Universal container for audio data

• US 7,624,021 B2
• Filed: 07/02/2004
• Issued: 11/24/2009
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Stewart, William G., McCartney, James E., Wyatt, Douglas S.
• Primary Examiner(s): Dorvil; Richemond
• Assistant Examiner(s): Saint Cyr; Leonard
• Application Number:
  US10/883,898
• Publication Number:
  US 20060020474A1
• Time in Patent Office: 1,971 Days
• Field of Search: 707/104.1
• US Class Current: 704/500
• CPC Class Codes: G10L 19/167 Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99948 Application of database or data structure, e.g. distributed, multimedia, or image
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

Storing audio data encoded in any of a plurality of different audio encoding formats is enabled by parametrically defining the underlying format in which the audio data is encoded, in audio format and packet table chunks. A flag can be used to manage storage of the size of the audio data portion of the file, such that premature termination of an audio recording session does not result in an unreadable corrupted file. This capability can be enabled by initially setting the flag to a value that does not correspond to a valid audio data size and that indicates that the last chunk in the file contains the audio data. State information for the audio data, to effectively denote a version of the file, and a dependency indicator for dependent metadata, may be maintained, where the dependency indicator indicates the state of the audio data on which the metadata is dependent.

Claims

1. A method for handling audio information, comprising:

storing a set of chunks in a single audio file, wherein said set of chunks includes an audio data chunk and a plurality of metadata chunks;

wherein each chunk of said set of chunks includes metadata indicating a chunk size;

storing, as part of said single audio file, a flag that initially is in a first state to indicate that a last chunk in said single audio file is said audio data chunk that contains audio data;

while parsing said single audio file, a computing device performing the steps of determining whether said flag is in said first state; and

if said flag is in said first state, then determining a size for said audio data chunk based on a file size of said single audio file and a starting position of said last chunk in said single audio file; and

if said flag is not in said first state, then determining a size for said audio data chunk by reading audio data chunk size information stored in said single audio file.

2. The method of claim 1, further comprising setting said flag to a second state in response to successfully storing said audio data chunk in said single audio file.

3. The method of claim 2, wherein:

said flag is a parameter that indicates the size of the audio data chunk;

said parameter is initially set to a value that does not correspond to a valid audio data chunk size; and

the step of setting said flag to a second state in response to successfully storing said audio data chunk in said single audio file includes setting said parameter to a value that reflects an actual size of said audio data chunk.

4. The method of claim 1, further comprising setting said flag to a second state in response to adding to said single audio file a chunk that follows said audio data chunk within said single audio file.

5. The method of claim 1, further comprising setting said flag to a second state in response to adding audio data to said audio data chunk.

6. The method of claim 1, wherein:

the flag is a parameter that indicates the size of said audio data chunk; and

the parameter is initially set to a value that does not correspond to a valid audio data chunk size.

7. The method of claim 1, further comprising:

if said flag is in said first state, then determining, based on a file size of said single audio file and a starting position of said last chunk in said single audio file, a particular size value that indicates a size of said audio data chunk; and

setting said flag to said particular size value.

8. A computer-readable storage medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

storing a set of chunks in a single audio file, wherein said set of chunks includes an audio data chunk and a plurality of metadata chunks;

wherein each chunk of said set of chunks includes metadata indicating a chunk size;

storing, as part of said audio file, a flag that initially is in a first state to indicate that a last chunk in said single audio file is said audio data chunk that contains audio data;

while parsing said single audio file, performing the steps of determining whether said flag is in said first state; and

if said flag is in said first state, then determining a size for said audio data chunk based on a file size of said single audio file and a starting position of said last chunk in said single audio file; and

if said flag is not in said first state, then determining a size for said audio data chunk by reading audio data chunk size information stored in said single audio file.

9. The computer-readable medium of claim 8, wherein said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

setting said flag to a second state in response to successfully storing said audio data chunk in said single audio file.

10. The computer-readable medium of claim 9, wherein:

said flag is a parameter that indicates the size of the audio data chunk;

said parameter is initially set to a value that does not correspond to a valid audio data chunk size; and

the step of setting said flag to a second state in response to successfully storing said audio data chunk in said single audio file includes setting said parameter to a value that reflects an actual size of said audio data chunk.

11. The computer-readable medium of claim 8, wherein said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

setting said flag to a second state in response to adding to said single audio file a chunk that follows said audio data chunk within said single audio file.

12. The computer-readable medium of claim 8, wherein said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

setting said flag to a second state in response to adding audio data to said audio data chunk.

13. The computer-readable medium of claim 8, wherein:

the flag is a parameter that indicates the size of said audio data chunk; and

the parameter is initially set to a value that does not correspond to a valid audio data chunk size.

14. The computer-readable medium of claim 8, the computer-readable medium further storing one or more sequences of instructions which, when executed by one or more processors, cause:

if said flag is in said first state, then determining, based on a file size of said single audio file and a starting position of said last chunk in said single audio file, a particular size value that indicates a size of said audio data chunk; and

setting said flag to said particular size value.

15. A method for handling audio information, comprising:

storing, as part of an audio file,

(a) audio data;

(b) metadata information that includes one or more metadata values that have a dependency on a particular state of the audio data;

(c) state information for said audio data that identifies a current version of said audio data; and

(d) one or more dependency indicators, wherein each of the one or more dependency indicators is associated with one or more of the one or more metadata values, wherein each dependency indicator identifies a version of the audio data on which the one or more metadata values that are associated with said each dependency indicator are dependent; and

while parsing said audio file, a computing device determining whether a metadata value of said one or more metadata values is valid based on a comparison between a dependency indicator associated with the metadata value and the state information for said audio data.

16. The method of claim 15, further comprising changing said state information in response to changes made to said audio data.

17. The method of claim 15, further comprising initially setting the one or more dependency indicators to a value that corresponds to said state information for said audio data.

18. The method of claim 15, wherein said one or more metadata values include a plurality of metadata values, each of which has a distinct dependency indicator.

19. The method of claim 15, wherein:

a dependency indicator associated with a particular metadata value of said one or more metadata values corresponds to an outdated state of said audio data; and

the method further comprises

setting said particular metadata value to a new value that is derived from a current state of said audio data; and

in response to setting said particular metadata to said new value, changing said dependency indicator for said particular metadata value to a value that corresponds to said current state information for said audio data.

20. The method of claim 15, wherein:

said audio file stores said metadata information in one or more metadata chunks;

said audio file stores said audio data in an audio data chunk; and

each of said one or more dependency indicators corresponds to a metadata chunk of said one or more metadata chunks, and indicates what version of said data chunk was used to derive metadata values within said metadata chunk.

21. The method of claim 15, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that represents a maximum amplitude within said audio data.

22. The method of claim 15, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that represents a minimum amplitude within said audio data.

23. The method of claim 15, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that identifies a frame, in said audio data, in which a maximum amplitude occurs within said audio data.

24. A computer-readable storage medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

storing, as part of an audio file,

(a) audio data;

(b) metadata information that includes one or more metadata values that have a dependency on a particular state of the audio data;

(c) state information for said audio data that identifies a current version of said audio data; and

(d) one or more dependency indicators, wherein each of the one or more dependency indicators is associated with one or more of the one or more metadata values, wherein each dependency indicator identifies a version of the audio data on which the one or more metadata values that are associated with said each dependency indicator are dependent; and

while parsing said audio file, determining whether a metadata value of said one or more metadata values is valid based on a comparison between a dependency indicator associated with the metadata value and the state information for said audio data.

25. The computer-readable medium of claim 24, wherein said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

changing said state information in response to changes made to said audio data.

26. The computer-readable medium of claim 24, wherein said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

initially setting the one or more dependency indicators to a value that corresponds to said state information for said audio data.

27. The computer-readable medium of claim 24, wherein said one or more metadata values include a plurality of metadata values, each of which has a distinct dependency indicator.

28. The computer-readable medium of claim 24, wherein a dependency indicator associated with a particular metadata value of said one or more metadata values corresponds to an outdated state of said audio data;

and

said one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform

setting said particular metadata value to a new value that is derived from a current state of said audio data; and

in response to setting said particular metadata to said new value, changing said dependency indicator for said particular metadata value to a value that corresponds to said current state information for said audio data.

29. The computer-readable medium of claim 24, wherein:

said audio file stores said metadata information in one or more metadata chunks;

said audio file stores said audio data in an audio data chunk; and

each of said one or more dependency indicators corresponds to a metadata chunk of said one or more metadata chunks, and indicates what version of said data chunk was used to derive metadata values within said metadata chunk.

30. The computer-readable medium of claim 24, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that represents a maximum amplitude within said audio data.

31. The computer-readable medium of claim 24, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that represents a minimum amplitude within said audio data.

32. The computer-readable medium of claim 24, wherein storing one or more dependency indicators associated with said one or more metadata values includes storing a dependency indicator associated with a metadata value that identifies a frame, in said audio data, in which a maximum amplitude occurs within said audio data.

33. A method for storing audio information, the method comprising:

storing a set of chunks in a single audio file, wherein said set of chunks includes an audio data chunk and a plurality of metadata chunks;

wherein said audio data chunk includes packets that correspond to a stream of encoded audio;

wherein each chunk of said set of chunks includes metadata indicating

a chunk version;

a chunk size; and

a chunk type;

wherein said set of chunks includes a format chunk that precedes said audio data chunk in said single audio file, said format chunk including metadata indicating a number of sample frames per second of said audio data in said stream;

data indicating the general kind of data in said stream;

how many bytes are in each packet of data;

how many sample frames are in each packet of data;

how many channels are in each frame of data;

how many bits of sample data are for each channel in a frame of data;

wherein at least one of said metadata chunks includes a flag that initially is in a first state to indicate that a last chunk in said single audio file is said audio data chunk that contains said audio data;

while parsing said single audio file, a computing device performing the steps of determining whether said flag is in said first state; and

if said flag is in said first state, then determining a size for said audio data chunk based on a file size of said single audio file and a starting position of said last chunk in said single audio file; and

if said flag is not in said first state, then determining a size for said audio data chunk by reading audio data chunk size information stored in said single audio file;

storing, as part of said single audio file,

metadata information that includes one or more metadata values that have a dependency on a particular state of said audio data;

state information for said audio data that identifies a current version of said audio data; and

one or more dependency indicators, wherein each of the one or more dependency indicators is associated with one or more of said one or more metadata values, wherein each dependency indicator identifies a version of the audio data on which the one or more metadata values that are associated with said each dependency indicator are dependent;

changing said state information in response to changes made to said audio data; and

while parsing said single audio file, a computing device determining whether a metadata value of said one or more metadata values is valid based on a comparison between a dependency indicator associated with said metadata value and said state information for said audio data.

34. The method of claim 33, wherein said data indicating the general kind of data in said stream indicates a specific format of said stream, selected from a set of formats consisting of:

Linear PCM,

ADPCM,

MPEG-4 AAC,

MACE 3;

1,

MACE 6;

1,

μ

Law 2;

1,

aLaw 2;

1,

MPEG-1, MPEG-2 or MPEG 2.5, Layer 3 audio,

AC-3, and

AC-3 packaged for transport over an JEC 60958 compliant digital audio interface.

35. The method of claim 33, wherein:

said metadata about how many bytes are in each packet indicates that said audio data is encoded in a format, of said plurality of formats, that has a variable packet size; and

at least one of said metadata chunks includes packet size information that indicates sizes for packets in said audio stream.

36. The method of claim 35, wherein at least one of said metadata chunks includes:

metadata that indicates how many sample frames that said audio stream uses for priming or processing latency; and

metadata that indicates how many sample frames, in a last packet that contains actual audio data, in said audio stream follow a last sample frame of actual audio data.

37. The method of claim 33, wherein:

said metadata about how many sample frames are in each packet indicates that said audio data is encoded in a format, of said plurality of formats, that has a variable number of sample frames per packet; and

at least one of said metadata chunks includes frame count information that indicates how many sample frames are in packets in said audio stream.

38. The method of claim 37, wherein at least one of said metadata chunks includes:

metadata that indicates how many sample frames that said audio stream uses for priming or processing latency; and

metadata that indicates how many sample frames, in a last packet that contains actual audio data, in said audio stream follow a last sample frame of actual audio data.

39. A computer-readable storage medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform:

storing a set of chunks in a single audio file, wherein said set of chunks includes an audio data chunk and a plurality of metadata chunks;

wherein said audio data chunk includes packets that correspond to a stream of encoded audio;

wherein each chunk of said set of chunks includes metadata indicating

a chunk version;

a chunk size; and

a chunk type;

wherein said set of chunks includes a format chunk that precedes said audio data chunk in said single audio file, said format chunk including metadata indicating a number of sample frames per second of said audio data in said stream;

data indicating the general kind of data in said stream;

how many bytes are in each packet of data;

how many sample frames are in each packet of data;

how many channels are in each frame of data;

how many bits of sample data are for each channel in a frame of data;

wherein at least one of said metadata chunks includes a flag that initially is in a first state to indicate that a last chunk in said single audio file is said audio data chunk that contains said audio data;

while parsing said single audio file, performing the steps of determining whether said flag is in said first state; and

if said flag is in said first state, then determining a size for said audio data chunk based on a file size of said single audio file and a starting position of said last chunk in said single audio file; and

if said flag is not in said first state, then determining a size for said audio data chunk by reading audio data chunk size information stored in said single audio file;

storing, as part of said single audio file,

metadata information that includes one or more metadata values that have a dependency on a particular state of said audio data;

state information for said audio data that identifies a current version of said audio data; and

one or more dependency indicators, wherein each of the one or more dependency indicators is associated with one or more of said one or more metadata values, wherein each dependency indicator identifies a version of the audio data on which the one or more metadata values that are associated with said each dependency indicator are dependent;

changing said state information in response to changes made to said audio data; and

while parsing said single audio file, determining whether a metadata value of said one or more metadata values is valid based on a comparison between a dependency indicator associated with said metadata value and said state information for said audio data.

40. The computer-readable medium of claim 39, wherein said data indicating the general kind of data in said stream indicates a specific format of said stream, selected from a set of formats consisting of:

Linear PCM,

ADPCM,

MPEG-4 AAC,

MACE 3;

1,

MACE 6;

1,

μ

Law 2;

1,

aLaw 2;

1,

MPEG-1, MPEG-2 or MPEG 2.5, Layer 3 audio,

AC-3, and

AC-3 packaged for transport over an JEC 60958 compliant digital audio interface.

41. The computer-readable medium of claim 39, wherein:

said metadata about how many bytes are in each packet indicates that said audio data is encoded in a format, of said plurality of formats, that has a variable packet size; and

at least one of said metadata chunks includes packet size information that indicates sizes for packets in said audio stream.

42. The computer-readable medium of claim 41, wherein at least one of said metadata chunks includes:

metadata that indicates how many sample frames that said audio stream uses for priming or processing latency; and

metadata that indicates how many sample frames, in a last packet that contains actual audio data, in said audio stream follow a last sample frame of actual audio data.

43. The computer-readable medium of claim 39, wherein:

said metadata about how many sample frames are in each packet indicates that said audio data is encoded in a format, of said plurality of formats, that has a variable number of sample frames per packet; and

at least one of said metadata chunks includes frame count information that indicates how many sample frames are in packets in said audio stream.

44. The computer-readable medium of claim 43, wherein at least one of said metadata chunks includes:

metadata that indicates how many sample frames that said audio stream uses for priming or processing latency; and

metadata that indicates how many sample frames, in a last packet that contains actual audio data, in said audio stream follow a last sample frame of actual audio data.