the configuration of a parameter file.

[Figure 8] Video capture file, audio
FIG. 2 is a conceptual diagram for explaining the relationship among a capture file, a parameter file, and an audio combination file.

FIG. 9 is a conceptual diagram showing the structure of a combination file.

FIG. 10 is a conceptual diagram showing the structure of data types.

[Explanation of symbols]

2,5 Time code writing circuit 3
Video encoder 6 Audio encoder 7
Time code reading circuit 8 Host computer 10 Memory 11 Buffer memory 12 Video decoder 14 Audio decoder 16 Monitor

Claims (1)

[Claims] Claim 1: A step of adding a time code to image data having a frame structure, encoding it for compression, and storing it in a memory, and adding a time code for the start of recording only to the beginning of audio data and performing compression. and calculating the amount of bits of audio data to be added to one frame of video data from the bit rate of the audio data and the frame rate of the video data, and calculating the amount of bits of audio data to be added to one frame of video data, and the video data and the audio data are combined frame by frame based on the time code included in the header of each frame of the video data, while dividing the audio data from the beginning by the amount of the video data. How to edit.