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

Daniel Thor Kristjansson danielk at mrl.nyu.edu
Mon Jan 10 12:54:07 EST 2005


On Mon, 10 Jan 2005, Taylor Jacob wrote:

]Quoting Daniel Thor Kristjansson <danielk at mrl.nyu.edu>:
]> This is a bug for ATSC. The version number is a 4 bit number you should
]> not expect it to be accurate after you close and reopen the stream.
]
]Why are the verison numbers not valid for you?  The only place I have 
]seen the versions change in the last 2 months is my PBS station which 
]they have verified that their PSIP is screwed up.. (Version changes 
]every 5 seconds)..  The reason the version number is there is NOT for 
]speeding up guide insertion but not having to hit the DB more than once 
]and validate the program ID, names, etc of each channel unless the 
]version DID change.. If the ServiceVersion is removed from 
]dtv_multiplex then everytime you change channels it will re-hit the 
]database and do about 10-20 queries.. I don't follow your logic..  If 
]you were flipping around with LiveTV you would be hitting the database 
]a good deal when the VersionNumber will let you know if you need to or 
]not..

Broadcasters are only encouraged to not change the TVCT too often, 
they not required to. A 4 bit number will roll over too quickly to 
depend on it. You can achieve the goal of not hitting the database too 
often by storing the PSIP CRC instead, at the cost of storing a 4 byte 
number instead of a 4 bit number in the database.

Why have MythTV fail whenever the broadcaster reboots their equipment, 
when you don't have to?

-- Daniel


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