No Period duration for DASH

[s3bubble]

Hi,

We use Bento4 to package our content then we upload our content to AWS S3.

We have recently been on support with AWS after trying to playback content and also insert ads using Mediatailor both were failing.

They stated.

We looked at the source manifest and found out that it doesn't contain the duration attribute which is the reason behind the failure. See below : Looking at the dash-IF[1] documents, we see that it is necessary for periods to include the duration attribute. A reference manifest can be seen here https://docs.aws.amazon.com/mediatailor/latest/ug/dash-manifest-vod.html

Here is our manifest encoded with Bento4

<?xml version="1.0" ?>
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" minBufferTime="PT2.00S" mediaPresentationDuration="PT1M46.517S" type="static">
  <!-- Created with Bento4 mp4-dash.py, VERSION=2.0.0-639 -->
  <Period>
    <!-- Video -->
    <AdaptationSet mimeType="video/mp4" segmentAlignment="true" startWithSAP="1" maxWidth="1920" maxHeight="1080">
      <SegmentTemplate timescale="15360" initialization="$RepresentationID$/init.mp4" media="$RepresentationID$/seg-$Number$.m4s" startNumber="1">
        <SegmentTimeline>
          <S d="30720" r="52"/>
          <S d="7936"/>
        </SegmentTimeline>
      </SegmentTemplate>
      <Representation id="video/avc1/1" codecs="avc1.4D402A" width="1920" height="1080" scanType="progressive" frameRate="60" bandwidth="1544536"/>
      <Representation id="video/avc1/2" codecs="avc1.4D4020" width="1280" height="720" scanType="progressive" frameRate="60" bandwidth="1029836"/>
      <Representation id="video/avc1/3" codecs="avc1.4D401F" width="842" height="480" scanType="progressive" frameRate="60" bandwidth="625632"/>
      <Representation id="video/avc1/4" codecs="avc1.4D401F" width="640" height="360" scanType="progressive" frameRate="60" bandwidth="444305"/>
      <Representation id="video/avc1/5" codecs="avc1.4D401E" width="426" height="240" scanType="progressive" frameRate="60" bandwidth="198266"/>
    </AdaptationSet>
    <!-- Audio -->
    <AdaptationSet mimeType="audio/mp4" startWithSAP="1" segmentAlignment="true">
      <SegmentTemplate timescale="48000" initialization="$RepresentationID$/init.mp4" media="$RepresentationID$/seg-$Number$.m4s" startNumber="1">
        <SegmentTimeline>
          <S d="96256"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="95232"/>
          <S d="96256" r="2"/>
          <S d="24440"/>
        </SegmentTimeline>
      </SegmentTemplate>
      <Representation id="audio/und/mp4a.40.2/1" codecs="mp4a.40.2" bandwidth="194349" audioSamplingRate="48000">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="2"/>
      </Representation>
      <Representation id="audio/und/mp4a.40.2/2" codecs="mp4a.40.2" bandwidth="130248" audioSamplingRate="48000">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="2"/>
      </Representation>
      <Representation id="audio/und/mp4a.40.2/3" codecs="mp4a.40.2" bandwidth="97200" audioSamplingRate="48000">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="2"/>
      </Representation>
      <Representation id="audio/und/mp4a.40.2/4" codecs="mp4a.40.2" bandwidth="65397" audioSamplingRate="48000">
        <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="2"/>
      </Representation>
    </AdaptationSet>
  </Period>
</MPD>

Any suggestion on how to implement this.

[barbibulle]

Hi. Thanks for reporting the issue. We'll take a look at it shortly and come up with an appropriate fix.

[barbibulle]

Looking at the latest DASH-IF document, it seems that the Period@duration attribute is not necessary here: Section [3.10.2.2.3 - Period Information] states that:

The Period end time PEwc[i] for a regular Period i is determined as follows:
+ If the Period is the last one in the MPD, the time PEwc[i] is obtained as
  * the Media Presentation Duration MPDur, with MPDur the value of MPD@mediaPresentationDuration if present, or the sum of PSwc[i] of the last Period and the value of Period@duration of the last Period.
+ else
  * the time PEwc[i] is obtained as the Period start time of the next Period, i.e. PEwc[i] = PSwc[i+1].

So in the case here, with a single that spans the entire presentation, the period duration would be inferred to be the value of MPD@mediaPresentationDuration, which does exist.

[s3bubble]

Hi thanks for the response this is a strange one.

We had this issue when encoding with Mediaconvert and this was the resolution.

After reviewing the MediaConvert job, we found that Write segment timeline in representation was disabled. DASH input manifests must contain segment templates with segment timelines in them. In our testing, once we enabled this setting in the DASH output group MediaTailor was able to accept the manifest and insert the ads properly.

For more information on integrating an MPEG-DASH source, please review

https://docs.aws.amazon.com/mediatailor/latest/ug/manifest-dash.html

We had to enable this.

https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-mediaconvert/modules/dashisogroupsettings.html#writesegmenttimelineinrepresentation

Seems like something AWS is specifically implementing for mediatailor ad insertion we are getting back to AWS currently awaiting a response.

We will update.

[s3bubble]

Hi we have just got a response from the AWS Mediatailor team see below.

I have the following update from the service team:

Thanks for linking to that ticket at the Bento4 project.

We have updated our plan a little bit and plan to allow a manifest where the period@start and period@duration is either specified in the tag or is calculable from other tags' start and duration attributes. And the first period will not require a Period@start as it will be 0.

However we do plan to require a Period@duration on the final period of a static mpd, as the DASH-IF guidelines say:

    In a static presentation, the last period SHALL have a Period@duration.

https://dashif-documents.azurewebsites.net/Guidelines-TimingModel/master/Guidelines-TimingModel.html#timing-period-static

This means that will be allowed for the first period, but then either the subsequent ones must have a start, or the 1st+ ones must have a duration. And the final period must have a duration.

   <Period>
   <Period start=x>
   <Period start=y duration=z>

Is allowed.

   <Period duration=a>
   <Period duration=b>

Is also allowed.

About the MediaPresentationDuration, I see this in the DASH-IF doc:

MPD@mediaPresentationDuration MAY be present in an MPD. If present, it SHALL accurately match the duration between the zero point on the MPD timeline and the end of the last period, including the duration of any XLink periods. Clients SHALL calculate the total duration of a static presentation by adding up the durations of each period and SHALL NOT rely on the presence of MPD@mediaPresentationDuration.

https://dashif-documents.azurewebsites.net/Guidelines-TimingModel/master/Guidelines-TimingModel.html#timing-and-presentation-types

It doesn't look to me like MediaPresentationDuration is a substitute for Period@duration. Let me know if you/they have comments about that.

Thank you!

Is this something that could be implemented into the Bento4? Or are there any comments to send back to the Mediatailor team. Thanks