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Flow Control Experiments

An early implementation of this protocol is provided in the IVS software, available by anonymous ftp fom zenon.inria.fr in the directory rodeo/ivs.

In addition to the generic parameters described in the memo, IVS uses an application specific option to transmit audio/video encoding flags and for "flow control" experiments:

0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |F|  APP=127    |  Length = 3   |          subtype = 0          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                         name = 'IVS '                         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |     version   |A|V|     R     |            probaQoS           |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The different fields have the following values:

_________________________________________________________________
|F        |   Last option bit, as defined by RTP.               |
|_________|_____________________________________________________|
|APP      |   Application-specific option (127)                 |
|_________|_____________________________________________________|
|Length   |   Three 32 bits word.                               |
|_________|_____________________________________________________|
|name     |   "IVS ". Others programs may use this option       |
|         |   to interoperate with IVS.                         |
|_________|_____________________________________________________|
|version  |   IVS version (e.g. 0x33 for 3.3 version).          |
|_________|_____________________________________________________|
|A        |   Audio flag. Set if audio encoding is in progress. |
|_________|_____________________________________________________|
|V        |   Video flag. Set if video encoding is in progress. |
|_________|_____________________________________________________|
|R        |   reserved.                                         |
|_________|_____________________________________________________|
|probaQoS |   This value, function of the number of participants|
|         |   in a session is computed by the each coder site.  |
|_________|_____________________________________________________|

Note that this is experimental.