Data processing: speech signal processing – linguistics – language – Speech signal processing – Synthesis
Reexamination Certificate
1996-12-23
2001-01-09
Voeltz, Emanuel Todd (Department: 2761)
Data processing: speech signal processing, linguistics, language
Speech signal processing
Synthesis
C704S201000, C704S270000, C704S214000, C704S215000
Reexamination Certificate
active
06173265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a voice recording and/or reproducing device.
2. Description of the Related Art
Recently, a device, which is a so-called digital voice recording and/or reproducing device (hereinafter called simply “digital voice recorder”), for recording and/or reproducing a voice has been developed.
The digital recorder collects a voice as an analog signal by a microphone or the like. The analog signal representing the collected voice is converted to a digital signal which is then stored in a storage medium (for example, an IC memory) of the digital recorder. When the recorded voice is reproduced, the stored digital voice is read out from the storage medium and converted to an analog signal. The analog signal is then reproduced by a speaker or the like.
When the digital signal is stored in the storage medium, the digital recorder generally applies a coding technique to compress the volume of data efficiently for saving the space of the storage medium.
The lower the bit rate for coding becomes, the more the volume of the stored digital signal is compressed so that the voice can be recorded for a long time. However, when the bit rate for coding becomes lower, the quality of the reproduced voice deteriorates in proportion to the decline of the bit rate.
Reversely, when the bit rate for coding becomes higher, the quality of the reproduced voice improves in proportion to the increase of the bit rate. However, the data compression rate declines so that the voice cannot be recorded for a long time.
Japanese Laid-Open Patent Application Publication No. Hei 2-94200 discloses a method for recording a voice that switches, if necessary, a coding means between a high quality recording mode for reproducing the recorded voice in high quality and a long time recording mode for recording the voice for a long time.
However, if the recording modes are changed over during the voice recording, the device will reproduce at the change over point a reproduced voice that sounds substantially differently than the input voice and that may be uneasy to listen.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a digital voice recorder for reproducing a voice in high quality at a change over point where a plurality of coding means are changed over from each other during a voice recording.
In order to achieve the object, a digital voice recorder of the present invention comprises a plurality of voice coding means having different bit rates for coding a voice by providing coded voice data. A selecting means disposed in the digital voice recorder of the present invention selects one of the plurality of voice coding means and provides a coding selection data. Coupled to the selecting means is a recording means for recording the coding selection data and the coded voice data in a storage medium. An IC memory. When the selecting means changes over the coding from one voice coding means to another voice coding means, a deterioration reducing means performs a predetermined process for reducing a deterioration of the voice due to the change over of the coding.
A digital voice recorder according to another aspect of the present invention comprises a plurality of voice decoding means having different bit rates for decoding voice data coded by using a predetermined process for reducing a deterioration of voice due to a change over of coding bit rates. In this embodiment a detecting means detects the coding selection data relating to the coding bit rate at which the voice was recorded, and a reproduction mode for automatically selecting one of the plurality of voice decoding means the voice decoding means which is associated with the bit rate corresponding to the coding selection data detected by the detecting means.
Other and further objects, features and advantages of the invention will appear more fully from the following description.
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Kroon, Peter. A High Quality Multirate Real-Time CELP Coder. IEEE Journal on Selected Areas in Communications. 850-857, Jun. 1992.*
Kenyon & Kenyon
Olympus Optical Co,. Ltd.
Sofocleous M. David
Todd Voeltz Emanuel
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