[linux-dvb] a strange EIT Section

Johannes Stezenbach js at linuxtv.org
Tue Jun 21 13:36:09 CEST 2005


Patrick Boettcher wrote:
> I'm playing around with a si-parser and encountered a strangeness.
> 
> I supposed when using the section-demux-API and providing a large enough 
> buffer for reading, I always get a complete (valid?) section. Indeed, this 
> works most of the time. The following example is a section I received 
> yesterday:
> 
> The first 8 bytes of the table header:
> 
> 68 61 6E 20  68 65 69 72		han  heir
> 
> obviously trash, it is part of the section maybe... the binary data goes 
> on: "aten wo.lgn, macht di. Sache ni.ht besser"
> 
> and what the parser made of it:
> 
>   table_id = 68 104      (is a valid EIT table_id, but not on PID 0x12?)
>   section_syntax_indicator = 0 0

invalid -> drop it

>   reserved_future_use0 = 1 1
>   reserved0 = 2 2
>   section_length = 16e 366 (valid, the packet is 369 bytes)
>   service_id = 2068 8296
>   reserved1 = 1 1
> 
> Who should take card about such problems? The parser or the section-dmx of 
> the DVB API?

IIRC the DMX_CHECK_CRC flag only checks it the CRC if the
section_syntax_indicator == 1. If you receive a section with
a broken section_syntax_indicator the check is not performed
and you must drop it. EN 300 468 specifies that ssi must be
set in the EIT.

Johannes




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