Mobicents Media Server
Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's  detectors From secondary sources From another connection ...
Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's  detectors From secondary sources From another connection ...
DSP algorithms Conference bridge, packet relay, media player/recorder </li></ul>Source Sink DSP Source Sink DSP DSP
Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's  detectors From secondary sources From another connection ...
Connection mode send only, receive only, send/receive, conference, loop, network loop </li></ul>Source Sink DSP Source Sin...
Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's  detectors From secondary sources From another connection ...
Connection DTMF, Busy tone, VAD, ASR, TTS, Media player </li></ul>Source Sink DSP Source Sink DSP DSP
Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's  detectors From secondary sources From another connection ...
Filters AEC, Gain Control, etc </li></ul>Source Sink DSP Source Sink DSP DSP
Time constraints <ul><li>Live media stream (sequencing packets)
Distributed DSP procedures
Clock skew problem </li></ul>Logic of Media server includes actions whose completions are time-constrained.
Deadlines, Time/Utility function <ul>A deadline is limited in expressiveness by its singular inflection point and linear t...
Example: Scheduling with Round robin <ul><li>Task set: T1=(1,5; 4), T2=(2;6), T3=(3,8)
Time slice: 1 </li></ul><ul><li>Observe since time t=6 at least one task misses its deadline
Latency unpredictable </li></ul>0  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22
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Mobicents Media Server theory, practice, cloud considerations, design discussion - Mobicents Summit 2011

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Mobicents Media Server theory, practice, cloud considerations, design discussion - Mobicents Summit 2011

  1. 1. Mobicents Media Server
  2. 2. Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's detectors From secondary sources From another connection (cnf mode) To another connection (cnf mode) To endpoint's generators To secondary sinks RTP/Local channel Video channel Source Sink DSP Source Sink DSP DSP
  3. 3. Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's detectors From secondary sources From another connection (cnf mode) To another connection (cnf mode) To endpoint's generators To secondary sinks RTP/Local channel Video channel <ul>Primary source/sink <li>Represents external media streams TDM channels, Sound card, Video card, etc
  4. 4. DSP algorithms Conference bridge, packet relay, media player/recorder </li></ul>Source Sink DSP Source Sink DSP DSP
  5. 5. Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's detectors From secondary sources From another connection (cnf mode) To another connection (cnf mode) To endpoint's generators To secondary sinks RTP/Local channel Video channel <ul>Switching hub <li>Data flow management Distribution and mixing signals
  6. 6. Connection mode send only, receive only, send/receive, conference, loop, network loop </li></ul>Source Sink DSP Source Sink DSP DSP
  7. 7. Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's detectors From secondary sources From another connection (cnf mode) To another connection (cnf mode) To endpoint's generators To secondary sinks RTP/Local channel Video channel <ul>Secondary sources/sinks <li>Endpoint DTMF, Busy tone, VAD, ASR, TTS, Media player
  8. 8. Connection DTMF, Busy tone, VAD, ASR, TTS, Media player </li></ul>Source Sink DSP Source Sink DSP DSP
  9. 9. Endpoint/connection model Audio Video Rx/Tx Rx/Tx To endpoint's detectors From secondary sources From another connection (cnf mode) To another connection (cnf mode) To endpoint's generators To secondary sinks RTP/Local channel Video channel <ul>Signaling Processors <li>Coders, Decoders G711, GSM, etc
  10. 10. Filters AEC, Gain Control, etc </li></ul>Source Sink DSP Source Sink DSP DSP
  11. 11. Time constraints <ul><li>Live media stream (sequencing packets)
  12. 12. Distributed DSP procedures
  13. 13. Clock skew problem </li></ul>Logic of Media server includes actions whose completions are time-constrained.
  14. 14. Deadlines, Time/Utility function <ul>A deadline is limited in expressiveness by its singular inflection point and linear timeliness metric (lateness). Time/utility function - an action time constraint expresses the utility (either reward or penalty) for completing the action as a function of when the action is completed. </ul>The best-known example of a time constraint is a deadline
  15. 15. Example: Scheduling with Round robin <ul><li>Task set: T1=(1,5; 4), T2=(2;6), T3=(3,8)
  16. 16. Time slice: 1 </li></ul><ul><li>Observe since time t=6 at least one task misses its deadline
  17. 17. Latency unpredictable </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
  18. 18. Early Deadline First (EDF) <ul><li>Earliest deadline first (EDF) or least time to go is a dynamic scheduling algorithm used in real-time operating systems. It places processes in a priority queue. Whenever a scheduling event occurs (task finishes, new task released, etc.) the queue will be searched for the process closest to its deadline.
  19. 19. EDF is an optimal scheduling algorithm on preemptive uniprocessors, in the following sense: if a collection of independent jobs, each characterized by an arrival time, an execution requirement, and a deadline, can be scheduled (by any algorithm) such that all the jobs complete by their deadlines, the EDF will schedule this collection of jobs such that they all complete by their deadlines.
  20. 20. EDF can guarantee that all deadlines are met provided that the total CPU utilization is not more than 100%. So, compared to fixed priority scheduling techniques like rate-monotonic scheduling, EDF can guarantee all the deadlines in the system at higher loading.
  21. 21. The feasibility test for periodic task sets: </li></ul>
  22. 22. Early Deadline First <ul><li>Task set: T1=(1,5; 4), T2=(2;6), T3=(3,8)
  23. 23. Time slice: 1 </li></ul>0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
  24. 24. Scheduler implementation Acceptor (Feasibility test) Priority Queue Executors(Threads) feadback
  25. 25. Exception In case of task sets with equal periods and task execution time less then time slice for RR both algorithms become First Comes First Serviced (FCFS) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
  26. 26. Multiple processors <ul><li>Global EDF allow task migration between processors
  27. 27. Partitioning EDF task migration is not allowed
  28. 28. Utilization guarantee for EDF or any other static-priority multiprocessor scheduling algorithm – partitioned or global – cannot be higher than (m + 1)/2 for an m-processor platform </li></ul>
  29. 29. Determinism
  30. 30. Early Gap - Early Deadline First
  31. 31. Java Computitional benchmarks

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