JP3632583B2 - Compressed audio data editing and playback method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a method for editing compressed audio signals, particularly compressed signals in which data corresponding to frames such as MPEG1-LAYER3 and MPEG2-LAYER3 (hereinafter referred to as MP3) exist other than that frame. The present invention relates to a method for editing and reproducing compressed audio data applicable to a device that performs reproduction.
[0002]
[Prior art]
A conventional method for editing compressed audio data is, for example, a method used in a mini-disc (MD). When dividing, the audio data is divided before the header in each frame to make different audio data. The audio data is continuously read out and reproduced.
[0003]
[Problems to be solved by the invention]
However, in the configuration as described above, when the data of the corresponding frame is recorded prior to the beginning of the frame, such as MP3, the second audio data is continuously continued from the first audio data. If the data is to be reproduced, the data for the first frame of the second audio data must be present at the end of the first audio data. What is selected as the first and second audio data? Since the person who operates the apparatus can select freely, it does not necessarily exist. In this case, since the data for the first frame of the second audio data is different from the original data, there is a problem that abnormal noise is generated.
[0004]
SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a compressed audio data editing and reproducing method in which no abnormal sound is generated even when any audio data is reproduced continuously.
[0005]
[Means for Solving the Problems]
In order to solve this problem, the present invention is configured in units of frames starting from a header, and audio data that has been compressed in a format in which data corresponding to this frame exists in addition to this frame is stored at a predetermined position. And (1) dividing the audio data into the front part and the rear part, and the rear part audio data with respect to the front part audio data. Adding a predetermined byte of data at the beginning to the end, (2) dividing the audio data into a front part and a rear part,BackwardAt least one of the steps (1) and (2) of the step of placing the last predetermined byte data of the front audio data in front of the head of the rear data with respect to the audio dataPerforming a step of sequentially reading frames for the audio data, and a step of determining whether or not the data corresponding to the frame exists in the first frame, and if there is no determination result, The method includes a step of returning to the step of reading and determining the next frame, and if present, includes a step of reproducing the read frame.
[0006]
Thus, it is possible to determine the continuity of two audio data using the data of the tail part of the front audio data and the data of the head part of the rear audio data.In addition, if there is no data corresponding to the frame, playback is not performed,Processing for preventing abnormal noise can be appropriately performed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is configured in units of frames beginning with a header, and audio data compressed in a format in which data corresponding to the frame exists in addition to the frame An editing method for dividing the audio data into two audio data of a front part and a rear part at a position includes: (1) a step of dividing the audio data into a front part and a rear part; (2) a step of dividing the audio data into a front part and a rear part, and a rear part of the data of the last part of the front part audio data with respect to the front part and rear part audio data. At least one of the steps of arranging in front of the beginning of the part data. By comparing the data of the tail part of the front audio data and the head part of the rear audio data, it is determined whether or not these two audio data were originally continuous, By selecting whether or not to reproduce the data at the beginning of the rear audio data according to the result, there is an effect of suppressing the occurrence of abnormal noise when reproducing the rear audio data.
[0008]
According to a second aspect of the present invention, the data of a predetermined byte at the beginning of the rear audio data is at least the first frame of the rear audio data, and the data of the last predetermined byte of the front audio data is This is the last one or more frames of the front audio data, and this has the effect that it is possible to reliably determine whether the front part and the rear part match or do not match.
[0009]
The invention according to claim 3 further includes a step of sequentially reading frames from the audio data, and a step of determining whether data corresponding to the frame exists or does not exist in the head frame. If the determination result does not exist, the method includes a step of reading the next frame and returning to the determination step. If the determination result exists, the method includes a step of reproducing the read frame. When there is no data corresponding to the frame, the reproduction is not performed and the occurrence of abnormal noise is suppressed.
[0010]
According to the fourth aspect of the present invention, when the rear audio data is reproduced following the front audio data, data of a predetermined byte at the end of the front audio data and the beginning of the rear audio data are reproduced. And a step of determining whether or not to reproduce the rear audio data from the beginning based on the comparison result, whereby two pieces of audio data are obtained. If the audio data that was originally generated by dividing one audio data into two is reproduced, the comparison result is “match”. Even if the data corresponding to the beginning is not in the audio data, the data exists in the audio data in the front part. An effect that it is possible to perform seamless reproduction.
[0011]
According to a fifth aspect of the present invention, the audio data is data recorded on a recording medium having one cluster as a writing / reading unit, which is necessary for writing / reading. The capacity of the data for indicating the location of the audio data can be reduced.
[0012]
Further, in the invention according to claim 6, the reproducing method includes a step of determining whether the data required by the audio data exists or does not exist in a cluster before the cluster that is the head of the audio data. If the data does not exist, the corresponding data is not reproduced, so that the audio data is started from the middle of the cluster and the data required by the audio data is not found. Even when the audio data exists prior to the audio data, if the data exists in the same cluster, the data is played back, and the head is cut off during playback.
[0013]
Further, in the invention according to claim 7, when the editing method divides the audio data, a step of creating a cluster having the same content by duplicating a final cluster of the front audio data; In the case where any one of the audio data is erased by having a boundary to be divided in the cluster, In the case where the other side is not affected, and the audio data in the front part and the audio data in the rear part are reproduced in succession, the matching of the respective clusters at the connection part allows It has an effect that it becomes easy to check whether or not the audio data is divided.
[0014]
According to an eighth aspect of the present invention, the editing method includes a step of determining whether or not a division position of the audio data matches a boundary of the cluster. As a result, it is possible to ensure that the first half and the second half of the divided audio data always have common data, so that two audio data originally divide one audio data. It has the effect of making it possible to determine whether or not it is obtained.
[0015]
The editing method may further include a step of determining whether or not the dividing position of the audio data matches a boundary of the cluster. A step of adding data for one cluster at the beginning of the rear audio data to the rear end of the front audio data with respect to the audio data, so that the division position coincides with the boundary of the clusters Even so, if two pieces of audio data are formed by dividing one piece of audio data, the two pieces of audio data originally have one piece of audio data. It has the effect of making it possible to determine whether or not it is obtained by dividing.
[0016]
The editing method may further include a step of determining whether or not the dividing position of the audio data matches a boundary of the cluster. And a step of adding the last cluster of the front audio data as invalid data to the front audio data before the head portion of the rear audio data with respect to the audio data. Even if there are two pieces of audio data formed by dividing one audio data, the two pieces of audio data originally divide one piece of audio data by always having common data. Thus, it is possible to determine whether or not it is obtained.
[0017]
According to the eleventh aspect of the present invention, when the reproduction method reproduces the rear audio data following the front audio data, the last one cluster of the front audio data and the rear audio data are reproduced. A step of comparing one cluster at the beginning of the data and a step of determining whether or not to reproduce the rear audio data from the beginning based on the comparison result. In the case of reproducing audio data obtained by dividing one audio data into two, the comparison result is “match”. Therefore, the data corresponding to the beginning of the second audio data is assumed to be the audio data. It has the effect that seamless playback can be performed even if it is not in the data.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
(Embodiment)
FIG. 1 is a conceptual diagram for explaining a method for editing and reproducing compressed audio data according to an embodiment of the present invention. Explaining this figure, (1) shows the compressed audio data 1 in which the section indicated by α is one frame, which is shown as frame 1, frame 2,. ing. (2) and (3) show the audio data 2 and the audio data 3 which are the audio data of the front part and the rear part when the audio data 1 is divided at the division point D indicated by the arrow. .
[0020]
Here, in order to make the explanation easy to understand, the audio data is configured in units of frames such as MP3 with the header at the head, and the data corresponding to the frame exists outside the corresponding frame. Is described. FIG. 2 shows the structure of the audio data 20 by MP3. There is one frame from the header to the front of the next header, and four frames are shown here. Each frame has side information (side information) following the header, and it indicates where and how much data is used in the frame. In the first frame of normal audio data, the data corresponding to that frame starts after the side information 1 (arrow 21). However, when a large amount of data is not required, the data of the next frame can be stored in the frame, and the head position is indicated by the side information 2 (arrow 22).
[0021]
In (2) of FIG. 1, when the division is made at the boundary between the frame 3 and the frame 4, since the audio data 2 which is the audio data in the front part is reproduced up to the frame 3, the frame 4 is reproduced. Although not necessary for this, the frame 4 is connected to the end of the audio data 2 in consideration of the case where the audio data 3 as the audio data in the rear part is reproduced continuously with the audio data 2. As a result, when the audio data 3 is reproduced in a form subsequent to the audio data 2, the final frame of the audio data 2 and the first frame of the audio data 3 are compared. It is determined that one audio data is obtained by dividing. These series of processes can be realized using a microprocessor and a storage device such as a RAM. That is, the frame 4 may be copied to another area of the storage device, and the frame 5 and the following may be moved behind it.
[0022]
As a specific method of division, as shown in FIG. 6, when dividing between frame 3 and frame 4, for a file as audio data, (1) change of the number of frames and file size And (2) copy the frame 4 to the empty area, designate it as the head of the audio data stream in the rear part, and (3) link the frame 4 and subsequent frames.
[0023]
As described above, when the audio data to be continuously reproduced is originally obtained by dividing one audio data, the frame 1, frame 2, frame 3, frame 4,. It plays correctly even if you do.
[0024]
Here, if the front audio data 2 is not originally obtained by dividing one audio data, it is the last frame of the audio data 2 and the first frame of the audio data 3. Frame 4 is different. Since these frames are checked beforehand to match, in such a case, when reproducing the audio data 3 in the rear part, the side information of the frame 4 which is the head frame is checked, If the point to which it points is its own frame (here, frame 4), that frame is played back; otherwise, that is, in the case of the arrow 22 in FIG. Is reproduced from the frame after the first frame (here, frame 4) of the audio data. As a result, the generation of abnormal noise can be suppressed.
[0025]
A series of these processes is performed by a digital signal processing device (hereinafter referred to as a DSP). That is, in the DSP, the frame 4 of the audio data 2 and the frame 4 of the audio data 3 are compared in the first step. If the result of “mismatch” is obtained, the side information of the frame 4 is checked in the next step, and if the destination is the own frame (here, frame 4), the process proceeds to the step of reproducing the frame, Otherwise, that is, in the case of the arrow 22 in FIG. 2, the frame is not reproduced, and the process proceeds to the step of checking the side information of the next frame. This step is looped until the point indicated by the side information is after the first frame (here, frame 4) of the audio data, and then the process proceeds to the step of reproducing the frame.
[0026]
The specific reproduction processing steps described above are shown in FIG. First, a certain frame N is read and reproduced, updated to the next frame (+1), and it is determined whether or not the end of the file is reached. If there is a continuation, the playback process is repeated. If finished, go to the next step.
[0027]
Read the last frame and store it in memory. A pointer is set to the next audio data, N is set to 1, the first frame of the data is read, the frame stored in the memory is compared with the first frame, and it is determined whether or not they match.
[0028]
In the case of coincidence, this frame is reproduced, and thereafter, reproduction is performed while updating the frame until the final frame is reached. If they do not match, one frame is updated and read, the side information is confirmed, and it is determined whether there is corresponding data. If there is no corresponding data, the process returns to the step of updating the frame, and if there is corresponding data, the process proceeds to the case of matching.
[0029]
In this embodiment, one frame of the audio data 3 is added to the audio data 2, but it goes without saying that it may be two frames or more, or one frame + several bytes. Needless to say. In short, it is sufficient if there is data for comparison.
[0030]
In (3) of FIG. 1, when the division is made at the boundary between the frame 3 and the frame 4, the audio data 5 as the audio data in the rear part is reproduced from the frame 4, so that the frame 3 is for reproduction. Although not necessary, the frame 3 is connected to the front of the audio data 4 in consideration of the case where the audio data 4 which is audio data in the front part is reproduced prior to the audio data 5. As a result, when the audio data 4 is reproduced in a form prior to the audio data 5, the final frame of the audio data 4 and the first frame of the audio data 5 are compared. It is determined that it was originally obtained by dividing one piece of audio data. In this case, in the audio data 5, it is necessary to prevent the frame 3 indicated by the arrow DO from being reproduced as invalid data, that is, a data offset. As a matter of course, when the audio data 2 is reproduced alone, only the frame 3 is reproduced and the frame 4 is not reproduced.
[0031]
As described above, when the continuously reproduced audio data is originally obtained by dividing one piece of audio data, the frame 1, frame 2, frame 3, frame 4,. Will play correctly.
[0032]
Here, if the front audio data 4 is not originally obtained by dividing one audio data, it is the last frame of the audio data 4 and the first frame of the audio data 5. Frame 3 is different. Since these frames are checked beforehand to match, in such a case, when reproducing the audio data 5 in the rear part, the side information of the frame 4 that is the first frame is checked, If the point to which it points is within its own audio data 5, that frame is played back; otherwise, the division point is the boundary between frames 2 and 3 in FIG. In such a case, the frame is not reproduced, and the destination indicated by the side information in the frame is reproduced from the frame existing in the audio data 5. As a result, the generation of abnormal noise can be suppressed.
[0033]
In FIG. 1, only one frame is connected to the front audio data 2 or the rear audio data 3. However, a plurality of frames may be connected, and it is not always necessary to be a frame unit. It is.
[0034]
In this embodiment, the last one frame of the audio data 4 is added to the audio data 5, but it goes without saying that the last two frames, or the last one frame and several bytes immediately before it, etc. Needless to say, it may be a thing. In short, it is sufficient if there is data for comparison.
[0035]
FIG. 3 shows a case where the audio data is data recorded on a recording medium having one cluster as a writing / reading unit. For example, a floppy disk or the like is read / written in this way. Each cluster stores a plurality of frames of compressed audio data signals. In such a case, the processing in the case where the division is performed at the place shown in (1) of FIG. 3 is shown.
[0036]
(2) of FIG. 3 shows a case where the division point does not coincide with the cluster boundary. In the figure, the section indicated by β is one cluster. This is because when the audio data 31 is divided, the last cluster 2 of the audio data 32 which is the front part is copied to be the first cluster 2 of the audio data 33 which is the rear part. Yes. In other words, the data is present in physically different places but has the same data. And the boundary which should be divided | segmented comes in this cluster. The portion indicated by DO in the audio data 33 is not reproduced as a data offset, as in (3) of FIG.
[0037]
Of course, the first cluster 2 of the audio data 33 which is the rear part may be copied to be the last cluster 2 of the audio data 32 which is the front part.
[0038]
With this configuration, even if one of them is deleted, the audio data is correctly reproduced. Even when the audio data 33 is reproduced subsequent to the audio data 32, the last cluster of the audio data 32 and the head of the audio data 33 are reproduced. Are compared, and if they match, it is determined that the data is originally obtained by dividing one piece of audio data, and is reproduced sequentially, that is, from the first frame of the audio data 33.
[0039]
On the contrary, when the above comparison result is “mismatch” or when only the audio data 33 in the rear part is reproduced, the data required by the audio data 33 is obtained from the cluster at the head of the audio data. If it exists in the previous cluster, that is, if there is a cluster boundary at point A in FIG. 2 and point B is a division point, the corresponding data, that is, the frame is not reproduced. The generation of abnormal noise is suppressed.
[0040]
FIG. 4 illustrates a case where the division position of the audio data 41 matches the cluster boundary as shown in (1). The first cluster of the rear audio data 43 shown in (3) is added to the end of the front audio data 42 with respect to the front audio data 42 shown in (2). In this way, the last cluster 3 of the audio data 42 and the first cluster 3 of the audio data 43 are compared to determine whether or not the audio data was originally obtained by dividing one piece of audio data. be able to.
[0041]
Further, as shown in FIG. 5, the last one cluster (cluster 2) immediately before the front audio data 42 is added to the rear audio data 53 as a data offset prior to the head of the rear audio data. It is a thing. In this way, the same effect as in the case of FIG. 4 can be obtained. Furthermore, even when the audio data 53 is reproduced alone, the data for the first frame always exists, so that the reproduction is started from the first frame. It can be carried out.
[0042]
In addition to the method shown in FIG. 5, that is, the method of adding one cluster to the rear audio data 53 prior to the head, the method of adding one more cluster to the front audio data 42 as shown in FIG. It goes without saying that both of these may be used.
[0043]
Also, as shown in FIGS. 4 and 5, when the division position of the audio data coincides with the boundary of the cluster, the division at that position may not be allowed and the frame may be moved around one frame. Since one frame is several tens of ms, there is usually almost no problem.
[0044]
As described above, the compressed audio data editing and playback method according to the present invention generates abnormal noise even in compressed data such as MP3 where the location of the frame and the data used by the frame does not necessarily match. In addition, if two pieces of audio data originally divided from one piece of audio data are to be reproduced continuously, they can be reproduced seamlessly.
[0045]
【The invention's effect】
As described above, according to the present invention, the audio data is configured in units of frames starting from the header, and data compressed in a format in which data corresponding to a certain frame exists outside this frame is also obtained at a desired position. When dividing the audio data into two pieces of audio data of the front part and the rear part, (1) adding data of a predetermined byte at the beginning of the rear part audio data to the front part audio data, and (2) rear part audio data. For example, a frame represented by MP3 can be obtained by performing at least one of the processing of placing the last predetermined byte data of the front audio data in front of the head of the rear data. Even if the compressed data does not necessarily match the location where the data used by the frame exists, it may generate abnormal noise. It is not, also, the effect is obtained that can be reproduced seamlessly in the case of continuously reproducing two audio data Deki originally divide one audio data.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining an audio data editing and reproduction method according to an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing a data format by MP3.
FIG. 3 is an explanatory diagram for explaining another audio data editing and reproduction method according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram for explaining another audio data editing and reproduction method according to the embodiment of the present invention;
FIG. 5 is an explanatory diagram for explaining another audio data editing and reproduction method according to the embodiment of the present invention;
FIG. 6 is a flowchart for explaining the operation of the audio editing and playback method according to the embodiment of the present invention;
FIG. 7 is a flowchart for explaining the operation of the audio editing and playback method according to the embodiment of the present invention;
[Explanation of symbols]
1-5, 31-33, 41-43, 53 Audio data

Claims (6)

The audio data is composed of a frame unit starting from the header, and the data corresponding to the frame is compressed in a format in which there is data other than the frame. The editing method to divide into data is
(1) dividing the audio data into a front part and a rear part, and adding a predetermined byte of data at the beginning of the rear part audio data to the front part of the front part audio data,
(2) dividing the audio data into a front part and a rear part, and disposing the data of the last predetermined byte of the front part audio data in front of the rear part data in front of the rear part data;
Process at least one of
Sequentially reading frames for the audio data;
Determining whether the data corresponding to the frame is present or absent in the first frame;
If the determination result does not exist, the method includes a step of reading the next frame and returning to the determination step;
If the present, compressed audio data editing and reproducing method you further comprising a reproduction performed step of the read frame. The audio data is composed of a frame unit starting from the header, and the data corresponding to the frame is compressed in a format in which there is data other than the frame. The editing method to divide into data is
(1) dividing the audio data into a front part and a rear part, and adding a predetermined byte of data at the beginning of the rear part audio data to the front part of the front part audio data,
(2) dividing the audio data into a front part and a rear part, and disposing the data of the last predetermined byte of the front part audio data in front of the rear part data in front of the rear part data;
Process at least one of
The audio data is data recorded on a recording medium having one cluster as a writing / reading unit,
The reproduction method includes a step of determining whether or not the data required by the audio data exists in a cluster before the cluster that is the head of the audio data, and does not exist. compressed audio data editing and reproducing method characterized in that so as not to perform regeneration. The audio data is composed of a frame unit starting from the header, and the data corresponding to the frame is compressed in a format in which there is data other than the frame. The editing method to divide into data is
(1) dividing the audio data into a front part and a rear part, and adding a predetermined byte of data at the beginning of the rear part audio data to the front part of the front part audio data,
(2) dividing the audio data into a front part and a rear part, and disposing the data of the last predetermined byte of the front part audio data in front of the rear part data in front of the rear part data;
Process at least one of
The audio data is data recorded on a recording medium having one cluster as a writing / reading unit,
The editing method comprising the step of dividing the position of the audio data to determine whether they match with the boundary of the cluster, if they match you characterized in that so as not to perform division compressed audio data editing and reproducing method. The audio data is composed of a frame unit starting from the header, and the data corresponding to the frame is compressed in a format in which there is data other than the frame. The editing method to divide into data is
(1) dividing the audio data into a front part and a rear part, and adding a predetermined byte of data at the beginning of the rear part audio data to the front part of the front part audio data,
(2) dividing the audio data into a front part and a rear part, and disposing the data of the last predetermined byte of the front part audio data in front of the rear part data in front of the rear part data;
Process at least one of
The audio data is data recorded on a recording medium having one cluster as a writing / reading unit,
The editing method includes a step of determining whether a division position of the audio data is coincident with a boundary of the cluster, and in the case of coincidence, the audio data of the rear audio data is compared with the front audio data. compressed audio data editing and reproducing method you further comprising a step of adding data for one cluster at the beginning to the end of the front portion the audio data. The audio data is composed of a frame unit starting from the header, and the data corresponding to the frame is compressed in a format in which there is data other than the frame. The editing method to divide into data is
(1) dividing the audio data into a front part and a rear part, and adding a predetermined byte of data at the beginning of the rear part audio data to the front part of the front part audio data,
(2) dividing the audio data into a front part and a rear part, and disposing the data of the last predetermined byte of the front part audio data in front of the rear part data in front of the rear part data;
Process at least one of
The audio data is data recorded on a recording medium having one cluster as a writing / reading unit,
The editing method includes a step of determining whether a division position of the audio data is coincident with a boundary of the cluster. compressed audio data editing and reproducing method characterized by the step of adding to the head portion before the rear portion audio data last cluster as invalid data. When the playback method plays back the rear audio data following the front audio data, a step of comparing the last one cluster of the front audio data with the first cluster of the rear audio data 6. The compressed audio data according to claim 4, further comprising a step of determining whether or not to reproduce the rear audio data from the beginning based on the comparison result. Editing and playback method.

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