while decoding vbi lines embedded in MPEG PS, I noticed missing packets once
in a while. After checking my own decoding routines, capturing each line
correctly, I started to debug the incoming MPEG PS stream (/dev/video); looks
like they are already missing here...
After some tests, I suspect it's in the embedding option to enable VPS:
ivtvctl -b teletext,wss -x 1 (no VPS) and
cat /dev/video |hexdump|less gives:
004A9CA0: 05 4E 84 80 07 21 84 85 F1 77 FF FF 69 74 76 30 .N...!..qw..itv0
004A9CB0: FE F7 FB DF 07 00 00 00 01 C7 B6 15 02 15 EA 2F ~w{_.....G6...j/
004A9CC0: EA 5E 02 15 EA EA EA EA 15 15 EA EA EA 2F 49 15 j^..jjjj..jjj/I.
004A9CD0: EA 2F EA EA 49 C7 EA EA EA 9B 49 C7 EA EA EA 9B j/jjIGjjj.IGjjj.
004A9CE0: EA 1D 29 01 C7 15 04 9D 97 7C 7C 20 E0 70 70 B0 j.).G....|| `pp0
004A9CF0: 68 7C 34 E0 70 70 B0 68 7C 34 20 70 70 70 20 7C h|4`pp0h|4 ppp |
004A9D00: 7C E0 70 B0 E0 70 70 B0 68 7C 34 20 20 1C 01 C7 |`p0`pp0h|4 ..G
004A9D10: EA A1 38 EA EA EA EA EA EA 24 1C 20 4E 6F 7A 65 j!8jjjjjj$. Noze
004A9D20: 6D 61 20 44 61 74 61 63 61 73 74 69 6E 67 20 20 ma Datacasting
004A9D30: 20 20 20 20 20 20 20 60 8E 01 02 02 04 9D 97 7F `........
004A9D40: 7F 34 7F 7F EF 7F EA 7F B5 7F 7F EF 7F EA 7F FD .4..o.j.5..o.j.}
004A9D50: EA 7F BF 7F B5 7F 7F EA 7F B5 7F 7F EF 7F EA 7F j.?.5..j.5..o.j.
004A9D60: FD 20 20 1C 01 C7 02 04 9D 97 7F 7F 20 7F 7F FE } ..G...... ..~
004A9D70: 7F EA 7F B5 7F 7F FE 7F EA 7F B5 EA 7F FD 7F B5 .j.5..~.j.5j.}.5
004A9D80: 7F 7F EA 7F B5 7F 7F F2 73 EA 7F B5 20 20 1C 01 ..j.5..rsj.5 ..
004A9D90: 02 49 04 9D 97 7F 7F 20 7F 7F 68 7C EA 7F B5 7F .I..... ..h|j.5.
004A9DA0: 7F 68 7C EA 7F B5 EA 7F B5 7C 34 7F 7F 6B 7C 34 .h|j.5j.5|4..k|4
004A9DB0: 7C 7C EA 7F EA 7F B5 20 20 1C 01 C7 49 04 9D 97 ||j.j.5 ..GI...
004A9DC0: EF 7F 20 EF 7F FE BF EA 7F B5 EF 7F 7F BF 2A 7F o. o.~?j.5o..?*.
004A9DD0: B5 2A 7F 7F 7F 25 7F 7F EA 7F B5 EF 7F FE BF 2A 5*...%..j.5o.~?*
004A9DE0: 7F B5 20 20 1C 01 02 5E 94 7F 75 70 7A 75 70 70 .5 ...^..upzupp
004A9DF0: 70 7F 70 70 7F 70 70 70 7F 70 70 7F 70 70 70 7A p.pp.ppp.pp.pppz
004A9E00: 75 70 7A 70 70 75 70 70 70 7F 70 70 7F 7F 7F 20 upzppuppp.pp...
004A9E10: 01 C7 5E 94 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C .G^.||||||||||||
004A9E20: 7C 7C 7C 7C 7C 7C 7C 7C 2C 2C 2C 2C 2C 2C 2C 2C ||||||||,,,,,,,,
004A9E30: 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 20 01 02 64 94 9D ,,,,,,,,,, ..d..
004A9E40: 97 B5 07 52 D5 C2 52 49 45 CB 20 20 20 49 CE C4 .5.RUBRIEK IND
004A9E50: 45 58 07 1C 9D 01 20 20 20 20 20 20 04 01 20 20 EX.... ..
004A9E60: 20 20 32 2F B3 20 01 C7 EA A1 38 EA EA EA EA EA 2/3 .Gj!8jjjjj
004A9E70: EA 25 1C 20 4E 6F 7A 65 6D 61 20 44 61 74 61 63 j%. Nozema Datac
004A9E80: 61 73 74 69 6E 67 20 20 20 20 20 20 20 20 20 06 asting .
004A9E90: E4 01 C7 64 94 9D 97 B5 07 6E E9 E5 75 F7 73 20 d.Gd...5.nieuws
004A9EA0: 31 B0 31 20 20 31 B0 32 07 1C 9D 01 46 E5 F2 6E 101 102....Fern
ivtvctl -b teletext,wss,vps -x 1 (VPS enabled) and
cat /dev/video |hexdump|less gives:
0066EB50: 07 21 8D DB CD 05 FF FF 69 74 76 30 FE F3 FB CF .!.[M...itv0~s{O
0066EB60: 07 00 00 00 01 C7 B6 15 02 15 EA 2F EA 5E 02 15 .....G6...j/j^..
0066EB70: EA EA EA EA 15 15 EA EA EA 2F 49 15 EA 2F EA EA jjjj..jjj/I.j/jj
0066EB80: 49 C7 EA EA EA 9B 49 C7 EA EA EA 9B EA 1D 29 01 IGjjj.IGjjj.j.).
0066EB90: C7 15 04 9D 97 7C 7C 20 E0 70 70 B0 68 7C 34 E0 G....|| `pp0h|4`
0066EBA0: 70 70 B0 68 7C 34 20 70 70 70 20 7C 7C E0 70 B0 pp0h|4 ppp ||`p0
0066EBB0: E0 70 70 B0 68 7C 34 20 20 1C 01 C7 EA A1 38 EA `pp0h|4 ..Gj!8j
0066EBC0: EA EA EA EA EA C2 1C 20 4E 6F 7A 65 6D 61 20 44 jjjjjB. Nozema D
0066EBD0: 61 74 61 63 61 73 74 69 6E 67 20 20 20 20 20 20 atacasting
0066EBE0: 20 20 20 D5 57 01 02 02 04 9D 97 7F 7F 34 7F 7F UW........4..
0066EBF0: EF 7F EA 7F B5 7F 7F EF 7F EA 7F FD EA 7F BF 7F o.j.5..o.j.}j.?.
0066EC00: B5 7F 7F EA 7F B5 7F 7F EF 7F EA 7F FD 20 20 1C 5..j.5..o.j.} .
0066EC10: 01 C7 02 04 9D 97 7F 7F 20 7F 7F FE 7F EA 7F B5 .G...... ..~.j.5
0066EC20: 7F 7F FE 7F EA 7F B5 EA 7F FD 7F B5 7F 7F EA 7F ..~.j.5j.}.5..j.
0066EC30: B5 7F 7F F2 73 EA 7F B5 20 20 1C 01 02 49 04 9D 5..rsj.5 ...I..
0066EC40: 97 7F 7F 20 7F 7F 68 7C EA 7F B5 7F 7F 68 7C EA ... ..h|j.5..h|j
0066EC50: 7F B5 EA 7F B5 7C 34 7F 7F 6B 7C 34 7C 7C EA 7F .5j.5|4..k|4||j.
0066EC60: EA 7F B5 20 20 1C 01 C7 49 04 9D 97 EF 7F 20 EF j.5 ..GI...o. o
0066EC70: 7F FE BF EA 7F B5 EF 7F 7F BF 2A 7F B5 2A 7F 7F .~?j.5o..?*.5*..
0066EC80: 7F 25 7F 7F EA 7F B5 EF 7F FE BF 2A 7F B5 20 20 .%..j.5o.~?*.5
0066EC90: 1C 01 02 5E 94 7F 75 70 7A 75 70 70 70 7F 70 70 ...^..upzuppp.pp
0066ECA0: 7F 70 70 70 7F 70 70 7F 70 70 70 7A 75 70 7A 70 .ppp.pp.pppzupzp
0066ECB0: 70 75 70 70 70 7F 70 70 7F 7F 7F 20 01 C7 5E 94 puppp.pp... .G^.
0066ECC0: 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C 7C ||||||||||||||||
0066ECD0: 7C 7C 7C 7C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C 2C ||||,,,,,,,,,,,,
0066ECE0: 2C 2C 2C 2C 2C 2C 20 01 C7 EA A1 38 EA EA EA EA ,,,,,, .Gj!8jjjj
0066ECF0: EA EA C3 1C 20 4E 6F 7A 65 6D 61 20 44 61 74 61 jjC. Nozema Data
0066ED00: 63 61 73 74 69 6E 67 20 20 20 20 20 20 20 20 20 casting
0066ED10: B3 3D 01 C7 64 94 9D 97 B5 07 6E E9 E5 75 F7 73 3=.Gd...5.nieuws
0066ED20: 20 31 B0 31 20 20 31 B0 32 07 1C 9D 01 46 E5 F2 101 102....Fer
Both present page 0x100 of dutch teletext. The non-VPS (upper) hexdump
contains packet 8 containing "RUBRIEK INDEX". In the VPS (lower) hexdump,
this packet/line is missing.
Is there some dependency between VPS and Teletext such that things are
overwritten/ignored?
Martin
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