AUDIO TIME SYNCHRONIZATION USING PRIORITIZED SCHEDULE

Abstract

Disclosed herein are system, method, and computer program product embodiments for synchronizing playback of an audio and/or video content. An embodiment operates by collectively selecting, by a first device in concert with a second device of a plurality of devices in a computer network session, and in accordance with a predetermined synchronization list comprising a first and second synchronization mechanism, the first synchronization mechanism over the second synchronization mechanism such that the first synchronization mechanism is more precise than the second synchronization mechanism. The first and second synchronization mechanisms are configured to provide a synchronized playback of the at least one of the audio content and the video content.

Claims

1. A method for synchronizing playback of at least one of an audio and a video content, the method comprising: collectively selecting, by a first device in concert with a second device of a plurality of devices in a computer network session and in accordance with a predetermined synchronization list comprising a first and second synchronization mechanism, the first synchronization mechanism over the second synchronization mechanism such that the first synchronization mechanism is more precise than the second synchronization mechanism, wherein the first and second synchronization mechanisms are configured to provide a synchronized playback of the at least one of the audio content and the video content.

2. The method of claim 1, wherein: the plurality of devices further comprises a third device providing a default synchronization mechanism, and the predetermined synchronization list further comprises the default synchronization mechanism and specifies that the default synchronization mechanism has a lower priority than the first and second synchronization mechanisms.

3. The method of claim 1, wherein the default synchronization mechanism is an audio clock.

4. The method of claim 2, wherein the third device serves as an original session master in the computer network session.

5. The method of claim 4, wherein the first device serves as a new session master in the computer network session.

6. The method of claim 4, further comprising: searching, by the first device, for the second device in the computer network session; and forming, by the first device in concert with the second device, a group of devices comprising the first and second devices and separate from the third device, wherein the collectively selecting of the first synchronization mechanism is after the forming of the group of devices.

7. The method of claim 5, wherein the first device is selected as a group leader of the first device and the second device.

8. The method of claim 1, wherein the first or second synchronization mechanisms is a custom radio frequency-based synchronization mechanism, a custom infrared-based synchronization mechanism, a global positioning system based synchronization mechanism, a standard radio clock-based synchronization mechanism, or a network time protocol server-based synchronization mechanism.

9. The method of claim 1, wherein the first synchronization mechanism comprises a virtual clock.

10. The method of claim 9, wherein the virtual clock is generated in response to a timing of an audio codec.

11. The method of claim 9, wherein the virtual clock is generated in response to a clock system of the audio or to periodic measurements of the audio codec.

12. The method of claim 9, wherein the second synchronization mechanism is a system clock.

13. The method of claim 12, wherein the second synchronization mechanism is preferred over the first synchronization mechanism.

14. The method of claim 1, wherein the first or second synchronization mechanisms operate within a communication channel on which the at least one of the audio content and the video content is streamed.

15. The method of claim 1, wherein the first or second synchronization mechanisms operate on a communication channel separate from a communication channel on which the at least one of the audio content and the video content is streamed.

16. The method of claim 1, wherein the at least one of the audio content and the video content is streamed via a wi-fi channel.

17. The method of claim 16, wherein the first device is configured to provide the synchronization playback via a wireless channel different from the wi-fi channel.

18. The method of claim 1, wherein the first and second devices are configured to provide the synchronization playback to a left and right stereo channel of an audio stream, respectively.

19. A non-transitory, computer-readable device having instructions stored thereon that, when executed by a device, cause the device to perform operations comprising: collectively selecting, by a first device in concert with a second device of a plurality of devices in a computer network session and in accordance with a predetermined synchronization list comprising a first and second synchronization mechanism, the first synchronization mechanism over the second synchronization mechanism such that the first synchronization mechanism is more precise than the second synchronization mechanism, wherein the first and second synchronization mechanisms are configured to provide a synchronized playback of at least one of an audio and video content.

20. A device comprising a processor and a network interface arranged to receive audio and/or video content via a computer network session from a source in a synchronized manner in response to synchronization information, wherein the processor is programmed to: collectively selecting, by a first device in concert with a second device of a plurality of devices in a computer network session and in accordance with a predetermined synchronization list comprising a first and second synchronization mechanism, the first synchronization mechanism over the second synchronization mechanism such that the first synchronization mechanism is more precise than the second synchronization mechanism, wherein the first and second synchronization mechanisms are configured to provide a synchronized playback of at least one of an audio and video content.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0021] The invention will now be described in more detail with regard to the accompanying figures of which

[0022] FIG. 1 shows a synchronization session with a TV (10) and a stereo set of loudspeakers, left and right (20 and 21), where the TV (10) is the session master (leader) and therefore provides the overall synchronization (30 and 31),

[0023] FIG. 2 illustrates a synchronization mechanism selection algorithm embodiment.

[0024] FIG. 3 illustrates an example of a synchronization hierarchy. The session master (leader) (50) is the authoritative time synchronization source for the session, and it provides timing information to all other devices (52), (54), and (56) via the session's default synchronization. Two groups have been formed with an out-of-band synchronization, each group having a group master (leader) (52) and two group members (54).

[0025] FIG. 4 illustrates steps of a clock synchronization selection algorithm embodiment.

[0026] The figures illustrate specific ways of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 shows a synchronization session with a TV (10) and two speakers (20 and 21). The TV (10) is the session master and therefore provides the overall synchronization (30 and 31). The Right speaker (21) and the Left speaker (20) form a group (40) wherein the Right speaker (21) acts as the group master. The group master (21) synchronizes against the session master (10). The Left speaker (20) ignores the synchronization from the session master (10) and instead uses the synchronization (32) from the group master (21).

[0028] FIG. 2 illustrates a synchronization mechanism selection algorithm.

[0029] FIG. 3 illustrates a synchronization hierarchy: The session master (50) is the authoritative time source for the session. It provides timing information to all other devices (52), (54), and (56) via the session's default synchronization. Two groups have been formed with an out-of-band synchronization. Each group has a group master (52) and two group members (54). These use an out-of-band synchronization mechanism. As indicated by the dashed line, (54) still utilizes the default synchronization with the session master (50).

[0030] The group masters (52) also maintain a direct synchronization with the Session Master (50). Devices (56) do not use any out-of-band synchronization, and fall back to the default synchronization with the session master (50).

[0031] FIG. 4 illustrates a simple example of a selection algorithm implemented in each of the separate devices taking part in a computer network session of synchronous playback of audio and/or video.

[0032] In a specific example, the prioritized list of synchronization mechanisms may include two or more of the following, in prioritized order. [0033] 1) a custom radio frequency (RF) based synchronization mechanism, [0034] 2) a custom infrared (IR) based synchronization mechanism, [0035] 3) a Global Positioning System (GPS) based synchronization mechanism, [0036] 4) a standard radio clock (e.g. DCF77 or WWVB) based synchronization mechanism, and [0037] 5) a Network Time Protocol (NTP) based synchronization mechanism.

[0038] To sum up: the invention provides a method for providing a synchronization in a computer network for synchronized playback of audio and/or video by a plurality of separate devices, e.g. in a wi-fi network. Each separate device is programmed to select a synchronization mechanism in accordance with a predetermined prioritized list of at least two different synchronization mechanisms, and to use the selected synchronization mechanism for synchronizing audio and/or video playback. E.g. use of a clock based on the audio codec clock can be set to a higher priority than use of the system clock, which provides a poorer precision. A session leader serves to provide the synchronization to other separate devices in a session, however a group of two or more separate devices within the session may agree on selecting a synchronization mechanism providing a higher precision than the one provided by the session leader. E.g. to allow high precision timing between separate left and right loudspeakers in a stereo setup. A group leader can be elected to provide synchronization to a group of devices using a higher synchronization precision than the synchronization mechanism provided by the overall session leader. E.g. a dedicated synchronization channel separate from the audio/video streaming channel may be selected.

[0039] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is to be interpreted in the light of the accompanying claim set. In the context of the claims, the terms “including” or “includes” do not exclude other possible elements or steps. Also, the mentioning of references such as “a” or “an” etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.