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15 APPENDIX D: AVAILABLE FEC'
MPX STREAMING (
FEC (Forward Error Correction) is a mechanism which consists in sending redundant information (redundant frames) to the
decoder so that it can compensate for packet transmission errors on unreliable networks.
An FEC can be selected when defining the parameters of the stream to be generated (Send page) and/or to be received
(Receive page).
Inband FEC
Redundant frames are sent in the same stream as the IP audio stream.
The FEC to be selected is "+50% bandwidth, recovery 2, 1 stream (audio)".
Its characteristics are: +50% bandwidth, additional delay of 2 frames, recovers 1 lost packet at 100%, recovers 2 consecutive
lost packets at 75%.
FEC through an additional stream
Standard FECs
Redundant frames are sent as a second stream of data. The used UDP port is: port of the IP audio stream + 2.
Selectable FECs are:
●
+100% bandwidth, recovery 3, 2 streams (audio + FEC)
+100% bandwidth, additional delay of 1 frame, recovers 2 consecutive lost packet at 100%, recovers 3 consecutive
lost packet at 75%
●
+100% bandwidth, recovery 4, 2 streams (audio + FEC)
+100% bandwidth, additional delay of 3 frames, recovers 3 lost packet at 100%, recovers 4 consecutive lost packet
at 80%
●
+50% bandwidth, recovery 1/2, 2 streams (audio + FEC)
+50% bandwidth, additional delay of 1 frame, recovers 1 lost packet over 2 consecutive packets.
●
+33% bandwidth, recovery 1/3, 2 streams (audio + FEC)
+33% bandwidth, additional delay of 2 frames, recovers 1 lost packet over 3 consecutive packets.
●
+25% bandwidth, recovery 1/4, 2 streams (audio + FEC)
+25% bandwidth, additional delay of 3 frames, recovers 1 lost packet over 4 consecutive packets.
●
+20% bandwidth, recovery 1/5, 2 streams (audio + FEC)
+20% bandwidth, additional delay of 4 frames, recovers 1 lost packet over 5 consecutive packets.
●
+10% bandwidth, recovery 1/10, 2 streams (audio + FEC) – From firmware 2.31
+10% bandwidth, additional delay of 9 frames, recovers 1 lost packet over 10 consecutive packets.
Redundant dual streaming
Redundant dual streaming is activated by selecting an appropriate "Dual stream" FEC. A dual stream FEC consists in
considering the redundant stream as an FEC.
In addition, the duplicated stream can be delayed to offer time diversity, thus avoiding that a network disturbance affects the
same frames on the primary stream and on the FEC stream. Selectable delay is from 0 to 3000 ms, by steps of 100 ms.
Notes:
●
When in-band audio format signaling is enabled, FEC stream is sent to the same IP address as the primary stream,
and on UDP port + 2.
FOR RAW RTP AUDIO OR UNCOMPRESSED
S
TS
NO
ENCAPSULATION
IQOYA X/LINK-MPX user manual
)
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