On 14/06/16 19:31, Nick Whitehead wrote:
I've just started to use this to recover EIT information from the
transmitted stream (UK, freeview).
I've managed to get the tables OK, but the EIT name / description for
all HD channels is scrambled. Some research indicates these are
huffman encoded for an unclear reason.
Given the right tables, it should be possible therefore to decode them
when they appear in the linked list of descriptors in each event.
However, it appears that dvb_parse_string() called all the way down
from dvb_read_sections() converts the character sets name /
description strings so that they can no longer be decoded. If huffman
encoded, I think the first character of each is a 0x1f, followed by a
0x01 or 0x02 which probably indicates the table to use.
It seems to me therefore that the 0x1f needs to be picked up in the
switch (*src) {} at line 395 in parse_string.c, and huffman decode
done there. After the return from dvb_parse_string(), and certainly
when they appear in the EIT table, it's too late.
I am not sure if I'm right about all this as I know very little about
DVB. However it looks like that to me. Have I got this right or is
already successfully handled somewhere I haven't realised?
FYI mythtv decodes the EIT successfully so is probably a good place to
start looking. The original patch to add it in is here:
https://svn.mythtv.org/trac/attachment/ticket/5365/freesat_epg.diff
AFAIK Freeview HD is done the same way as Freesat.
Jemma.
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