Video on Demand Support for Media with Multiple Audio Tracks and Multiple Subtitles

Question

Our requirement to use Azure Media Services is to stream stored (in Azure Storage) videos on demand. The videos shall be played on the mobile devices using an HLS media player (not Azure Media Player).

Below are the specifications of the videos that we upload to Azure storage:
* container format: MKV
* # video tracks: 1
* # audio tracks: multiple (anywhere between 1 to 10)
* # subtitle tracks: multiple (anywhere between 1 to 15)
* subtitle format: advanced substation alpha (ASS)

Question: Does the Azure Media Encoding Services support encoding of the video file with the above specification to a multi-bitrate standard format, and then distributed via HLS?

Note: We have confirmed that our media player is capable of (a) switching the audio tracks (b) switching the subtitle tracks and (c) rendering the SSA subtitle files.

Answer 1

Sorry no. This is not supported scenario.

We can encode the MKV file, but require that you only have a single audio track - unless you are trying to do some form of multi channel audio mapping, in which case look at this sample for that scenario.
https://github.com/Azure-Samples/media-services-v3-dotnet/tree/main/VideoEncoding/Encoding_MultiChannel_Audio

The service does not have support for the ASS file format.

If you need to add multiple subtitle tracks, you can upload .vtt or .imsc1 side car files, but you would need to reference those in your player framework as a side-car subtitle file. Meaning, you will need some javascript logic to load them. We are working on some future features to more easily update the manifest when uploading side-car vtt or imsc1 track files for VOD delivery. That work is ongoing this semester and should be ready in Q1 of CY22.