| /* |
| * Copyright (C) 2013 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| //#define LOG_NDEBUG 0 |
| #define LOG_TAG "CharacterEncodingDector" |
| #include <utils/Log.h> |
| |
| #include <media/CharacterEncodingDetector.h> |
| #include "CharacterEncodingDetectorTables.h" |
| |
| #include <utils/Vector.h> |
| #include <media/StringArray.h> |
| |
| #include <unicode/ucnv.h> |
| #include <unicode/ucsdet.h> |
| #include <unicode/ustring.h> |
| |
| namespace android { |
| |
| CharacterEncodingDetector::CharacterEncodingDetector() { |
| |
| UErrorCode status = U_ZERO_ERROR; |
| mUtf8Conv = ucnv_open("UTF-8", &status); |
| if (U_FAILURE(status)) { |
| ALOGE("could not create UConverter for UTF-8"); |
| mUtf8Conv = NULL; |
| } |
| } |
| |
| CharacterEncodingDetector::~CharacterEncodingDetector() { |
| ucnv_close(mUtf8Conv); |
| } |
| |
| void CharacterEncodingDetector::addTag(const char *name, const char *value) { |
| mNames.push_back(name); |
| mValues.push_back(value); |
| } |
| |
| size_t CharacterEncodingDetector::size() { |
| return mNames.size(); |
| } |
| |
| status_t CharacterEncodingDetector::getTag(int index, const char **name, const char**value) { |
| if (index >= mNames.size()) { |
| return BAD_VALUE; |
| } |
| |
| *name = mNames.getEntry(index); |
| *value = mValues.getEntry(index); |
| return OK; |
| } |
| |
| static bool isPrintableAscii(const char *value, size_t len) { |
| for (size_t i = 0; i < len; i++) { |
| if ((value[i] & 0x80) || value[i] < 0x20 || value[i] == 0x7f) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| void CharacterEncodingDetector::detectAndConvert() { |
| |
| int size = mNames.size(); |
| ALOGV("%d tags before conversion", size); |
| for (int i = 0; i < size; i++) { |
| ALOGV("%s: %s", mNames.getEntry(i), mValues.getEntry(i)); |
| } |
| |
| if (size && mUtf8Conv) { |
| |
| UErrorCode status = U_ZERO_ERROR; |
| UCharsetDetector *csd = ucsdet_open(&status); |
| const UCharsetMatch *ucm; |
| bool goodmatch = true; |
| int highest = 0; |
| |
| // try combined detection of artist/album/title etc. |
| char buf[1024]; |
| buf[0] = 0; |
| bool allprintable = true; |
| for (int i = 0; i < size; i++) { |
| const char *name = mNames.getEntry(i); |
| const char *value = mValues.getEntry(i); |
| if (!isPrintableAscii(value, strlen(value)) && ( |
| !strcmp(name, "artist") || |
| !strcmp(name, "albumartist") || |
| !strcmp(name, "composer") || |
| !strcmp(name, "genre") || |
| !strcmp(name, "album") || |
| !strcmp(name, "title"))) { |
| strlcat(buf, value, sizeof(buf)); |
| // separate tags by space so ICU's ngram detector can do its job |
| strlcat(buf, " ", sizeof(buf)); |
| allprintable = false; |
| } |
| } |
| |
| const char *combinedenc = "UTF-8"; |
| if (allprintable) { |
| // since 'buf' is empty, ICU would return a UTF-8 matcher with low confidence, so |
| // no need to even call it |
| ALOGV("all tags are printable, assuming ascii (%zu)", strlen(buf)); |
| } else { |
| ucsdet_setText(csd, buf, strlen(buf), &status); |
| int32_t matches; |
| const UCharsetMatch** ucma = ucsdet_detectAll(csd, &matches, &status); |
| const UCharsetMatch* bestCombinedMatch = getPreferred(buf, strlen(buf), |
| ucma, matches, &goodmatch, &highest); |
| |
| ALOGV("goodmatch: %s, highest: %d", goodmatch ? "true" : "false", highest); |
| if (!goodmatch && (highest < 15 || strlen(buf) < 20)) { |
| ALOGV("not a good match, trying with more data"); |
| // This string might be too short for ICU to do anything useful with. |
| // (real world example: "Björk" in ISO-8859-1 might be detected as GB18030, because |
| // the ISO detector reports a confidence of 0, while the GB18030 detector reports |
| // a confidence of 10 with no invalid characters) |
| // Append artist, album and title if they were previously omitted because they |
| // were printable ascii. |
| bool added = false; |
| for (int i = 0; i < size; i++) { |
| const char *name = mNames.getEntry(i); |
| const char *value = mValues.getEntry(i); |
| if (isPrintableAscii(value, strlen(value)) && ( |
| !strcmp(name, "artist") || |
| !strcmp(name, "album") || |
| !strcmp(name, "title"))) { |
| strlcat(buf, value, sizeof(buf)); |
| strlcat(buf, " ", sizeof(buf)); |
| added = true; |
| } |
| } |
| if (added) { |
| ucsdet_setText(csd, buf, strlen(buf), &status); |
| ucma = ucsdet_detectAll(csd, &matches, &status); |
| bestCombinedMatch = getPreferred(buf, strlen(buf), |
| ucma, matches, &goodmatch, &highest); |
| if (!goodmatch && highest <= 15) { |
| ALOGV("still not a good match after adding printable tags"); |
| bestCombinedMatch = NULL; |
| } |
| } else { |
| ALOGV("no printable tags to add"); |
| } |
| } |
| |
| if (bestCombinedMatch != NULL) { |
| combinedenc = ucsdet_getName(bestCombinedMatch, &status); |
| } else { |
| combinedenc = "ISO-8859-1"; |
| } |
| } |
| |
| for (int i = 0; i < size; i++) { |
| const char *name = mNames.getEntry(i); |
| uint8_t* src = (uint8_t *)mValues.getEntry(i); |
| int len = strlen((char *)src); |
| |
| ALOGV("@@@ checking %s", name); |
| const char *s = mValues.getEntry(i); |
| int32_t inputLength = strlen(s); |
| const char *enc; |
| |
| if (!allprintable && (!strcmp(name, "artist") || |
| !strcmp(name, "albumartist") || |
| !strcmp(name, "composer") || |
| !strcmp(name, "genre") || |
| !strcmp(name, "album") || |
| !strcmp(name, "title"))) { |
| if (!goodmatch && highest < 0) { |
| // Give it one more chance if there is no good match. |
| ALOGV("Trying to detect %s separately", name); |
| int32_t matches; |
| bool goodmatchSingle = true; |
| int highestSingle = 0; |
| ucsdet_setText(csd, s, inputLength, &status); |
| const UCharsetMatch** ucma = ucsdet_detectAll(csd, &matches, &status); |
| const UCharsetMatch* bestSingleMatch = getPreferred(s, inputLength, |
| ucma, matches, &goodmatchSingle, &highestSingle); |
| if (goodmatchSingle || highestSingle > highest) |
| enc = ucsdet_getName(bestSingleMatch, &status); |
| else |
| enc = combinedenc; |
| } else { |
| // use encoding determined from the combination of artist/album/title etc. |
| enc = combinedenc; |
| } |
| } else { |
| if (isPrintableAscii(s, inputLength)) { |
| enc = "UTF-8"; |
| ALOGV("@@@@ %s is ascii", mNames.getEntry(i)); |
| } else { |
| ucsdet_setText(csd, s, inputLength, &status); |
| ucm = ucsdet_detect(csd, &status); |
| if (!ucm) { |
| mValues.setEntry(i, "???"); |
| continue; |
| } |
| enc = ucsdet_getName(ucm, &status); |
| ALOGV("@@@@ recognized charset: %s for %s confidence %d", |
| enc, mNames.getEntry(i), ucsdet_getConfidence(ucm, &status)); |
| } |
| } |
| |
| if (strcmp(enc,"UTF-8") != 0) { |
| // only convert if the source encoding isn't already UTF-8 |
| ALOGV("@@@ using converter %s for %s", enc, mNames.getEntry(i)); |
| status = U_ZERO_ERROR; |
| UConverter *conv = ucnv_open(enc, &status); |
| if (U_FAILURE(status)) { |
| ALOGW("could not create UConverter for %s (%d), falling back to ISO-8859-1", |
| enc, status); |
| status = U_ZERO_ERROR; |
| conv = ucnv_open("ISO-8859-1", &status); |
| if (U_FAILURE(status)) { |
| ALOGW("could not create UConverter for ISO-8859-1 either"); |
| continue; |
| } |
| } |
| |
| // convert from native encoding to UTF-8 |
| const char* source = mValues.getEntry(i); |
| int targetLength = len * 3 + 1; |
| char* buffer = new char[targetLength]; |
| // don't normally check for NULL, but in this case targetLength may be large |
| if (!buffer) |
| break; |
| char* target = buffer; |
| |
| ucnv_convertEx(mUtf8Conv, conv, &target, target + targetLength, |
| &source, source + strlen(source), |
| NULL, NULL, NULL, NULL, TRUE, TRUE, &status); |
| |
| if (U_FAILURE(status)) { |
| ALOGE("ucnv_convertEx failed: %d", status); |
| mValues.setEntry(i, "???"); |
| } else { |
| // zero terminate |
| *target = 0; |
| // strip trailing spaces |
| while (--target > buffer && *target == ' ') { |
| *target = 0; |
| } |
| // skip leading spaces |
| char *start = buffer; |
| while (*start == ' ') { |
| start++; |
| } |
| mValues.setEntry(i, start); |
| } |
| |
| delete[] buffer; |
| |
| ucnv_close(conv); |
| } |
| } |
| |
| for (int i = size - 1; i >= 0; --i) { |
| if (strlen(mValues.getEntry(i)) == 0) { |
| ALOGV("erasing %s because entry is empty", mNames.getEntry(i)); |
| mNames.erase(i); |
| mValues.erase(i); |
| } |
| } |
| |
| ucsdet_close(csd); |
| } |
| } |
| |
| /* |
| * When ICU detects multiple encoding matches, apply additional heuristics to determine |
| * which one is the best match, since ICU can't always be trusted to make the right choice. |
| * |
| * What this method does is: |
| * - decode the input using each of the matches found |
| * - recalculate the starting confidence level for multibyte encodings using a different |
| * algorithm and larger frequent character lists than ICU |
| * - devalue encoding where the conversion contains unlikely characters (symbols, reserved, etc) |
| * - pick the highest match |
| * - signal to the caller whether this match is considered good: confidence > 15, and confidence |
| * delta with the next runner up > 15 |
| */ |
| const UCharsetMatch *CharacterEncodingDetector::getPreferred( |
| const char *input, size_t len, |
| const UCharsetMatch** ucma, size_t nummatches, |
| bool *goodmatch, int *highestmatch) { |
| |
| *goodmatch = false; |
| Vector<const UCharsetMatch*> matches; |
| UErrorCode status = U_ZERO_ERROR; |
| |
| ALOGV("%zu matches", nummatches); |
| for (size_t i = 0; i < nummatches; i++) { |
| const char *encname = ucsdet_getName(ucma[i], &status); |
| int confidence = ucsdet_getConfidence(ucma[i], &status); |
| ALOGV("%zu: %s %d", i, encname, confidence); |
| matches.push_back(ucma[i]); |
| } |
| |
| size_t num = matches.size(); |
| if (num == 0) { |
| return NULL; |
| } |
| if (num == 1) { |
| int confidence = ucsdet_getConfidence(matches[0], &status); |
| if (confidence > 15) { |
| *goodmatch = true; |
| } |
| return matches[0]; |
| } |
| |
| ALOGV("considering %zu matches", num); |
| |
| // keep track of how many "special" characters result when converting the input using each |
| // encoding |
| Vector<int> newconfidence; |
| for (size_t i = 0; i < num; i++) { |
| const uint16_t *freqdata = NULL; |
| float freqcoverage = 0; |
| status = U_ZERO_ERROR; |
| const char *encname = ucsdet_getName(matches[i], &status); |
| int confidence = ucsdet_getConfidence(matches[i], &status); |
| if (!strcmp("GB18030", encname)) { |
| freqdata = frequent_zhCN; |
| freqcoverage = frequent_zhCN_coverage; |
| } else if (!strcmp("Big5", encname)) { |
| freqdata = frequent_zhTW; |
| freqcoverage = frequent_zhTW_coverage; |
| } else if (!strcmp("EUC-KR", encname)) { |
| freqdata = frequent_ko; |
| freqcoverage = frequent_ko_coverage; |
| } else if (!strcmp("EUC-JP", encname)) { |
| freqdata = frequent_ja; |
| freqcoverage = frequent_ja_coverage; |
| } else if (!strcmp("Shift_JIS", encname)) { |
| freqdata = frequent_ja; |
| freqcoverage = frequent_ja_coverage; |
| } |
| |
| ALOGV("%zu: %s %d", i, encname, confidence); |
| status = U_ZERO_ERROR; |
| UConverter *conv = ucnv_open(encname, &status); |
| int demerit = 0; |
| if (U_FAILURE(status)) { |
| ALOGV("failed to open %s: %d", encname, status); |
| confidence = 0; |
| demerit += 1000; |
| } |
| const char *source = input; |
| const char *sourceLimit = input + len; |
| status = U_ZERO_ERROR; |
| int frequentchars = 0; |
| int totalchars = 0; |
| while (true) { |
| // demerit the current encoding for each "special" character found after conversion. |
| // The amount of demerit is somewhat arbitrarily chosen. |
| int inchar; |
| if (source != sourceLimit) { |
| inchar = (source[0] << 8) + source[1]; |
| } |
| UChar32 c = ucnv_getNextUChar(conv, &source, sourceLimit, &status); |
| if (!U_SUCCESS(status)) { |
| break; |
| } |
| if (c < 0x20 || (c >= 0x7f && c <= 0x009f)) { |
| ALOGV("control character %x", c); |
| demerit += 100; |
| } else if ((c == 0xa0) // no-break space |
| || (c >= 0xa2 && c <= 0xbe) // symbols, superscripts |
| || (c == 0xd7) || (c == 0xf7) // multiplication and division signs |
| || (c >= 0x2000 && c <= 0x209f)) { // punctuation, superscripts |
| ALOGV("unlikely character %x", c); |
| demerit += 10; |
| } else if (c >= 0xe000 && c <= 0xf8ff) { |
| ALOGV("private use character %x", c); |
| demerit += 30; |
| } else if (c >= 0x2190 && c <= 0x2bff) { |
| // this range comprises various symbol ranges that are unlikely to appear in |
| // music file metadata. |
| ALOGV("symbol %x", c); |
| demerit += 10; |
| } else if (c == 0xfffd) { |
| ALOGV("replacement character"); |
| demerit += 50; |
| } else if (c >= 0xfff0 && c <= 0xfffc) { |
| ALOGV("unicode special %x", c); |
| demerit += 50; |
| } else if (freqdata != NULL) { |
| totalchars++; |
| if (isFrequent(freqdata, c)) { |
| frequentchars++; |
| } |
| } |
| } |
| if (freqdata != NULL && totalchars != 0) { |
| int myconfidence = 10 + float((100 * frequentchars) / totalchars) / freqcoverage; |
| ALOGV("ICU confidence: %d, my confidence: %d (%d %d)", confidence, myconfidence, |
| totalchars, frequentchars); |
| if (myconfidence > 100) myconfidence = 100; |
| if (myconfidence < 0) myconfidence = 0; |
| confidence = myconfidence; |
| } |
| ALOGV("%d-%d=%d", confidence, demerit, confidence - demerit); |
| newconfidence.push_back(confidence - demerit); |
| ucnv_close(conv); |
| if (i == 0 && (confidence - demerit) == 100) { |
| // no need to check any further, we'll end up using this match anyway |
| break; |
| } |
| } |
| |
| // find match with highest confidence after adjusting for unlikely characters |
| int highest = newconfidence[0]; |
| size_t highestidx = 0; |
| int runnerup = -10000; |
| int runnerupidx = -10000; |
| num = newconfidence.size(); |
| for (size_t i = 1; i < num; i++) { |
| if (newconfidence[i] > highest) { |
| runnerup = highest; |
| runnerupidx = highestidx; |
| highest = newconfidence[i]; |
| highestidx = i; |
| } else if (newconfidence[i] > runnerup){ |
| runnerup = newconfidence[i]; |
| runnerupidx = i; |
| } |
| } |
| status = U_ZERO_ERROR; |
| ALOGV("selecting: '%s' w/ %d confidence", |
| ucsdet_getName(matches[highestidx], &status), highest); |
| if (runnerupidx < 0) { |
| ALOGV("no runner up"); |
| if (highest > 15) { |
| *goodmatch = true; |
| } |
| } else { |
| ALOGV("runner up: '%s' w/ %d confidence", |
| ucsdet_getName(matches[runnerupidx], &status), runnerup); |
| if (runnerup < 0) { |
| runnerup = 0; |
| } |
| if ((highest - runnerup) > 15) { |
| *goodmatch = true; |
| } |
| } |
| *highestmatch = highest; |
| return matches[highestidx]; |
| } |
| |
| |
| bool CharacterEncodingDetector::isFrequent(const uint16_t *values, uint32_t c) { |
| |
| int start = 0; |
| int end = 511; // All the tables have 512 entries |
| int mid = (start+end)/2; |
| |
| while(start <= end) { |
| if(c == values[mid]) { |
| return true; |
| } else if (c > values[mid]) { |
| start = mid + 1; |
| } else { |
| end = mid - 1; |
| } |
| |
| mid = (start + end) / 2; |
| } |
| |
| return false; |
| } |
| |
| |
| } // namespace android |
