Closed Captioning + ATSC3 not working

Channels DVR Server
#21

Great, you've discovered an error/bug in how Ffmpeg/Avcodec reports CCs in H.265 streams. (Maybe you can document your situation and file a bug report.) The output you posted shows 4 streams:

  1. H.265 video
  2. AC-4 English
  3. Data (most likely the TTML subtitles that Channels does not yet support)
  4. AC-4 Spanish

Just because your output shows that the stream does not contain closed captions, your experience shows it obviously does. (Also, the manner of how CCs are embedded has evolved since the beginning of digital transmission. Perhaps whichever flag that is being flipped for CCs is checking for a previous method, rather than the current method.)

In short, if you see CCs on ATSC3 feeds, they are from ATSC1–style CCs. At present, Channels does not support ATSC3 subtitles.

#22

It appears that data stream is the subtitles.

Subtitles for MPEG-DASH

The MIME type of the subtitle track listed in the MPD is application/mp4, the @contentType attribute is text, the @codecs attribute is stpp for TTML-based samples and wvtt for VTTCue samples.

From

#23

I have been Prety Lucky with ATSC 3.0 ... in my area they removed DRM on allChannels and I get Captions.

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