[mythtv] DVB, HD-2000, and CRCs

[Daniel Thor Kristjansson]

]> Then explain to me how I'm seeing log entries like this:
]> Title [4001][003B] = Lixe With Rewis and Kel,y\uffff\uffff         Mon
]> Mar 21 09:00:00 2005 - Mon Mar 21 10:00:00 2005
]Probbably the errors are slipping past CRC32.. There isn't any validation on the
]ATSC tables like there is for the DVB ones in my code yet.. If the guide on
]those shows is huffman compressed then its even more likely you will get worse
]results by 1 bit being off.. I need to write some more robust table validation

CRC-32 is robust against 1 bit errors, and should be robust against 
multiple bit errors caused by random error sources. I'm actually 
surprised that the driver is doing CRC checks, since you have to 
assemble an entire PES Packet to check the CRC (i.e. you need about 
2.5 MB of buffers for 20 streams). With the pcHDTV drivers I only 
bothered to do this for PSIP tables.

BTW you can tell ffmpeg to check the PES Packet CRC's on playback, but 
we're not currently doing this.

-- Daniel