[linux-dvb] Re: Which CRC-code is used in TS of DVB?

[emard@softhome.net]

> Maybe the CRC check fails because some TS packets have errors?
Could be, maybe FEC doesn't correct the stream or autodetected FEC
is not the appropriate for that transponder? 
> We could add a check for the transport_error_indicator to
> dvb_dmx_swfilter_section_packet().
I'd like to have that, could be a module option to log any detected
errorneous packets, maybe accumulate errors counts and every 10-30
seconds log accumulated error count if non-zero 
> I'm not a network specialist and could be wrong here, but IIRC
> ethernet has a CRC for the full packet, but IP only has a header
> checksum. So without CRC you could silently get wrong data.
I'm occasionally seeing small network corruptions, smaller than the
missing packet, perhaps one byte is corrupted. Corrupt packets
(and as well missing ones) increase with total bandwidth the network
provider is putting into the transponder 
Note that I receive the small corruptions even with the crc enabled,
only in that case there are much more missing packets 
> Sometimes wrong data is better then no data, so maybe we should
> add a flag to NET_ADD_IF which allows one to specify if the
> CRC check is wanted. (Not that this would solve any real problems, but
> it might be nice for testing.)
This would be good and flexible option to have, even if CRC and
everything is working perfectly well 
some more observation: when I'm using the net_without_crc, then network
bandwidth reported with simple raw ts/pid scan by dvbtraffic appears
almost doubled than its actual value, 
Emard 

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