Dynamic information storage or retrieval – Editing of stored information
Reexamination Certificate
2000-10-05
2002-06-18
Edun, Muhammad (Department: 2651)
Dynamic information storage or retrieval
Editing of stored information
C369S059100, C369S047100
Reexamination Certificate
active
06407972
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an editing apparatus and an editing method for editing for example audio data recorded on a record medium.
2. Description of the Related Art
As a related art reference of a highly efficiently encoding method for an audio signal, for example, a transform encoding method is known. The transform encoding method is one example of a block-segmentation frequency band dividing method. In the transform encoding method, a time-base audio signal is segmented into blocks at intervals of a predetermined unit time period. The time-base signal of each block is converted into a frequency-base signal (namely, orthogonally transformed). Thus, the time-base signal is divided into a plurality of frequency bands. In each frequency band, blocks are encoded. As another related art reference, a sub band coding (SBC) method as an example of a non-block-segmentation frequency band dividing method is known. In the SBC method, a time-base audio signal is divided into a plurality of frequency bands and then encoded without segmenting the signal into blocks at intervals of a predetermined unit time period.
As another related art reference, a highly efficiently encoding method that is a combination of the band division encoding method and the SBC method is also known. In this highly efficiently encoding method, a signal of each sub band is orthogonally transformed into a frequency-base signal corresponding to the transform encoding method. The transformed signal is encoded in each sub band.
As an example of a band dividing filter used for the above-described sub band coding method, for example a QMF (Quadrature Mirror Filter) is known. The QMF is described in for example R. E. Crochiere “Digital coding of speech in sub bands” Bell Syst. Tech. J. Vol. 55. No. 8 (1976). An equal band width filter dividing method for a poly-phase quadrature filter and an apparatus thereof are described in ICASSP 83, BOSTON “Polyphase Quadrature filters—A new sub band coding technique”, Joseph H. Rothwiler.
As an example of the orthogonal transform method, an input audio signal is segmented into blocks at intervals of a predetermined unit time period (for each frame). Each block is transformed by for example a fast Fourier transforming (FFT) method, a discrete cosine transforming (DCT) method, or a modified DCT transforming (MDCT) method. As a result, a time-base signal is converted into a frequency-base signal. The MDCT is described in for example ICASSP 1987, “Sub band/Transform coding Using Filter Bank Designs Based on Time Domain Aliasing Cancellation”, J. P. Princen and A. B. Bradley, Univ. of Surrey Royal Melbourne Inst. of Tech.
On the other hand, an encoding method that uses a frequency division width in consideration of the hearing characteristics of humans for quantizing each sub band frequency component is known. In other words, so-called critical bands of which their band widths are proportional to their frequencies have been widely used. With the critical bands, an audio signal may be divided into a plurality of sub bands (for example, 25 sub bands). According to such a sub band coding method, when data of each sub band is encoded, a predetermined number of bits is allocated for each sub band. Alternatively, an adaptive number of bits is allocated for each sub band. For example, when MDCT coefficient data generated by the MDCT process is encoded with the above-described bit allocating method, an adaptive number of bits is allocated to the MDCT coefficient data of each block of each sub band. With the allocated bits, each block is encoded.
An example of a related art reference of such a bit allocating method and an apparatus corresponding thereto is described as “a method for allocating bits corresponding to the strength of a signal of each sub band” in IEEE Transactions of Acoustics, Speech, and Signal Processing, vol. ASSP-25, NO. 4, August (1977). As another related art reference, “a method for fixedly allocating bits corresponding to a signal to noise ratio for each sub band using a masking of the sense of hearing” is described in ICASP, 1980, “The critical band coder—digital encoding of the perceptual requirements of the auditory system”, M. A. Kransner MIT.
When each block is encoded for each sub band, each block is normalized and quantized for each sub band. Thus, each block is effectively encoded. This process is referred to as block floating process. When MDCT coefficient data generated by the MDCT process is encoded, the maximum value of the absolute values of the MDCT coefficients is obtained for each sub band. Corresponding to the maximum value, the MDCT coefficient data is normalized and then quantized. Thus, the MDCT coefficient data can be more effectively encoded. The normalizing process can be performed as follows. From a plurality of numbered values, a value used for the normalizing process is selected for each block using a predetermined calculating process. The number assigned to the selected value is used as normalization information. The plurality of values are numbered so that they increment by 2 dB of an audio level.
The above-described highly effectively encoded signal is decoded as follows. With reference to the bit allocation information, the normalization information, and so forth for each sub band, MDCT coefficient data is generated corresponding to a signal that has been highly efficiently encoded. Since a so-called inversely orthogonally transforming process is performed corresponding to the MDCT coefficient data, time-base data is generated. When the highly efficiently encoding process is performed, if the frequency band is divided into sub bands by a band dividing filter, the time-base data is combined using a sub band combining filter.
When numbered normalization information is changed by an adding process, a subtracting process, or the like, a reproduction level adjusting function, a filtering function, and so forth can be accomplished for a time-base signal of which a highly efficiently encoded data has been decoded. According to this method, since the reproduction level can be adjusted by a calculating process such as an adding process or a subtracting process, the structure of the apparatus becomes simple. In addition, since a decoding process, an encoding process, and so forth are not excessively required, the reproduction level can be adjusted without a deterioration of the signal quality. In addition, in this method, even if a highly efficiently encoded signal is changed, since the time period of the decoded signal does not vary, when numbered normalization information is changed, part of the signal generated by the decoding process can be changed. As a result of a partial change of such a signal, for example, a fade-in process and a fade-out process can be performed for a music program recorded on a disc. In this case, in the fade-in process, the fade-out process, and so forth, parameters of transition time, transition shape, transition start position, and transition end position can be designated. Thus, the fade shape can be more accurately formed.
As a record medium on which a signal that has been highly efficiently encoded is recorded, an MD (mini disc) that is a magneto-optical disc is known. In addition, an MD system that records and/or reproduces data such as audio data using an MD as a record medium is known. By adding a structure that performs a process for reflecting a changed result of numbered normalization information to recorded data to such an MD system, an editing function can be accomplished.
In the record format of an MD, besides a main data record area such as audio data, a management information area for recording information that represents a recorded area and a non-recorded area for data is formed. The management information area is referred to as U-TOC (User-Table Of Contents). When data is recorded on an MD, a non-recorded area is detected with reference to U-TOC. When data is reproduced from an MD, a area in which desired data has been recorded is detected with re
Aramaki Junichi
Koyata Tomohiro
Oba Akira
Yasuda Ryohei
Edun Muhammad
Sony Corporation
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