RTP-formatted media clips
View Patent ↗A transmitter ( 14 ) of audio, video, or other real-time information reads the information from a persistent store ( 22 ) in which the real-time information has been stored in the Real-time-Transport Protocol (“RTP”) format (FIG. 4 ). A receiver ( 18 ) receives the information from the channel ( 16 ) through which the transmitter ( 14 ) has transmitted it, and the receiver may store the information in a persistent store ( 24 ) in RTP format instead of or in addition to playing it by applying it to an appropriate player ( 20 ). Parts of this communications circuit may be tested by a tester unit ( 26 ) that also employs RTP-format information from a persistent store ( 22 ).
1. A method of performing persistent storage comprising:
receiving real-time data in received RTP packets, of which each includes a received RTP payload and a respective received RTP timestamp based on a time period measured from an initial packet, wherein an RTP timestamp of an initial packet is a randomly generated timestamp;
in response to the received real-time data, storing in a persistent medium a first stored record as stored packets of which each corresponds to a respective one of the received RTP packets, each stored packet including the RTP payload contained in the respective received RTP packet and further including a respective stored RTP timestamp derived from the corresponding received RTP packet's received RTP timestamp;
retrieving the stored record;
retrieving a relation between the randomly generated timestamp and a local wall clock of an apparatus playing the stored record; and
playing the stored record in accordance with the stored RTP timestamps contained therein by determining times to play data in the RTP payload contained in the respective stored packets, the times to play the data in the RTP payload contained in the respective stored packets being determined as local times corresponding to the stored RTP timestamp contained in the stored packets based on the relation between the randomly generated timestamp and the local wall clock.
2. A method as defined in claim 1 wherein the stored RTP timestamp in each stored packet equals the received RTP timestamp contained in the respective received RTP packet.
3. A method as defined in claim 2 wherein a format of the stored packets is that of the corresponding received RTP packets.
4. A method as defined in claim 1 wherein:
the first stored record includes audio data; and
the method further includes retrieving the first stored record and playing the first stored record in accordance with the stored RTP timestamps contained therein.
5. A method as defined in claim 1 wherein:
the first stored record includes video data; and
the method further includes retrieving the first stored record and playing the stored record in accordance with the stored RTP timestamps contained therein.
6. A method as defined in claim 5 wherein the method additionally includes:
receiving second RTP packets containing audio data, each second RTP packet including a received RTP payload and a respective received RTP timestamp;
in response to the second RTP packets, storing in the persistent medium a second stored record as second stored packets of which each corresponds to a respective one of the second received RTP packets, each second stored packet including the RTP payload contained in the respective received RTP packet and further including a respective stored RTP timestamp derived from the corresponding second received RTP packet's received RTP timestamp;
retrieving the second stored record; and
playing the second stored record simultaneously with the first stored record in accordance with the stored RTP timestamps contained in the second stored record.
7. A method as defined in claim 1 further including retrieving the stored record and transmitting in accordance with the RTP timestamp in each recorded packet a corresponding transmitted RTP packet including a transmitted RTP timestamp and including a payload the same as that of the recorded packet to which that transmitted packet corresponds.
8. An apparatus comprising:
a persistent medium operable to store received real-time data and retrieve data thus stored;
a receiver that receives the real-time data in received RTP packets, of which each includes a received RTP payload and a respective received RTP timestamp based on a time period measured from an initial packet, wherein the real-time data includes an audio session of RTP packets and a video session of RTP packets, wherein an RTP timestamp of an initial packet of the audio session is randomly generated and an RTP timestamp of an initial packet of the video session is randomly generated;
a persistent-store driver that responds to the receiver by storing in the persistent medium a stored record as stored packets of which each corresponds to a respective one of the received RTP packets, each stored packet including the RTP payload contained in the respective received RTP packet and further including a respective stored RTP timestamp derived from the corresponding received RTP packet's received RTP timestamp; and
a player that plays the audio session and the video session in the stored record in accordance with the stored timestamps contained therein by determining the times to play the data contained in the respective stored packets, the times to play the data in the RTP payload contained in the respective stored packets being determined as local times corresponding to the stored timestamp contained in the stored packets.
9. An apparatus as defined in claim 8 wherein the stored RTP timestamp in each stored packet equals the received RTP timestamp contained in the respective received RTP packet.
10. An apparatus as defined in claim 9 wherein a format of the stored packets is that of the corresponding received RTP packets.
11. An apparatus as defined in claim 8 wherein:
the stored record includes audio data;
the persistent-store driver also retrieves the stored record; and
the apparatus further includes an audio player and an audio driver that drives the audio player to play the stored record in accordance with the stored RTP timestamps contained therein.
12. An apparatus as defined in claim 8 wherein:
the received and stored records contain video data;
the persistent-store driver also retrieves the stored record; and
the apparatus further includes a video player and a video driver that drives the video player to play the stored record in accordance with the stored RTP timestamps contained therein.
13. An apparatus as defined in claim 12 wherein:
the receiver additionally receives second RTP packets containing audio data, each second RTP packet including a received RTP payload and a respective received RTP timestamp;
in response to the second received RTP packets, the persistent-store driver stores in the persistent medium a second stored record as second stored packets of which each corresponds to a respective one of the second received RTP packets, each second stored packet including the RTP payload contained in the corresponding received RTP packet and further including a respective stored RTP timestamp derived from the corresponding second received RTP packet's received RTP timestamp;
the persistent-store driver also retrieves the second stored record; and
the apparatus further includes an audio player and an audio driver that drives the audio player, simultaneously with the video driver's driving of the video player, to play the second stored record in accordance with the stored timestamps contained therein.
14. An apparatus as defined in claim 8 wherein:
the persistent-store driver also retrieves the stored record; and
the apparatus further includes a transmitter that transmits in accordance with the RPT timestamp in each thus-retrieved recorded packet a corresponding transmitted RTP packet that both includes a transmitted RTP timestamp and includes a payload the same as that of the recorded packet to which that transmitted packet corresponds.
15. A method of performing persistent storage comprising:
receiving real-time data in received RTP packets, of which each includes a received RTP payload and a RTP header including a respective received RTP timestamp based on a time period measured from an initial packet, wherein an RTP timestamp of an initial packet is a randomly generated timestamp and successive RTP timestamps are defined by a type of data code in the RTP header;
in response to the received real-time data, storing in a persistent medium a first stored record as stored packets of which each corresponds to a respective one of the received RTP packets, each stored packet including the RTP payload contained in the respective received RTP packet and further including a respective stored RTP timestamp derived from the corresponding received RTP packet's received RTP timestamp;
retrieving the stored record;
retrieving a relation between the randomly generated timestamp and a local wall clock of an apparatus playing the stored record; and
playing the stored record in accordance with the stored RTP timestamps contained therein by determining times to play data in the RTP payload contained in the respective stored packets, the times to play the data in the RTP payload contained in the respective stored packets being determined as local times corresponding to the stored RTP timestamp contained in the stored packets based on the relation between the randomly generated timestamp and the local wall clock.