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Grazza
omg lolcano

Posts: 9587
Registered: 07-02

WARNING: Highly technical information follows. You probably don't need to study this at all unless you want to investigate this stuff. Worth a quick look to see if there are any known issues on any maps you plan to record on though. Or if you're making a "vanilla" wad and just want some tips on how to avoid triggering overflows (or at least reduce the risk of them), read the text immediately below (in yellow).

To avoid spechits overflows: Avoid a situation where you have more than 8 special lines so close together that a player or monster is able to cross them all at the same time. Remember that some monsters have a larger radius than the player.

To avoid reject overflows: Use a good reject map builder - any modern one should be OK.

To reduce the chance of intercepts overflows: Make sure that linedef 0 is very short, and perhaps out of the main area of play.

To avoid playeringame overflows: Don't obstruct your player start positions.

If you've read this thread you'll know roughly what a spechits overflow is, and that it can lead to desyncs. You may also be aware that recent versions of Prboom-plus can detect them, and attempt to emulate the behaviour of the vanilla exes and Dosdoom/Tasdoom in this respect. Chocolate-Doom also includes similar code to emulate the vanilla behaviour.

I have compiled a list of maps where spechits overflows can occur, together with some notes on their effects. I have also done so for maps with Reject overflows and demos with Intercepts overflows (which often results in the all ghosts bug). Here are the tables; some notes follow.

Table of maps for which spechits overflows are possible

pwad	map red if critical	example demo yellow if Tasdoom	lines leading to overflow	*comments on effects, desyncs and emulation in current Prboom-plus; bold* if critical**
1024	map23	2423-301.lmp	3055, 3056, 3057, 3058, 3066, 3072, 3073, 3074, 3075	behaviour depends on magic number; 2423-301.lmp is OK with the default magic number, but desyncs with the alternate (2230937832)
2sectors	map01	2s01-030.lmp	1025, 1050, 1069, 1093, 1152, 1153, 1154, 1155, 1158	benign?
aboo4 (original version)	map01	none	613, 616, 617, 619, 620, 622, 623, 625, 626	unknown - no demos to test it with
av	map05	av05-227.lmp	2265, 2266, 2269, 2270, 2281, 2284, 2305, 2306, 2309	benign?
av	map15	av15-317.lmp av15-612.lmp av15-623.lmp av15-638.lmp av15-715.lmp af151000.lmp	2098, 2106, 2109, 2110, 2097, 2104, 2105, 2108, 2111 or similar	system-dependent in Doom2.exe; emulated OK; the example demos need a magic number with prboom-plus: -spechit 2230937832 works in all cases; other compet-n demos on this map play back OK with the default magic number
av	map21	at211122.lmp	1316, 1506, 1507, 1965, 1967, 1968, 1969, 1226, 1966	benign? this is the only demo on this map with this overflow
av	map26	av261924.lmp	4131, 4132, 4133, 4140, 4141, 4142, 4143, 4144, 4145	benign? this is the only demo on this map with this overflow; it also features a benign intercepts overflow
base666	map01	btas1056.lmp	1206, 1217, 1218, 1592, 1593, 1598, 1599, 1600, 1601	benign?
belltoll	map02	none	8082, 8083, 8084, 8085, 8086, 8087, 8088, 8109, 8111	unknown - no demos to test it with
biotech	map03	none	848, 849, 850, 851, 852, 854, 853, 855, 856	unknown - no demos to test it with
biowar	map13	bw131304.lmp	1650, 1651, 1652, 1653, 1654, 1655, 1656, 1657, 1658	benign?
cchest2	map24	none	6260, 6261, 6262, 6263, 6265, 6268, 6271, 6264, 6267 and other(s)	unknown; there's more than one place where an overflow can occur - the map is full of special lines
class_e2	e1m8	none	566, 568, 572, 562, 563, 595, 596, 597, 598	unknown - no demos to test it with
darken	map08	darken08.lmp	1837, 1844, 1834, 1835, 1836, 1838, 1839, 1840, 1841	benign?
datavill (hacx pwad)	map19	none	1005, 1004, 1495, 1496, 1499, 1500, 1509, 1510, 1524	unknown - no demos to test it with
dmdhzfan	map01	none	18, 19, 20, 21, 22, 25, 48, 50, 56	unknown - this map is a tech demo; note that the fan causes the overflow
dmplylnd	e2m3	none	447, 448, 449, 450, 459, 461, 463, 465, 499	unknown - no demos to test it with
doom	e4m1	c4m1o139.lmp c4m1v139.lmp c4n1-055.lmp c4x1-055.lmp e4m1-216.lmp ep4-2207.lmp ep4-2631.lmp ep4-3500.lmp ep4-3945.lmp f4m1-243.lmp f4m1-256.lmp f4m1-426.lmp n4s1-058.lmp r4m1-137.lmp r4m1-344.lmp t4m1long.lmp u4m1-228.lmp u4m1-232.lmp e4ns1246.lmp r4m1-152.lmp r4m1-525.lmp	256, 257, 258, 262, 264, 266, 267, 268, 270 or similar	An overflow in an id map! It occurs when a spectre walks over the NIN secret; emulated OK, it seems, and can lead to desyncs: e4ns1246 desyncs without emulation (though the player exits E4M1, and dies early in E4M2), and so does r4m1-152; r4m1-525 requires -spechit 2230937832; the others listed all play back OK with or without emulation
doom2 v1.666	map02	uvlev2.lmp	117, 118, 119, 122, 123, 124, 453, 454, 455	benign? These bars were removed in v1.9; the demo can be found here
dv	map01	dv01-max-2942-wh.lmp	3461, 3526, 3536, 3609, 3655, 4420, 4568, 1472, 1946	benign?
dyst3	map08	dyst3-08.lmp	1180, 1181, 1184, 1185, 1190, 1196, 1197, 1203, 1214	benign?
eternal	map12	et122614.lmp	1350, 1355, 1356, 15, 1349, 16, 1348, 1362, 1361	benign?
eternall.wad (from eternal.zip)	map25	et252031.lmp	638, 1910, 1911, 1914, 1915, 1916, 1917, 1919, 1920	benign?
eternal	map31	et312225.lmp	2921, 2922, 2923, 2924, 2933, 2936, 2942, 2943, 2965	emulated OK; likely to lead to desyncs if not emulated
extremal	e3m8	none	271, 272, 273, 276, 277, 278, 279, 280, 281	unknown - no demos to test it with
flsofdth	e4m3	fod3uv.lmp	604, 605, 716, 717, 718, 719, 728, 729, 730	the example demo is for tasdoom, and it is emulated OK
grind2x	map01	gr2x_847.lmp	1522, 1538, 1539, 1542, 1540, 1543, 1544, 1545, 1547	a spechits magic number such as 2230937832 is needed with prboom-plus
gunsmoke	map01	none	2509, 2510, 2511, 2512, 2513, 2515, 2514, 2517, 2518	unknown - no demos to test it with; overflow can occur when running into any of the three bars, which have many blue-keyed sides
h2h-xmas	map26	xm26-313.lmp	586, 587, 588, 590, 591, 592, 594, 595, 596	benign?
hacx	map04	hx04-724.lmp	1336, 1338, 1340, 1341, 1344, 1345, 1348, 1349, 1350	benign?
hacx	map09	hx09-847.lmp	1149, 1151, 1163, 1169, 1170, 1171, 1172, 1176, 1177	benign?
hr	map18	hr18-348.lmp hr181329.lmp	1077, 1080, 1151, 1152, 1153, 1154, 1171, 1173, 1174	emulated OK (Doom2.exe and Tasdoom); likely to lead to desyncs if not emulated
hr2final	map19	hr2-lv19.lmp	169, 3068, 3081, 3087, 3088, 3089, 3096, 3097, 3098	benign?
hr2final	map31	hr2-lv31.lmp	522, 560, 561, 562, 563, 564, 565, 566, 1858	probably emulated OK; demos recorded without emulation desync if played back with emulation in the same way they do with Doom2.exe
icarus	map09	ic09uvgb.lmp ic09uv.lmp	389, 400, 434, 436, 437, 439, 440, 441, 442	benign?; ic09uv.lmp is for tasdoom and it is emulated OK
ksutra	map18	ks181235.lmp	5748, 5749, 5750, 2848, 2885, 2886, 5745, 5746, 5747	benign?
ksutra	map23	ks23-201.lmp	3099, 3100, 3101, 3104, 3105, 3106, 3107, 3108, 3109	benign?
ksutra	map31	ks311117.lmp	1892, 1893, 1895, 1897, 1898, 1899, 1900, 1901, 1904	benign?
mm	map02	mm021204.lmp	307, 965, 966, 968, 974, 975, 964, 967, 970	benign?
mm	map05	mm05r554.lmp	961, 963, 952, 953, 954, 955, 956, 957, 958	playback is presumably system-dependent with Doom2.exe; a spechits magic number such as 2230937832 is needed with prboom-plus; this demo crashes timer.exe; the overflow occurs when a pain elemental crosses the (lowered) red key bars.
mm	map08	mm08-119.lmp	714, 722, 723, 726, 733, 734, 735, 736, 738	benign?
mm	map28	30mm8356.lmp	2022, 2023, 2025, 2015, 2016, 2017, 2018, 2019, 2020	benign?
mm2	map18	m218nmx.lmp	3163, 3164, 3534, 3535, 3536, 3537, 3538, 3539, 3540	benign?
mm2	map20	m220-547.lmp	441, 507, 524, 533, 612, 613, 611, 615, 519	benign? the overflow occurs when an arachnotron (large radius) crosses these lines
ndcp	map06	none	1315, 1370, 1371, 3755, 3756, 3757, 3758, 3759, 3760	unknown
ongar	map10	none	128, 130, 131, 132, 134, 135, 122, 123, 124	unknown
pe4_dt2	e4m2	p4e2s052.lmp p4p2s118.lmp	243, 244, 245, 246, 247, 248, 249, 250, 251	p4p2s118.lmp plays back OK with or without emulation (but crashes timer.exe); p4e2s052.lmp requires, e.g., -spechit 2230937832
requiem	map03	rq03-136.lmp	1186, 1284, 1285, 1286, 1287, 1294, 1295, 1296, 1297	benign?
requiem	map15	rq151440.lmp	2000, 2004, 2010, 1976, 1981, 1982, 1983, 2014, 2018	benign?
requiem	map16	rr16-955.lmp	1115, 1116, 1117, 1119, 1122, 1123, 1124, 1125, 1118	benign?
requiem + req21fix	map21	rq21-636.lmp	2507, 2508, 2510, 2511, 2513, 2514, 2516, 2517, 2512	benign? note that the overflow occurs even with the fixed version of the map, used for recording
requiem	map31	rq31s115.lmp	317, 320, 1779, 1780, 1784, 1785, 1786, 1787, 1788	benign?
squadron	map01	sq417-01.lmp	209, 210, 211, 212, 217, 218, 219, 220, 229	benign? trivial map anyway
sci2	map03	s203n245.lmp	1262, 1263, 1264, 1265, 1266, 1268, 1267, 1269, 1270	benign?
sci2	map05	s205n546.lmp	2268, 2269, 2270, 2271, 2273, 2274, 2275, 2287, 2288	emulated OK; playback is system-dependent with Doom2.exe; a spechits magic number such as 2230937832 is needed with prboom-plus
sci2	map07	s207n516.lmp	1527, 1528, 1529, 1531, 1532, 1533, 1535, 1536, 1537	emulated OK; playback is system-dependent with Doom2.exe; a spechits magic number such as 2231485512 is needed with prboom-plus
sci2	map16	s216n241.lmp	1527, 1528, 1529, 1531, 1532, 1533, 1535, 1536, 1537	benign?
scythe	map18	sc18-sp.lmp sc18e036.lmp sc18m036.lmp	351, 352, 353, 354, 355, 360, 361, 362, 363 or 356, 357, 358, 363, 364, 365, 366, 367, 368, etc.	sc18-sp.lmp plays back OK with or without emulation; the 0:36 coop by Erik/Method needs -spechit 2230937832
scythe	map30	sc30-uv.lmp sf304509.lmp	2565, 2577, 2571, 2578, 2576, 2569, 2570, 2575, 2567	emulated OK?; can lead to desyncs if not emulated; for sf304509.lmp (an egg in the scythe demopack), a spechits magic number is needed: one that works is 2230937832
scythe2	map02	s202-207.lmp	649, 650, 651, 658, 643, 644, 645, 646, 652	emulated OK; playback is system-dependent with Doom2.exe; a spechits magic number such as 2230220160 is needed with prboom-plus
scythe2	map08	none	2202, 2203, 2206, 3053, 3054, 2200, 2208, 3055, 3056	unknown
scythe2	map10	s210-245.lmp	673, 674, 676, 681, 682, 684, 686, 687, 688	benign?; emulated OK
scythe2	map18	s218-428.lmp	1578, 1579, 1617, 1635, 1636, 1680, 1681, 1682, 1683	benign?
strain	map06	str06-uv.lmp	1736, 1786, 2333, 1737, 1738, 1785, 2334, 2336, 2332	benign?
strain	map07	st07-237.lmp	986, 998, 999, 1000, 1007, 1008, 1009, 1010, 1011	spechits overflow necessary to exit the map! emulated OK, it seems; precise behaviour depends on magic number - st07-237.lmp is OK with the default magic number, but desyncs (no exit) with the alternate (2230937832), or with Chocolate-Doom
strain	map14	st14-832.lmp	2351, 2353, 2355, 2357, 2358, 2359, 2360, 2361, 2362	benign?
tnt	map25	ep25-908.lmp	704, 705, 706, 707, 708, 893, 894, 895, 896	benign?
vesperas	map09	vesp_729.lmp	707, 713, 714, 715, 716, 717, 718, 719, 720	benign?
wotdoom3	map07	none	1117, 1122, 1129, 1108, 1109, 1110, 1115, 1120, 1106	unknown - no demos to test it with
zomheart	map01	none	1622, 1625, 1626, 1627, 1629, 1642, 1643, 1644, 1645	unknown - no demos to test it with

Table of maps with a REJECT overflow

pwad	map	example demo	size of overflow	emulation in current Prboom-plus
berserk	e1m1	berm1032.lmp and bert2740.lmp	too short (666<667)	emulation not guaranteed; both demos play back OK with or without emulation
bldnight	map05	bld51351.lmp	too short (21218<29404)	too large for emulation; the example demo desyncs
bldnight	map07	bld71232.lmp	too short (14792<14965)	too large for emulation, but the example demo plays back OK
dmonfear	map25	ydfear25.lmp	too short (2702<2888)	too large for emulation, but the example demo plays back OK (padding with zeros + attempted emulation); Donner's other dfear demos on maps with reject problems desync
flsofdth	e4m2	fod2uv.lmp	too short (2415<2416)	emulation not guaranteed (?)
hellroom	map01	hlrmp257.lmp hlrfp555.lmp	too short (84<85)	emulated; both demos play back OK without emulation too
hyena	e1m1	none	too short (325<326)	emulation not guaranteed
invasion (inva_19.zip)	e1m1	none	too short (760<761)	emulated
lwfirst (equino-x.zip)	e1m3	equ3-104.lmp	too short (21841<22050)	too large for emulation, but the desyncs in Doom.exe and Prboom-plus with emulation appear the same; another demo, equ3-114.lmp, plays back OK with or without emulation; because these demos were recorded with an older version of prboom, -pad_reject_with_ff is needed
lwfirst (equino-x.zip)	e1m7	equ7-108.lmp	too short (596<1082)	too large for emulation, but the sample demo plays back OK with or without emulation; because this demo was recorded with an older version of prboom, -pad_reject_with_ff is needed
requiem	map08	any on this map	too short (13944<13945)	emulated
requiem	map16	any on this map	too short (10224<10225)	emulated
requiem	map22	any on this map (e.g. rq22-518.lmp)	too short (10804<10805)	emulated
requiem	map31	any on this map	too short (3784<3785)	emulated
rrd201	map02	none	too short (7750<7751)	emulation not guaranteed
te	map06	none	too short (5778<5779)	emulation not guaranteed
teeth (Master Levels)	map32	teeth-32.lmp te32-106.lmp	too short (24<25)	emulated / tends to lead to a desync if not emulated
too1337	e1m1	too1-035.lmp	too short (3120<3121)	emulated; the sample demo plays back OK without emulation too
ultdtv	maps 02-07	none	all too short by one byte	emulated (?)
yaotzin	map01	yao-uv.lmp yao-750.lmp	too short (50404<51200)	too large an overflow for emulation, but yao-uv.lmp plays back OK in prboom-plus 2.4.6.2 (REJECT padded with zeroes) with or without emulation; yao-750.lmp desyncs though

Table of demos with an INTERCEPTS overflow

pwad	map	demo	outcome	emulation in current Prboom-plus
av	map08	av08-odd.lmp	"all ghosts"	emulated OK
av	map26	av261924.lmp	benign	no bad effects, it seems
blacktwr	map25	blackbug.lmp	"all ghosts" and exit	not emulated perfectly, but well enough that the player exits
doom	e1m3	n1m3bug.lmp	"all ghosts"	emulated OK; this demo is by Donatas Tamonis and can be found in his web space
doom	e1m9	e1m9-uv.lmp (dm-atm.zip)	benign	no bad effects, it seems; yes, another intercepts overflow on one of the original E1/shareware maps; this is a dht3 demo
doom2	map02	lv02-!!!.lmp (fa02-132.zip)	"all ghosts"	emulated OK
doom2	map18	ty18-bug.lmp (ty18c810.zip)	"all ghosts"	probably emulated OK, but not fully checked; this is a DANG demo
eternall.wad (from eternal.zip)	map18	wtf.lmp	"all ghosts"	emulated OK? (not fully checked); the demo is in et18-227.zip
hr	map27	hr27odd.lmp	"all ghosts"	emulated OK
hr2final	map24	h2241828.lmp	benign	no bad effects, it seems
hr2final	map32	h2323105.lmp	"all ghosts"	the demo was recorded without emulation
ksutra	map10	ks101018.lmp	benign	no bad effects, it seems
manor	map01	manorbug.lmp	"all ghosts"	emulated OK
mm	map12	mm12r406.lmp	benign	no bad effects, it seems
nuts	map01	nutsnp52.lmp	"all ghosts"	emulated OK, but with a significant slow-down
plutonia	map15	pl15-odd.lmp	"all ghosts"	emulated OK? (not fully checked); demo is in pl15-238.zip
ssbase	e1m1	ssba-heh.lmp	crash with Doom2.exe	"all ghosts" with prboom-plus, but no crash

Sorry, I haven't given hyperlinks for the wads or demos; I presume that anyone interested in this stuff will already have them or be able to find them. The idgames database, Compet-n, DSDA and this Demos Forum are the places to look. This is a useful link in this respect (replace "demoname" with the filename you're seeking):
http://www.google.com/search?q=site...m2.net+demoname

When I have described an overflow as "benign?", this means that any demos I have tested have played back OK whether the overflow is emulated or not. In some cases it is hard to judge if the overflow is being emulated correctly, as there are no demos on the map in question that play back OK with Doom2.exe.

If you are recording in Prboom-plus on any of maps where the spechits overflow is liable to cause desyncs, then if you want your demo to play back with Doom2.exe, set the program to attempt to emulate the overflow. Note that this is not guaranteed to work, and that it might not play back with Eternity (as it doesn't at present have this feature, as far as I am aware). If you record with Doom2.exe on one of these maps and the demo desyncs with Prboom-plus, try it with overflows emulated.

I'll note that so far I haven't come across an instance where Prboom-plus 2.4.8.1 is clearly unable to emulate a spechits overflow.

Obviously I haven't tested every map in existence, but as you can see I have tested a fair few, including most of the popular wads for recording. Let me know if you find any more, or can help resolve any of those listed more clearly, or if there are some obscure desynching demos that ought to be tested.

I have also added short tables of INTERCEPTS and REJECT overflows. These are based on far less testing (just ad hoc, really). There are probably quite a lot of maps with the REJECT problem, but one wouldn't expect to find many demos where there is a large overflow in any case, as they often lead to desyncs in Doom2.exe itself. Prboom+ can emulate them as long as the size of the overflow is no more than 16 bytes and the size of the REJECT lump is divisible by 4. Demos with INTERCEPTS overflows are also rare, as they sometimes result in a crash with the vanilla engine, and often in "all ghosts" behaviour, which in most cases makes it impossible to exit the map (you need to find a damage/exit sector, which most maps don't have). There also appear to be a few where the overflow is small and has no effects.

In some cases, a spechits overflow makes a demo play back differently on different systems with the vanilla exe. In these cases, you may need to get the spechits "magic number", generated by a patched "e6y" version of Doom2.exe or Doom-plus running on a system where the demo plays back OK, and enter that in the command line using the "-spechit" parameter. However, if you want to use a shortcut and just try something that has a good chance of working if the demo is an old one, or was recorded on an older OS, or with Chocolate-Doom, use this:
-spechit 2230937832
So far, all demos that have been found not to work with the default value, play back OK with this one.

Last updated: 16-March-2008

12-26-05 23:03 #

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entryway
Senior Member

Posts: 1155
Registered: 01-04

DeePsea has very good, powerful and best error checking system. It will be fine if authors will add check on an opportunity of this overflow and very badly that it not free-of-charge. I cannot use it for correction of map errors. Only for detection :(

12-26-05 23:44 #

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ultdoomer
Junior Member

Posts: 191
Registered: 06-04

How about Cameron Prosser's hf24-359.lmp? Does anyone know why that desyncs in PrBoom?

01-09-06 04:30 #

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Grazza
omg lolcano

Posts: 9587
Registered: 07-02

It's a Dosdoom (converted TasDoom) demo, and there's no spechits overflow. It plays back fine in Prboom 2.3.x and Prboom+ 2.2.6.25. Earlier versions didn't have this compatibility level, which is why they couldn't play it back successfully.

prboom hr hf24-359.lmp -complevel 5

BTW, if anyone spots any spechits overflows in any maps or demos, please let me know. If you have prboom+ 2.2.6.25 set to detect them, it displays an on-screen message if one occurs, and outputs details of the overflow into stdout.txt.

01-09-06 04:40 #

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ultdoomer
Junior Member

Posts: 191
Registered: 06-04

I tried playing hf24-359.lmp and hr181329.lmp on -complevel 5 using Andrey's latest build, but they both still desync (for me). For the Post Mortem demo, I had everything turned off on the last page of the Status Bar/HUD menu; for the Hard Attack demo, I had everything turned off except for Try To Emulate It under spechit. How do I know when to use these? Also, what do those other two at the bottom do and how do I know when to use those?

Last edited by ultdoomer on 01-09-06 at 08:33

01-09-06 08:09 #

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Grazza
omg lolcano

Posts: 9587
Registered: 07-02

spechits overflow emulation is for doom2.exe only, not for dosdoom.

The only dosdoom/tasdoom demos I've found to desync with 2.2.6.25 are the following, all with memory overflows that aren't emulated (yet?):
flsofdth.wad fod3uv.lmp - spechits overflow
hr.wad hf181430.lmp - spechits overflow
hr.wad hr181329.lmp - spechits overflow
icarus.wad ic09uv.lmp - spechits overflow
yaotzin.wad yao-uv.lmp - REJECT overflow (and too large an overflow to be emulated even for a Doom2.exe demo)

As for hf24-359.lmp, I've no idea what could be going wrong for you. You're definitely using 2.2.6.25? You've never modified hr.wad in any way? And you're using the command line as I gave in my last post? It's essential that -complevel 5 actually goes in the command line in order to override the autodetect - this should be enough on its own, with the rest of the settings all irrelevant. One last thing to try (though it shouldn't make any difference): overwrite your cfgs with the ones provided in prboom-plus-2.2.6.25.zip. If that does make a difference, say so, because it would suggest something was wrong.

As for what settings for the overflow emulation to use, personally I just have them all turned on (warn and emulate). I would only turn the warning off if I wanted to record a demo on a map where I knew there were these issues. I would only turn the emulation off in order to play back a specific demo where the emulation would itself cause a desync (there aren't many of those - hr2 map31 and scythe2 map02 are only cases I can think of; it's basically when prboom has been used to record on a map where there is a "bad" spechits overflow, as shown in bold italic in the table above).

Regarding compatibility with common mapping errors, these options are disabled for recording and playback. Their purpose is solely to make it possible in prboom+ to play maps afflicted by these errors. I have them turned off (I want to know if a map has these bugs), and would only turn them on when it's necessary in order to play a particular map (it's easier than editing the map to fix these problems...).

01-09-06 08:39 #

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entryway
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ultdoomer said:
I tried playing hf24-359.lmp and hr181329.lmp on -complevel 5 using Andrey's latest build, but they both still desync (for me).

hf24-359.zip
glboom -file hr.wad -playdemo hf24-359.lmp -complevel 5
works without decync for me

01-09-06 08:49 #

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ultdoomer
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Grazza said:
It's essential that -complevel 5 actually goes in the command line in order to override the autodetect

I just changed the number in the cfg file to 5; I didn't know you have to use the command line. The Post Mortem demo is working with the command line. Thanks.

01-09-06 08:55 #

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entryway
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Grazza said:
The only dosdoom/tasdoom demos I've found to desync with 2.2.6.25 are the following, all with memory overflows that aren't emulated (yet?)

Yes. I can't debug dos applications. Also I can't start it in WinXP :)

01-09-06 08:58 #

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Grazza
omg lolcano

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ultdoomer said:
I just changed the number in the cfg file to 5; I didn't know you have to use the command line. The Post Mortem demo is working with the command line. Thanks.

You're welcome.

The explanation is that if prboom+ doesn't find a -complevel in the command line, it will examine the header info in the demo itself, and choose its compatibility level based on what the demo appears to be (and the iwad used). In this case, it would think it is a Doom2.exe demo (-complevel 2).

Normally the autodetect of the demo type works excellently, and you wouldn't want it to be overriden by the default compatibility level that you've put in the cfg.

Andrey: Yes I expected that emulating dosdoom's overflows would be a problem (and even if somehow possible, too much work for just a handful of demos). I can't run it on XP either, but I've still got an old Win98 notebook fortunately.

01-09-06 09:08 #

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ultdoomer
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entryway said:
Yes. I can't debug dos applications. Also I can't start it in WinXP :)

I can't either, that's why I'm so happy I could view some DOSDoom/TASDoom demos with PrBoom. Thanks for all the hard work.

As far as those DOS-port demos with memory overflow problems go, would it be possible to teach someone with good DOS support how to fix those?

01-09-06 09:14 #

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Opulent
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Hate to make a post about nothing.
but that is a lot of information, Mr. G(razza) and Mr. E(ntryway).
thanks.

01-09-06 23:54 #

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Grazza
omg lolcano

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Thanks. I'm quite fond of the table myself. :) And the detection feature, of course.

From my testing, I'd say that on average about 1 in 20 maps feature a possibility of a spechits overflow. (Making the assumptions that a max demo on the map has a high probability of triggering it, and that my selection of maps/demos to test isn't for some reason skewed towards or away from maps with possible overflows.)

I'd also estimate (or rather guesstimate) that the overall proportion of maps where there is a possibility of an overflow that has any practical impact in Doom2.exe may be less than 1 in 100.

Those are rough statistical conclusions, and not scientific ones - I'm just judging from what tends to happen in practice as far as I have observed.

01-10-06 00:11 #

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Quasar
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Are you guys aware of any maps with zero-size reject lumps? DOOM would load them without crashing, but it would allocate a 32-byte block of RAM for the reject, and would then read what was effectively random data from memory. This would render any demo recorded on such a map impossible to sync, but I've never heard of this problem actually being noticed. So much so, in fact, that this bug persisted in Eternity for a long time (except it made BOOM/MBF/Eternity crash due to changes made to the zone allocator).

01-13-06 00:19 #

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Grazza
omg lolcano

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It has been noticed, especially by those who try to record a demo on such a map and find it won't play back even with the exe that was used to record it.

Fenris is an example of such a map. I've put an initial (desynching) test run I recorded here. Rebuilding the reject solved the problem - I could record as normal and the demo plays back with everything you would expect it to.

There are quite a few other examples though. Most of the maps in the original Akce Korian, for instance.

Prboom(+)'s current behaviour in such cases is to have the monsters unable to see or target the player. And prb+ displays its reject overflow message, if you have it enabled.

01-13-06 00:51 #

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entryway
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I've found it in the risen3d\R3D_WhatsNew.txt

Algo introduced to detect valid line side triggering where the radius of the player exactly matches the distance between the activating line and a blocking line which prevents the player crossing and thus activating the line trigger. The algo determines whether the line should be activated or not. E.g. STRAIN map 07 line 986 should be activated, Herian2 map03 line 17 should not.

01-17-06 23:02 #

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Grazza
omg lolcano

Posts: 9587
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Hmmm. I notice that R3D doesn't handle the identical set-up in your spechits wad correctly (the player doesn't exit). Also, if you edit STRAIN map07 so as to remove the overflow (e.g. by making enough of the relevant lines non-special), you can still exit the map in R3D.

So I wonder what this algo is really doing.

It's nice that they've made it possible to exit this map, but if it is a map-specific workaround, why not say so?

01-18-06 03:53 #

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Grazza
omg lolcano

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Updated to take into account the latest improvements in emulation, etc.

07-30-06 16:18 #

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Grazza
omg lolcano

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Magic numbers needed!

Can anyone supply the spechits magic numbers for the following demos?

Vile's h2322437.lmp on hr2.wad (that's the public beta, not the final)
Anthony Soto's av15-612.lmp on av.wad (compet-n edition)

If these demos play back correctly on your system with Doom2.exe, then you will hopefully be able to supply a valid magic number using the method and tools described here. I'd imagine Win98 users might have the best chance.

08-07-06 23:25 #

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Opulent
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why didn't somebody tell me there was a prboom-plus-2.4.4.1.test2-win32.zip version.

darn it!

Vile's h2322437.lmp -spechit 2301487060
Anthony Soto's av15-612.lmp -spechit 2358693508

edit: hmm... still doesn't work for me. I must be doing something wrong.
edit 2: oh, you got rid of the -spechit -# requirement.

/round of beers (or hopefully a better beverage) for Mr e6y!

Last edited by Opulent on 08-08-06 at 00:57

08-08-06 00:33 #

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Grazza
omg lolcano

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av15-612.lmp works fine for me with your magic number, but sadly h2322437.lmp doesn't. That may be due to other issues with that map though.

08-08-06 01:28 #

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Opulent
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doesn't work for me either.
re-ran it and it generated 2434295764
that doesn't work either.
another generated number 2415921108 untested. ;)

08-08-06 01:53 #

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entryway
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Hell Revealed 2 Beta
?

08-08-06 08:17 #

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myk
The Disciple of L�t

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Opulent said:
doesn't work for me either.

Same here, but then Doom2 desynchs. Does the demo play back using Doom2 on your machine?

another generated number 2415921108

This one failed.

In the old thread where this issue was first mentioned it seems it wasn't synching for me on this computer. Unfortunately I don't currently have access to other machines.

Vile said on that thread:
What was really weird was Casey (Altima) saying that it wouldn't play back at first, but after moving it to another directory it ran fine. Crazy, but at least it plays back sometimes..

I'm guessing Altima got a different spechit number that worked.

I tried moving it around but no luck yet.

I wonder if it wouldn't be possible to create some sort of rapid testing feature in PrBoom+ for these spechit numbers, somehow having PrBoom+ go through the demo really fast (without displaying graphics) in order to determine if the demo's sequence includes the exit event around the time where the demo is supposed to end. Like that we could search for a valid number without spending many minutes waiting to see if it synchs under PrBoom+.

entryway said:
Hell Revealed 2 Beta
?

In my case, yeah, I've been using this wad.

08-08-06 08:35 #

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entryway
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myk said:
I wonder if it wouldn't be possible to create some sort of rapid testing feature in PrBoom+ for these spechit numbers, somehow having PrBoom+ go through the demo really fast (without displaying graphics) in order to determine if the demo's sequence includes the exit event around the time where the demo is supposed to end. Like that we could search for a valid number without spending many minutes waiting to see if it synchs under PrBoom+.

glboom-plus.cfg
---------------

code:overrun_spechit_warn          0
overrun_spechit_emulate       1

glboom-plus -playdemo demo ... and press <End> key (by default), if you see the stat screen, so the demo works correctly. Also you may use somthing like this:
glboom-plus.exe -window -file hr2.wad -playdemo h2322437.lmp -skipsec 1145

Last edited by entryway on 08-08-06 at 10:53

08-08-06 10:15 #

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Opulent
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myk said:
Same here, but then Doom2 desynchs. Does the demo play back using Doom2 on your machine?

yes sir.

08-09-06 03:02 #

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myk
The Disciple of L�t

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entryway said:
press key (by default), if you see the stat screen, so the demo works correctly.

Yeah, that works, the only drawback being that if the demo is bad the screen freezes (but I can end the task).

It seems, though, that for now any further testing would be in vain, as on Doug's machine the numbers that fail under PrBoom+ work under Doom2.

08-09-06 04:00 #

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entryway
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myk said:
Yeah, that works, the only drawback being that if the demo is bad the screen freezes (but I can end the task).

No. It will quit after ending

08-09-06 09:03 #

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entryway
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myk said:
It seems, though, that for now any further testing would be in vain, as on Doug's machine the numbers that fail under PrBoom+ work under Doom2.

Sounds strange...

08-09-06 14:24 #

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myk
The Disciple of L�t

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entryway said:
Sounds strange...

Yeah. I could keep trying later if it could help. Any hints on how to somehow get different spechit numbers that might work? Is that even possible on a single machine?

I even tried going to full DOS, but Doom+ starting the demo crashed; not sure why, but it said something weird, that there was an unknown thing 32007 (or so) then DOS got monged up (all the dirs and were messed up) and I had to restart. Maybe some sort of memory overflow killed it.

Have you thought about trying to make a hack of PrBoom+ that tries different spechit numbers until it spots one that works? (Kind of like a password hacking app, I mean).

08-09-06 14:48 #