Setting the fragment length for streaming outputs - MediaConvert
Rule for fragment lengthFragment length examplesFinding the settings related to fragment length
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Setting the fragment length for streaming outputs

For all ABR streaming output groups other than HLS (CMAF, DASH, and Microsoft Smooth Streaming), the value that you specify for Fragment length (FragmentLength) must work with the other output settings that you specify. If you set Fragment length incorrectly, when viewers watch the output video, their player might crash. This can happen because the player expects additional segments at the end of the video and requests segments that don't exist.

Fragment length is constrained by your values for Closed GOP cadence (GopClosedCadence), GOP size (GopSize), and Frame rate (FramerateNumerator, FramerateDenominator). For information about finding these settings on the console and in your JSON job specification, see Finding the settings related to fragment length.

Note

When you set your output Frame rate to Follow source, make sure that the frame rate of your input video file works with the value that you specify for the output Fragment length. The frame rate of your input video file functions as your output frame rate.

Rule for fragment length

Fragment length must be a whole number and must be a multiple of this value: GOP size x Closed GOP cadence ÷ Frame rate

Fragment length examples

Example: Correct settings

Closed GOP cadence = 1

Frame rate = 30

GOP size = 60 frames

Fragment length = 2

Example: Incorrect settings

Closed GOP Cadence = 1

Frame rate = 50

GOP size = 90 frames

Fragment length = 2

When you set Fragment length, check your values for Closed GOP cadence, GOP size, and Frame rate.

Fragment length

You can set the fragment length using either the console or the JSON job specification. The Fragment length setting applies to an output group and affects every output in the group.

To find the Fragment length setting (console)

  1. On the Create job page, in the Job pane on the left, under Output groups, choose the name of your CMAF, DASH ISO, or Microsoft Smooth Streaming output group.

  2. In the group settings section on the right, find Fragment length.

    The group settings section is titled CMAF group settings, DASH ISO group settings, or MS Smooth group settings.

To find the Fragment length setting (JSON job specification)

  • Find FragmentLength as a child of OutputGroupSettings, as in the following example.

    {
  "Settings": {
    ...
    "Inputs": [
      ...
    ],
    "OutputGroups": [
      {
        "Name": "DASH ISO",
        "OutputGroupSettings": {
          "Type": "DASH_ISO_GROUP_SETTINGS",
          "DashIsoGroupSettings": {
            "SegmentLength": 30,
            "FragmentLength": 2,
            "SegmentControl": "SINGLE_FILE",
            "HbbtvCompliance": "NONE"
          }
        },
		...

Closed GOP cadence, GOP size, and frame rate

You can set Closed GOP cadence, GOP size, and Frame rate using either the console or the JSON job specification. These settings apply to each output individually. Make sure that the values that you set for each output in the output group work with the value that you specify for the output group's Fragment length.

Note

Your ABR stack has multiple outputs. Make sure to set these values in each output.

To find the encoding settings for an output (console)

  1. On the Create job page, in the Job pane on the left, under Output groups, choose the name of your output, such as Output 1, Output 2, and so on.

  2. In the Encoding settings section, the Video tab is selected automatically. Find Closed GOP cadence, GOP size, and Frame rate on this tab.

To find the encoding settings for an output (JSON job specification)

  • Find GopClosedCadence, GopSize, FramerateNumerator, and FramerateDenominator as children of the codec settings, as in the following example. In this example, the codec is H_264, so the parent of the codec settings is H264Settings.

    {
  "Settings": {
    ...
    "Inputs": [
      ...
    ],
    "OutputGroups": [
      {
        "Name": "DASH ISO",
        ...
        },
        "Outputs": [
          {
            "VideoDescription": {
              ...
              "CodecSettings": {
                "Codec": "H_264",
                "H264Settings": {
                  "InterlaceMode": "PROGRESSIVE",
                  "NumberReferenceFrames": 3,
                  "Syntax": "DEFAULT",
                  "Softness": 0,
                  "GopClosedCadence": 1,
                  "GopSize": 60,
				  ...
                  "FramerateNumerator": 60,
                  "FramerateDenominator": 1
                }
              },
              ...
            },