Digital signal processor

• US 20010018657A1
• Filed: 11/29/2000
• Published: 08/30/2001
• Est. Priority Date: 11/29/1999
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hatanaka, Norio
• Granted Patent: US 6,785,657 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/42646 for reading from or writing on a non-volatile solid state storage medium, e.g. DVD, CD-ROM
• CPC Class Codes: H04N 21/4396 by muting the audio signal
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/482 End-user interface for program selection broadcast systems using EPGs H04H60/72
• CPC Class Codes: H04N 21/8106 involving special audio data, e.g. different tracks for different languages
• CPC Class Codes: H04N 5/602 for digital sound signals
• CPC Class Codes: H04N 5/607 for more than one sound signal, e.g. stereo, multilanguages H04N5/602 takes precedence
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 5/9265 with processing of the sound signal

Abstract

A digital signal processor comprises a coded audio data generation unit for generating coded audio data; an audio data generation unit for generating audio data; a signal switching unit for outputting one of the coded audio data and the audio data respectively supplied from the coded audio data generation unit and the audio data generation unit, and switching the output between these data; and a signal switching control unit for detecting the periodicity of the coded audio data outputted from the coded audio data generation unit, and controlling the signal switching unit so as to switch the output at the boundary of periods of the coded audio data. Therefore, when a DVD player including this digital signal processor receives an output switching instruction from the viewer during playback of a disk, the DVD player can supply a decoder with coded audio data for which periodicity is ensured, thereby avoiding malfunction of the decoder and occurrence of noise. Accordingly, audio output switching operation, which has conventionally been performed only when the operation of the DVD player is suspended, can be performed even when the disk is being played, whereby the viewer can easily switch the audio while watching the video, resulting in improved convenience.

Claims

1. A digital signal processor for switching its output between plural digital audio data, according to an output switching instruction from the outside, comprising:

a coded audio data generation unit for generating coded audio data;

an audio data generation unit for generating audio data;

a signal switching unit for outputting one of the coded audio data and the audio data respectively supplied from the coded audio data generation unit and the audio data generation unit, and switching the output between these data; and

a signal switching control unit for detecting the periodicity of the coded audio data outputted from the coded audio data generation unit, and controlling the signal switching unit so as to switch the output at the boundary of periods of the coded audio data.

2. The digital signal processor of

claim 1

, wherein said signal switching control unit controls the coded audio data generation unit or the audio data generation unit so that generation of coded audio data or audio data, which is to be output after the output switching, is started simultaneously with the output switching of the signal switching unit.

3. The digital signal processor of

claim 1

:

wherein said audio data generation unit performs soft muting on the audio data so as to gradually reduce the output level of the audio data, immediately before the output from the signal switching unit is switched from the audio data to the coded audio data; and

performs muting on the audio data when the output from the signal switching unit is switched from the coded audio data to the audio data and, thereafter, gradually increases the audio output level.

4. The digital signal processor of

claim 2

:

wherein said audio data generation unit performs soft muting on the audio data so as to gradually reduce the output level of the audio data, immediately before the output from the signal switching unit is switched from the audio data to the coded audio data; and

performs muting on the audio data when the output from the signal switching unit is switched from the coded audio data to the audio data and, thereafter, gradually increases the audio output level.

5. A digital signal processor for switching its output between plural digital audio data, according to an output switching instruction from the outside, comprising:

a first coded audio data generation unit for generating first coded audio data;

a second coded audio data generation unit for generating second coded audio data;

a signal switching unit for outputting one of the first and second coded audio data respectively supplied from the first and second coded audio data generation units, and switching the output between these data; and

a signal switching control unit for controlling the output switching of the signal switching unit;

wherein, on receipt of the output switching instruction from the outside, said signal switching control unit detects the periodicity of the first or second coded audio data outputted from the signal switching unit, and controls the signal switching unit so as to switch the output when a period of the coded audio data is ended and, simultaneously, controls the first or second coded audio data generation unit so as to generate data to be output after the output switching, from the beginning of a period of the data.

6. A digital signal processor for switching its output between plural digital audio data, according to an output switching instruction from the outside, comprising:

a plurality of signal generation units for generating plural pieces of digital data, respectively;

a signal switching unit for outputting one of the plural pieces of digital data supplied from the signal generation units, and switching its output; and

a signal switching control unit for controlling the timing of output switching of the signal switching unit;

wherein periodical coded data is output from the signal switching means, and when the signal switching control unit receives an output switching instruction from the outside, it controls the signal switching unit so that output switching is performed at the time when a period is ended, and

when the signal switching unit switches its output data to the coded data, the signal switching control unit controls the signal generation unit so that the coded data is generated from the beginning of the period, simultaneously with the output switching.