Efficient techniques for modifying audio playback rates
First Claim
Patent Images
1. An audio playback system, comprising:
- a user interface that enables a user of the audio playback system to specify a selected playback rate SR for an input audio stream that is faster or slower than a normal playback rate NR;
a memory for storage of at least one rate adjustment parameter, the at least one rate adjustment parameter comprising an overlap frequency OF, wherein the overlap frequency OF is related to the selected playback rate SR;
a processing device having limited computational resources operatively connected to the user interface and the memory, the processing device being operable to;
receive the input audio stream associated with the normal playback rate NR,wherein the input audio stream is comprised of a plurality of audio blocks,determine the overlap frequency OF based on the selected playback rate SR;
generate a modified audio stream for any value of the selected playback rate SR by modifying every Nth audio block of the plurality of audio blocks, wherein N is an integer value corresponding to an integer portion of the overlap frequency OF; and
an audio output device for outputting the modified audio stream, wherein if the selected playback rate SR is greater than 1.0 and less than 2.0, indicating faster than normal playback, then the overlap frequency OF is equal to 1/(SR−
1), and if the selected playback rate SR is less than 1.0, indicating slower than normal playback, then the overlap frequency OF is equal to 0.5/((1/SR)−
1).
2 Assignments
0 Petitions
Accused Products
Abstract
Improved techniques for modifying a playback rate of an audio item (e.g., an audio stream) are disclosed. As a result, the audio item can be played back faster or slower than normal. The improved techniques are resource efficient and well suited for audio items containing speech. The resource efficiency of the improved techniques make them well suited for use with portable media devices, such as portable media players.
-
Citations
24 Claims
-
1. An audio playback system, comprising:
-
a user interface that enables a user of the audio playback system to specify a selected playback rate SR for an input audio stream that is faster or slower than a normal playback rate NR; a memory for storage of at least one rate adjustment parameter, the at least one rate adjustment parameter comprising an overlap frequency OF, wherein the overlap frequency OF is related to the selected playback rate SR; a processing device having limited computational resources operatively connected to the user interface and the memory, the processing device being operable to; receive the input audio stream associated with the normal playback rate NR, wherein the input audio stream is comprised of a plurality of audio blocks, determine the overlap frequency OF based on the selected playback rate SR; generate a modified audio stream for any value of the selected playback rate SR by modifying every Nth audio block of the plurality of audio blocks, wherein N is an integer value corresponding to an integer portion of the overlap frequency OF; and an audio output device for outputting the modified audio stream, wherein if the selected playback rate SR is greater than 1.0 and less than 2.0, indicating faster than normal playback, then the overlap frequency OF is equal to 1/(SR−
1), and if the selected playback rate SR is less than 1.0, indicating slower than normal playback, then the overlap frequency OF is equal to 0.5/((1/SR)−
1). - View Dependent Claims (2, 3)
-
-
4. A method for altering a playback rate of an input audio stream, comprising:
-
specifying a selected playback rate SR for the input audio stream formed of a plurality of audio blocks, wherein the selected playback rate SR is either faster or slower than a normal playback rate NR of the input audio stream; determining an overlap frequency OF based on the selected playback rate SR, wherein if the selected playback rate SR is greater than 1.0 and less than 2.0, indicating faster than normal playback, then the overlap frequency OF is equal to 1/(rate−
1), and if the playback rate SR is less than 1.0, indicating slower than normal playback, then the overlap frequency OF is equal to 0.5/((1/rate)−
1);changing the playback rate of the input audio stream for any value of the selected playback rate SR by modifying every Nth audio block of the plurality of audio blocks, wherein N is an integer value corresponding to an integer portion of the overlap frequency OF; and outputting the modified audio stream at the selected playback rate SR. - View Dependent Claims (5, 6)
-
-
7. Computer readable medium including at least computer program code for changing a playback rate of an input audio stream, the computer readable medium comprising:
-
computer program code for specifying a selected playback rate SR for the input audio stream formed of a plurality of audio blocks, wherein the selected playback rate SR is either faster or slower than a normal playback rate NR of the input audio stream; computer program code for determining an overlap frequency OF based on the selected playback rate SR, wherein if the selected playback rate SR is greater than 1.0 and less than 2.0, indicating faster than normal playback, then the overlap frequency OF is equal to 1/(rate−
1), and if the playback rate SR is less than 1.0, indicating slower than normal playback, then the overlap frequency OF is equal to 0.5/((1/rate)−
1);computer program code for changing the playback rate of the input audio stream for any value of the selected playback rate SR by modifying every Nth audio block of the plurality of audio blocks, wherein N is an integer value corresponding to an integer portion of the overlap frequency OF; and computer program code for outputting the modified audio stream at the selected playback rate SR. - View Dependent Claims (8, 9)
-
-
10. A method for changing a selected playback rate SR of an audio stream, the method comprising:
-
(a) receiving a next audio block from the input audio stream having a normal playback rate NR; (b) incrementing an audio block count; (c) determining if the audio block count equals an integer value N corresponding to an integer portion of an overlap frequency OF related to the selected playback rate SR, wherein the integer value N determines which of the audio blocks of the input audio stream to alter; (d) outputting the next audio block as part of an output audio stream without alteration when the audio block count does not equal the integer value N; and for all SR less than 2.0, (e) using the overlap frequency OF to alter only every Nth audio block, outputting the altered Nth audio block as part of the output audio stream, and resetting the block count when the audio block count does equal the integer value N. - View Dependent Claims (11, 12, 13, 14, 15, 16)
-
-
17. Computer readable medium including at least computer program code for changing a selected playback rate SR of an audio stream, the computer readable medium comprising:
-
computer program code for receiving a next audio block from the input audio stream having a normal playback rate; computer program code for incrementing an audio block count; computer program code determining if the audio block count equals an integer value N corresponding to an integer portion of an overlap frequency OF that is related to the selected playback rate SR, wherein the integer value N determines which of the audio blocks of the input audio stream to alter; computer program code outputting the next audio block as part of an output audio stream without alteration when the audio block count does not equal the integer value N; and computer program code for using the overlap frequency OF to alter only every Nth audio block for all SR less than 2.0, outputting the altered Nth audio block as part of the output audio stream, and resetting the block count when the audio block count does equal the integer value N. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
-
Specification