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Section 3 Protocol Settings

Creating a Channel
1Route Information
3Protocol Settings (SRT only)

If TS over SRT is chosen in Section 2 Source, follow the instructions below for your chosen stream protocol. For all other protocols, continue to  Section 4 Destinations  as there are no additional protocol settings.

The following figure shows the SRT Parameters section of the Create Route screen. The numbered callouts in the figure indicate the step number in this procedure.

  1. Enter the desired latency. This specifies the SRT receiver buffer that permits lost packet recovery. The size of this buffer adds to the total end-to-end latency. It is recommended to use a value that is at least 3 times the round-trip-time (RTT). Range = 20–8000 ms.


    Latency is for the SRT protocol only and does not include the capture, encoding, decoding, and display processes of the endpoint devices.

  2. (For advanced users only.) Enter the desired Receive Buffer Size. High-bandwidth (≥60 Mbps), high-latency streams may experience video dropouts due to the default receive buffer size. If you notice this issue for your stream, use the following formulas to guide you in setting an appropriate buffer size, where:

    • MTU size is defined at the stream's source.

    • Bitrate and negotiated latency are found on the route statistics page while the route is running. (See Viewing a Route’s Statistics.) The negotiated latency is not necessarily the value set in Step #2.

    MTU SizeSuggested Receiver Buffer Size (in kByte)
    1000–1500(Bitrate in kbps ÷ 8) × negotiated latency in seconds × 1.5
    750–1000(Bitrate in kbps ÷ 8) × negotiated latency in seconds × 1.7
    < 750(Bitrate in kbps ÷ 8) × negotiated latency in seconds × 2.0
  3. If using Encryption on any destinations, enter the desired passphrase to protect the stream. Must be between 10 to 79 UTF8 characters.
  4. If you have entered an encryption passphrase in the previous step, you may optionally choose Authenticated Encryption Associated Data (AEAD) mode in the Authentication dropdown by selecting AES-GCM. For SRT Listener mode, by default Auto is selected, which will connect to a peer no matter if the peer is configured for AES-GCM or not. For Caller and Rendezvous modes, if AES-CTR is desired, select None at both peers. If AEAD mode is desired, select AES-GCM at both peers for the connection to succeed.
  5. If you have a Haivision SRT Gateway, for SRT Caller mode click the 
    icon to open the Stream ID editor. In the editor:
    1. Select the desired Stream ID format.
      • If Default Stream ID format is selected, enter the Resource Name and User Name. The resulting Stream ID appears below.
      • If Custom Stream ID format is selected, enter the desired text string for the Stream ID.
    2. Click the Apply button to close the Stream ID editor.
  6. In SRT Caller mode with Path Redundancy disabled, select the Error Correction Method: ARQ (Automatic Repeat Request), FEC, or FEC+ARQ. See Choosing an Error Correction Method for SRT Streams for more information on using SRT FEC. When FEC or FEC+ARQ is selected:
    1. Select the Layout: Even or Staircase.
    2. Enter the number of rows and columns in the FEC matrix.

Continue to Section 4 Destinations.

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