Method to eliminate noise in repeated sound start during digital sound recording

• US 5,802,250 A
• Filed: 11/15/1994
• Issued: 09/01/1998
• Est. Priority Date: 11/15/1994
• Status: Expired due to Term

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Kao, Oliver C. K.
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): EDOUARD, PATRICK NESTOR
• Application Number:
  US08/340,001
• Time in Patent Office: 1,386 Days
• Field of Search: 395/2.74, 395/2.76, 395/2.42, 395/2.67, 395/2.39, 395/2.37, 395/2.35, 381/34, 381/40, 381/35, 381/52, 381/51
• US Class Current: 704/228
• CPC Class Codes: G11B 20/22 for reducing distortions
• CPC Class Codes: G11C 2207/16 Solid state audio deprecated, only for historical reasons, G06F3/16, G11B
• CPC Class Codes: G11C 7/16 Storage of analogue signals in digital stores using an arrangement comprising analogue/digital [A/D] converters, digital memories and digital/analogue [D/A] converters

Abstract

A method to eliminate noise in repeated sound start during a digital sound recording playback by using a slowly descending or ascending waveform to eliminate the discontinuity between sound waves which can be utilized in applications such as a playback only sound synthesis or a recording and playback system.

Claims

1. A method for eliminating discontinuity noise in repeated sound start during the playback of a digital synthesis or recording playback system comprising the step of:

examining a bit position of a sound in a playback of a waveform on a digital axis at a point of said sound being interrupted by triggering a playback of another sound;

determining a bit distance between said bit position and a mid-point position on the digital axis;

generating an incrementally decreasing or increasing digital sequence based on said determined bit distance, and

adding said incrementally decreasing or increasing digital sequence to said bit position such that said playback of said sound slowly descends or ascends to said mid-point position on the digital axis thus avoiding a discontinuity of said waveform occurring at said point of interruption thereby eliminating noise resulted from said discontinuity.

2. The method according to claim 1, wherein said incrementally decreasing or increasing digital sequence is generated by a signal controlled by triggering a playback of another sound.

3. The method according to claim 1, wherein said incrementally decreasing digital sequence is composed of a most significant bit (MSB) of "one" and a number of "zeros" shifting towards said mid-point position, said mid-point position being defined as noiseless discontinuity position.

4. The method according to claim 1, wherein said incrementally increasing code is composed of a most significant bit (MSB) of "zero" and a number of "ones" shifting towards said mid-point position, said mid-point position being defined as noiseless discontinuity position.

7. The method according to claim 1 wherein said bit position at said point of said sound being interrupted is a non-midpoint.

5. An apparatus for eliminating noise in repeated sound starts during playback of a digital waveform sound recording, comprising a signal processor for generating an incrementally decreasing or increasing digital sequence to be added to a sound bit position on a digital axis such that a discontinuity in the digital waveform and the related noise generated can be avoided.

6. An apparatus for playback of a digital sound recording eliminating noise in repeated sound starts during the playback of the digital sound recording, the apparatus comprising:

an address generator for producing speaking sound code storage addresses;

a memory unit for storing said addresses and reading the same therefrom, said memory unit being connected to said address generator;

a signal processor for generating an incrementally decreasing or increasing digital sequence to be added to a sound bit position on a digital axis such that a discontinuity in the playback of the digital sound recording and the related noise generated by said discontinuity can be avoided, said processor being fed by a signal controlled by triggering a start of a playback of another digital sound recording; and

a control unit for controlling said processor, said control unit being input from the output of said signal processor and having its output connected to a control input of said signal processor.

8. The apparatus according to claim 6 wherein said bit position at said point of said sound being interrupted is a non-midpoint.