PROVIDING MEDIA FOR SYNCHRONIZED PRESENTATION BY MULTIPLE DEVICES

• US 20120232682A1
• Filed: 05/22/2012
• Published: 09/13/2012
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moore, Jeffrey C., Stewart, William G., Lengeling, Gerhard
• Granted Patent: US 8,904,066 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• 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 for providing audio data to multiple audio output devices, the method comprising:

writing audio data into a plurality of buffers associated with a plurality of audio output devices, the plurality of audio output devices having separate device clocks;

determining a difference between a device clock rate of a first audio output device of the plurality of audio output devices and a device clock rate of a second audio output device of the plurality of audio output devices;

resampling audio data to be written into a buffer of the plurality of buffers based at least in part on said difference;

wherein the method is performed by a computing device.

6. One or more non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause performance of a method according to claim 1.

2. A method comprising:

writing data into a plurality of ring buffers for consumption by a plurality of devices, wherein each device of the plurality of devices consumes data from a corresponding buffer of the plurality of ring buffers;

upon reaching the end of any ring buffer of the plurality of ring buffers while writing data to the ring buffer, performing a wrap-around operation to continue writing data beginning at the start of the ring buffer;

upon reaching the end of any ring buffer of the plurality of ring buffers while reading data from the ring buffer, the corresponding device performing a wrap-around operation to continue reading data beginning at the start of the ring buffer;

a first device of the plurality of devices currently reading data from a first current position in a first ring buffer of the plurality of ring buffers;

a second device of the plurality of devices currently reading data from a second current position in a second ring buffer of the plurality of ring buffers;

storing first timestamp information when the first device performs a wrap-around operation while reading data from the first buffer;

storing second timestamp information when the second device performs a wrap-around operation while reading data from the second buffer;

determining a timing difference between the first device and the second device based on the first timestamp information and the second timestamp information; and

accounting for the timing difference when writing data to the second ring buffer.

3. A method according to claim 2, wherein accounting for the timing difference when writing data to the second ring buffer comprises resampling data to be written to the second ring buffer based on the timing difference.

7. One or more non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause performance of a method according to claim 2.

8. One or more non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause performance of a method according to claim 3.

4. A system comprising:

one or more processors;

a plurality of buffers corresponding to a plurality of audio devices, the plurality of audio devices having separate device clocks; and

a system-side handling input/output unit configured to;

write audio data into the plurality of buffers,

determine a difference between a device clock rate of a first audio device of the plurality of audio devices and a device clock rate of a second audio device of the plurality of audio devices, and

resample audio data to be written into a buffer of the plurality of buffers based at least in part on said difference.