[mythtv] DVB3.5 - removed channels won't come back

Daniel Thor Kristjansson danielk at mrl.nyu.edu
Mon Jan 10 13:25:01 EST 2005


On Mon, 10 Jan 2005, Taylor Jacob wrote:
]Have you actually seen these version numbers change that quickly?

No, but I have seen the TVCT change, while the version number remains 0.


]If the VersionChanges so does the CRC, unless you mean do a CRC on the 
]payload only..

Yes, if the version changes so does the CRC. If the CRC changes, meaning 
the TVCT changes, the version does not always change. I'd rather err on 
the side of detecting more changes to the TVCT.


]> Why have MythTV fail whenever the broadcaster reboots their equipment,
]> when you don't have to?
]The only time it would fail is is they:
]- rebooted their equipment kept the same VCT version
]- changed the payload
]This also would break all Set Top Boxes out there as well..

Not all, only the ones that trust the TVCT across sessions
without checking the CRC. This is actually the reason ATSC
gives for recommending that a broadcaster not change the 
TVCT every 5 seconds. But we can, and should, be more robust
than that.


]I also made a follow up post that was much clearer.. Sorry for shooting 
]from the hip before..

I understand the motivation. I think my initial post was a little too 
terse as well. I think we should cache the TVCT, but I don't think we 
should depend on the broadcaster never making a mistake. My experience 
with the quality of PSIP data in leads me to be very suspect of it.


-- Daniel


More information about the mythtv-dev mailing list