Method and apparatus for elapsed playback timekeeping of variable bit-rate digitally encoded audio data files

• US 7,283,880 B2
• Filed: 06/28/2002
• Issued: 10/16/2007
• Est. Priority Date: 09/06/2001
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Dick, Robert James
• Primary Examiner(s): Tran; Sinh
• Assistant Examiner(s): Briney, III; Walter F
• Application Number:
  US10/488,918
• Publication Number:
  US 20040249489A1
• Time in Patent Office: 1,936 Days
• Field of Search: 700/94, 386/68, 386/69, 386/6, 386/7, 386/40
• US Class Current: 700/94
• CPC Class Codes: G11B 19/022 Control panels
• CPC Class Codes: G11B 19/125 involving the detection of carrier data format
• 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 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/61 wherein solid state memory is used for storing A/V content storing computer data in solid state memories G06F
• CPC Class Codes: G11B 27/007 reproducing continuously a part of the information, i.e. repeating
• CPC Class Codes: G11B 27/105 of operating discs
• 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
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06

Abstract

The present invention involves a digital audio player and a method for processing encoded digital audio data, wherein the digital audio data is encoded using one of a plurality of encoding formats. The audio data player has a hard disk or other data storage medium for storing data files, a microcontroller, buffer memory for anti-skip protection, and an audio decoder. The encoded audio data files and associated decoder files are downloaded from a personal computer or similar device to the audio data player hard drive. The player provides a menu-driven user interface for selection, sorting, and playback of stored audio data files. During playback, elapsed playback time is computed and displayed. For variable bit-rate audio data files, the audio data player generates an elapsed playback timekeeping map concurrently with playback and fast forward scan of audio data files. Concurrently with playback, forward scan, and reverse scan of the audio data file, the audio data player determines the compression ratio for each data portion traversed, and calculates a playback time for each data portion traversed.

Claims

1. A method for monitoring in an audio data player, during the processing of an audio data file having data portions capable of having different compression ratios, the elapsed playback for the audio data file, comprising the steps of:

determining the compression ratio and size of each data portion traversed;

calculating the playback time for each data portion traversed based on the compression ratio and size of each data portion traversed; and

displaying the playback time on a display of the audio data player in response to the calculation.

2. The method of claim 1, wherein the determining step comprises determining elapsed time within the current data portion by interpolation.

3. The method of claim 1, further including the step of storing the playback time for each data portion traversed in a timekeeping map.

4. The method of claim 1, further including the step of adjusting an elapsed playback time counter based on the playback time for each data portion traversed.

5. The method of claim 1, wherein the calculating step comprises calculating elapsed playback time at an input to a buffer feeding an audio data decoder;

and the elapsed playback time is adjusted by subtracting an estimated playback time of the data contained in the buffer.

6. The method of claim 1, wherein the compression ratio is determined based on the bit rate stored in data frame headers of the audio data file;

and a confidence estimator locates frame headers and thereby locates the bit rate.

7. The method of claim 1, wherein the compression ratio is determined based on the bit rate stored in data frame headers of the audio data file;

and an interval skipper locates frame headers and thereby locates the bit rate.

8. The method of claim 1, wherein each data portion includes a fixed time length of audio data and a variable length of data, the length of data being determined by the compression ratio for each data portion.