Method and apparatus for extracting digital data from a medium
View Patent ↗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 files wherein each file contains one or more complete and distinct tracks, and the data representing sound levels below the specified threshold can be excluded from the resulting files. The files 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 track 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 a plurality of separate files, each file containing one or more tracks and each file excluding the digital audio data having levels of sound below the specified threshold,
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 file and within each segment, said method further comprising reading and storing the TOC data, and
wherein dividing includes:
if the level of sound at a point where a first track ends and a second track begins is not below the specified threshold, then including the first and second tracks in the same file; and
if the level of sound at a point where a third track ends and a fourth track begins is below the specified threshold, then including the third and fourth tracks in separate files.
2. The method of claim 1 further comprising:
encoding at least one of the files to generate a playback file that may be read by an audio player.
3. The method of claim 2 wherein the encoding includes compressing the digital audio data contained on the file.
4. The method of claim 2 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.
5. The method of claim 2 further comprising:
if a first file is contiguous to a second file, determining an amount of time equal to the digital audio data that was excluded, during said dividing, from between the first and second files; and
storing the amount of time and its position relative to the one or more files; and
inserting 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 file and prior to an audio player's playback of the one or more tracks contained in the second file.
6. The method of claim 3 wherein the compressing comprises MP3 compression.
7. The method of claim 3 wherein the compressing comprises AC-3 compression.
8. The method of claim 1 wherein the variable is time.
9. The method of claim 1 wherein the variable is a number of data sectors.
10. The method of claim 1 wherein the source medium is a compact disc (“CD”).
11. The method of claim 1 wherein the source medium is a mini-disc.
12. The method of claim 1 wherein the source medium is a digital video disc (“DVD”).
13. The method of claim 1 wherein the file is a chunk of contiguous digital audio data.
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, causes 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 as 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 a plurality of files, each file containing one or more tracks and each file excluding the digital audio data having levels of sound below the specified threshold,
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 file, and
wherein the digital audio data is divided according to the following steps:
if the level of sound at a point where a first track ends and a second track begins is not below the specified threshold, then including the first and second tracks in the same file; and
if the level of sound at a point where a third track ends and a fourth track begins is below the specified threshold, then including the third and fourth tracks in separate files.
16. The machine readable medium of claim 15 further causing said machine to:
encode at least one of the files to generate a playback file that may be read by an audio player.
17. The method of claim 16 wherein the encoding includes compressing the digital audio data contained on the file.
18. The machine readable medium of claim 16 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.
19. The machine readable medium of claim 16 further causing said machine to:
determine, wherein a first file is contiguous to a second file, an amount of time equal to the digital audio data that was excluded between the first and second files;
store the amount of time and its position relative to the one or more files; 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 file and prior to an audio player's playback of the one or more tracks contained in the second file.
20. 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 data 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 a plurality of distinct files, each file containing one or more of said tracks and each file excluding the digital audio data having levels of sound below the specified threshold,
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, and
wherein dividing includes:
if the level of sound at a point where a first track ends and a second track begins is not below the specified threshold, then including the first and second tracks in the same file; and
if the level of sound at a point where a third track ends and a fourth track begins is below the specified threshold, then including the third and fourth tracks in separate files.
21. The method of claim 20 further comprising:
encoding one or more of the files to generate a playback file that may be read by an audio player.