[mythtv-users] dtv_multiplex table for US OTA ATSC

[Tom Dexter]

On 11/6/18, Devin Heitmueller <dheitmueller at kernellabs.com> wrote:
>> The one's I'm primarily curious about are the following. While these
>> have table defaults, many of my existing records accumulated over the
>> years for very similar stations vary between having NULL values, or
>> the table defaults (for example values like 'a', 'auto' etc). That
>> tends to make me suspect that these may be totally moot for US ATSC:
>>
>> inversion
>> fec
>> bandwidth
>> lp_code_rate
>> transmission_mode
>> guard_interval
>> constellation
>> hierarchy
>> hp_code_rate
>>
>> Does anyone know if any of those even matter for US ATSC?
>
> So I cannot comment on the actual database implementation in MythTV,
> but in general none of those parameters apply to ATSC/ClearQAM.  They
> are all DVB specific.  That said, inversion could be a property found
> in ATSC, but there hasn't been a demodulator made in the last 15 years
> which doesn't run in "auto" mode.  Oh, and it's possible you'll have
> to set bandwidth to 6 MHz, but for both ATSC and ClearQAM it's
> *always* 6 MHz (i.e. doesn't change by frequency).
>
> Devin
>

Thanks! Exactly what I needed to know. Here are the existing values
for those inversion and bandwidth fields in my current data (created
by various versions of MythTV):

select distinct inversion, bandwidth from dtv_multiplex;
+-----------+-----------+
| inversion | bandwidth |
+-----------+-----------+
| NULL      | NULL      |
| a         | a         |
| 0         | a         |
| 1         | a         |
+-----------+-----------+

That looks pretty arbitrary and pointless I'd say.

Thanks again!
Tom