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RM_FEC_INFO structure (wsrm.h)

  • Article

The RM_FEC_INFO structure specifies settings for using forward error correction (FEC) with Reliable Multicast. This structure is used with the RM_USE_FEC socket option.

Syntax

typedef struct _RM_FEC_INFO {
  USHORT  FECBlockSize;
  USHORT  FECProActivePackets;
  UCHAR   FECGroupSize;
  BOOLEAN fFECOnDemandParityEnabled;
} RM_FEC_INFO;

Members

FECBlockSize

Maximum number of packets that can be sent for any group, including original data and parity packets. Maximum and default value is 255.

FECProActivePackets

Number of packets to send proactively with each group. Use this option when the network is dispersed, and upstream NAK requests would have an impact on throughput.

FECGroupSize

Number of packets to be treated as one group for the purpose of computing parity packets. Group size must be a power of two. In lossy networks, keep the group size relatively small.

fFECOnDemandParityEnabled

Specifies whether the sender is enabled for sending parity repair packets. When TRUE, receivers should only request parity repair packets.

Remarks

The RM_USE_FEC socket option notifies the Reliable Multicast sender to apply forward error correction techniques to send repair data. there are three modes of using forward error correction:

  1. Pro-active parity packets only
  2. OnDemand parity packets only
  3. Both pro-active and OnDemand parity packets
Since the use of this structure implies the need for forward error correction, either the FECProActivePackets or fFECOnDemandParityEnabled member must be nonzero, otherwise the function call fails.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Header wsrm.h

See also

RM_USE_FEC

Reliable Multicast Programming

Socket Options