Talk:PC speaker sound effects

Hardcoded values

If you look at DOOM2.EXE v1.9 with a hex editor, you'll see at offset 0x89064 the beginning of a table of unsigned 16-bit LE values which correspond to the counter values.

Pos Hex pair Value 0 00 00 0 1 A2 1A 6818 2 E4 19 6628 3 31 19 6449 4 87 18 6279 5 C7 17 6087 6 12 17 5906 7 68 16 5736 8 C7 15 5575 9 2F 15 5423 10 9F 14 5279 11 00 14 5120 12 6B 13 4971 13 DE 12 4830 14 59 12 4697 15 CA 11 4554 16 53 11 4435 17 D3 10 4307 18 5A 10 4186 19 DA 0F 4058 20 6E 0F 3950 21 FC 0E 3836 22 90 0E 3728 23 1F 0E 3615 24 BF 0D 3519 25 5A 0D 3418 26 FB 0C 3323 27 98 0C 3224 28 3B 0C 3131 29 E3 0B 3043 30 90 0B 2960 31 3B 0B 2875

Pos Hex pair Value 32 EA 0A 2794 33 97 0A 2711 34 49 0A 2633 35 00 0A 2560 36 B5 09 2485 37 6F 09 2415 38 2C 09 2348 39 E9 08 2281 40 A5 08 2213 41 69 08 2153 42 29 08 2089 43 F0 07 2032 44 B7 07 1975 45 7E 07 1918 46 48 07 1864 47 12 07 1810 48 DD 06 1757 49 AD 06 1709 50 7B 06 1659 51 4C 06 1612 52 1D 06 1565 53 F1 05 1521 54 C6 05 1478 55 9B 05 1435 56 73 05 1395 57 4B 05 1355 58 24 05 1316 59 00 05 1280 60 DA 04 1242 61 B7 04 1207 62 95 04 1173 63 74 04 1140

Pos Hex pair Value 64 53 04 1107 65 33 04 1075 66 15 04 1045 67 F7 03 1015 68 DA 03 986 69 BF 03 959 70 A3 03 931 71 89 03 905 72 6F 03 879 73 56 03 854 74 3D 03 829 75 26 03 806 76 0F 03 783 77 F8 02 760 78 E3 02 739 79 CE 02 718 80 B9 02 697 81 A5 02 677 82 92 02 658 83 80 02 640 84 6D 02 621 85 5C 02 604 86 4A 02 586 87 3A 02 570 88 29 02 553 89 1A 02 538 90 0A 02 522 91 FB 01 507 92 ED 01 493 93 DF 01 479 94 D1 01 465 95 C4 01 452

Pos Hex pair Value 96 B7 01 439 97 AB 01 427 98 9F 01 415 99 93 01 403 100 87 01 391 101 7C 01 380 102 71 01 369 103 67 01 359 104 5C 01 348 105 53 01 339 106 49 01 329 107 3F 01 319 108 36 01 310 109 2E 01 302 110 25 01 293 111 1D 01 285 112 14 01 276 113 0D 01 269 114 05 01 261 115 FD 00 253 116 F6 00 246 117 EF 00 239 118 E8 00 232 119 E2 00 226 120 DB 00 219 121 D5 00 213 122 CF 00 207 123 C9 00 201 124 C3 00 195 125 BE 00 190 126 B8 00 184 127 B3 00 179

After the 128th value, there are several null bytes. This really looks like the table containing all the counter values that get programmed into the 8253 chip. This also shows that there are valid values above 95 -- the doc included with Andrew Apted & Simon Howard's specifications said that it "is not known if higher values are supported" -- I think this shows that they most certainly are. --Gez 18:40, 24 January 2014 (UTC)

The same table exists in strife1.exe v1.2 @ dseg03:0009A09C and is xref'd from a DMX subroutine at cseg01:0004BC79.Here is the code in the immediate vicinity of the access. --Quasar 07:04, 25 January 2014 (UTC)

On further research, that function is the function which does the actual output. It is invoked after setup code is run to initialize the global variables it accesses, which is in sub_4BD70. sub_4BD70 is invoked from SFX_PlayPatch when the DMX sample format byte is " < 1u" (DMX sample formats 1 and 2, which are unknown, are dispatched to sub_4C260; format 0x03, which we know to be the sound format, is dispatched to sub_48430, which I already did substantial reversing work on earlier). --Quasar 07:21, 25 January 2014 (UTC)

DMX formats 1 & 2

This is an interesting discovery by Alexey Khokholov: DMX sample formats 1 and 2 correspond to MIDI data! --Gez (talk) 13:28, 10 November 2015 (CST)

I knew at least one was considered as being for "AdLib" due to code that is present in the pre-beta, but I was never able to crack the DMX code doing the format reading for them because it devolved into a bunch of function pointer calls and a ton of data movement that I couldn't effectively trace. Interesting to have my suspicions confirmed. --Quasar (talk) 16:35, 10 November 2015 (CST)