JP4765460B2 - Speech coding apparatus and speech coding method - Google Patents

Description

  The present invention relates to a speech encoding apparatus and speech encoding method for re-encoding encoded speech data such as MP3 and AAC.

  In recent years, speech coding (compression) technology for compressing digitized speech data by discarding information that is not perceived using human auditory characteristics has progressed, and more than 1/10 of the amount of data before encoding. Even when compressed to a data amount, the sound quality is comparable to that before encoding, and it has been actively used in audio players using optical disks, hard disks, semiconductor memories, and the like.

  Such an audio player is generally used by transferring the content stored on a personal computer to the audio player or recording medium after reducing the amount of data using the encoding technique as described above. It is.

  Encoded audio data is generally created from a compact disc owned by the user, etc., but is obtained by using a data encoded by a specific encoding method such as music distribution. In some cases. The current situation is that the encoding method of these encoded audio data or the encoding rate of the encoded audio data does not necessarily match the capability of the audio player possessed by the user.

  In order to solve the above-mentioned problem, some software for managing encoded audio data on a personal computer includes audio that is re-encoded into an encoding method desired by the user or an encoding method suitable for the capability of the audio player. Some have an encoding processing function. For example, Patent Document 1 discloses the technique. Hereinafter, the conventional speech coding apparatus will be described.

  In a conventional speech encoding apparatus, speech data encoded by the first encoding method is decoded by a decoding unit, and the decoded data is stored in a temporary storage unit. Next, the audio data is encoded by the encoding unit using the second encoding method. When a predetermined amount of data is accumulated in the temporary storage unit, the encoding unit reads the data from the temporary storage unit, encodes the data by the second encoding method, outputs the data to the temporary storage unit, and outputs the data to the recording medium. This only needs to be performed for the necessary content.

  Note that the processing of the decoding unit is appropriately switched according to the encoding method of the conversion source, and the processing of the encoding unit is an encoding method suitable for a device that uses the converted audio data. At the same time, processing is switched appropriately.

As described above, by re-encoding the encoded audio data according to the device to be used and the purpose, the use range of the audio data can be greatly expanded.
JP 2005-12277 A

  By the way, in speech encoding methods such as MP3 and AAC that are generally used at present, a certain amount is cut out from speech data, and time domain data is converted into frequency domain data by MDCT (Modified Discrete Discrete Cosine Transform). I do. Although this processing unit is called a frame, at the time of encoding, data is cut out using a window function that overlaps with a neighboring frame at a certain rate. Conversely, at the time of decoding, the overlapped portions are added to each other to restore the original audio data. The reason for overlapping with adjacent frames is to reduce distortion between frames caused by compression by encoding. Thus, in order to restore a frame with encoded audio data, information on adjacent frames is required.

  When creating encoded audio data from audio data such as a compact disc, the encoded audio data is usually filed for each track. Some music contents stored on compact discs have separate tracks, but some audio is stored continuously across multiple tracks. These are encoded and filed for each track. However, at the time of reproduction, it is necessary to reproduce the sound of these tracks continuously without interruption. Therefore, at the time of encoding, it is necessary to divide after encoding by overlapping with adjacent frames even at the track division point. Also, at the time of decoding, decoding is performed after adjacent frames before and after the track division point. It is necessary to restore the continuous audio data by adding the overlapped audio data.

  However, in the conventional speech encoding apparatus, at the time of decoding, since the first frame and the last frame of each content do not have adjacent frames, the frames cannot be correctly restored and are encoded again. Even if the encoded audio data overlaps with an adjacent frame, the original frame cannot be restored, and sound interruption occurs.

  The present invention provides a re-encoding so that sound is not interrupted when continuously reproduced, even when encoded audio data to which a sound should be continuously connected when continuously reproduced is re-encoded. An object of the present invention is to provide a speech encoding apparatus that performs encoding.

In order to achieve the above object, a speech encoding apparatus according to a first aspect of the present invention continuously converts a plurality of encoded speech data encoded by the first encoding method and divided for each content. decoding means for generating a single continuous speech data and decodes, as well as sign-reduction in the communication Zokuoto voice data generated by the decoding means a second encoding method, encoded audio Coding means for dividing the data again for each content.

  The speech encoding apparatus according to a second aspect of the present invention is the speech encoding apparatus according to the first aspect, wherein the encoding means decodes the audio data encoded by the second encoding method for each content. It divides | segments on the boundary of the encoding frame of the 2nd encoding method close | similar to the division | segmentation point before decoding by a means.

  According to the speech encoding apparatus of the present invention, even when encoded speech data is re-encoded, it is possible to perform continuous decoding processing and encoding processing. It is possible to obtain re-encoded content in which no sound interruption occurs.

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

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a speech encoding apparatus according to Embodiment 1 of the present invention. First, the configuration of the speech coding apparatus according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, the speech encoding apparatus according to the first embodiment includes a first recording medium 10 that stores a plurality of encoded speech data encoded by a first encoding method, A first temporary storage unit 11 that sequentially reads out and temporarily stores the encoded audio data stored in the recording medium 10, and decodes the encoded audio data stored in the first temporary storage unit 11. , A second temporary storage unit 13 for temporarily storing the audio data decoded by the decoding unit 12, and a decoding stored in the second temporary storage unit 13 An encoding unit 14 that encodes the encoded audio data by the second encoding method, a third temporary storage unit 15 that temporarily stores the audio data encoded by the encoding unit 14, A second storage medium 16 for storing the encoded audio data, and the entire device And a control unit 17 for performing the control.

  Next, the operation will be described. The recording medium 10 stores a plurality of encoded audio data files encoded by the first encoding method. These encoded audio data have a playback order designated according to a certain rule. The control unit 17 reads the encoded audio data from the recording medium 10 in accordance with the reproduction order and sequentially stores it in the first temporary storage unit 11. When a predetermined amount of audio data is accumulated in the first temporary storage unit 11, the control unit 17 instructs the decoding unit 12 to start decoding. When decoding is started and the amount of audio data in the first temporary storage unit 11 falls below a predetermined amount, the encoded audio data is read again from the first storage medium 10 and added to the first temporary storage unit 11. This is repeated until the end of the encoded audio data file. When all the data of a certain file has been read, the next encoded audio data file is opened according to the reproduction order, and the audio data is read and stored in the first temporary storage unit 11. , Store the data of the previous file. Here, the control unit 17 stores the timing of the file boundary.

  The audio data decoded by the decoding unit 12 is sequentially stored in the second temporary storage unit 13. The decoding unit 12 is stored in the second temporary storage unit 13 in order to perform the decoding process continuously without depending on the file boundary of the encoded audio data encoded by the first encoding method. The audio data is continuous data. When a predetermined amount of audio data is accumulated in the second temporary storage unit 13, the control unit 17 instructs the encoding unit 14 to start encoding. The audio data encoded by the encoding unit 14 is sequentially stored in the third temporary storage unit 15. The control unit 17 sequentially records the encoded audio data accumulated in the third temporary storage unit 15 on the second recording medium 16. Here, when recording on the second recording medium 16 based on the timing of the boundary of the file stored when the encoded audio data is stored in the first temporary storage unit 11, the encoded audio is recorded. Divide the data file.

  As described above, according to the audio encoding device according to Embodiment 1 of the present invention, when re-encoding a plurality of encoded audio data files, adjacent frames are connected at the connection point of each file. Is decoded and restored as continuous audio data, and further, encoded as continuous audio data and then divided in units of the original file, so that even when re-encoded encoded audio data is continuously played back, There is no interruption.

  Note that the processing unit (referred to as a frame) in the time axis direction of audio data may be different between the first encoding method and the second encoding method. Processing at this time will be described with reference to FIG.

  Since the encoded audio data is the smallest unit that can be divided into frames, it is necessary to pay attention to the division point of the file when converting between encoding methods having different frame lengths. In the processing according to the first embodiment of the present invention, as shown in FIG. 2, the audio data of a plurality of files encoded by the first encoding method is once decoded into continuous audio data. Then, the continuous audio data is continuously encoded by the second encoding method. Finally, the file is divided and recorded at the division point of the frame closest to the division point of the original file. Although it is different from the division point of the original file, it can be re-encoded as a plurality of encoded audio data files that can be reproduced continuously.

  In selecting a file division point, whether to select the closest division point or the closest division point on the front side or the rear side may be determined as a design matter of the apparatus.

(Embodiment 2)
FIG. 3 is a block diagram showing a configuration of a speech encoding apparatus according to Embodiment 2 of the present invention. The configuration is the same as that of the first embodiment of the present invention, except that the control unit 17 acquires information attached to each encoded audio data file from the first recording medium 10.

  The operation is also common to the first embodiment of the present invention, and only different parts will be described.

  In the second embodiment of the present invention, the control unit 17 acquires information on continuity between different audio data files as information accompanying the encoded audio data file. This information may be flag information that directly indicates continuity between files, or may be information that indirectly indicates content group attributes and their permutations. In the latter case, for example, if the original audio data is created from a compact disc, attributes such as “album” and “track number” can be provided for each content. These pieces of information may be input by the user or may be information acquired from an external network such as the Internet. A plurality of audio data having the same “album” attribute and having a continuous “track number” attribute can be determined to have continuity.

  Then, when re-encoding a plurality of encoded audio data files determined to have continuity, the control unit 17 performs continuous decoding so that the continuity of the audio after decoding is maintained. When re-encoding by encoding and re-encoding a plurality of encoded audio data files determined not to be continuous, each encoded audio data file is independently re-encoded.

  As described above, in the second embodiment of the present invention, it is possible to perform re-encoding processing that maintains audio continuity only on a plurality of encoded audio data files that should be reproduced continuously. .

  In each of the above embodiments, first, the recording medium 10 and the second recording medium 16 may be separate recording media or the same recording medium. Also, the first to third temporary storage units 11, 13, and 15 may be configured as individual recording units or may be configured by dividing the area of the same recording unit.

  Needless to say, part or all of the speech encoding apparatus in each of the above embodiments can be realized as software that can be executed by a computer including a CPU and a memory. In this case, the present invention can also be realized as a speech encoding method having steps corresponding to each configuration shown in FIG. 1 or FIG.

  The speech coding apparatus according to the present invention can be configured as a device, and is also useful as software that manages speech data on a personal computer and performs re-encoding on an external device that reproduces the speech data. In addition, as a music distribution server or terminal, it is useful as a system that re-encodes audio data with an encoding method that is optimal for the user when selling audio data.

FIG. 1 is a block diagram showing the configuration of a speech coding apparatus according to Embodiment 1 of the present invention. Explanatory drawing which shows the example of the file division | segmentation of the audio | voice coding apparatus in Embodiment 1. Block diagram showing the configuration of a speech encoding apparatus according to Embodiment 2 of the present invention.

Explanation of symbols

10, 16 Recording medium 11, 13, 15 Temporary storage unit 12 Decoding unit 14 Encoding unit 17 Control unit

Claims (4)

A decoding unit that continuously decodes a plurality of pieces of encoded audio data encoded by the first encoding method and divided for each content to generate one continuous audio data; and the product is the communication Zokuoto voice data, as well as sign-reduction by the second coding method, speech coding apparatus and a coding means for dividing the audio data encoded again for each content. When the encoding means divides the audio data encoded by the second encoding method for each content, the code of the second encoding method is close to the division point before being decoded by the decoding means. 2. The speech encoding apparatus according to claim 1, wherein the speech encoding apparatus divides at a boundary of the encoded frame. A plurality of encoded audio data encoded by the first encoding method and divided for each content, a decoding step for continuously generating one continuous audio data, and generated by the decoding means wherein the communicating Zokuoto voice data, as well as sign-reduction by the second coding method, speech coding method and a coding step of dividing the audio data encoded again for each content. In the encoding step, when the audio data encoded by the second encoding method is divided for each content, the code of the second encoding method is close to the division point before being decoded by the decoding step. 4. The speech encoding method according to claim 3 , wherein the audio encoding method is divided at the boundaries of the encoded frames.

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