Data processing: speech signal processing – linguistics – language – Audio signal bandwidth compression or expansion
Reexamination Certificate
2000-04-20
2003-06-24
McFadden, Susan (Department: 2654)
Data processing: speech signal processing, linguistics, language
Audio signal bandwidth compression or expansion
C704S501000, C704S502000, C704S503000, C704S504000
Reexamination Certificate
active
06584443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for digitally transferring audio data and audio-related information.
2. Description of the Related Art
As used herein, “audio data” is distinguished from “audio-related information”. The “audio data” is the information representing the actual sounds to be reproduced. The “audio-related information” is defined as any information that does not directly represent the actual sounds to be reproduced, e.g., category codes, source numbers, and channel numbers.
Conventional methods for digitally transferring audio data and audio-related information are based on, for example, international standards such as IEC60958 and IEC61937.
IEC60958, which is used for transferring 2-channel linear PCM data, is used in a wide range of digital data transfer applications including CDs and DVDs. IEC61937 is used for the transfer of data other than linear PCM data, such as compressed data (e.g., data compressed according to the MPEG standards). In recent years, IEC61937 is used in applications where the multi-channel audio outputs from a DVD apparatus are utilized for reproduction by an external decoder amplifier connected to the DVD apparatus.
The aforementioned conventional methods for transferring audio data and audio-related information aim at simply reproducing the transferred audio data.
In recent years, frequencies such as 96 kHz, up to 192 kHz, are adopted as sampling frequencies for DVDs and the like.
However, the aforementioned conventional transfer standards do not support sampling frequencies such as 96 kHz and 192 kHz. Therefore, when a player is connected to an external apparatus, the original audio data is subjected to a down sampling process or the like for converting the sampling frequency to 48 kHz before transfer. In this case, however, there is a problem in that the external apparatus receiving the transferred data is not aware of the value of the sampling frequency at which the original audio data was sampled.
FIG. 5
shows an audio data transfer apparatus
100
as a consumer-use digital audio apparatus. The audio data transfer apparatus
100
includes an audio data transmitter
101
for transmitting audio data and an audio data receiver
102
for receiving the transmitted audio data, the transmitter
101
and the receiver
102
being interconnected via an audio data transfer interface
103
designed for audio data transfer.
Tables 1 and 2 show transfer conditions for transferring audio data from the audio data transmitter
101
in the aforementioned audio data transfer apparatus
100
.
TABLE 1
Signal processing
Sampling
Monitoring
or date transfer
frequency of
frequency at the
processing
transferred data
receiving end
down-sampling
sampling frequency
sampling frequency
after down-sampling
after down-sampling
up-sampling
sampling frequency
sampling frequency
after up-sampling
after up-sampling
sampling
sampling frequency
sampling frequency
conversion
after sampling
after sampling
conversion
conversion
N times speed
original sampling
N times
transfer
frequency
1/N times speed
original sampling
1/N times
transfer
frequency
TABLE 2
Signal processing
or data transfer
processing
Monitoring ability
down-sampling
possible
up-sampling
possible
sampling conversion
possible
N times speed transfer
impossible
1/N times speed transfer
impossible
As shown in Table 1, the transfer conditions for the audio data transfer apparatus
100
include up-sampling, down-sampling, sampling conversion, N times speed transfer, 1/N times speed transfer, etc., in addition to transferring the original audio data at the originally-intended speed.
Under up-sampling, down-sampling, sampling conversion conditions, the sampling frequency of the transferred audio data differs from that of the original audio data. However, the audio-related information which is transferred In the conventional audio data transfer apparatus
100
does not include information concerning the sampling frequency of the original audio data. As a result, there is a problem in that the audio data receiver
102
cannot obtain any information concerning the sampling frequency of the original audio data.
Under conditions where audio data is transferred at an N times transfer speed or a 1/N times transfer speed, the sampling frequency of the original audio data is retained; however, the audio data receiver
102
cannot monitor the transferred data as it is (see Table 2). In order to properly monitor the audio data transferred under N times transfer or 1/N times transfer conditions, it is necessary to reproduce the audio data at an N times or 1/N times speed, or to reproduce the audio data at the sampling frequency of the original audio data while storing the transferred audio data in large memories. In the case of non-PCM data, subjecting the transferred data to a decoding process which does not involve some special measures would result in the audio information being reproduced with unwanted interruptions because the audio data receiver
102
often cannot perform the decoding process in time.
FIG. 6
illustrates an example of a conventional audio data/audio-related information recording format
300
. As shown in
FIG. 6
, the conventional audio data/audio-related information recording format
300
contains no information indicating the sampling frequency of the original audio data or no information indicating the transfer speed of the transferred audio data. Hence, it is impossible for the audio data receiver
102
to detect the sampling frequency of the original audio data or the transfer speed of the transferred audio data.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method for transferring audio data and audio-related information, comprising: a generation step of generating second audio data from first audio data; a transmission step of transmitting the second audio data and audio-related information associated with the second audio data; and a reception step of receiving the second audio data and the audio-related information, wherein the audio-related information includes information representing a sampling frequency of the first audio data.
In one embodiment of the invention, the transmission step comprises a conversion step of converting the sampling frequency of the first audio data into a sampling frequency which is suitable for reproduction at the reception step.
In another embodiment of the invention, the conversion step comprises a down-sampling.
In still another embodiment of the invention, the conversion step comprises an up-sampling.
In still another embodiment of the invention, the conversion step comprises a sampling conversion.
In still another embodiment of the invention, the reception step comprises displaying the sampling frequency of the first audio data on a display.
Alternatively, there is provided a method for transferring audio data and audio-related information, comprising: a transmission step of transmitting the audio data and audio-related information associated with the audio data; and a reception step of receiving the audio data and the audio-related information, wherein the audio-related information includes monitor information indicating whether or not the audio data is capable of being monitored in the reception step.
In one embodiment of the invention, the reception step comprises displaying the monitor information on a display.
In another embodiment of the invention, the method further comprises a muting step of muting the audio data if the monitor information indicates that the audio data is not capable of being monitored in the reception step.
Alternatively, there is provided a method for transferring audio data and audio-related information, comprising: a transmission step of transmitting the audio data and audio-related information associated with the audio data; and a reception stop of receiving the audio data and the audio-related information, wherein the audio-related information includes information representing a transfer speed of the audio da
Ejima Naoki
Kawamura Akihisa
Shimbo Masatoshi
Matsushita Electric - Industrial Co., Ltd.
McFadden Susan
Snell & Wilmer LLP
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