Change of behavior in AudioCVT & SDL_ConvertAudio from 2.0.5 to 2.0.6

Cobrand · July 8, 2018, 12:16pm

Hi guys,

I’m Cobrand, the current maintainer of the Rust-lang bindings for SDL2. Recently we’ve discovered that by upgrading SDL2 from 2.0.5 to 2.0.6, our test suite fails because the behavior of the SDL2 lib changed.

I just wanted to report the changes we’ve noticed for you to confirm whether or not this looks like a bug/regression. Note that this still happens with the stable version of 2.0.8

The Operating System doesn’t seem to be a factor, although I can say for 100% sure this “regression” happens on linux x86_64.

Here is the sample:

// compile with: gcc main.c -o app -lSDL2
// run with: ./app
#include <SDL2/SDL.h>
#include <stdio.h>

int test_audio_stuff() {
    SDL_AudioCVT cvt;
    SDL_BuildAudioCVT(&cvt, AUDIO_U8, 1, 48000, AUDIO_U8, 2, 48000);
    SDL_assert(cvt.needed); // obviously, this one is always needed.
    cvt.len = 256; // 256 mono u8 frames.
    cvt.buf = (Uint8 *) SDL_malloc(cvt.len * cvt.len_mult);

    for (int i = 0; i < 256; i++) {
        cvt.buf[i] = i;
    }
    SDL_ConvertAudio(&cvt);
    printf("Converted buffer has size of %d\n", cvt.len_cvt); 
    for (int i = 0; i < cvt.len_cvt; i++) {
        printf("%02d ", cvt.buf[i]);
    }
    printf("\n");

    printf("expected buffer:\n");
    for (int i = 0; i < cvt.len_cvt; i++) {
        printf("%02d ", i / 2);
    }
    printf("\n");
}

int main(int argc, char* args[]) {
    test_audio_stuff();
    return 0;
}

(My C is rusty, sorry about that)

This example has the simple goal to convert a U8-mono stream into a U8-stereo stream. Simple, right?

If the original stream goes like [0 1 2 3 4 5 6 7] we expect to see [0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7], right? Each byte gets simply duplicated once. Our test suite did exactly that but with 255 values: https://github.com/Rust-SDL2/rust-sdl2/blob/07723632dfa7a019ab4d3e153dc9b808337460fd/src/sdl2/audio.rs#L819-L835

However, it failed (the code above is the equivalent in C), here is what it outputs:

Converted buffer has size of 512
00 00 01 01 02 02 03 03 04 04 05 05 06 06 07 07 08 08 09 09 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 24 25 25 26 26 27 27 28 28 29 29 30 30 31 31 32 32 33 33 3434 35 35 36 36 37 37 38 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 51 51 52 52 53 53 54 54 55 55 56 56 57 57 58 58 59 59 60 60 61 61 62 62 63 63 64 64 64 64 65 65 66 66 67 6768 68 69 69 70 70 71 71 72 72 73 73 74 74 75 75 76 76 77 77 78 78 79 79 80 80 81 81 82 82 83 83 84 84 85 85 86 86 87 87 88 88 89 89 90 90 91 91 92 92 93 93 94 94 95 95 96 96 97 97 98 98 99 99 100 100 101 101 102 102 103 103 104 104 105 105 106 106 107 107 108 108 109 109 110 110 111 111 112 112 113 113 114 114 115 115 116 116 117 117 118 118 119 119 120 120 121 121 122 122 123 123 124 124 125 125 126 126 127 127 128 128 129 129 130 130 131 131 132 132 133 133 134 134 135 135 136 136 137 137 138 138 139 139 140 140 141 141 142 142 143 143 144 144 145 145 146 146 147 147 148 148 149 149 150 150 151 151 152 152 153 153 154 154 155 155 156 156 157 157 158 158 159 159 160 160 161 161 162 162 163 163 164 164 165 165 166 166 167 167 168 168 169 169 170 170 171 171 172 172 173 173 174 174 175 175 176 176 177 177 178 178 179179 180 180 181 181 182 182 183 183 184 184 185 185 186 186 187 187 188 188 189 189 190 190 190 190 191 191 192 192 193 193 194 194 195 195 196 196 197 197 198 198 199 199 200 200 201 201 202 202 203 203 204 204 205 205 206 206 207 207 208 208 209 209 210 210 211 211 212 212 213 213 214 214 215 215 216 216 217 217 218 218 219 219 220 220 221 221 222 222 223 223 224 224 225 225 226 226 227 227 228 228 229 229 230 230 231 231 232 232 233 233 234 234 235 235 236 236 237 237 238 238 239 239 240 240 241 241 242 242 243 243 244 244 245 245 246 246 247 247 248 248 249 249 250 250 251 251 252 252 253 253
expected buffer:
00 00 01 01 02 02 03 03 04 04 05 05 06 06 07 07 08 08 09 09 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 24 25 25 26 26 27 27 28 28 29 29 30 30 31 31 32 32 33 33 3434 35 35 36 36 37 37 38 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 51 51 52 52 53 53 54 54 55 55 56 56 57 57 58 58 59 59 60 60 61 61 62 62 63 63 64 64 65 65 66 66 67 67 68 6869 69 70 70 71 71 72 72 73 73 74 74 75 75 76 76 77 77 78 78 79 79 80 80 81 81 82 82 83 83 84 84 85 85 86 86 87 87 88 88 89 89 90 90 91 91 92 92 93 93 94 94 95 95 96 96 97 97 98 98 99 99 100 100 101 101 102 102 103 103 104 104 105 105 106 106 107 107 108 108 109 109 110 110 111 111 112 112 113 113 114 114 115 115 116 116 117 117 118 118 119 119 120 120 121 121 122 122 123 123 124 124 125 125 126 126 127 127 128128 129 129 130 130 131 131 132 132 133 133 134 134 135 135 136 136 137 137 138 138 139 139 140 140 141 141 142 142 143 143 144 144 145 145 146 146 147 147 148 148 149 149 150 150 151 151 152 152 153 153 154 154 155 155 156 156 157 157 158 158 159 159 160 160 161 161 162 162 163 163 164 164 165 165 166 166 167 167 168 168 169 169 170 170 171 171 172 172 173 173 174 174 175 175 176 176 177 177 178 178 179 179 180 180 181 181 182 182 183 183 184 184 185 185 186 186 187 187 188 188 189 189 190 190 191 191 192 192 193 193 194 194 195 195 196 196 197 197 198 198 199 199 200 200 201 201 202 202 203 203 204 204 205 205 206 206 207 207 208 208 209 209 210 210 211 211 212 212 213 213 214 214 215 215 216 216 217 217 218 218 219 219 220 220 221 221 222 222 223 223 224 224 225 225 226 226 227 227 228 228 229 229 230 230 231 231232 232 233 233 234 234 235 235 236 236 237 237 238 238 239 239 240 240 241 241 242 242 243 243 244 244 245 245 246 246 247 247 248 248 249 249 250 250 251 251 252 252 253 253 254 254 255 255

It’s quite hard to catch but in the first result the bytes “64” and “190” are duplicated one too many times each (being there 4 times instead of 2 times). As a result, we can see the buffers ends with 253 253 instead of 255 255.

This looks like nothing but I suspect this may cause very slight audio glitches that I think can be noticeable (since we have this issue 2 times for 256 bytes, we can only assume it’s going to be much worse for a buffer of a whole second or 48000 bytes…)

I’m almost certain this is a bug, but please feel free to correct me if I’m wrong in any way

automaciej · January 5, 2024, 9:07am

I just spent a bit of time on this, and I can still reproduce it. I’m using SDL 2.26.5 from Debian. I’m writing a unit test in C++ and using googlemock to generate detailed error messages. Here’s what I’m getting:

Value of: got
Expected: has 512 elements where
element #0 is equal to '\0',
element #1 is equal to '\0',
element #2 is equal to '\x1' (1),
element #3 is equal to '\x1' (1),
element #4 is equal to '\x2' (2),
element #5 is equal to '\x2' (2),
element #6 is equal to '\x3' (3),
element #7 is equal to '\x3' (3),
element #8 is equal to '\x4' (4),
element #9 is equal to '\x4' (4),
element #10 is equal to '\x5' (5),
element #11 is equal to '\x5' (5),
element #12 is equal to '\x6' (6),
element #13 is equal to '\x6' (6),
element #14 is equal to '\a' (7),
element #15 is equal to '\a' (7),
element #16 is equal to '\b' (8),
element #17 is equal to '\b' (8),
element #18 is equal to '\t' (9),
element #19 is equal to '\t' (9),
element #20 is equal to '\n' (10, 0xA),
element #21 is equal to '\n' (10, 0xA),
element #22 is equal to '\v' (11, 0xB),
element #23 is equal to '\v' (11, 0xB),
element #24 is equal to '\f' (12, 0xC),
element #25 is equal to '\f' (12, 0xC),
element #26 is equal to '\r' (13, 0xD),
element #27 is equal to '\r' (13, 0xD),
element #28 is equal to '\xE' (14),
element #29 is equal to '\xE' (14),
element #30 is equal to '\xF' (15),
element #31 is equal to '\xF' (15),
element #32 is equal to '\x10' (16),
element #33 is equal to '\x10' (16),
element #34 is equal to '\x11' (17),
element #35 is equal to '\x11' (17),
element #36 is equal to '\x12' (18),
element #37 is equal to '\x12' (18),
element #38 is equal to '\x13' (19),
element #39 is equal to '\x13' (19),
element #40 is equal to '\x14' (20),
element #41 is equal to '\x14' (20),
element #42 is equal to '\x15' (21),
element #43 is equal to '\x15' (21),
element #44 is equal to '\x16' (22),
element #45 is equal to '\x16' (22),
element #46 is equal to '\x17' (23),
element #47 is equal to '\x17' (23),
element #48 is equal to '\x18' (24),
element #49 is equal to '\x18' (24),
element #50 is equal to '\x19' (25),
element #51 is equal to '\x19' (25),
element #52 is equal to '\x1A' (26),
element #53 is equal to '\x1A' (26),
element #54 is equal to '\x1B' (27),
element #55 is equal to '\x1B' (27),
element #56 is equal to '\x1C' (28),
element #57 is equal to '\x1C' (28),
element #58 is equal to '\x1D' (29),
element #59 is equal to '\x1D' (29),
element #60 is equal to '\x1E' (30),
element #61 is equal to '\x1E' (30),
element #62 is equal to '\x1F' (31),
element #63 is equal to '\x1F' (31),
element #64 is equal to ' ' (32, 0x20),
element #65 is equal to ' ' (32, 0x20),
element #66 is equal to '!' (33, 0x21),
element #67 is equal to '!' (33, 0x21),
element #68 is equal to '"' (34, 0x22),
element #69 is equal to '"' (34, 0x22),
element #70 is equal to '#' (35, 0x23),
element #71 is equal to '#' (35, 0x23),
element #72 is equal to '$' (36, 0x24),
element #73 is equal to '$' (36, 0x24),
element #74 is equal to '%' (37, 0x25),
element #75 is equal to '%' (37, 0x25),
element #76 is equal to '&' (38, 0x26),
element #77 is equal to '&' (38, 0x26),
element #78 is equal to '\'' (39, 0x27),
element #79 is equal to '\'' (39, 0x27),
element #80 is equal to '(' (40, 0x28),
element #81 is equal to '(' (40, 0x28),
element #82 is equal to ')' (41, 0x29),
element #83 is equal to ')' (41, 0x29),
element #84 is equal to '*' (42, 0x2A),
element #85 is equal to '*' (42, 0x2A),
element #86 is equal to '+' (43, 0x2B),
element #87 is equal to '+' (43, 0x2B),
element #88 is equal to ',' (44, 0x2C),
element #89 is equal to ',' (44, 0x2C),
element #90 is equal to '-' (45, 0x2D),
element #91 is equal to '-' (45, 0x2D),
element #92 is equal to '.' (46, 0x2E),
element #93 is equal to '.' (46, 0x2E),
element #94 is equal to '/' (47, 0x2F),
element #95 is equal to '/' (47, 0x2F),
element #96 is equal to '0' (48, 0x30),
element #97 is equal to '0' (48, 0x30),
element #98 is equal to '1' (49, 0x31),
element #99 is equal to '1' (49, 0x31),
element #100 is equal to '2' (50, 0x32),
element #101 is equal to '2' (50, 0x32),
element #102 is equal to '3' (51, 0x33),
element #103 is equal to '3' (51, 0x33),
element #104 is equal to '4' (52, 0x34),
element #105 is equal to '4' (52, 0x34),
element #106 is equal to '5' (53, 0x35),
element #107 is equal to '5' (53, 0x35),
element #108 is equal to '6' (54, 0x36),
element #109 is equal to '6' (54, 0x36),
element #110 is equal to '7' (55, 0x37),
element #111 is equal to '7' (55, 0x37),
element #112 is equal to '8' (56, 0x38),
element #113 is equal to '8' (56, 0x38),
element #114 is equal to '9' (57, 0x39),
element #115 is equal to '9' (57, 0x39),
element #116 is equal to ':' (58, 0x3A),
element #117 is equal to ':' (58, 0x3A),
element #118 is equal to ';' (59, 0x3B),
element #119 is equal to ';' (59, 0x3B),
element #120 is equal to '<' (60, 0x3C),
element #121 is equal to '<' (60, 0x3C),
element #122 is equal to '=' (61, 0x3D),
element #123 is equal to '=' (61, 0x3D),
element #124 is equal to '>' (62, 0x3E),
element #125 is equal to '>' (62, 0x3E),
element #126 is equal to '?' (63, 0x3F),
element #127 is equal to '?' (63, 0x3F),
element #128 is equal to '@' (64, 0x40),
element #129 is equal to '@' (64, 0x40),
element #130 is equal to 'A' (65, 0x41),
element #131 is equal to 'A' (65, 0x41),
element #132 is equal to 'B' (66, 0x42),
element #133 is equal to 'B' (66, 0x42),
element #134 is equal to 'C' (67, 0x43),
element #135 is equal to 'C' (67, 0x43),
element #136 is equal to 'D' (68, 0x44),
element #137 is equal to 'D' (68, 0x44),
element #138 is equal to 'E' (69, 0x45),
element #139 is equal to 'E' (69, 0x45),
element #140 is equal to 'F' (70, 0x46),
element #141 is equal to 'F' (70, 0x46),
element #142 is equal to 'G' (71, 0x47),
element #143 is equal to 'G' (71, 0x47),
element #144 is equal to 'H' (72, 0x48),
element #145 is equal to 'H' (72, 0x48),
element #146 is equal to 'I' (73, 0x49),
element #147 is equal to 'I' (73, 0x49),
element #148 is equal to 'J' (74, 0x4A),
element #149 is equal to 'J' (74, 0x4A),
element #150 is equal to 'K' (75, 0x4B),
element #151 is equal to 'K' (75, 0x4B),
element #152 is equal to 'L' (76, 0x4C),
element #153 is equal to 'L' (76, 0x4C),
element #154 is equal to 'M' (77, 0x4D),
element #155 is equal to 'M' (77, 0x4D),
element #156 is equal to 'N' (78, 0x4E),
element #157 is equal to 'N' (78, 0x4E),
element #158 is equal to 'O' (79, 0x4F),
element #159 is equal to 'O' (79, 0x4F),
element #160 is equal to 'P' (80, 0x50),
element #161 is equal to 'P' (80, 0x50),
element #162 is equal to 'Q' (81, 0x51),
element #163 is equal to 'Q' (81, 0x51),
element #164 is equal to 'R' (82, 0x52),
element #165 is equal to 'R' (82, 0x52),
element #166 is equal to 'S' (83, 0x53),
element #167 is equal to 'S' (83, 0x53),
element #168 is equal to 'T' (84, 0x54),
element #169 is equal to 'T' (84, 0x54),
element #170 is equal to 'U' (85, 0x55),
element #171 is equal to 'U' (85, 0x55),
element #172 is equal to 'V' (86, 0x56),
element #173 is equal to 'V' (86, 0x56),
element #174 is equal to 'W' (87, 0x57),
element #175 is equal to 'W' (87, 0x57),
element #176 is equal to 'X' (88, 0x58),
element #177 is equal to 'X' (88, 0x58),
element #178 is equal to 'Y' (89, 0x59),
element #179 is equal to 'Y' (89, 0x59),
element #180 is equal to 'Z' (90, 0x5A),
element #181 is equal to 'Z' (90, 0x5A),
element #182 is equal to '[' (91, 0x5B),
element #183 is equal to '[' (91, 0x5B),
element #184 is equal to '\\' (92, 0x5C),
element #185 is equal to '\\' (92, 0x5C),
element #186 is equal to ']' (93, 0x5D),
element #187 is equal to ']' (93, 0x5D),
element #188 is equal to '^' (94, 0x5E),
element #189 is equal to '^' (94, 0x5E),
element #190 is equal to '_' (95, 0x5F),
element #191 is equal to '_' (95, 0x5F),
element #192 is equal to '`' (96, 0x60),
element #193 is equal to '`' (96, 0x60),
element #194 is equal to 'a' (97, 0x61),
element #195 is equal to 'a' (97, 0x61),
element #196 is equal to 'b' (98, 0x62),
element #197 is equal to 'b' (98, 0x62),
element #198 is equal to 'c' (99, 0x63),
element #199 is equal to 'c' (99, 0x63),
element #200 is equal to 'd' (100, 0x64),
element #201 is equal to 'd' (100, 0x64),
element #202 is equal to 'e' (101, 0x65),
element #203 is equal to 'e' (101, 0x65),
element #204 is equal to 'f' (102, 0x66),
element #205 is equal to 'f' (102, 0x66),
element #206 is equal to 'g' (103, 0x67),
element #207 is equal to 'g' (103, 0x67),
element #208 is equal to 'h' (104, 0x68),
element #209 is equal to 'h' (104, 0x68),
element #210 is equal to 'i' (105, 0x69),
element #211 is equal to 'i' (105, 0x69),
element #212 is equal to 'j' (106, 0x6A),
element #213 is equal to 'j' (106, 0x6A),
element #214 is equal to 'k' (107, 0x6B),
element #215 is equal to 'k' (107, 0x6B),
element #216 is equal to 'l' (108, 0x6C),
element #217 is equal to 'l' (108, 0x6C),
element #218 is equal to 'm' (109, 0x6D),
element #219 is equal to 'm' (109, 0x6D),
element #220 is equal to 'n' (110, 0x6E),
element #221 is equal to 'n' (110, 0x6E),
element #222 is equal to 'o' (111, 0x6F),
element #223 is equal to 'o' (111, 0x6F),
element #224 is equal to 'p' (112, 0x70),
element #225 is equal to 'p' (112, 0x70),
element #226 is equal to 'q' (113, 0x71),
element #227 is equal to 'q' (113, 0x71),
element #228 is equal to 'r' (114, 0x72),
element #229 is equal to 'r' (114, 0x72),
element #230 is equal to 's' (115, 0x73),
element #231 is equal to 's' (115, 0x73),
element #232 is equal to 't' (116, 0x74),
element #233 is equal to 't' (116, 0x74),
element #234 is equal to 'u' (117, 0x75),
element #235 is equal to 'u' (117, 0x75),
element #236 is equal to 'v' (118, 0x76),
element #237 is equal to 'v' (118, 0x76),
element #238 is equal to 'w' (119, 0x77),
element #239 is equal to 'w' (119, 0x77),
element #240 is equal to 'x' (120, 0x78),
element #241 is equal to 'x' (120, 0x78),
element #242 is equal to 'y' (121, 0x79),
element #243 is equal to 'y' (121, 0x79),
element #244 is equal to 'z' (122, 0x7A),
element #245 is equal to 'z' (122, 0x7A),
element #246 is equal to '{' (123, 0x7B),
element #247 is equal to '{' (123, 0x7B),
element #248 is equal to '|' (124, 0x7C),
element #249 is equal to '|' (124, 0x7C),
element #250 is equal to '}' (125, 0x7D),
element #251 is equal to '}' (125, 0x7D),
element #252 is equal to '~' (126, 0x7E),
element #253 is equal to '~' (126, 0x7E),
element #254 is equal to '\x7F' (127),
element #255 is equal to '\x7F' (127),
element #256 is equal to '\x80' (128),
element #257 is equal to '\x80' (128),
element #258 is equal to '\x81' (129),
element #259 is equal to '\x81' (129),
element #260 is equal to '\x82' (130),
element #261 is equal to '\x82' (130),
element #262 is equal to '\x83' (131),
element #263 is equal to '\x83' (131),
element #264 is equal to '\x84' (132),
element #265 is equal to '\x84' (132),
element #266 is equal to '\x85' (133),
element #267 is equal to '\x85' (133),
element #268 is equal to '\x86' (134),
element #269 is equal to '\x86' (134),
element #270 is equal to '\x87' (135),
element #271 is equal to '\x87' (135),
element #272 is equal to '\x88' (136),
element #273 is equal to '\x88' (136),
element #274 is equal to '\x89' (137),
element #275 is equal to '\x89' (137),
element #276 is equal to '\x8A' (138),
element #277 is equal to '\x8A' (138),
element #278 is equal to '\x8B' (139),
element #279 is equal to '\x8B' (139),
element #280 is equal to '\x8C' (140),
element #281 is equal to '\x8C' (140),
element #282 is equal to '\x8D' (141),
element #283 is equal to '\x8D' (141),
element #284 is equal to '\x8E' (142),
element #285 is equal to '\x8E' (142),
element #286 is equal to '\x8F' (143),
element #287 is equal to '\x8F' (143),
element #288 is equal to '\x90' (144),
element #289 is equal to '\x90' (144),
element #290 is equal to '\x91' (145),
element #291 is equal to '\x91' (145),
element #292 is equal to '\x92' (146),
element #293 is equal to '\x92' (146),
element #294 is equal to '\x93' (147),
element #295 is equal to '\x93' (147),
element #296 is equal to '\x94' (148),
element #297 is equal to '\x94' (148),
element #298 is equal to '\x95' (149),
element #299 is equal to '\x95' (149),
element #300 is equal to '\x96' (150),
element #301 is equal to '\x96' (150),
element #302 is equal to '\x97' (151),
element #303 is equal to '\x97' (151),
element #304 is equal to '\x98' (152),
element #305 is equal to '\x98' (152),
element #306 is equal to '\x99' (153),
element #307 is equal to '\x99' (153),
element #308 is equal to '\x9A' (154),
element #309 is equal to '\x9A' (154),
element #310 is equal to '\x9B' (155),
element #311 is equal to '\x9B' (155),
element #312 is equal to '\x9C' (156),
element #313 is equal to '\x9C' (156),
element #314 is equal to '\x9D' (157),
element #315 is equal to '\x9D' (157),
element #316 is equal to '\x9E' (158),
element #317 is equal to '\x9E' (158),
element #318 is equal to '\x9F' (159),
element #319 is equal to '\x9F' (159),
element #320 is equal to '\xA0' (160),
element #321 is equal to '\xA0' (160),
element #322 is equal to '\xA1' (161),
element #323 is equal to '\xA1' (161),
element #324 is equal to '\xA2' (162),
element #325 is equal to '\xA2' (162),
element #326 is equal to '\xA3' (163),
element #327 is equal to '\xA3' (163),
element #328 is equal to '\xA4' (164),
element #329 is equal to '\xA4' (164),
element #330 is equal to '\xA5' (165),
element #331 is equal to '\xA5' (165),
element #332 is equal to '\xA6' (166),
element #333 is equal to '\xA6' (166),
element #334 is equal to '\xA7' (167),
element #335 is equal to '\xA7' (167),
element #336 is equal to '\xA8' (168),
element #337 is equal to '\xA8' (168),
element #338 is equal to '\xA9' (169),
element #339 is equal to '\xA9' (169),
element #340 is equal to '\xAA' (170),
element #341 is equal to '\xAA' (170),
element #342 is equal to '\xAB' (171),
element #343 is equal to '\xAB' (171),
element #344 is equal to '\xAC' (172),
element #345 is equal to '\xAC' (172),
element #346 is equal to '\xAD' (173),
element #347 is equal to '\xAD' (173),
element #348 is equal to '\xAE' (174),
element #349 is equal to '\xAE' (174),
element #350 is equal to '\xAF' (175),
element #351 is equal to '\xAF' (175),
element #352 is equal to '\xB0' (176),
element #353 is equal to '\xB0' (176),
element #354 is equal to '\xB1' (177),
element #355 is equal to '\xB1' (177),
element #356 is equal to '\xB2' (178),
element #357 is equal to '\xB2' (178),
element #358 is equal to '\xB3' (179),
element #359 is equal to '\xB3' (179),
element #360 is equal to '\xB4' (180),
element #361 is equal to '\xB4' (180),
element #362 is equal to '\xB5' (181),
element #363 is equal to '\xB5' (181),
element #364 is equal to '\xB6' (182),
element #365 is equal to '\xB6' (182),
element #366 is equal to '\xB7' (183),
element #367 is equal to '\xB7' (183),
element #368 is equal to '\xB8' (184),
element #369 is equal to '\xB8' (184),
element #370 is equal to '\xB9' (185),
element #371 is equal to '\xB9' (185),
element #372 is equal to '\xBA' (186),
element #373 is equal to '\xBA' (186),
element #374 is equal to '\xBB' (187),
element #375 is equal to '\xBB' (187),
element #376 is equal to '\xBC' (188),
element #377 is equal to '\xBC' (188),
element #378 is equal to '\xBD' (189),
element #379 is equal to '\xBD' (189),
element #380 is equal to '\xBE' (190),
element #381 is equal to '\xBE' (190),
element #382 is equal to '\xBF' (191),
element #383 is equal to '\xBF' (191),
element #384 is equal to '\xC0' (192),
element #385 is equal to '\xC0' (192),
element #386 is equal to '\xC1' (193),
element #387 is equal to '\xC1' (193),
element #388 is equal to '\xC2' (194),
element #389 is equal to '\xC2' (194),
element #390 is equal to '\xC3' (195),
element #391 is equal to '\xC3' (195),
element #392 is equal to '\xC4' (196),
element #393 is equal to '\xC4' (196),
element #394 is equal to '\xC5' (197),
element #395 is equal to '\xC5' (197),
element #396 is equal to '\xC6' (198),
element #397 is equal to '\xC6' (198),
element #398 is equal to '\xC7' (199),
element #399 is equal to '\xC7' (199),
element #400 is equal to '\xC8' (200),
element #401 is equal to '\xC8' (200),
element #402 is equal to '\xC9' (201),
element #403 is equal to '\xC9' (201),
element #404 is equal to '\xCA' (202),
element #405 is equal to '\xCA' (202),
element #406 is equal to '\xCB' (203),
element #407 is equal to '\xCB' (203),
element #408 is equal to '\xCC' (204),
element #409 is equal to '\xCC' (204),
element #410 is equal to '\xCD' (205),
element #411 is equal to '\xCD' (205),
element #412 is equal to '\xCE' (206),
element #413 is equal to '\xCE' (206),
element #414 is equal to '\xCF' (207),
element #415 is equal to '\xCF' (207),
element #416 is equal to '\xD0' (208),
element #417 is equal to '\xD0' (208),
element #418 is equal to '\xD1' (209),
element #419 is equal to '\xD1' (209),
element #420 is equal to '\xD2' (210),
element #421 is equal to '\xD2' (210),
element #422 is equal to '\xD3' (211),
element #423 is equal to '\xD3' (211),
element #424 is equal to '\xD4' (212),
element #425 is equal to '\xD4' (212),
element #426 is equal to '\xD5' (213),
element #427 is equal to '\xD5' (213),
element #428 is equal to '\xD6' (214),
element #429 is equal to '\xD6' (214),
element #430 is equal to '\xD7' (215),
element #431 is equal to '\xD7' (215),
element #432 is equal to '\xD8' (216),
element #433 is equal to '\xD8' (216),
element #434 is equal to '\xD9' (217),
element #435 is equal to '\xD9' (217),
element #436 is equal to '\xDA' (218),
element #437 is equal to '\xDA' (218),
element #438 is equal to '\xDB' (219),
element #439 is equal to '\xDB' (219),
element #440 is equal to '\xDC' (220),
element #441 is equal to '\xDC' (220),
element #442 is equal to '\xDD' (221),
element #443 is equal to '\xDD' (221),
element #444 is equal to '\xDE' (222),
element #445 is equal to '\xDE' (222),
element #446 is equal to '\xDF' (223),
element #447 is equal to '\xDF' (223),
element #448 is equal to '\xE0' (224),
element #449 is equal to '\xE0' (224),
element #450 is equal to '\xE1' (225),
element #451 is equal to '\xE1' (225),
element #452 is equal to '\xE2' (226),
element #453 is equal to '\xE2' (226),
element #454 is equal to '\xE3' (227),
element #455 is equal to '\xE3' (227),
element #456 is equal to '\xE4' (228),
element #457 is equal to '\xE4' (228),
element #458 is equal to '\xE5' (229),
element #459 is equal to '\xE5' (229),
element #460 is equal to '\xE6' (230),
element #461 is equal to '\xE6' (230),
element #462 is equal to '\xE7' (231),
element #463 is equal to '\xE7' (231),
element #464 is equal to '\xE8' (232),
element #465 is equal to '\xE8' (232),
element #466 is equal to '\xE9' (233),
element #467 is equal to '\xE9' (233),
element #468 is equal to '\xEA' (234),
element #469 is equal to '\xEA' (234),
element #470 is equal to '\xEB' (235),
element #471 is equal to '\xEB' (235),
element #472 is equal to '\xEC' (236),
element #473 is equal to '\xEC' (236),
element #474 is equal to '\xED' (237),
element #475 is equal to '\xED' (237),
element #476 is equal to '\xEE' (238),
element #477 is equal to '\xEE' (238),
element #478 is equal to '\xEF' (239),
element #479 is equal to '\xEF' (239),
element #480 is equal to '\xF0' (240),
element #481 is equal to '\xF0' (240),
element #482 is equal to '\xF1' (241),
element #483 is equal to '\xF1' (241),
element #484 is equal to '\xF2' (242),
element #485 is equal to '\xF2' (242),
element #486 is equal to '\xF3' (243),
element #487 is equal to '\xF3' (243),
element #488 is equal to '\xF4' (244),
element #489 is equal to '\xF4' (244),
element #490 is equal to '\xF5' (245),
element #491 is equal to '\xF5' (245),
element #492 is equal to '\xF6' (246),
element #493 is equal to '\xF6' (246),
element #494 is equal to '\xF7' (247),
element #495 is equal to '\xF7' (247),
element #496 is equal to '\xF8' (248),
element #497 is equal to '\xF8' (248),
element #498 is equal to '\xF9' (249),
element #499 is equal to '\xF9' (249),
element #500 is equal to '\xFA' (250),
element #501 is equal to '\xFA' (250),
element #502 is equal to '\xFB' (251),
element #503 is equal to '\xFB' (251),
element #504 is equal to '\xFC' (252),
element #505 is equal to '\xFC' (252),
element #506 is equal to '\xFD' (253),
element #507 is equal to '\xFD' (253),
element #508 is equal to '\xFE' (254),
element #509 is equal to '\xFE' (254),
element #510 is equal to '\xFF' (255),
element #511 is equal to '\xFF' (255)
  Actual: { '\0', '\0', '\x1' (1), '\x1' (1), '\x2' (2), '\x2' (2), '\x3' (3), '\x3' (3), '\x4' (4), '\x4' (4), '\x5' (5), '\x5' (5), '\x6' (6), '\x6' (6), '\a' (7), '\a' (7), '\b' (8), '\b' (8), '\t' (9), '\t' (9), '\n' (10, 0xA), '\n' (10, 0xA), '\v' (11, 0xB), '\v' (11, 0xB), '\f' (12, 0xC), '\f' (12, 0xC), '\r' (13, 0xD), '\r' (13, 0xD), '\xE' (14), '\xE' (14), '\xF' (15), '\xF' (15), ... }, whose element #130 doesn't match

And using my own small routine to print the results:

  for (int i = 0; i < cvt.len_cvt; i++) {                                                             
    int observed_value = cvt.buf[i];
    int expected_value = i/2;
    if (observed_value != expected_value) {                                                           
      std::cout << "[i=" << i << "]: " << observed_value << " != " << expected_value << std::endl;    
    }
  }

I’m getting:

[i=130]: 64 != 65
[i=131]: 64 != 65
[i=132]: 65 != 66
[i=133]: 65 != 66
[i=134]: 66 != 67
[i=135]: 66 != 67
[i=136]: 67 != 68
[i=137]: 67 != 68
[i=138]: 68 != 69
[i=139]: 68 != 69
[i=140]: 69 != 70
[i=141]: 69 != 70
[i=142]: 70 != 71
[i=143]: 70 != 71
[i=144]: 71 != 72
[i=145]: 71 != 72
[i=146]: 72 != 73
[i=147]: 72 != 73
[i=148]: 73 != 74
[i=149]: 73 != 74
[i=150]: 74 != 75
[i=151]: 74 != 75
[i=152]: 75 != 76
[i=153]: 75 != 76
[i=154]: 76 != 77
[i=155]: 76 != 77
[i=156]: 77 != 78
[i=157]: 77 != 78
[i=158]: 78 != 79
[i=159]: 78 != 79
[i=160]: 79 != 80
[i=161]: 79 != 80
[i=162]: 80 != 81
[i=163]: 80 != 81
[i=164]: 81 != 82
[i=165]: 81 != 82
[i=166]: 82 != 83
[i=167]: 82 != 83
[i=168]: 83 != 84
[i=169]: 83 != 84
[i=170]: 84 != 85
[i=171]: 84 != 85
[i=172]: 85 != 86
[i=173]: 85 != 86
[i=174]: 86 != 87
[i=175]: 86 != 87
[i=176]: 87 != 88
[i=177]: 87 != 88
[i=178]: 88 != 89
[i=179]: 88 != 89
[i=180]: 89 != 90
[i=181]: 89 != 90
[i=182]: 90 != 91
[i=183]: 90 != 91
[i=184]: 91 != 92
[i=185]: 91 != 92
[i=186]: 92 != 93
[i=187]: 92 != 93
[i=188]: 93 != 94
[i=189]: 93 != 94
[i=190]: 94 != 95
[i=191]: 94 != 95
[i=192]: 95 != 96
[i=193]: 95 != 96
[i=194]: 96 != 97
[i=195]: 96 != 97
[i=196]: 97 != 98
[i=197]: 97 != 98
[i=198]: 98 != 99
[i=199]: 98 != 99
[i=200]: 99 != 100
[i=201]: 99 != 100
[i=202]: 100 != 101
[i=203]: 100 != 101
[i=204]: 101 != 102
[i=205]: 101 != 102
[i=206]: 102 != 103
[i=207]: 102 != 103
[i=208]: 103 != 104
[i=209]: 103 != 104
[i=210]: 104 != 105
[i=211]: 104 != 105
[i=212]: 105 != 106
[i=213]: 105 != 106
[i=214]: 106 != 107
[i=215]: 106 != 107
[i=216]: 107 != 108
[i=217]: 107 != 108
[i=218]: 108 != 109
[i=219]: 108 != 109
[i=220]: 109 != 110
[i=221]: 109 != 110
[i=222]: 110 != 111
[i=223]: 110 != 111
[i=224]: 111 != 112
[i=225]: 111 != 112
[i=226]: 112 != 113
[i=227]: 112 != 113
[i=228]: 113 != 114
[i=229]: 113 != 114
[i=230]: 114 != 115
[i=231]: 114 != 115
[i=232]: 115 != 116
[i=233]: 115 != 116
[i=234]: 116 != 117
[i=235]: 116 != 117
[i=236]: 117 != 118
[i=237]: 117 != 118
[i=238]: 118 != 119
[i=239]: 118 != 119
[i=240]: 119 != 120
[i=241]: 119 != 120
[i=242]: 120 != 121
[i=243]: 120 != 121
[i=244]: 121 != 122
[i=245]: 121 != 122
[i=246]: 122 != 123
[i=247]: 122 != 123
[i=248]: 123 != 124
[i=249]: 123 != 124
[i=250]: 124 != 125
[i=251]: 124 != 125
[i=252]: 125 != 126
[i=253]: 125 != 126
[i=254]: 126 != 127
[i=255]: 126 != 127
[i=256]: 127 != 128
[i=257]: 127 != 128
[i=258]: 128 != 129
[i=259]: 128 != 129
[i=260]: 129 != 130
[i=261]: 129 != 130
[i=262]: 130 != 131
[i=263]: 130 != 131
[i=264]: 131 != 132
[i=265]: 131 != 132
[i=266]: 132 != 133
[i=267]: 132 != 133
[i=268]: 133 != 134
[i=269]: 133 != 134
[i=270]: 134 != 135
[i=271]: 134 != 135
[i=272]: 135 != 136
[i=273]: 135 != 136
[i=274]: 136 != 137
[i=275]: 136 != 137
[i=276]: 137 != 138
[i=277]: 137 != 138
[i=278]: 138 != 139
[i=279]: 138 != 139
[i=280]: 139 != 140
[i=281]: 139 != 140
[i=282]: 140 != 141
[i=283]: 140 != 141
[i=284]: 141 != 142
[i=285]: 141 != 142
[i=286]: 142 != 143
[i=287]: 142 != 143
[i=288]: 143 != 144
[i=289]: 143 != 144
[i=290]: 144 != 145
[i=291]: 144 != 145
[i=292]: 145 != 146
[i=293]: 145 != 146
[i=294]: 146 != 147
[i=295]: 146 != 147
[i=296]: 147 != 148
[i=297]: 147 != 148
[i=298]: 148 != 149
[i=299]: 148 != 149
[i=300]: 149 != 150
[i=301]: 149 != 150
[i=302]: 150 != 151
[i=303]: 150 != 151
[i=304]: 151 != 152
[i=305]: 151 != 152
[i=306]: 152 != 153
[i=307]: 152 != 153
[i=308]: 153 != 154
[i=309]: 153 != 154
[i=310]: 154 != 155
[i=311]: 154 != 155
[i=312]: 155 != 156
[i=313]: 155 != 156
[i=314]: 156 != 157
[i=315]: 156 != 157
[i=316]: 157 != 158
[i=317]: 157 != 158
[i=318]: 158 != 159
[i=319]: 158 != 159
[i=320]: 159 != 160
[i=321]: 159 != 160
[i=322]: 160 != 161
[i=323]: 160 != 161
[i=324]: 161 != 162
[i=325]: 161 != 162
[i=326]: 162 != 163
[i=327]: 162 != 163
[i=328]: 163 != 164
[i=329]: 163 != 164
[i=330]: 164 != 165
[i=331]: 164 != 165
[i=332]: 165 != 166
[i=333]: 165 != 166
[i=334]: 166 != 167
[i=335]: 166 != 167
[i=336]: 167 != 168
[i=337]: 167 != 168
[i=338]: 168 != 169
[i=339]: 168 != 169
[i=340]: 169 != 170
[i=341]: 169 != 170
[i=342]: 170 != 171
[i=343]: 170 != 171
[i=344]: 171 != 172
[i=345]: 171 != 172
[i=346]: 172 != 173
[i=347]: 172 != 173
[i=348]: 173 != 174
[i=349]: 173 != 174
[i=350]: 174 != 175
[i=351]: 174 != 175
[i=352]: 175 != 176
[i=353]: 175 != 176
[i=354]: 176 != 177
[i=355]: 176 != 177
[i=356]: 177 != 178
[i=357]: 177 != 178
[i=358]: 178 != 179
[i=359]: 178 != 179
[i=360]: 179 != 180
[i=361]: 179 != 180
[i=362]: 180 != 181
[i=363]: 180 != 181
[i=364]: 181 != 182
[i=365]: 181 != 182
[i=366]: 182 != 183
[i=367]: 182 != 183
[i=368]: 183 != 184
[i=369]: 183 != 184
[i=370]: 184 != 185
[i=371]: 184 != 185
[i=372]: 185 != 186
[i=373]: 185 != 186
[i=374]: 186 != 187
[i=375]: 186 != 187
[i=376]: 187 != 188
[i=377]: 187 != 188
[i=378]: 188 != 189
[i=379]: 188 != 189
[i=380]: 189 != 190
[i=381]: 189 != 190
[i=382]: 190 != 191
[i=383]: 190 != 191
[i=384]: 190 != 192
[i=385]: 190 != 192
[i=386]: 191 != 193
[i=387]: 191 != 193
[i=388]: 192 != 194
[i=389]: 192 != 194
[i=390]: 193 != 195
[i=391]: 193 != 195
[i=392]: 194 != 196
[i=393]: 194 != 196
[i=394]: 195 != 197
[i=395]: 195 != 197
[i=396]: 196 != 198
[i=397]: 196 != 198
[i=398]: 197 != 199
[i=399]: 197 != 199
[i=400]: 198 != 200
[i=401]: 198 != 200
[i=402]: 199 != 201
[i=403]: 199 != 201
[i=404]: 200 != 202
[i=405]: 200 != 202
[i=406]: 201 != 203
[i=407]: 201 != 203
[i=408]: 202 != 204
[i=409]: 202 != 204
[i=410]: 203 != 205
[i=411]: 203 != 205
[i=412]: 204 != 206
[i=413]: 204 != 206
[i=414]: 205 != 207
[i=415]: 205 != 207
[i=416]: 206 != 208
[i=417]: 206 != 208
[i=418]: 207 != 209
[i=419]: 207 != 209
[i=420]: 208 != 210
[i=421]: 208 != 210
[i=422]: 209 != 211
[i=423]: 209 != 211
[i=424]: 210 != 212
[i=425]: 210 != 212
[i=426]: 211 != 213
[i=427]: 211 != 213
[i=428]: 212 != 214
[i=429]: 212 != 214
[i=430]: 213 != 215
[i=431]: 213 != 215
[i=432]: 214 != 216
[i=433]: 214 != 216
[i=434]: 215 != 217
[i=435]: 215 != 217
[i=436]: 216 != 218
[i=437]: 216 != 218
[i=438]: 217 != 219
[i=439]: 217 != 219
[i=440]: 218 != 220
[i=441]: 218 != 220
[i=442]: 219 != 221
[i=443]: 219 != 221
[i=444]: 220 != 222
[i=445]: 220 != 222
[i=446]: 221 != 223
[i=447]: 221 != 223
[i=448]: 222 != 224
[i=449]: 222 != 224
[i=450]: 223 != 225
[i=451]: 223 != 225
[i=452]: 224 != 226
[i=453]: 224 != 226
[i=454]: 225 != 227
[i=455]: 225 != 227
[i=456]: 226 != 228
[i=457]: 226 != 228
[i=458]: 227 != 229
[i=459]: 227 != 229
[i=460]: 228 != 230
[i=461]: 228 != 230
[i=462]: 229 != 231
[i=463]: 229 != 231
[i=464]: 230 != 232
[i=465]: 230 != 232
[i=466]: 231 != 233
[i=467]: 231 != 233
[i=468]: 232 != 234
[i=469]: 232 != 234
[i=470]: 233 != 235
[i=471]: 233 != 235
[i=472]: 234 != 236
[i=473]: 234 != 236
[i=474]: 235 != 237
[i=475]: 235 != 237
[i=476]: 236 != 238
[i=477]: 236 != 238
[i=478]: 237 != 239
[i=479]: 237 != 239
[i=480]: 238 != 240
[i=481]: 238 != 240
[i=482]: 239 != 241
[i=483]: 239 != 241
[i=484]: 240 != 242
[i=485]: 240 != 242
[i=486]: 241 != 243
[i=487]: 241 != 243
[i=488]: 242 != 244
[i=489]: 242 != 244
[i=490]: 243 != 245
[i=491]: 243 != 245
[i=492]: 244 != 246
[i=493]: 244 != 246
[i=494]: 245 != 247
[i=495]: 245 != 247
[i=496]: 246 != 248
[i=497]: 246 != 248
[i=498]: 247 != 249
[i=499]: 247 != 249
[i=500]: 248 != 250
[i=501]: 248 != 250
[i=502]: 249 != 251
[i=503]: 249 != 251
[i=504]: 250 != 252
[i=505]: 250 != 252
[i=506]: 251 != 253
[i=507]: 251 != 253
[i=508]: 252 != 254
[i=509]: 252 != 254
[i=510]: 253 != 255
[i=511]: 253 != 255

Is this expected?

icculus · January 17, 2024, 1:34am

This was fixed in SDL2’s revision control today, by backporting some improved code from SDL3.