Extensible kernel-mode audio processing architecture

• US 20050107901A1
• Filed: 12/17/2004
• Published: 05/19/2005
• Est. Priority Date: 04/12/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Puryear, Martin G.
• Granted Patent: US 7,283,881 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: G10H 1/0066 using a MIDI interface
• CPC Class Codes: G10H 1/183 Channel-assigning means for polyphonic instruments
• CPC Class Codes: G10H 2210/225 Portamento, i.e. smooth continuously variable pitch-bend, without emphasis of each chromatic pitch during the pitch change, which only stops at the end of the pitch shift, as obtained, e.g. by a MIDI pitch wheel or trombone pitch bend with emphasis of each chromatic pitch during pitch change, e.g. glissando, G10H2210/221
• CPC Class Codes: G10H 2210/281 Reverberation or echo
• CPC Class Codes: G10H 2240/291 SCSI, i.e. Small Computer System Interface
• CPC Class Codes: G10H 2240/295 Packet switched network, e.g. token ring circuit-switched networks, e.g. traditional analog telephone transmission G10H2240/241
• CPC Class Codes: G10H 2240/305 Internet or TCP/IP protocol use for any electrophonic musical instrument data or musical parameter transmission purposes
• CPC Class Codes: G10H 7/00 Instruments in which the tones are synthesised from a data store, e.g. computer organs
• CPC Class Codes: G10H 7/002 using a common processing for different operations or calculations, and a set of microinstructions (programme) to control the sequence thereof

Abstract

An extensible kernel-mode audio (e.g., MIDI) processing architecture is implemented using multiple modules that together comprise a module graph. The module graph is implemented in kernel-mode, reducing latency and jitter when handling audio data by avoiding transfers of the audio data to user-mode applications for processing. In one embodiment, the audio processing architecture is readily extensible. A graph builder can readily change the module graph, adding new modules, removing modules, or altering connections as necessary, all while the graph is running.

Claims

1. A method comprising:

maintaining a pool of memory available for allocation to a plurality of transform filters executing at a privileged level;

allocating a portion of the pool of memory to one of the plurality of transform filters to use to store audio data, wherein the portion comprises sufficient memory to store a data structure including;

a data portion that can include one of;

audio data, a pointer to a chain of additional data structures that include the audio data, and a pointer to a data buffer;

a structure byte count portion that identifies the size of the data structure;

a channel group portion that identifies which of a plurality of channel groups the data identified in the data portion corresponds to;

a presentation time portion indicating when audio data is to be rendered;

a flag portion indicating whether the data portion includes either the pointer to the chain of additional data structures or one of either the audio data or the pointer to the data buffer; and

an event byte count portion that identifies, if the data portion does not include the pointer to the chain of additional data structures, whether the data portion includes the audio data or a pointer to the data buffer; and

returning the allocated portion to the pool of memory after the plurality of transform filters have finished processing the audio data.

2. A method as recited in claim 1, wherein the privileged level comprises kernel-mode.

3. A method as recited in claim 1, wherein the portion comprises a data buffer to store a plurality of audio data messages.

4. A system having stored therein a transform filter for execution in kernel-mode comprising:

a first interface means for allowing identification to the transform filter of a next transform filter in a transform filter graph to which audio data packets should be communicated by the transform filter; and

a second interface means for allowing the audio data packets to be communicated to the next transform filter;

wherein each of the audio data packets includes a flag portion that includes an event incomplete flag that can be set to indicate that data identified in a data portion of the audio data packet extends beyond a buffer pointed to by a pointer maintained in the data portion.

5. A system as recited in claim 4, wherein the transform filter further comprises third interface means for allowing other transform filters in the transform filter graph to obtain data structures for the audio data packets.

6. A system as recited in claim 4, wherein the transform filter further comprises third interface means for allowing other transform filters in the transform filter graph to obtain a size of data buffers allocated by the transform filter.

7. A system as recited in claim 4, wherein the transform filter further comprises third interface means for allowing other transform filters to obtain data buffers for storage of audio data corresponding to an audio data packet.

8. A system as recited in claim 4, wherein the transform filter further comprises third interface means for allowing other transform filters to return data buffers to a memory pool for re-allocation.

9. A system as recited in claim 4, wherein the transform filter comprises sequencer filter means for reordering the audio data packets by timestamp and for delaying forwarding the audio packets to the next transform filter until an appropriate time.

10. A system as recited in claim 4, wherein the transform filter comprises allocator filter means for obtaining memory from a memory manager and making portions of the obtained memory available to other transform filters.

11. A computer comprising:

a processor; and

a memory, coupled to the processor, storing a transform filter for execution in kernel-mode that, when executed in kernel-mode by the processor, causes the processor to implement;

a ConnectOutput interface to allow identification to the transform filter of a next transform filter in a transform filter graph to which audio data packets should be communicated by the transform filter; and

a PutMessage interface to allow the audio data packets to be communicated to the next transform filter;

wherein each of the audio data packets includes a flag portion that includes an event incomplete flag that can be set to indicate that data identified in a data portion of the audio data packet extends beyond a buffer pointed to by a pointer maintained in the data portion.

12. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a SetState interface to allow a state of the transform filter to be set, including a run state and a stop state.

13. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a DisconnectOutput interface to allow a previously identified next transform filter to be changed.

14. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a GetMessage interface to allow other transform filters in the transform filter graph to obtain data structures for the audio data packets.

15. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a GetBufferSize interface to allow other transform filters in the transform filter graph to obtain a size of data buffers allocated by the transform filter.

16. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a GetBuffer interface to allow other transform filters to obtain data buffers for storage of audio data corresponding to an audio data packet.

17. A computer as recited in claim 11, wherein the transform filter further causes the processor to implement a PutBuffer interface to allow other transform filters to return data buffers to a memory pool for re-allocation.

18. A computer as recited in claim 11, wherein the transform filter comprises a sequencer filter to reorder the audio data packets by timestamp and to delay forwarding the audio packets to the next transform filter until an appropriate time.

19. A computer as recited in claim 11, wherein the transform filter comprises an allocator filter to obtain memory from a memory manager and make portions of the obtained memory available to other transform filters.