Using a plurality of buffers to provide audio for synchronized playback to multiple audio devices having separate device clocks

• US 9,569,169 B2
• Filed: 11/02/2015
• Issued: 02/14/2017
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moore, Jeffrey C., Stewart, William George, Lengeling, Gerhard
• Primary Examiner(s): PEYTON, TAMMARA R
• Application Number:
  US14/930,601
• Publication Number:
  US 20160098247A1
• Time in Patent Office: 470 Days
• Field of Search: 710 8- 10, 710 52- 54, 700/94
• US Class Current: 1/1
• CPC Class Codes: G06F 3/00 Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
• CPC Class Codes: G06F 3/162 Interface to dedicated audio devices, e.g. audio drivers, interface to CODECs
• CPC Class Codes: G06F 3/165 Management of the audio stream, e.g. setting of volume, audio stream path
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 21/43076 of the same content streams on multiple devices, e.g. when family members are watching the same movie on different devices
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/8106 involving special audio data, e.g. different tracks for different languages

Abstract

According to one embodiment, a media system communicates with an aggregate device that includes multiple media output devices. When providing media data for presentation, the system adjusts for device clock drift by resampling the media data provided to a media output device based at least in part on a device clock rate difference between a device clock of one of the media output devices and a device clock of another of the media output devices.

Claims

1. A method comprising:

reading, by a device-side audio handling input/output unit (DIO) of an audio playback device, audio data from a buffer at a DIO position of the buffer during playing back audio from the buffer;

wrapping the DIO position to a start of the buffer upon reaching an end of the buffer;

generating timestamp information usable by a system-side audio handling input/output unit (SIO) to estimate the DIO position, the timestamp information including a clock time of a central processing unit (CPU) clock of the SIO and an indication of which audio samples have been processed by the DIO; and

providing the timestamp information by the DIO to the SIO.

2. The method of claim 1, wherein the buffer is a ring buffer.

3. The method of claim 1, wherein the SIO is an audio hardware abstraction layer provided in a core audio framework of an operating system.

4. The method of claim 1, wherein generating the timestamp information occurs at time the DIO performs the wrapping.

5. The method of claim 1, wherein the timestamp information is further usable by the SIO to determine an insertion point, the insertion point including a point at which to insert audio data with the buffer.

6. An audio playback device comprising:

a device-side audio handling input/output unit (DIO); and

a non-transitory computer-readable medium storing instructions operable to cause the DIO to perform operations comprising;

reading audio data from a buffer at a DIO position of the buffer during playing back audio from the buffer;

wrapping the DIO position to a start of the buffer upon reaching an end of the buffer;

generating timestamp information usable by a system-side audio handling input/output unit (SIO) to estimate the DIO position, the timestamp information including a clock time of a central processing unit (CPU) clock of the SIO and an indication of which audio samples have been processed by the DIO; and

providing the timestamp information by the DIO to the SIO.

7. The audio playback device of claim 6, wherein the buffer is a ring buffer.

8. The audio playback device of claim 6, wherein the SIO is an audio hardware abstraction layer provided in a core audio framework of an operating system.

9. The audio playback device of claim 6, wherein generating the timestamp information occurs at time the DIO performs the wrapping.

10. The audio playback device of claim 6, wherein the timestamp information is further usable by the SIO to determine an insertion point, the insertion point including a point at which to insert audio data with the buffer.

11. A non-transitory computer-readable medium storing instructions operable to cause a device-side audio handling input/output unit (DIO) to perform operations comprising:

reading, by a device-side audio handling input/output unit (DIO) of an audio playback device, audio data from a buffer at a DIO position of the buffer during playing back audio from the buffer;

wrapping the DIO position to a start of the buffer upon reaching an end of the buffer;

generating timestamp information usable by a system-side audio handling input/output unit (SIO) to estimate the DIO position, the timestamp information including a clock time of a central processing unit (CPU) clock of the SIO and an indication of which audio samples have been processed by the DIO; and

providing the timestamp information by the DIO to the SIO.

12. The non-transitory computer-readable medium of claim 11, wherein the buffer is a ring buffer.

13. The non-transitory computer-readable medium of claim 11, wherein the SIO is an audio hardware abstraction layer provided in a core audio framework of an operating system.

14. The non-transitory computer-readable medium of claim 11, wherein generating the timestamp information occurs at time the DIO performs the wrapping.

15. The non-transitory computer-readable medium of claim 11, wherein the timestamp information is further usable by the SIO to determine an insertion point, the insertion point including a point at which to insert audio data with the buffer.