[mythtv] HDHomeRun lineup.json for ATSC

Scott T scott.the.elm at gmail.com
Mon Sep 27 21:46:59 UTC 2021

On 9/27/21 2:07 PM, Nick Kelsey wrote:
> Full mux is useful for obtaining a capture on one tuner however 
> generally shouldn't be used for an end user application like mythtv 
> where all tuners may be used at once and bandwidth could be much 
> higher than 8VSB. For CableCARD and ATSC 3.0 full mux isn't an option 
> as the HDHomeRun has to be involved in the tuning/filtering process.
> Happy to help with any protocol questions. 

Could you clarify what devices, if not all, support the HTTP API?

When using the HTTP API, if there are multiple digital subchannels on 
one RF channel, would tuning to two different subchannels use one 
tuner?  e.g.


Or would you have to specify the tuner (for the second or both)? I know 
this may require two tuners for some ATSC 3.0 broadcasts.

I know the full mux is not possible when:

  * decrypting with a CableCARD (only one stream can be decrypted per tuner)
  * using the hardware transcoder of the "Extend" models (can only
    process one stream per tuner)
  * ATSC 3.0 (because the differing modulations of the Physical Layer
    Pipes are not necessarily all mutually compatible simultaneously on
    one tuner)

The total data rate is not of concern for ATSC 1 (8VSB) broadcasts 
(19.39 × 4 < 100), but may be for other quad tuners (RF channels wider 
than the US's 6 MHz, other modulation types) or ATSC 3.0 (theoretically 
a max 6 MHz channel capacity of 57 Mbps, but it remains to be seen what 
broadcasters actually use).



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