Synchronous play-out of media data packets
First Claim
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1. A media source, comprising:
- a global clock determination unit configured to determine, once within a session, a global wallclock time having a first statistical variation;
a sample clock determination unit configured to determine a sample clock time;
a communications unit configured to send out, only once within the session, a control packet to one or more receiving media sinks, said control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of said global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time;
a sending unit configured to send out time-stamped media data packets to the one or more receiving media sinks, each of the time-stamped media data packets including a timestamp that is a time of creation of the time-stamped media data packet;
a determining unit configured to determine a play-out time offset based, in part, on the first statistical variation; and
a transmission unit configured to send out the play-out time offset to said one or more receiving media sinks once for all time-stamped media data packets of the session.
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Abstract
A media source, including a sending unit that sends out time-stamped media data packets to one or more receiving media sinks. A timestamp of one of the time-stamped media data packets indicates a time of creation of the one of the time-stamped media data packets. The media source also includes a determining unit that determines a play-out time offset. The media source additionally includes a transmission unit that sends out the play-out time offset to the one or more receiving media sinks once for all time-stamped media data packets of a session.
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Citations
23 Claims
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1. A media source, comprising:
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a global clock determination unit configured to determine, once within a session, a global wallclock time having a first statistical variation; a sample clock determination unit configured to determine a sample clock time; a communications unit configured to send out, only once within the session, a control packet to one or more receiving media sinks, said control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of said global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time; a sending unit configured to send out time-stamped media data packets to the one or more receiving media sinks, each of the time-stamped media data packets including a timestamp that is a time of creation of the time-stamped media data packet; a determining unit configured to determine a play-out time offset based, in part, on the first statistical variation; and a transmission unit configured to send out the play-out time offset to said one or more receiving media sinks once for all time-stamped media data packets of the session. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A media sink, comprising:
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a receiving unit configured to receive a control packet, time-stamped media data packets, and a play-out time offset from a media source, the control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of a global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time, the global wallclock time having a statistical variation, the play-out time offset being received once for all time-stamped media data packets of a session; a determining unit configured to determine the global wallclock time; an addition unit configured to determine a common play-out time of one of the time-stamped media data packets by adding a time, which is a timestamp included in the one of the time-stamped media data packets, and the play-out time offset; and a play-out unit configured to play-out the one of the time-stamped media data packets when the determined common play-out time of the one of the time-stamped media data packets is reached, wherein the receiving unit is configured to receive the play-out time offset, which is based, in part, on the statistical variation. - View Dependent Claims (10, 11, 12, 13)
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14. A method, implemented by a media source, for synchronously playing-out media data packets, the method comprising:
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determining, once within a session, at the media source, a global wallclock time having a statistical variation; determining a sample clock time; sending out, only once within the session, a control packet to one or more receiving media sinks, said control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of said global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time; sending out time-stamped media data packets to said one or more receiving media sinks, each of the time-stamped media data packets including a timestamp, the timestamp being a time of creation of the time-stamped media data packet; determining, at the media source, a play-out time offset based, in part, on the statistical variation; and sending out the play-out time offset to said one or more receiving media sinks once for all time-stamped media data packets of the session. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A system, comprising:
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a media source including, a global clock determination unit configured to determine, once within a session, a global wallclock time having a statistical variation; a sample clock determination unit configured to determine a sample clock time; a communications unit configured to send out, only once within the session, a control packet to one or more receiving media sinks, said control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of said global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time; a sending unit configured to send out a time-stamped media data packet to a media sink, the time-stamped media data packet including a timestamp that is a time of creation of the time-stamped media data packet, an offset determining unit configured to determine a play-out time offset, based, in pan, on the statistical variation, and a transmission unit configured to send out the play-out time offset to the media sink once for all time-stamped media data packets of the session, the media sink including, a receiving unit configured to receive the time-stamped media data packet and the play-out time offset from the media source, the play-out time offset being received once for all time-stamped media data packets of the session, a determining unit configured to determine the global wallclock time, an addition unit configured to determine a common play-out time of the time-stamped media data packet by adding the play-out time offset and the time of the creation of the time-stamped media data packet, and a play-out unit configured to play-out the time-stamped media data packet when the determined common play-out time of the time-stamped media data packet is reached. - View Dependent Claims (21, 22)
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23. A method, implemented by a media source and one or more receiving media sinks, the method comprising:
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determining, once within a session, at the media source, a global wallclock time having a statistical variation; determining a sample clock time; sending out, only once within the session, from the media source, a control packet to the one or more receiving media sinks, said control packet including two control packet timestamps, one of the control packet timestamps defining a moment in time in time units of said global wallclock time, another of the control packet timestamps defining the moment in time in time units of said sample clock time; sending out a time-stamped media data packet to the one or more receiving media sinks, the time-stamped media data packet including a timestamp that is a time of creation of the time-stamped media data packet; determining, using a processor of the media source, a play-out time offset based, in part, on the statistical variation; sending out the play-out time offset once for all time-stamped media data packets of the session; receiving the time-stamped media data packet and the play-out time offset, the play-out time offset being received once for all time-stamped media data packets of the session; determining the global wallclock time at the one or more receiving media sinks; determining a common play-out time of the time-stamped media data packet by adding the play-out time offset and the time of the creation of the time-stamped media data packet; and playing the time-stamped media data packet when the determined common play-out time of the time-stamped media data packet is reached.
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Specification