Determining buffer refilling time when playing back variable bit rate media streams

• US 20070097816A1
• Filed: 11/04/2004
• Published: 05/03/2007
• Est. Priority Date: 11/18/2003
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Gassel, Jozef
• Granted Patent: US 7,869,316 B2
• Time in Patent Office: Days
• US Class Current: 369/47.33
• CPC Class Codes: G06F 1/3225 of memory devices
• CPC Class Codes: G06F 1/3256 Power saving in optical drive
• CPC Class Codes: G06F 1/3268 Power saving in hard disk drive
• CPC Class Codes: G11B 19/28 Speed controlling, regulating, or indicating G11B19/24 takes precedence
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 20/1258 where blocks are arranged within multiple radial zones, e.g. Zone Bit Recording or Constant Density Recording discs, MCAV discs, MCLV discs
• CPC Class Codes: G11B 2020/10814 involving specific measures to prevent a buffer underrun
• CPC Class Codes: G11B 2020/10944 Real-time recording or reproducing, e.g. for ensuring seamless playback of AV data
• CPC Class Codes: G11B 2020/10953 Concurrent recording or playback of different streams or files
• CPC Class Codes: G11B 2020/10962 wherein both recording and playback take place simultaneously
• CPC Class Codes: G11B 2020/1896 using skip or slip replacement to relocate data from a defective block to the next usable block, e.g. with a primary defect list [PDL]
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A playback device for playback of a media stream stored on a storage medium, the device comprising control means for controlling the reading, buffering and playback of the media stream. During playback a buffer is filled by reading means and emptied by a playback unit. At each buffer filling a buffer refilling time, i.e. the moment when the buffer will be empty and thus has to be refilled, is calculated. After each buffer filling the storage medium can change to standby mode till buffer refilling is to occur. Thus power consumption by the storage medium is minimized. The buffer refilling time (28) depends on the total consumption time (27) and the buffer filling period (22). The total consumption time (27) is determined depending on playback mode control information. The buffer filling period (22) is calculated depending on information about the retrieval of the media stream or an estimation of the buffer filling period (22) is made.

Claims

1. A playback device (8) for playback of a media stream from a storage medium (1), the device comprising reading means (3) for reading at least a part of the media stream, a buffer (4) for holding the part of the media stream, a playback unit (5) for consuming the part of the media stream from the buffer (4) at a predefined rate, and control means (6) for controlling the reading of the media stream from the storage medium (1), filling of the buffer (4) and the playback of the media stream, which control means (6) comprise means (9) for retrieving playback mode control information (7), and means (10) for calculating a buffer refilling time (28) depending on the playback mode control information.

2. A playback device (8) as claimed in claim 1, wherein the means for retrieving playback mode control information (7) are arranged for retrieving characteristic point information and the means for calculating the buffer refilling time (28) are arranged for calculating the buffer refilling time (28) depending on the characteristic point information.

3. A playback device (8) as claimed in claim 1, in which the control means (6) are arranged for calculating the buffer filling period (22) depending on information concerning retrieval of the media stream.

4. A playback device (8) as claimed in claim 3, in which the control means (6) are arranged for calculating the buffer filling period (22) depending on information about the location of the part of the media stream on the storage medium (1).

5. A playback device (8) as claimed in claim 3, in which the control means (6) are arranged for calculating the buffer filling period (22) depending on information from the file system info.

6. A playback device (8) as claimed in claim 4, in which the control means (6) are arranged for calculating the buffer filling period (22) depending on information about the position of a disk head (2).

7. A playback device (8) as claimed in claim 1, in which the control means (6) are arranged for turning the device (8) in a low power consuming mode for a time interval depending on the buffer refilling time (28).

8. A method for playback of a media stream from a storage medium, the method comprising the steps of reading at least a part of the media stream, holding the part of the media stream in a buffer, playing back the part of the media stream from the buffer at a predefined rate, and controlling the reading of the media stream from the storage medium, filling of the buffer and the playback of the media stream, which step of controlling comprises the sub steps of retrieving playback mode control information, and calculating a buffer refilling time (28) depending on the playback mode control information.

9. A method as claimed in claim 8, comprising the step of calculating the buffer filling period (22) depending on information concerning the retrieval of the media stream.

10. A computer program product which program is operative to cause a processor to perform the method as claimed in claim 8.