Using settings variables with streaming outputs - MediaConvert
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Using settings variables with streaming outputs

Variables in your job settings, also called format identifiers, function differently for outputs in Apple HLS and DASH ISO output groups. Here are the differences:

For Apple HLS Outputs

When you use the date and time format identifiers ($dt$, $t$, $d$) in the Segment modifier setting, these format identifiers resolve to the completion time of each segment, rather than to the start time of the job.

Note

For jobs that use accelerated transcoding, segments might complete at the same time. This means that date and time format identifiers don't always resolve to unique values.

For DASH ISO Outputs

You can use two additional format identifiers in the Name modifier setting. These affect the DASH manifest in addition to the output file name. Here are the identifiers:

$Number$

In your output file names, $Number$ resolves to a series of numbers that increment from 1. This replaces the default, nine-digit segment numbering in the segment file names. For example:

  • If you specify video_$Number$ for Name modifier, the service creates segment files named video_1.mp4, video_2.mp4, and so on.

  • If you specify only video_ for Name modifier, the service creates segment files named video_000000001.mp4, video_000000002.mp4, and so on.

In your DASH manifest, AWS Elemental MediaConvert includes duration and startNumber inside the SegmentTemplate element, like this: <SegmentTemplate timescale="90000" media="main_video_$Number$.mp4" initialization="main_video_$Number$init.mp4" duration="3375000"/>

Note

If you use the $Number$ format identifier in an output, you must also use it in every other output of the output group.

$Bandwidth$

In your output file names, $Bandwidth$ resolves to the value of Video, Bitrate plus the value of Audio, Bitrate in the output. Regardless of whether you include this format identifier, the service uses nine-digit segment numbering in the segment file names.

For example, suppose you specify these values:

  • Video, Bitrate (bits/s): 50000000

  • Audio, Bitrate (kbits/s): 96.0 (96,000 bits/s)

  • Name modifier: video_$Bandwidth$

The value for $Bandwidth$ resolves to 50,096,000. The service creates segment files named video_50096000_000000001.mp4, video_50096000_000000002.mp4, and so on.

In the manifest, AWS Elemental MediaConvert includes duration and startNumber inside the SegmentTemplate element, like this: <SegmentTemplate timescale="90000" media="main_video_$Bandwidth$.mp4" initialization="main_video_$Bandwidth$init.mp4" duration="3375000"/>.

$Time$

In your output file names, $Time$ resolves to the duration, in milliseconds, of the segment. When you include this format identifier, the service doesn't use the default nine-digit segment numbering in the segment file names.

For example, if you specify video180__$Time$ for Name modifier, the service creates segment files named video180__345600.mp4, video180__331680.mp4, and so on. In these examples, the segment durations are 345,600 ms and 331,680 ms.

In the manifest, AWS Elemental MediaConvert includes SegmentTimeline inside the SegmentTemplate element, like this: 

<Representation id="5" width="320" height="180" bandwidth="200000" codecs="avc1.4d400c">
        <SegmentTemplate media="video180_$Time$.mp4" initialization="videovideo180_init.mp4">
          <SegmentTimeline>
            <S t="0" d="345600" r="2"/>
            <S t="1036800" d="316800"/>
          </SegmentTimeline>
        </SegmentTemplate>
      </Representation>
Note

If you use the $Time$ format identifier in an output, you must also use it in every other output of the output group.