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Improve HCA key detection for small/silent HCA [Dragalia Lost (iOS)]

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This commit is contained in:
bnnm 2018-12-22 19:44:30 +01:00
parent 1d97f9ad78
commit 87972f55eb
3 changed files with 39 additions and 19 deletions
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52
src/coding/hca_decoder.c
View File

@ -151,15 +151,22 @@ void free_hca(hca_codec_data * data) {
}
#define HCA_KEY_MAX_BLANK_FRAMES 15 /* ignored up to N blank frames (not uncommon to have ~10, if more something is off) */
#define HCA_KEY_MAX_TEST_FRAMES 10 /* 5~15 should be enough, but mostly silent or badly mastered files may need more */
#define HCA_KEY_MAX_ACCEPTABLE_SCORE 150 /* more is unlikely to work correctly, 10~30 isn't uncommon */
/* arbitrary scale to simplify score comparisons */
#define HCA_KEY_SCORE_SCALE 10
/* ignores beginning frames (~10 is not uncommon, Dragalia Lost vocal layers have lots) */
#define HCA_KEY_MAX_SKIP_BLANKS 400
/* 5~15 should be enough, but almost silent or badly mastered files may need tweaks */
#define HCA_KEY_MIN_TEST_FRAMES 5
#define HCA_KEY_MAX_TEST_FRAMES 10
/* score of 10~30 isn't uncommon in a single frame, too many frames over that is unlikely */
#define HCA_KEY_MAX_FRAME_SCORE 150
#define HCA_KEY_MAX_TOTAL_SCORE (HCA_KEY_MAX_TEST_FRAMES * 50*HCA_KEY_SCORE_SCALE)
/* Test a number of frames if key decrypts correctly.
* Returns score: <0: error/wrong, 0: unknown/silent file, >0: good (the closest to 1 the better). */
int test_hca_key(hca_codec_data * data, unsigned long long keycode) {
size_t test_frame = 0, current_frame = 0, blank_frames = 0;
int total_score = 0;
size_t test_frames = 0, current_frame = 0, blank_frames = 0;
int total_score = 0, found_regular_frame = 0;
const unsigned int blockSize = data->info.blockSize;
/* Due to the potentially large number of keys this must be tuned for speed.
@ -168,43 +175,56 @@ int test_hca_key(hca_codec_data * data, unsigned long long keycode) {
clHCA_SetKey(data->handle, keycode);
while (test_frame < HCA_KEY_MAX_TEST_FRAMES && current_frame < data->info.blockCount) {
/* Test up to N non-blank frames or until total frames. */
/* A final score of 0 (=silent) is only possible for short files with all blank frames */
while (test_frames < HCA_KEY_MAX_TEST_FRAMES && current_frame < data->info.blockCount) {
off_t offset = data->info.headerSize + current_frame * blockSize;
int score;
size_t bytes;
/* read frame */
/* read and test frame */
bytes = read_streamfile(data->data_buffer, offset, blockSize, data->streamfile);
if (bytes != blockSize) {
total_score = -1;
break;
}
/* test frame */
score = clHCA_TestBlock(data->handle, (void*)(data->data_buffer), blockSize);
if (score < 0) {
if (score < 0 || score > HCA_KEY_MAX_FRAME_SCORE) {
total_score = -1;
break;
}
current_frame++;
/* skip blank block at the beginning */
if (score == 0 && blank_frames < HCA_KEY_MAX_BLANK_FRAMES) {
/* ignore silent frames at the beginning, up to a point */
if (score == 0 && blank_frames < HCA_KEY_MAX_SKIP_BLANKS && !found_regular_frame) {
blank_frames++;
continue;
}
test_frame++;
found_regular_frame = 1;
test_frames++;
/* scale values to make scores of perfect frames more detectable */
switch(score) {
case 1: score = 1; break;
case 0: score = 3*HCA_KEY_SCORE_SCALE; break; /* blanks after non-blacks aren't very trustable */
default: score = score*HCA_KEY_SCORE_SCALE;
}
total_score += score;
/* too far, don't bother checking more frames */
if (total_score > HCA_KEY_MAX_ACCEPTABLE_SCORE)
/* don't bother checking more frames, other keys will get better scores */
if (total_score > HCA_KEY_MAX_TOTAL_SCORE)
break;
}
//;VGM_LOG("HCA KEY: blanks=%i, tests=%i, score=%i\n", blank_frames, test_frames, total_score);
/* signal best possible score */
if (total_score > 0 && total_score <= HCA_KEY_MAX_TEST_FRAMES) {
/* signal best possible score (many perfect frames and few blank frames) */
if (test_frames > HCA_KEY_MIN_TEST_FRAMES && total_score > 0 && total_score <= test_frames) {
total_score = 1;
}

4
src/meta/hca.c
View File

@ -88,8 +88,8 @@ static inline void test_key(hca_codec_data * hca_data, uint64_t key, uint16_t su
if (score < 0)
return;
/* score 0 is not trustable, update too if something better is found */
if (*best_score < 0 || (score < *best_score && score > 0) || (*best_score == 0 && score == 1)) {
/* update if something better is found */
if (*best_score <= 0 || (score < *best_score && score > 0)) {
*best_score = score;
*best_keycode = key;
}

2
src/meta/hca_keys.h
View File

@ -228,7 +228,7 @@ static const hcakey_info hcakey_list[] = {
// Taga Tame no Alchemist (iOS/Android)
{5047159794308}, // 00000497222AAA84
// Shin Tennis no Ouji-sama: Rising Beat (iOS/Android)
// Shin Tennis no Ouji-sama: Rising Beat (iOS/Android) voices?
{4902201417679}, // 0000047561F95FCF
// Kai-ri-Sei Million Arthur (Vita)