Data processing: generic control systems or specific application – Specific application – apparatus or process – Digital audio data processing system
Reexamination Certificate
1997-07-16
2001-05-29
Mei, Xu (Department: 2644)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Digital audio data processing system
C381S119000
Reexamination Certificate
active
06240327
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an audio-mixing apparatus and an audio-mixing processing method and more particularly, to audio-mixing apparatus and processing method for digital audio signals.
In recent years, with advancement of digital technologies, digitization of video and audio apparatus has been promoted and a mixing process in which digitized audio signals or digital audio signals as they are mixed has been widely employed even in editing of audio signals.
Conventionally, in a general method of performing the mixing process of this type of digital audio signal, pieces of serial audio data consecutively inputted from a plurality of channels are subjected to a predetermined operation process channel by channel, subjected to PCM conversion corresponding to each channel and subjected to the mixing process. Therefore, memories are provided by the same number as that of the channels and the serial audio data pieces are stored in individual channel data regions. The thus stored individual audio data pieces are subjected to the mixing process by means of a mixing processor and delivered as PCM output data pieces.
Referring to
FIG. 4
showing a conventional audio-mixing apparatus in block form, the audio-mixing apparatus has an operation processor
1
for performing, channel by channel, an inverse Fast Fourier transform (FFT) process of serial input data pieces DIi representing digital audio data pieces corresponding to a plurality of channels and a PCM converter
40
for performing a PCM conversion process each in correspondence to operation data pieces PDi of respective channels and delivering PCM conversion data pieces DCi. There is further provided a plurality of memories
30
for storing the individual PCM conversion data pieces DCi of the respective channels, and a mixing processor
20
for performing a mixing process of the PCM conversion data pieces MCi of the respective channels read out of the memories
30
and generating PCM output data pieces DOi.
The operation of the conventional audio-mixing apparatus will be described with reference to FIG.
4
. The operation processor
1
is supplied with serial input data pieces DIi of a plurality of channels via an input terminal TI, performs an operation process such as an inverse FFT process channel by channel to generate operation data pieces PDi corresponding to the respective channels and applies the operation data pieces PDi to the PCM converter
40
.
In the PCM converter
40
, a PCM conversion process corresponding to each channel is carried out in response to the supply of each of the operation data pieces PDi to deliver, channel by channel, PCM conversion data pieces DCi which in turn are supplied to the respective memories
30
. Each of the PCM conversion data DCi supplied to each memory
30
is temporarily stored therein for preparation for the mixing process.
The mixing processor
20
reads PCM conversion data pieces MCi of the respective channels out of the respective memories
30
, performs the mixing processing of the read-out PCM conversion data pieces and generates consecutive PCM output data pieces DOi of the respective channels which in turn are delivered via an output terminal TO. At that time, the mixing processor
20
does not operate before all of the memories
30
have completed storage of the PCM conversion data pieces DCi which are obtained by subjecting all of the serial input data pieces DIi of the plurality of channels to the operation process and subjecting the operated input data pieces to the PCM conversion.
According to the aforementioned conventional audio-mixing apparatus and processing method, in the mixing process of digital audio signals of the plurality of channels, the data pieces of the respective channels are separately subjected to the PCM process and PCM output data pieces are generated by combining necessary signal data pieces and mixing them. Therefore, the mixing process is carried out after completion of operation execution for all channels and completion of storage of operation data pieces regardless of whether or not the mixing process for all of the plurality of channels is necessary, leading to disadvantages that as the number of channels increases, the operation time increases and the capacity of memories for operation data storage increases.
SUMMARY OF THE INVENTION
The present invention contemplates the elimination of the above disadvantages and it is an object of the present invention to provide audio-mixing apparatus and processing method which can decrease the necessary memory capacity and can decrease the operation time.
To accomplish the above object, according to the present invention, in an audio-mixing apparatus having operation processing means for sequentially receiving digital audio data pieces corresponding to first and second channels and performing a predetermined operation process of the digital audio data pieces in respect of each of the first and second channels to sequentially deliver corresponding first and second operation data pieces which in turn undergo a mixing process, the apparatus comprises:
memory means for storing a first mixing data piece generated from the first operation data piece which precedes the second operation data piece being processed at present;
mixing processing means for performing a mixing operation process of the second operation data piece and the first mixing data piece read out of the memory means to generate a second mixing data piece; and
PCM conversion means for sequentially performing a PCM conversion process of the first and second mixing data pieces to deliver PCM output data pieces.
According to the present invention, in an audio-mixing processing method for performing a mixing process of digital audio data pieces sequentially supplied and corresponding to first and second channels, the method comprises the steps of:
performing a predetermined operation process in respect of each of the first and second channels and sequentially delivering first and second operation data pieces;
storing a first mixing data piece generated from the first operation data piece which precedes the second operation data piece being processed at present;
performing a mixing process of the second operation data piece and the read-out first mixing data piece to generate a second mixing data piece; and
sequentially performing a PCM conversion process of the first and second mixing data pieces to deliver PCM output data pieces.
REFERENCES:
patent: 4550425 (1985-10-01), Anderson et al.
patent: 5151998 (1992-09-01), Capps
patent: 5764775 (1998-06-01), Kim
patent: 0 310 456 A2 (1989-04-01), None
patent: 0 462 799 A2 (1991-12-01), None
patent: 0 743 640 A2 (1996-11-01), None
patent: 1-98177 (1989-04-01), None
Foley & Lardner
Mei Xu
NEC Corporation
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