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Alternate Surround Audio in HLS and MPD SMIL

Hi,

We have ABR streams with mutiple audio and video bitrates and would like to add extra audio channels with surround sound in AAC and AC-3 formats. We’ve successfully made the SMIL for MPD but for HLS it’s giving us nightmares. Here’s what the (simplified) SMIL looks like for MPD:

<?xml version="1.0" encoding="UTF-8"?>
<smil title="">
<body>
<switch>
<video height="360" width="640" src="mp4:MX586152-2223388-967603921890259.mp4">
<param name="videoBitrate" value="892928" valuetype="data"/>
<param name="audioBitrate" value="131072" valuetype="data"/>
<param name="audioRole" value="Stereo" valuetype="data"/>
</video>
<video height="480" width="852" src="mp4:MX586152-2223384-690093338489533.mp4">
<param name="videoBitrate" value="1763328" valuetype="data"/>
<param name="audioBitrate" value="131072" valuetype="data"/>
<param name="audioRole" value="Stereo" valuetype="data"/>
</video>
<video height="576" width="1024" src="mp4:MX586152-2222174-151339054107667.mp4">
<param name="videoBitrate" value="2363392" valuetype="data"/>
<param name="audioBitrate" value="196608" valuetype="data"/>
<param name="audioRole" value="Stereo" valuetype="data"/>
</video>
<video height="720" width="1280" src="mp4:MX586152-2227310-882769763469696.mp4">
<param name="videoBitrate" value="3131392" valuetype="data"/>
<param name="audioBitrate" value="196608" valuetype="data"/>
<param name="audioRole" value="Stereo" valuetype="data"/>
</video>
<video src="mp4:MX586152-2338134-072136878967286.aac">
<param name="audioBitrate" value="393216" valuetype="data"/>
<param name="audioOnly" value="TRUE" valuetype="data"/>
<param name="audioRole" value="AAC 5.1" valuetype="data"/>
</video>
<video src="mp4:MX586152-2338268-952219665050507.ac3">
<param name="audioBitrate" value="393216" valuetype="data"/>
<param name="audioOnly" value="TRUE" valuetype="data"/>
<param name="audioRole" value="AC-3 5.1" valuetype="data"/>
</video>
</switch>
</body>
</smil>

I’m not sure if we can misuse the audioRole this way but it works!\

How to change the SMIL so it also works for HLS. The https://www.wowza.com/docs/how-to-use-alternative-audio-or-video-tracks-with-apple-hls-streams page does not explain how to maintain the different audio and video bitrates, and just add the two alternate audio channels.

Anybody?

Thanks at lot.

Sorry you didn’t get an answer from the community, but this is a workflow that most folks may not have experience with. I know we’ve worked together with you in support tickets in the past, so I asked an engineer to take a peek at this post and they said it will require one. This a bit of a tricky configuration to nail down in the forums with wanting to create an HLS packetizer in parallel. It most likely requires a second SMIL file.

Let’s proceed through a ticket though so we can have full access to your files/logs and properly test and give you the correct guidance. Thanks Joost.