Audio transmitting apparatus and audio receiving apparatus

• US 6,904,403 B1
• Filed: 09/22/2000
• Issued: 06/07/2005
• Est. Priority Date: 09/22/1999
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Keiko, Muraki, Kenji, Nakajima, Yasushi, Ejima, Naoki
• Primary Examiner(s): Ometz, David L.
• Assistant Examiner(s): Opsasnick, Michael N.
• Application Number:
  US09/667,666
• Time in Patent Office: 1,719 Days
• Field of Search: 704/212, 704500-504
• US Class Current: 704/212
• CPC Class Codes: H04L 12/40058 Isochronous transmission
• CPC Class Codes: H04L 12/40071 Packet processing; Packet format adaptation of digital video signals for transport over a specific network H04N21/2381, H04N21/4363, H04N21/4381; packet switches H04L49/00; intermediate storage or scheduling H04L49/90
• CPC Class Codes: H04L 12/40117 Interconnection of audio or video/imaging devices home automation networks H04L12/2803; bitstream network arrangements specially adapted for distribution of digital video signals H04N7/24

Abstract

In transmission of digital audio data usingIEEE1394, for example, when the audio data is changed from linear PCM to nonlinear PCM, identifier adding means of the transmitting apparatus inserts a silent identifier and nearly zero data for a specific time, and first identifier distinguishing means of the receiving apparatus changes over the output of data processing selecting means from linear PCM processing side to nonlinear processing side when detecting the silent identifier, thereby preventing generation of noise when changing over the data.

Claims

1. An audio transmitting apparatus comprising:

data reproducer for outputting digital audio data and control information for the digital audio data;

identifier adder for identifying a coding type of the digital audio data, and for adding identification information showing the identified coding type on the digital audio data, and for sending out the identification information added on the digital audio data; and

controller for controlling an output of the digital audio data issued from the data reproducer,

wherein when the identification information changes from identification information A showing a first coding type to identification information B showing a second coding type,

(a) the controller stops the output of the digital audio data issued from the data reproducer for a specified time,

(b) the identifier adder

(i) generates silent identification information C indicating substantially zero data during the specified time, and

(ii) performs at least one of adding the identification information A on the silent identification information C in a first half of the specified time and adding the identification information B on the silent identification information C in a second half of the specified time,

and outputs the silent identification information C.

2. The audio transmitting apparatus of claim 1, wherein said identification information A shows linear PCM mode, and said identification information B shows nonlinear PCM mode.

3. The audio transmitting apparatus of claim 1, wherein the specified time of transition of said identification information from said identification information A to said identification Information B ranges from 3 msec to hundreds of msec.

4. The audio transmitting apparatus of claim 1, wherein the digital audio data of a coding type shown by said identification information A fades out immediately before transition.

5. The audio transmitting apparatus of claim 1, wherein the digital audio data of a coding type shown by said identification information B fades in for a specified time after transition.

6. The audio transmitting apparatus of any one of claims 1 to 5, wherein the transmission route for sending out data issued from the identifier adder is IEEE1394.

7. The audio transmitting apparatus of any one of claims 1 to 5, wherein the transmission route for sending out data issued from the identifier adder is IEEE1394, and said silent identification information C is ancillary data specified in Audio and Music Data Transmission Protocol of the IEEE1394.

8. The audio transmitting apparatus of any one of claims 1 to 5, wherein the transmission route for sending out data is IEEE1394, and said silent identification information C has a specified data region, and said data region is “

0”

in a specified bit row at the MSB side.

9. The audio transmitting apparatus of claim 1, wherein one of said identification information A or identification information B shows non-encode mode, and others show encode mode.

10. The audio transmitting apparatus of claim 1, wherein said T1 is 3 msec or more.

11. The audio transmitting apparatus of claim 1, wherein said T2 is 3 msec or more.

12. The audio receiving apparatus according to claim 1,

wherein the identification information A and the identification information B further including information showing at least one of a number of channels, a data length, a sampling frequency, channel allocation information, dynamic range control information, a down-mix coefficient, an emphasis flag, copy control information and an internal standard recording code (ISRC) of the digital audio data.

13. The audio transmitting apparatus of claim 1, wherein said silent identification information C includes a specified data region and includes the identification information A and the identification information B at an MSB side of the data specified region.

14. The audio transmitting apparatus of claim 13, wherein sequentially different data are stored in at an LSB side in the specified data region.

15. The audio transmitting apparatus of claim 13, wherein pseudo-random number data are stored in at an LSB side in the specified data region following said silent identification information C.

16. An audio receiving apparatus comprising identification information distinguishing means for distinguishing the identification information showing the type of the data received through a transmission route,

wherein digital audio data is issued directly in the case of identification information showing non-encode mode, depending on the output of said identification information distinguishing means, or issued by way of data decoding means in the case of identification information showing encode mode, and

when said identification information distinguishing means distinguishes silent identification information C,

the output is immediately muted nearly to zero in the case of identification information showing the identification information before the silent identification information C is non-encode mode, or

the output is muted nearly to zero after termination of processing of the data in process by said data decoding means in the case of identification information showing the identification information before the silent identification information C is encode mode.

18. The audio receiving apparatus of claim 16 or 17, wherein the transmission route for receiving data is IEEE1394.

19. The audio receiving apparatus of claim 16 or 17, wherein the transmission route for receiving data is IEEE1394, and said silent identification information C is ancillary data specified in Audio and Music Data Transmission Protocol of the IEEE1394.

17. An audio receiving apparatus comprising identification information distinguishing means for distinguishing the identification information showing the type of the data received through a transmission route,

wherein digital audio data is issued directly in the case of identification information showing non-encode mode, depending on the output of said identification information distinguishing means, or issued by way of data decoding means in the case of identification information showing encode mode, and

when said identifier distinguishing means distinguishes silent identification information C,

the output is immediately muted nearly to zero in the case of identification information showing the identification information before the silent identification information C is non-encode mode, or

the output is muted nearly to zero after termination of processing of the data in process by said data decoding means in the case of identification information showing the identification information before the silent identification information C is encode mode,

thereby changing to the setting for data output depending on the identification information accompanying said silent identification information C in the midst of muting by said silent identification information C.

20. An audio transmitting apparatus comprising:

data reproducer for outputting digital audio data and control information for the digital audio data;

identifier adder for identifying at least one of a coding type, a number of channels, and a sampling frequency of the digital audio data, and means for adding identification information showing at least one of the coding type, the number of channels, and the sampling frequency on the digital audio data, and for sending out the identification information added on the digital audio data; and

controller for controlling an output of the digital audio data issued from the data reproducing means,

wherein when said at least one of the coding type, the number of channels, and the sampling frequency shown by identification information A changes to said at least one of the coding type, the number of channels shown by identification information B which is different information than the information shown by the identification information A,

(a) the controller stops the output of the digital audio data issued from the data reproducer for a specified time,

(b) the identifier adder,

(i) generates silent identification information C indicating substantially zero data during the specified time, and

(ii) performs at least one of adding the identification information A on the silent identification information C in a first half of the specified time and adding the identification information B on the silent identification information C in a second half of the specified time,

and outputs the silent identification information C.