Extron electronic 325 ,

P1 P2 P3 P4 FR1 If packet P6 is lost or corrupted (x), the loss

can be corrected by using the FR2 FEC packet.

However, corrupt packets P14, P15, and P16

cannot be corrected using the row FEC packet

(FR4) because too much data is missing.

To correct these packets, the column FEC data is

used. Packets 15 and 16 can be corrected using

FC3 and FC4 column FEC packets. Before

P5 xP7 P8 FR2

P9 P10 P11 P12 FR3

P13 xxxFR4

P17 P18 P19 P20 FR5

FC1 FC2 FC3FC4

correcting packet 14, packet 6 must rst be corrected using the row FEC. After this,

the column FEC can be used to correct packet 14.

Ö Fec Rows and FEC Columns — Extron recommends a setting of 5 for rows and 5 for

columns, which should be the starting point for the error correction for the audio

transport and provides rugged operation on uncorrected IP networks.

The values that you set in the FEC row and column drop down lists depend on the

quality of the network link that is in use. The diagrams above show that the FEC data

can add large overhead to the overall bit rate transported over the network. Therefore

certain settings, while they may provide a high level of reliability, are inefficient.

Alternatively, settings that add little overhead may not provide a sufficient level of

protection on networks with a poor quality of service.

ñ Error Injection Rate — This setting should be left at 0. It used for test purposes only,

to drop packets artificially in order to test the effectiveness of the FEC scheme.

The audio encoder configuration page streams panel (see figure 29) provides details of any

active audio encoder streams. The data transport method, TCP or RTP, is defined on the

decoder configuration page (see “Configure Encoders or Decoders”). Audio multicasting

is selected in this panel (see “Enable multicast streaming“ to select the multicast and

“Data Transport Methods“ for definitions of the methods).

Figure 29. Audio Encoder Streams Panel

NOTE: This setting does NOT track the same setting applied in other (video, anc,

colfec, and rowfec) encoder configuration pages. For most applications, you

should set the same transport for all stream elements, but this is not mandatory.

The New Export Stream function is not supported.

The colfec and row encoder configuration pages (see figure 30, on the next page)

provide the same basic function, enabling of multicasting. The encoder that you may

need to configure depends on whether you have selected column only (colfec encoder) or

and Row + column (rowfec encoder) as the FEC mode (see “Forward error correction

(FEC) panel“). The streams panel provides details of any active FEC encoder streams.

The data transport method, TCP or RTP, is defined on the decoder configuration page

(see “Configure Encoders or Decoders”). FEC multicasting is selected on this page

(see “Enable multicast streaming“ to select the multicast and “Data Transport

Methods“ for definitions of the methods).

VN-Matrix 325 Serial Digital Over IP CODEC • Operation 41