Method and apparatus for extracting digital data from a medium
A computer-implemented method and apparatus for extracting digital data from a medium. Digital audio extraction techniques are implemented with additional features that improve the quality of the resulting audio playback files. In one embodiment of the invention, a user can extract digital audio data from a source medium and store the data as a file or, alternatively, stream the data into a memory. The file/stream can then be analyzed to determine the precise locations, in time, at which the sound levels represented by the data cross a specified threshold, particularly at locations near and between track edges. This information can be stored for reference. Subsequently, the file/stream can be accurately divided into smaller segments wherein each segment contains one or more complete and distinct tracks, and the data representing sound levels below the specified threshold can be excluded from the resulting segments. The segments may then be encoded and/or further divided into standard playback files. Another embodiment of the invention includes an audio player. The player can play the playback files, in their original order, and can automatically include sections of silence between tracks, where required, and will refrain from including sections of silence or pauses between tracks that are intended to be played end-to-end.
1. A computer implemented method comprising:
reading digital audio data from a source medium, the digital audio data divided into a plurality of tracks, each representing a discrete chunk of digital audio data and having sound levels varying as a function of a variable;
analyzing the digital audio data to determine the levels of sound as a function of the variable and determining one or more precise values of the variable at which the level of sound crosses a specified threshold; and
dividing the digital audio data into one or more segments, each segment containing one or more tracks and each segment excluding the digital audio data having levels of sound below the specified threshold, and wherein dividing includes:
if the level of sound at a track edge between a first track and a second track is not below the specified threshold, then including the first and second tracks in the same segment; and
if the level of sound at a track edge between a third track and a fourth track is below the specified threshold, then including the third and fourth tracks in separate segments.
2. The method of claim 1 where in the source medium contains Table of Contents (“TOC”) data identifying the values of the variable at which each track begins and ends within each segment, said method further comprising reading and storing the TOC data.
3. The method of claim 2 further comprising:
encoding at least one of the segments to generate a playback file that may be read by an audio player.
4. The method of claim 3 wherein the encoding includes compressing the digital audio data contained on the segment.
5. The method of claim 4 wherein the compressing comprises MP3 compression.
6. The method of claim 4 wherein the compressing comprises AC-3 compression.
7. The method of claim 3 further comprising:
if a playback file contains two or more tracks then, with reference to the TOC data, dividing the playback file into smaller playback files such that each smaller playback file represents a discrete track and two or more of the smaller playback files may be played consecutively without a pause or loss in sound quality during the time an audio player is switching between playing contiguous tracks.
8. The method of claim 3 further comprising:
if a first segment is contiguous to a second segment, determining an amount of time equal to the digital audio data that was excluded during said dividing, from between the first and second segments; and
storing the amount of time and its position relative to the one or more segments; and
inserting silence for a time equal in length to the said amount time after an audio player's playback of the one or more tracks contained in the first segment and prior to an audio player's playback of the one or more tracks contained in the second segment.
9. The method of claim 1 wherein the variable is time.
10. The method of claim 1 wherein the variable is a number of data sectors.
11. The method of claim 1 wherein the source medium is a compact disc (“CD”).
12. The method of claim 1 wherein the source medium is a mini-disc.
13. The method of claim 1 wherein the source medium is a digital video disk (“DVD”).
14. The method of claim 1 wherein the audio data is PCM data.
15. A machine readable medium including program code which, when executed by a machine cause said machine to:
read digital audio data from a source medium, the digital audio data divided into a plurality of tracks, each representing a discrete chunk of digital audio data and having sound levels varying a function of a variable;
analyze the digital audio data to determine the levels of sound as a function of the variable and determining one or more precise values of the variable at which the level of sound crosses a specified threshold; and
divide the digital audio data into one or more segments,each segment containing one or more tracks and each segment excluding the digital audio data having levels of sound below the specified threshold, wherein dividing includes:
if the level of sound at a track edge between a first track and a second track is not below the specified threshold, then including the first and second tracks in the same segment; and
if the level of sound at a track edge between a third track and a fourth track is below the specified threshold then including the third and fourth tracks in separate segments.
16. The machine readable medium of claim 15 wherein the source medium contains Table of Contents (TOC) data identifying the values of the variable at which each track begins and ends within each segment.
17. The machine readable medium of claim 16 further causing said machine to:
encode at least one of the segments to generate a playback file that may be read by an audio player.
18. The machine readable medium of claim 17 wherein the encoding includes compressing digital audio data contained on the segment.
19. The machine readable medium of claim 17 further causing said machine to:
if a playback file contains two or more tracks then with reference to the TOC data, divide the playback file into smaller playback files such that each smaller playback file represents a discrete track, and two or more of the smaller playback files may be played consecutively without a pause or loss in sound quality during the time an audio player is switching between playing contiguous tracks.
20. The machine readable medium of claim 17 further causing said machine to:
determine, wherein a first segment is contiguous a second segment, an amount of time equal to the digital audio data that was excluded between the first and second segments;
store the amount of time and its postion relative to the one or more segments; and
insert silence for a time equal in length to said amount time after an audio player's playback of the one or more tracks contained in the first segment and prior to an audio player's playback of the one or more tracks contained in the second segment.
21. An apparatus comprising:
a ripper module to read multimedia content from a medium into memory; and
a wave slicer module to divide said multimedia content into one or more segments based on a measured audio level of said multimedia content dropping below a predetermined threshold value at beginning and an end of each of said segments, wherein said multimedia content is divided such that, if the level of sound at a track edge between a first track and a second track is not below the specified threshold, the first and second tracks are included in the same segment; and if the level of sound at a track edge between a third track and a fourth track is below the specified threshold, the third and fourth tracks are included in separate segments.
22. The apparatus as in claim 21 further comprising:
one or more encoder modules to en encode said segments using a specified encoding algorithm.
23. The apparatus as in claim 22 further comprising:
a splitter module to split said segments into discrete a tracks based on index data identifying said tracks.
24. The apparatus as in claim 21 wherein said multimedia content is PCM audio content.
25. The apparatus as in claim 24 wherein said medium is a compact disk.
26. A computer-implemented method comprising:
reading digital audio data from a source medium, the digital audio data divided into a plurality of tracks and having sound levels changing over time;
analyzing the digital audio to determine the levels of sound as a function of time and determining one or more points in time at which the level of sound is below a specified threshold; and
dividing the digital audio data into one or more segments, each segment containing one or more of said tracks and each segment excluding the digital audio data having levels of sound below the specified threshold, wherein dividing includes:
if the level of sound at a track edge between a first track and a second track is not below the specified threshold, then inducing the first and second tracks in the same segment; and
if the level of sound at a track edge between a third track and a fourth track is below the specified threshold, then including the third and fourth tracks in separate segments.
27. The method of claim 26 wherein the source medium contains Table of Contents (“TOC”) data identifying the time at which each track begins and ends within each file and within each segment, said method further comprising reading and storing the TOC data.
28. The method of claim 27 further comprising:
encoding one or more of the segments to generate playback file that may be read by an audio player.