Method and apparatus for recording compressed variable bitrate audio information

• US 6,320,825 B1
• Filed: 07/26/1999
• Issued: 11/20/2001
• Est. Priority Date: 11/29/1997
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Van De Kerkhof, Leon M., De Haan, Wiebe, Bruekers, Alphons A.M.L., Bakx, Johannus L.
• Primary Examiner(s): DINH, TAN X
• Application Number:
  US09/355,380
• Time in Patent Office: 848 Days
• Field of Search: 369/32, 369/33, 369/47, 369/48, 369/59, 369/58, 369/54, 348/390.1, 348/405.1, 348/419.1, 360/8
• US Class Current: 369/30.17
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/329 on a disc [VTOC]
• CPC Class Codes: G11B 7/0045 Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence

Abstract

A method for recording audio information on a record carrier, typically a bitstream signal on an optical disc, is disclosed. In the method the audio information is encoded to compressed audio data having a variable bitrate, in particular using lossless compression. The compressed audio data is recorded at a transfer speed which is controlled in dependence on the variable bitrate. A transfer speed profile (53, 54, 55) is determined for items of audio information, e.g. for each track on a CD, in which profile the average transfer speed is higher than an average transfer speed minimally required to transfer the compressed audio data of said item. Stuffing data is added to the compressed audio data according to the transfer speed profile, and transfer speed profile information is recorded on the record carrier for enabling playback at a transfer speed as indicated by the transfer speed profile information. Also a recording device, a record carrier and a playback device are disclosed.

Claims

1. A method for recording audio information on a record carrier, the method comprising the steps of:

encoding the audio information into compressed audio data having a variable bitrate;

recording the compressed audio data at a transfer speed; and

controlling the transfer speed depending on the variable bitrate including;

determining a transfer speed profile for an item of audio information in which profile the average transfer speed is higher than an average transfer speed minimally required to transfer the compressed audio data of the item;

adding stuffing data to the compressed audio data according to the transfer speed profile; and

recording transfer speed profile information on the record carrier for enabling playback at a transfer speed as indicated by the transfer speed profile information.

2. The method of claim 1, in which the recording at the transfer speed includes:

storing the compressed audio data of at least part of the item in an edit buffer; and

,

after the determining the transfer speed profile, recording the contents of the edit buffer on the record carrier.

3. The method of claim 2, in which the recording of the contents of the edit buffer on the record carrier occurs at a speed higher than the transfer speed.

4. A recording device for recording audio information on a record carrier, the device comprising:

compression means for encoding the audio information into compressed audio data having a variable bitrate;

recording means for recording the compressed audio data at a transfer speed; and

control means for controlling the transfer speed depending on the variable bitrate and

for determining a transfer speed profile for an item of audio information in which profile the average transfer speed is higher than an average transfer speed minimally required to transfer the compressed audio data of the item; and

data combination means for adding stuffing data to the compressed audio data according to the transfer speed profile; and

in which the recording means records transfer speed profile information on the record carrier for enabling playback at a transfer speed as indicated by the transfer speed profile information.

5. A record carrier comprising:

audio information encoded as compressed audio data having a variable bitrate;

transfer speed information for controlling a transfer speed at playback, the transfer speed information including transfer speed profile information indicating the transfer speed at playback for an item of audio information, in which profile the average transfer speed is higher than an average transfer speed minimally required to transfer the compressed audio data of the item; and

stuffing data in addition to the compressed audio data, according to the transfer speed profile.

6. The record carrier of claim 5, in which the transfer speed profile includes a fixed bitrate per item.

7. The record carrier of claim 5, in which the transfer speed profile includes per item, at least one speed indicator of a bitrate at a specified time within the item.

8. The record carrier of claim 5, in which the transfer speed profile includes per item, at least one speed change indicator.

9. The record carrier of claim 5, in which:

the record carrier has a disc shape; and

the transfer speed profile includes a rotation rate of the record carrier as an indication of the bitrate.

10. The record carrier of claim 5, in which the record carrier includes a separate area and only the transfer speed profile is recorded in the separate area of the record carrier.

11. A playback device for retrieving from a record carrier, the device comprising:

reading means for retrieving compressed audio data at a transfer speed;

control means for controlling the transfer speed; and

data selection means for retrieving transfer speed profile information from the record carrier and for removing stuffing data from the data retrieved; and

in which

the control means sets the transfer speed for an item of audio information according to the transfer speed profile.

12. The playback device of claim 11, in which

the device further comprises de-compression means for decoding the compressed audio data having the variable bitrate.

13. The playback device of claim 11 in which:

the carrier is a disc-shaped record carrier; and

the control means calculates a rotation rate for the record carrier depending on the transfer speed profile.