Frame-based audio transmission/storage with overlap to facilitate smooth crossfading

• US 20050102049A1
• Filed: 11/12/2003
• Published: 05/12/2005
• Est. Priority Date: 11/12/2003
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Gundry, Kenneth James, Smithers, Michael J.
• Granted Patent: US 7,292,902 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: G10H 2250/035 Crossfade, i.e. time domain amplitude envelope control of the transition between musical sounds or melodies, obtained for musical purposes, e.g. for ADSR tone generation, articulations, medley, remix audio mixers H04H60/04
• CPC Class Codes: G10H 7/008 Means for controlling the transition from one tone waveform to another
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 20/24 for reducing noise control of amplification in general, e.g. dependent upon noise level H03G
• CPC Class Codes: G11B 27/038 Cross-faders therefor

Abstract

Methods for splicing PCM audio frames form modified frames by appending to each frame either a portion of the next preceding frame or the next following frame. According to a first approach, splices are obtained by fading up and fading down a frame end and a frame appendage only at a splice point, and overlapping and combining to provide a crossfade at the splice. Alternatively, every frame end and frame appendage is faded up and faded down, overlapped and combined. A subtractive method of providing complementary fade-up and fade-down reduces rounding errors.

Claims

1. A method for processing one or more ordered sequences of PCM audio frames, comprising

appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, whereby modified frames are produced,

maintaining for the modified frames a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or assigning a further sequential order to the modified frames, which sequential order is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames,

fading up the PCM audio appended to the beginning of the modified frame following a discontinuity and fading down the PCM audio in the end of the modified frame preceding a discontinuity when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of the modified frame preceding a discontinuity and fading up the PCM audio in the beginning of the modified frame following a discontinuity when segments are appended to the end of frames,

overlapping and additively combining the faded-up and faded-down PCM audio preceding and following a discontinuity in the sequence of faded-up and faded-down modified frames, and

removing the segment of PCM audio appended to a modified frame in sequential pairs of modified frames and joining the resulting PCM audio frames when the sequential pair of modified frames does not contain a discontinuity following or preceding the appendage,

whereby a further ordered sequence of PCM audio frames is provided having the same order as one of said one or more ordered sequences of PCM audio frames or having one or more discontinuities between sequences of PCM audio frames, each of said sequences having the same order as one of said one or more ordered sequences of PCM audio frames or a portion thereof, discontinuities having an associated PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

2. A method for processing one or more ordered sequences of PCM audio frames, comprising

appending only to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, whereby modified frames are produced, and

transmitting, storing, or transmitting and storing the modified frames.

3. A method according to claim 2 further comprising time compressing the modified frames and wherein said transmitting, storing, or transmitting and storing transmits, stores, or transmits and stores time-compressed modified frames.

4. A method according to claim 2 further comprising time compressing and encoding the modified frames and wherein said transmitting, storing, or transmitting and storing transmits, stores, or transmits and stores time-compressed and encoded modified frames.

5. A method for processing PCM audio data, comprising

receiving modified PCM audio frames, wherein the modified frames were produced by processing one or more ordered sequences of PCM audio frames by appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence,

maintaining for the modified frames a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or assigning a further sequential order to the modified frames, which sequential order is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames,

fading up the PCM audio appended to the beginning of the modified frame following a discontinuity and fading down the PCM audio in the end of the modified frame preceding a discontinuity when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of the modified frame preceding a discontinuity and fading up the PCM audio in the beginning of the modified frame following a discontinuity when segments are appended to the end of frames,

overlapping and additively combining the faded-up and faded-down PCM audio preceding and following a discontinuity in the sequence of faded-up and faded-down modified frames, and

removing the segment of PCM audio appended to a modified frame in sequential pairs of modified frames and joining the resulting PCM audio frames when the sequential pair of modified frames does not contain a discontinuity following or preceding the appendage,

whereby a further ordered sequence of PCM audio frames is provided having the same order as one of said one or more ordered sequences of PCM audio frames or having one or more discontinuities between sequences of PCM audio frames, each of said sequences having the same order as one of said one or more ordered sequences of PCM audio frames or a portion thereof, discontinuities having an associated PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

6. The method of claim 5 wherein the received modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

7. The method of claim 5 wherein the received modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

8. A method for processing PCM audio data, comprising

receiving modified PCM audio frames, wherein the modified frames

were produced by processing one or more ordered sequences of PCM audio frames by appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, and

have a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or have a further sequential order, which sequential order is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames,

fading up the PCM audio appended to the beginning of the modified frame following a discontinuity and fading down the PCM audio in the end of the modified frame preceding a discontinuity when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of the modified frame preceding a discontinuity and fading up the PCM audio in the beginning of the modified frame following a discontinuity when segments are appended to the end of frames,

overlapping and additively combining the faded-up and faded-down PCM audio preceding and following a discontinuity in the sequence of faded-up and faded-down modified frames, and

removing the segment of PCM audio appended to a modified frame in sequential pairs of modified frames and joining the resulting PCM audio frames when the sequential pair of modified frames does not contain a discontinuity following or preceding the appendage,

whereby a further ordered sequence of PCM audio frames is provided having the same order as one of said one or more ordered sequences of PCM audio frames or having one or more discontinuities between sequences of PCM audio frames, each of said sequences having the same order as one of said one or more ordered sequences of PCM audio frames or a portion thereof, discontinuities having an associated PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

9. The method of claim 8 wherein the received modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

10. The method of claim 8 wherein the received modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

11. The method of claim 8 further comprising

maintaining for the modified frames a sequential order that is the same as their order as received, whereby the modified frames may have a sequential order that has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, or assigning a further sequential order to the modified frames, which sequential order is different from their order as received, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames.

16. A method according to claim 8 wherein the fade-Lip and faded-down modified frames were produced by processing that multiplies a portion of PCM audio by a fading function and subtracts the portion of PCM audio resulting from the multiplication from another portion of PCM audio.

12. A method for processing one or more ordered sequences of PCM audio frames, comprising

appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, whereby modified frames are produced,

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames,

maintaining for the modified frames or for the faded-up and faded-down modified frames a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or assigning a further sequential order to the modified frames or to the faded-up and faded-down modified frames, which sequence is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, and

overlapping and additively combining sequential pairs of faded-up and faded-down PCM audio in the sequence of faded-up and faded-down modified frames having a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or having said further sequential order,

whereby a further ordered sequence of PCM audio frames is provided having the same order as one of said one or more ordered sequences of PCM audio frames or having one or more discontinuities between sequences of PCM audio frames, each of said sequences having the same order as one of said one or more ordered sequences of PCM audio frames or a portion thereof, consecutive pairs in the further order of PCM audio frames having an associated PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

13. A method for processing one or more ordered sequences of PCM audio frames, comprising

appending only to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, whereby modified frames are produced,

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames, and

transmitting, storing, or transmitting and storing the faded-up and faded-down modified frames.

14. A method according to claim 13 further comprising time compressing the faded-up and faded-down modified frames and wherein said transmitting, storing, or transmitting and storing transmits, stores, or transmits and stores time-compressed faded-up and faded-down modified frames.

15. A method according to claim 13 further comprising time compressing and encoding the faded-up and faded-down modified frames and wherein said transmitting, storing, or transmitting and storing transmits, stores, or transmits and stores time-compressed, encoded, faded-up and faded-down modified frames.

17. A method for processing PCM audio, comprising

receiving faded-up and faded-down modified PCM audio frames, wherein the faded-up and faded-down modified frames were produced by processing one or more ordered sequences of PCM audio frames by

appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, and

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames,

maintaining for the faded-up and faded-down modified frames a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or assigning a further sequential order to the faded-up and faded-down modified frames, which sequence is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, and

overlapping and additively combining sequential pairs of faded-up and faded-down PCM audio in the sequence of faded-up and faded-down modified frames,

whereby a further ordered sequence of PCM audio frames is provided in which consecutive pairs of PCM audio frames have a PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

18. The method of claim 17 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

19. The method of claim 17 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

20. The method of claim 19 wherein the received faded-up and faded-down modified PCM audio frames are encoded with a lossless coding.

21. A method according to claim 17 or 20 wherein the fade-up and faded-down modified frames were produced by processing that multiplies a portion of PCM audio by a fading function and subtracts the portion of PCM audio resulting from the multiplication from another portion of PCM audio and wherein the further sequence of PCM audio frames have the same order as at least a portion of the received ordered sequence of PCM audio frames, whereby the further sequence of PCM audio frames constitutes a substantially identical reconstruction of said at least a portion of the received ordered sequence of PCM audio frames.

22. A method for processing PCM audio, comprising

receiving faded-up and faded-down modified PCM audio frames, wherein the faded-up and faded-down modified frames were produced by processing one or more ordered sequences of PCM audio frames by

appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, and

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames,

wherein the faded-up and faded-down modified PCM audio frames have a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or have a further sequential order, which sequential order is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, and

overlapping and additively combining sequential pairs of faded-up and faded-down PCM audio in the sequence of faded-up and faded-down modified frames,

whereby a further ordered sequence of PCM audio frames is provided in which consecutive pairs of PCM audio frames have a PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

23. The method of claim 22 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

24. The method of claim 22 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

25. The method of claim 24 wherein the received faded-up and faded-down modified PCM audio frames are encoded with a lossless coding.

26. A method according to claim 22 or 25 wherein the fade-up and faded-down modified frames were produced by processing that multiplies a portion of PCM audio by a fading function and subtracts the portion of PCM audio resulting from the multiplication from another portion of PCM audio and wherein the further sequence of PCM audio frames have the same order as at least a portion of the received ordered sequence of PCM audio frames, whereby the further sequence of PCM audio frames constitutes a substantially identical reconstruction of said at least a portion of the received ordered sequence of PCM audio frames.

27. The method of claim 22 further comprising

maintaining for the modified frames a sequential order that is the same as their order as received, whereby the modified frames may have a sequential order that has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, or assigning a further sequential order to the modified frames, which sequential order is different from their order as received, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames.

28. A method for processing PCM audio, comprising

receiving modified PCM audio frames, wherein the modified frames were produced by processing one or more ordered sequences of PCM audio frames by appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence,

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames,

maintaining for the modified frames or for the faded-up and faded-down modified frames a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or assigning a further sequential order to the modified frames or to the faded-up and faded-down modified frames, which sequence is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, and

overlapping and additively combining sequential pairs of faded-up and faded-down PCM audio in the sequence of faded-up and faded-down modified frames, having a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or having said further sequential order,

whereby a further ordered sequence of PCM audio frames is provided in which consecutive pairs of PCM audio frames have a PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

29. The method of claim 28 wherein the received modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

30. The method of claim 28 wherein the received modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

31. The method of claim 30 wherein the received modified PCM audio frames are encoded with a lossless coding.

32. A method according to claim 28 or 31 wherein wherein fading up and fading down includes multiplying a portion of PCM audio by a fading function and subtracting the portion of PCM audio resulting from the multiplication from another portion of PCM and wherein the further sequence of PCM audio frames have the same order as at least a portion of the received ordered sequence of PCM audio frames, whereby the further sequence of PCM audio frames constitutes a substantially identical reconstruction of said at least a portion of the received ordered sequence of PCM audio frames.

33. A method for processing PCM audio, comprising

receiving modified PCM audio frames, wherein the modified frames

were produced by processing one or more ordered sequences of PCM audio frames by appending to the beginning of frames, a segment of PCM audio that is substantially a replica of PCM audio in the end of the next preceding frame in an ordered sequence, or, to the end of frames, a segment of PCM audio that is substantially a replica of PCM audio in the beginning of the next following frame in an ordered sequence, and

have a sequential order that is the same as the order of one of said one or more ordered sequences of the PCM audio frames or have a further sequential order, which sequential order is different from the order of one of said one or more ordered sequences of PCM audio frames, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames,

fading up the PCM audio appended to the beginning of modified frames and fading down the PCM audio in the end of modified frames when segments are appended to the beginning of frames or fading down the PCM audio appended to the end of modified frames and fading up the PCM audio in the beginning of modified frames when segments are appended to the end of frames, and

overlapping and additively combining sequential pairs of faded-up and faded-down PCM audio in the sequence of faded-up and faded-down modified frames,

whereby a further ordered sequence of PCM audio frames is provided in which consecutive pairs of PCM audio frames have a PCM audio crossfaded portion where said faded-up and faded-down PCM audio is overlapped and combined.

34. The method of claim 33 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed, the method further comprising time decompressing the received modified PCM audio frames.

35. The method of claim 33 wherein the received faded-up and faded-down modified PCM audio frames are time-compressed and encoded, the method further comprising time decompressing and decoding the received modified PCM audio frames.

36. The method of claim 33 further comprising

maintaining for the modified frames a sequential order that is the same as their order as received, whereby the modified frames may have a sequential order that has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames, or assigning a further sequential order to the modified frames, which sequential order is different from their order as received, whereby the further sequential order has at least one discontinuity in its order with respect to the order of one of said one or more ordered sequences of PCM audio frames.