Low power system and method for playing compressed audio data

• US 6,332,175 B1
• Filed: 02/12/1999
• Issued: 12/18/2001
• Est. Priority Date: 02/12/1999
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Kumar, Puneet, Birrell, Andrew, Laing, William
• Primary Examiner(s): Yoo, Do Hyun
• Assistant Examiner(s): MCLEAN MAYO, KIMBERLY N
• Application Number:
  US09/249,183
• Time in Patent Office: 1,040 Days
• Field of Search: 711/112, 711/111, 369/54, 369/48, 369/60, 369/33, 704/500, 704/504, 704/502
• US Class Current: 711/112
• 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 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/10768 by pre-caching the initial portion of songs or other recorded or downloaded data for starting playback instantly
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 2220/65 wherein solid state memory is used for storing indexing information or metadata
• 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 27/11 by using information not detectable on the record carrier
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D

Abstract

A portable audio player stores a large amount of compressed audio data on an internal disk drive, and loads a portion of this into an internal random access memory (RAM) which requires less power and less time to access. The audio player plays the data stored in RAM and monitors the amount of unplayed data. When the amount of unplayed data falls below a threshold, additional data is copied from the disk drive into RAM. Because the time necessary to copy a block of data from the disk drive to RAM is much less than the amount of time it takes to play the same block of audio data from RAM, this approach minimizes the amount of time that the disk drive must be operated, and thus minimizes the amount of power consumed by the system.

Claims

1. A self-contained portable audio player, comprising:

a disk storage unit for storing compressed audio data comprising a multiplicity of audio recordings;

a memory buffer for storing compressed audio data and a play list identifying a subset of the audio recordings and an order in which to play the identified subset of audio recordings;

a compressed audio data converter for converting compressed audio data in the memory buffer into a decompressed audio signal;

a communications port for transmitting the decompressed audio signal to a user; and

play control logic for copying compressed audio data from the disk storage unit into the memory buffer, wherein the copied data, when converted into a decompressed audio signal, has a transmission time that is greater than an amount of time required to copy data from the disk storage unit into the memory buffer;

wherein the play control logic is configured to increase power to the disk storage unit, to enable copying of audio data from the disk storage unit into the memory buffer, when the amount of compressed audio data remaining to be converted by the compressed audio data converter reaches a threshold level unless the play list is empty, and is configured to decrease power to the disk storage unit when copying of compressed audio data from the disk storage unit into the memory buffer reaches a predefined stop condition.

2. The portable audio player of claim 1, wherein the copied data, when converted into the decompressed audio signal, has a transmission time that is at least ten times greater than the amount of time required to copy the data from the disk storage unit into the memory buffer.

9. The self-contained portable audio player of claim 1, wherein the play control logic is further configured to prevent overwriting of a portion of the compressed audio data stored in the memory that was most recently converted into a decompressed audio signal, to enable re-use of that portion of the compressed audio data without retrieval from the disk storage unit.

3. A method for reducing the power consumption of a portable audio player, comprising:

storing in a temporary storage unit compressed audio data and a play list identifying a set of audio recordings and an order in which to play the identified set of audio recordings;

transmitting the compressed audio data from the temporary storage unit to a data converter;

converting the compressed audio data into a decompressed audio signal;

transmitting the decompressed audio signal to an output port;

when a predetermined amount of compressed audio data has been transmitted from the temporary storage unit, copying compressed audio data from a disk storage unit into the temporary storage unit, wherein the copied data, when converted into a decompressed audio signal, has a transmission time that is greater than the time taken to copy the data from the disk storage unit into the temporary storage unit;

decreasing power to the disk storage unit when copying of compressed audio data from the disk storage unit into the temporary storage unit reaches a predefined stop condition; and

increasing power to the disk storage unit, to enable copying of audio data from the disk storage unit into the temporary storage unit, when the amount of compressed audio data remaining to be converted reaches a threshold level unless the play list is empty.

4. The method of claim 3, wherein the copied data, when converted into the decompressed audio signal, has a transmission time that is at least ten times greater than the time taken to copy data from the disk storage unit into the temporary storage unit.

10. The method of claim 3, wherein the copying is performed so as to retain a portion of the compressed data stored in the (volatile memory) unit that was most recently converted into decompressed data, to enable re-use of that portion of the compressed data without retrieval from the (non-volatile memory) storage unit.

5. A data storage and transmission unit, comprising:

a non-volatile memory unit for storing compressed data comprising a multiplicity of units;

a volatile memory unit for storing compressed data and a list identifying a subset of the units and an order in which to process the identified subset of the units;

a converter for decompressing the compressed data so as to generate decompressed data;

an output port, coupled to the converter, for transmitting the decompressed data from to an output device; and

control logic for copying compressed data from the non-volatile memory unit into the volatile memory unit, wherein the copied compressed data, when converted into decompressed data, has an associated transmission time that is greater than the time required to copy the compressed data from the non-volatile memory unit into the volatile memory unit;

wherein the control logic is configured to increase power to the non-volatile memory unit, to enable copying of compressed data from the non-volatile memory unit into the volatile memory unit, when the amount of compressed data remaining to be converted by the compressed data converter reaches a threshold level unless the list is empty, and is configured to decrease power to the non-volatile memory unit when copying of compressed data from the non-volatile memory unit into the volatile memory unit reaches a predefined stop condition.

6. The data storage and transmission unit of claim 5, wherein the data comprises video data.

7. The data storage and transmission unit of claim 6, wherein the copied compressed data, when converted into decompressed data, has an associated transmission time that is at least ten times as great as the time required to copy the compressed data from the non-volatile memory unit into the volatile memory unit.

8. The data storage and transmission unit of claim 7, wherein the non-volatile memory unit is a hard disk storage unit and the volatile memory unit is random access memory.

11. The data storage and transmission unit of claim 5, wherein the control logic is further configured to prevent overwriting of a portion of the compressed data stored in the volatile memory unit that was most recently converted into decompressed data, to enable re-use of that portion of the compressed audio without retrieval from the non-volatile memory unit.